Applications & Pathways
Promotion Effect of Hydrogen Addition in Selective Catalytic Reduction of Nitrogen Oxide Emissions from Diesel Engines Fuelled with Diesel-biodiesel-ethanol Blends
Nov 2021
Publication
Ethanol and palm oil biodiesel blended with diesel fuel have the potential to reduce greenhouse gas emissions such as carbon dioxide (CO2) and can gradually decrease dependence on fossil fuels. However the combustion products from these fuels such as oxides of nitrogen (NOx) total hydrocarbons (THC) and particulate matter (PM) require to be examined and any beneficial or detrimental effect to the environment needs to be assessed. This study investigates the hydrocarbon selective catalyst reduction (HC-SCR) activities by the effect of combustion using renewable fuels (biodiesel-ethanol-diesel) blends and the effect of hydrogen addition to the catalyst with the various diesel engine operating conditions. Lower values rate of heat released were recorded as the ethanol fraction increases resulting in trade-off where lower NOx was produced while greater concentration of carbon monoxide (CO) and THC was measured in the exhaust. Consequently increasing the THC/NOx promoting the NOx reduction activity (up to 43%). Additionally the HC-SCR performance was greatly heightened when hydrogen was added into the catalyst and able to improve the NOx reduction activity up to 73%. The experiment demonstrated plausible alternatives to improve the HC-SCR performance through the aids from fuel blends and hydrogen addition.
Australian Hydrogen Hubs Study
Nov 2019
Publication
Arup have conducted interviews with targeted industry and government stakeholders to gather data and perspectives to support the development of this study. Arup have also utilised private and publicly available data sources building on recent work undertaken by Geoscience Australia and Deloitte and the comprehensive stakeholder engagement process to inform our research. This study considers the supply chain and infrastructure requirements to support the development of export and domestic hubs. The study aims to provide a succinct “Hydrogen Hubs” report for presentation to the hydrogen working group.
The hydrogen supply chain infrastructure required to produce hydrogen for export and domestic hubs was identified along with feedback from the stakeholder engagement process. These infrastructure requirements can be used to determine the factors for assessing export and domestic hub opportunities. Hydrogen production pathways transportation mechanisms and uses were also further evaluated to identify how hubs can be used to balance supply and demand of hydrogen.
A preliminary list of current or anticipated locations has been developed through desktop research Arup project knowledge and the stakeholder consultation process. Over 30 potential hydrogen export locations have been identified in Australia through desktop research and the stakeholder survey and consultation process. In addition to establishing export hubs the creation of domestic demand hubs will be essential to the development of an Australian hydrogen economy. It is for this reason that a list of criteria has been developed for stakeholders to consider in the siting and design of hydrogen hubs. The key considerations explored are based on demand supply chain infrastructure and investment and policy areas.
Based on these considerations a list of criteria were developed to assess the viability of export and domestic hydrogen hubs. Criteria relevant to assessing the suitability of export and domestic hubs include:
A framework that includes the assessment criteria has been developed to aid decision making rather than recommending specific locations that would be most appropriate for a hub. This is because there are so many dynamic factors that go into selecting a location of a hydrogen hub that it is not appropriate to be overly prescriptive or prevent stakeholders from selecting the best location themselves or from the market making decisions based on its own research and knowledge. The developed framework rather provides information and support to enable these decision-making processes.
The hydrogen supply chain infrastructure required to produce hydrogen for export and domestic hubs was identified along with feedback from the stakeholder engagement process. These infrastructure requirements can be used to determine the factors for assessing export and domestic hub opportunities. Hydrogen production pathways transportation mechanisms and uses were also further evaluated to identify how hubs can be used to balance supply and demand of hydrogen.
A preliminary list of current or anticipated locations has been developed through desktop research Arup project knowledge and the stakeholder consultation process. Over 30 potential hydrogen export locations have been identified in Australia through desktop research and the stakeholder survey and consultation process. In addition to establishing export hubs the creation of domestic demand hubs will be essential to the development of an Australian hydrogen economy. It is for this reason that a list of criteria has been developed for stakeholders to consider in the siting and design of hydrogen hubs. The key considerations explored are based on demand supply chain infrastructure and investment and policy areas.
Based on these considerations a list of criteria were developed to assess the viability of export and domestic hydrogen hubs. Criteria relevant to assessing the suitability of export and domestic hubs include:
- Health and safety provisions;
- Environmental considerations;
- Economic and social considerations;
- Land availability with appropriate zoning and buffer distances & ownership (new terminals storage solar PV industries etc.);•
- Availability of gas pipeline infrastructure;
- Availability of electricity grid connectivity backup energy supply or co-location of renewables;
- Road & rail infrastructure (site access);
- Community and environmental concerns and weather. Social licence consideration;
- Berths (berthing depth ship storage loading facilities existing LNG and/or petroleum infrastructure etc.);
- Port potential (current capacity & occupancy expandability & scalability);
- Availability of or potential for skilled workers (construction & operation);
- Availability of or potential for water (recycled & desalinated);
- Opportunity for co-location with industrial ammonia production and future industrial opportunities;
- Interest (projects priority ports state development areas politics etc.);
- Shipping distance to target market (Japan & South Korea);
- Availability of demand-based infrastructure (i.e. refuelling stations).
A framework that includes the assessment criteria has been developed to aid decision making rather than recommending specific locations that would be most appropriate for a hub. This is because there are so many dynamic factors that go into selecting a location of a hydrogen hub that it is not appropriate to be overly prescriptive or prevent stakeholders from selecting the best location themselves or from the market making decisions based on its own research and knowledge. The developed framework rather provides information and support to enable these decision-making processes.
The Social Dimensions of Moving Away From Gas Cookers and Hobs- Challenges and Opportunities in Transition to Low Carbon Cooking
May 2020
Publication
Heat is one of the UK’s largest energy-consuming and carbon-emitting sectors and potentially the most difficult to decarbonise. The UK’s Clean Growth Strategy identifies that heat decarbonisation in buildings and industry will likely involve shifting away from natural gas to alternative energy vectors like electricity and hydrogen. This will mean transition of existing cooking appliances away from natural gas resulting in social implications that require detailed analysis for optimal transition.
This report investigates the social dimensions of heat decarbonisation in cooking appliances specifically moving away from gas cookers and hobs. It presents a first step in tackling the following questions.
This report investigates the social dimensions of heat decarbonisation in cooking appliances specifically moving away from gas cookers and hobs. It presents a first step in tackling the following questions.
- How are current carbon-intensive cooking technologies part of existing cooking practices and broader social and material structures?
- What are the challenges and opportunities for cooking heat decarbonisation in terms of consumer acceptance carbon and energy reductions and business/market opportunities?
- What interventions are needed to realise policy objectives of heat de-carbonisation?
- The report builds on interviews with BEIS’s long-term heat strategy experts and key external stakeholders together with a review of secondary data on trends in cooking and appliance use in the UK. Further it presents an annotated bibliography of literature on the social implications of heat decarbonisation and sustainable food transitions more broadly. The multidisciplinary review of the literature is structured around Southerton et al.’s (2011) ISM (Individual- Social- and Material-context) framework for a systemic review of the various change-agents required for transition. Finally a comparative review of the social challenges and opportunities identified in the ISM contexts is presented along with the potential policy interventions in each. The report concludes with a list of recommendations in terms of evidence and data gathering; research; policy; and a set of general recommendations for heat decarbonisation policy.
Strategies to Accelerate the Production and Diffusion of Fuel Cell Electric Vehicles: Experiences from California
Sep 2020
Publication
Fuel cell electric vehicles (FCEVs) can play a key role in accelerating the electrification of road transport. Specifically they offer longer driving ranges and shorter refuelling times relative to Battery Electric Vehicles (BEVs) while reducing needs for space-intensive public charging infrastructure. Although the maturity and market penetration of hydrogen is currently trailing batteries transport planners in several countries are looking to both technologies to reduce carbon emissions and air pollution. Home to the world’s largest on-road fleet of FCEVs California is one such jurisdiction. Experiences in California provide an ideal opportunity to address a gap in literature whereby barriers to FCEV diffusion are well understood but knowledge on actual strategies to overcome these has lacked. This study thus examines governance strategies in California to accelerate the production and diffusion of FCEVs key outcomes lessons learned and unresolved challenges. Evidence is sourced from 19 expert interviews and an examination of diverse documents. Strategies are examined from four perspectives: (i) supply-side (i.e. stimulation of vehicle production) (ii) infrastructure (i.e. construction of refuelling stations and hydrogen production) (iii) demand-side (i.e. stimulation of vehicle adoption) and (iv) institutional (i.e. cross-cutting measures to facilitate collaboration innovation and cost-reduction). Findings reveal a comprehensive mix of stringent regulation market and consumer incentives and public–private collaboration. However significant challenges remain for spurring the development of fuel cell transport in line with initial ambitions. Highlighting these provides important cues for public policy to accelerate the deployment of FCEVs and hydrogen in California and elsewhere.
Prediction of Hydrogen-Heavy Fuel Combustion Process with Water Addition in an Adapted Low Speed Two Stroke Diesel Engine: Performance Improvement
Jun 2021
Publication
Despite their high thermal efficiency (>50%) large two-stroke (2 T) diesel engines burning very cheap heavy fuel oil (HFO) produce a high level of carbon dioxide (CO2). To achieve the low emission levels of greenhouse gases (GHG) that will be imposed by future legislation the use of hydrogen (H2) as fuel in 2 T diesel engines is a viable option for reducing or almost eliminate CO2 emissions. In this work from experimental data and system modelling an analysis of dual combustion is carried out considering different strategies to supply H2 to the engine and for different H2 fractions in energy basis. Previously a complete thermodynamic model of a 2 T diesel engine with an innovative scavenging model is developed and validated. The most important drawbacks of this type of engines are controlled in this work using dual combustion and water injection reducing nitrogen oxides emissions (NOx) self-ignition and combustion knocking. The results show that the developed model matches engine performance data in diesel mode achieving a higher efficiency and mean effective pressure (MEP) in hydrogen mode of 53% and 14.62 bar respectively.
Constrained Extended Kalman Filter Design and Application for On-line State Estimation of High-order Polymer Electrolyte Membrane Fuel Cell Systems
Jun 2021
Publication
In this paper an alternative approach to extended Kalman filtering (EKF) for polymer electrolyte membrane fuel cell (FC) systems is proposed. The goal is to obtain robust real-time capable state estimations of a high-order FC model for observer applications mixed with control or fault detection. The introduced formulation resolves dependencies on operating conditions by successive linearization and constraints allowing to run the nonlinear FC model at significantly lower sampling rates than with standard approaches. The proposed method provides state estimates for challenging operating conditions such as shut-down and start-up of the fuel cell for which the unconstrained EKF fails. A detailed comparison with the unscented Kalman filter shows that the proposed EKF reconstructs the outputs equally accurate but nine times faster. An application to measured data from an FC powered passenger car is presented yielding state estimates of a real FC system which are validated based on the applied model.
Improving Carbon Efficiency and Profitability of the Biomass to Liquid Process with Hydrogen from Renewable Power
Aug 2018
Publication
A process where power and biomass are converted to Fischer-Tropsch liquid fuels (PBtL) is compared to a conventional Biomass-to-Liquid (BtL) process concept. Based on detailed process models it is demonstrated that the carbon efficiency of a conventional Biomass to Liquid process can be increased from 38 to more than 90% by adding hydrogen from renewable energy sources. This means that the amount of fuel can be increased by a factor of 2.4 with the same amount of biomass. Electrical power is applied to split water/steam at high temperature over solid oxide electrolysis cells (SOEC). This technology is selected because part of the required energy can be replaced by available heat. The required electrical power for the extra production is estimated to be 11.6 kWh per liter syncrude (C ) 5+ . By operating the SOEC iso-thermally close to 850 °C the electric energy may be reduced to 9.5 kWh per liter which is close to the energy density of jet fuel. A techno-economic analysis is performed where the total investments and operating costs are compared for the BtL and PBtL. With an electrical power price of 0.05 $/kWh and with SOEC investment cost of the 1000 $/kW(el) the levelized cost of producing advanced biofuel with the PBtL concept is 1.7 $/liter which is approximately 30% lower than for the conventional BtL. Converting excess renewable electric power to advanced biofuel in a PBtL plant is a sensible way of storing energy as a fuel with a relatively high energy density.
Photovoltaic and Hydrogen Plant Integrated with a Gas Heat Pump for Greenhouse Heating: A Mathematical Study
Feb 2018
Publication
Nowadays the traditional energy sources used for greenhouse heating are fossil fuels such as LPG diesel and natural gas. The global energy demand will continue to grow and alternative technologies need to be developed in order to improve the sustainability of crop production in protected environments. Innovative solutions are represented by renewable energy plants such as photovoltaic wind and geothermal integrated systems however these technologies need to be connected to the power grid in order to store the energy produced. On agricultural land power grids are not widespread and stand-alone renewable energy systems should be investigated especially for greenhouse applications. The aim of this research is to analyze by means of a mathematical model the energy efficiency of a photovoltaic (8.2 kW) hydrogen (2.5 kW) and ground source gas heat pump (2.2 kW) integrated in a stand-alone system used for heating an experimental greenhouse tunnel (48 m2 ) during the winter season. A yearlong energy performance analysis was conducted for three different types of greenhouse cover materials a single layer polyethylene film an air inflated-double layer polyethylene film and a double acrylic or polycarbonate. The results of one year showed that the integrated system had a total energy efficiency of 14.6%. Starting from the electric energy supplied by the photovoltaic array the total efficiency of the hydrogen and ground source gas heat pump system was 112% if the coefficient of the performance of the heat pump is equal to 5. The heating system increased the greenhouse air temperatures by 3–9 ◦C with respect to the external air temperatures depending on the greenhouse cover material used.
A Novel Integration of a Green Power-to-ammonia to Power System: Reversible Solid Oxide Fuel Cell for Hydrogen and Power Production Coupled with an Ammonia Synthesis Unit
Mar 2021
Publication
Renewable energy is a key solution in maintaining global warming below 2 °C. However its intermittency necessitates the need for energy conversion technologies to meet demand when there are insufficient renewable energy resources. This study aims to tackle these challenges by thermo-electrochemical modelling and simulation of a reversible solid oxide fuel cell (RSOFC) and integration with the Haber Bosch process. The novelty of the proposed system is usage of nitrogen-rich fuel electrode exhaust gas for ammonia synthesis during fuel cell mode which is usually combusted to prevent release of highly flammable hydrogen into the environment. RSOFC round-trip efficiencies of 41–53% have been attained when producing excess ammonia (144 kg NH3/hr) for the market and in-house consumption respectively. The designed system has the lowest reported ammonia electricity consumption of 6.4–8.21 kWh/kg NH3 power-to-hydrogen power-to-ammonia and power-generation efficiencies of 80% 55–71% and 64–66%.
Low Carbon Scenario Analysis of a Hydrogen-Based Energy Transition for On-Road Transportation in California
Nov 2021
Publication
Fuel cell electric vehicles (FCEV) are emerging as one of the prominent zero emission vehicle technologies. This study follows a deterministic modeling approach to project two scenarios of FCEV adoption and the resulting hydrogen demand (low and high) up to 2050 in California using a transportation transition model. The study then estimates the number of hydrogen production and refueling facilities required to meet demand. The impact of system scale-up and learning rates on hydrogen price is evaluated using standalone supply chain models: H2A HDSAM HRSAM and HDRSAM. A sensitivity analysis explores key factors that affect hydrogen prices. In the high scenario light and heavy-duty fuel cell vehicle stocks reach 12.5 million and 1 million by 2050 respectively. The resulting annual hydrogen demand is 3.9 billion kg making hydrogen the dominant transportation fuel. Satisfying such high future demands will require rapid increases in infrastructure investments starting now but especially after 2030 when there is an exponential increase in the number of production plants and refueling stations. In the long term electrolytic hydrogen delivered using dedicated hydrogen pipelines to larger stations offers substantial cost savings. Feedstock prices size of the hydrogen market and station utilization are the prominent parameters that affect hydrogen price.
Integrated Electricity, Hydrogen and Methane System Modelling Framework: Application to the Dutch Infrastructure Outlook 2050
Mar 2021
Publication
The future energy system is widely expected to show increasing levels of integration across differing energy carriers. Electricity hydrogen methane and heat systems may become increasingly interdependent due to coupling through conversion and hybrid energy technologies. Market parties network operators policy makers and regulators require tools to capture implications of possible techno-economic and institutional developments in one system for the operation of others. In this article we provide an integrated electricity hydrogen and methane systems modelling framework focusing on interdependencies between them. The proposed integrated electricity and (renewable) gas system model is a market equilibrium model with hourly price and volume interactions considering ramp rates of conventional units variability of intermittent renewables conversion transport as well as storage of electricity hydrogen and methane. The integrated model is formulated as a linear program under the assumption of perfect competition. As proof-of-concept the model has been applied to a test case consisting of 34 electricity nodes 19 hydrogen nodes and 22 methane nodes reflecting the regional governance scenario in the Dutch Infrastructure Outlook 2050 study. The case study also includes different sensitivity analyses with regard to variable renewable capacity energy demand and biomass prices to illustrate model response to perturbations of its main drivers. This article demonstrates that the interweaving of electricity hydrogen and methane systems can provide the required flexibility in the future energy system.
PEFC System Reactant Gas Supply Management and Anode Purging Strategy: An Experimental Approach
Jan 2022
Publication
In this report a 5 kW PEFC system running on dry hydrogen with an appropriately sized Balance of Plant (BoP) was used to conduct experimental studies and analyses of gas supply subsystems. The improper rating and use of BoP components has been found to increase parasitic loads which consequently has a direct effect on the polymer electrolyte fuel cell (PEFC) system efficiency. Therefore the minimisation of parasitic loads while maintaining desired performance is crucial. Nevertheless little has been found in the literature regarding experimental work on large stacks and BoP with the majority of papers concentrating on modelling. A particular interest of our study was the anode side of the fuel cell. Additionally the rationale behind the use of hydrogen anode recirculation was scrutinised and a novel anode purging strategy was developed and implemented. Through experimental modelling the use of cathode air blower was minimised since it was found to be the biggest contributor to the parasitic loads.
Publication Handbook for Hydrogen Fuelled Vessels
Jun 2021
Publication
Green hydrogen could play a crucial role in the maritime industry’s journey towards decarbonization. Produced through electrolysis hydrogen is emission free and could be widely available across the globe in future – as a marine fuel or a key enabler for synthetic fuels. Many in shipping recognize hydrogen’s potential as a fuel but the barriers to realizing this potential are substantial.<br/>The 1st Edition of the ‘Handbook for Hydrogen-fuelled Vessels’ offers a road map towards safe hydrogen operations using fuel cells. It details how to navigate the complex requirements for design and construction and it covers the most important aspects of hydrogen operations such as safety and risk mitigation engineering details for hydrogen systems and implementation phases for maritime applications based on the current regulatory Alternative Design process framework.<br/>This publication is the result of the 1st phase of the DNV-led Joint Industry Project MarHySafe which has brought together a consortium of 26 leading company and associations. The project is ongoing and this publication will be continually updated to reflect the latest industry expertise on hydrogen as ship fuel.
Replacing Fossil Fuels with Bioenergy in District Heating – Comparison of Technology Options
May 2021
Publication
We combine previously separate models of Northern European power markets local district heating and cooling (DHC2) systems and biomass supply in a single modelling framework to study local and system level impacts of bioenergy technologies in phasing out fossil fuels from a DHC system of the Finnish capital. We model multiple future scenarios and assess the impacts on energy security flexibility provision economic performance and emissions. In the case of Helsinki heat only boiler is a robust solution from economic and climate perspective but reduces local electricity self-sufficiency. Combined heat and power solution is more valuable investment for the system than for the city indicating a conflict of interest and biased results in system level models. Bringing a biorefinery near the city to utilize excess heat would reduce emissions and increase investment's profitability but biomass availability might be a bigger limiting factor. Our results show that the availability of domestic biomass resources constrains bio-based technologies in Southern Finland and further highlights the importance of considering both local and system level impacts. Novel option to boost biorefinery's production with hydrogen from excess electricity is beneficial with increasing shares of wind power.
Review on Blended Hydrogen-fuel Internal Combustion Engines: A Case Study for China
Apr 2022
Publication
Under the dual pressure of energy conservation and environmental protection the internal combustion engine industry is facing huge challenges and it is imperative to find new clean energy. Hydrogen energy is expected to replace traditional fossil fuels as an excellent fuel for internal combustion engines because of its clean continuous regeneration and good combustion performance. This review article focuses on the research and development of blended hydrogen-fuel internal combustion engines in China since the beginning of this century. The main achievements gained by Chinese researchers in performing research on the effects of the addition of hydrogen into engines which predominantly include many types of hydrogen-blended engines such as gasoline diesel natural gas and alcohol engines rotary engines are discussed and analyzed in these areas of the engine’s performance and the combustion and emission characteristics etc. The merits and demerits of blended hydrogen-fuel internal combustion engines could be concluded and summarized after discussion. Finally the development trend and direction of exploration on hydrogen-fuel internal combustion engines could also be forecasted for relevant researchers.
Optimal Planning of Hybrid Electric-hydrogen Energy Storage Systems via Multi-objective Particle Swarm Optimization
Jan 2023
Publication
In recent years hydrogen is rapidly developing because it is environmentally friendly and sustainable. In this case hydrogen energy storage systems (HESSs) can be widely used in the distribution network. The application of hybrid electric-hydrogen energy storage systems can solve the adverse effects caused by renewable energy access to the distribution network. In order to ensure the rationality and effectiveness of energy storage systems (ESSs) configuration economic indicators of battery energy storage systems (BESSs) and hydrogen energy storage systems power loss and voltage fluctuation are chosen as the fitness function in this paper. Meanwhile multi-objective particle swarm optimization (MOPSO) is used to solve Pareto non-dominated set of energy storage systems’ optimal configuration scheme in which the technique for order preference by similarity to ideal solution (TOPSIS) based on information entropy weight (IEW) is used select the optimal solution in Pareto non-dominated solution set. Based on the extended IEEE-33 system and IEEE-69 system the rationality of energy storage systems configuration scheme under 20% and 35% renewable energy penetration rate is analyzed. The simulation results show that the power loss can be reduced by 7.9%–22.8% and the voltage fluctuation can be reduced by 40.0%–71% when the renewable energy penetration rate is 20% and 35% respectively in IEEE-33 and 69 nodes systems. Therefore it can be concluded that the locations and capacities of energy storage systems obtained by multi-objective particle swarm optimization can improve the distribution network stability and economy after accessing renewable generation.
Hydrogen for a Net Zero GB An Integrated Energy Market Perspective
Jul 2020
Publication
Our new independent report finds that hydrogen can play an important role in UK’s ambitious decarbonisation plan and boost its global industrial competitiveness.
Key insights from this new analysis include:
Key insights from this new analysis include:
- New independent report from Aurora Energy Research shows that hydrogen can meet up to half of Great Britain’s (GB) final energy demand by 2050 providing an important pathway to reaching UK’s ambitious Net Zero targets.
- The report concludes that both blue hydrogen (produced from natural gas after reforming to remove carbon content) and green hydrogen (produced by using power to electrolyse water) are expected to play an important role providing up to 480TWh of hydrogen or c.45% of GB’s final energy demand by 2050.
- All Net Zero scenarios require substantial growth in low-carbon generation such as renewables and nuclear. Large-scale hydrogen adoption could help to integrate renewables into the power system by reducing the power sector requirement for flexibility during peak winter months and boosting revenues for clean power generators by c. £3bn per year by 2050.
- The rollout of hydrogen could accelerate green growth and enable the development of globally competitive low-carbon industrial clusters while utilising UK’s competitive advantage on carbon capture.
- In facilitating the identification of a cost-effective hydrogen pathway there are some low-regret options for Government to explore including the stimulation of hydrogen demand in key sectors the deployment of CCS in strategic locations and the standardisation of networks. These initiatives could form an important part of the UK Government’s post-COVID stimulus plan.
Hydrogen Energy Systems: A Critical Review of Technologies, Applications, Trends and Challenges
May 2021
Publication
The global energy transition towards a carbon neutral society requires a profound transformation of electricity generation and consumption as well as of electric power systems. Hydrogen has an important potential to accelerate the process of scaling up clean and renewable energy however its integration in power systems remains little studied. This paper reviews the current progress and outlook of hydrogen technologies and their application in power systems for hydrogen production re-electrification and storage. The characteristics of electrolysers and fuel cells are demonstrated with experimental data and the deployments of hydrogen for energy storage power-to-gas co- and tri-generation and transportation are investigated using examples from worldwide projects. The current techno-economic status of these technologies and applications is presented in which cost efficiency and durability are identified as the main critical aspects. This is also confirmed by the results of a statistical analysis of the literature. Finally conclusions show that continuous efforts on performance improvements scale ramp-up technical prospects and political support are required to enable a cost-competitive hydrogen economy.
A Comprehensive Overview of Hydrogen-Fueled Internal Combustion Engines: Achievements and Future Challenges
Oct 2021
Publication
This paper provides a comprehensive review and critical analysis of the latest research results in addition to an overview of the future challenges and opportunities regarding the use of hydrogen to power internal combustion engines (ICEs). The experiences and opinions of various international research centers on the technical possibilities of using hydrogen as a fuel in ICE are summarized. The advantages and disadvantages of the use of hydrogen as a solution are described. Attention is drawn to the specific physical chemical and operational properties of hydrogen for ICEs. A critical review of hydrogen combustion concepts is provided drawing on previous research results and experiences described in a number of research papers. Much space is devoted to discussing the challenges and opportunities associated with port and direct hydrogen injection technology. A comparison of different fuel injection and ignition strategies and the benefits of using the synergies of selected solutions are presented. Pointing to the previous experiences of various research centers the hazards related to incorrect hydrogen combustion such as early pre‐ignition late pre‐ignition knocking combustion and backfire are described. Attention is focused on the fundamental importance of air ratio optimization from the point of view of combustion quality NOx emissions engine efficiency and performance. Exhaust gas scrubbing to meet future emission regulations for hydrogen powered internal combustion engines is another issue that is considered. The article also discusses the modifications required to adapt existing engines to run on hydrogen. Referring to still‐unsolved problems the reliability challenges faced by fuel injection systems in particular are presented. An analysis of more than 150 articles shows that hydrogen is a suitable alternative fuel for spark‐ignition engines. It will significantly improve their performance and greatly reduce emissions to a fraction of their current level. However its use also has some drawbacks the most significant of which are its high NOx emissions and low power output and problems in terms of the durability and reliability of hydrogen‐fueled engines.
Life Cycle Assessment Integration into Energy System Models: An Application for Power-to-Methane in the EU
Nov 2019
Publication
As the EU energy system transitions to low carbon the technology choices should consider a broader set of criteria. The use of Life Cycle Assessment (LCA) prevents burden shift across life cycle stages or impact categories while the use of Energy System Models (ESM) allows evaluating alternative policies capacity evolution and covering all the sectors. This study does an ex-post LCA analysis of results from JRC-EU-TIMES and estimates the environmental impact indicators across 18 categories in scenarios that achieve 80–95% CO2 emission reduction by 2050. Results indicate that indirect CO2 emissions can be as large as direct ones for an 80% CO2 reduction target and up to three times as large for 95% CO2 reduction. Impact across most categories decreases by 20–40% as the CO2 emission target becomes stricter. However toxicity related impacts can become 35–100% higher. The integrated framework was also used to evaluate the Power-to-Methane (PtM) system to relate the electricity mix and various CO2 sources to the PtM environmental impact. To be more attractive than natural gas the climate change impact of the electricity used for PtM should be 123–181 gCO2eq/kWh when the CO2 comes from air or biogenic sources and 4–62 gCO2eq/kWh if the CO2 is from fossil fuels. PtM can have an impact up to 10 times larger for impact categories other than climate change. A system without PtM results in ~4% higher climate change impact and 9% higher fossil depletion while having 5–15% lower impact for most of the other categories. This is based on a scenario where 9 parameters favor PtM deployment and establishes the upper bound of the environmental impact PtM can have. Further studies should work towards integrating LCA feedback into ESM and standardizing the methodology.
Renewable Hydrogen Potential for Low-carbon Retrofit of the Building Stocks
Dec 2015
Publication
Energy-related GHG emissions mainly from fossil fuels combustion account for around 70% of total emissions. Those emissions are the target of the recent sustainability policies. Indeed renewables exploitation is considered widely the weapon to deal with this challenge thanks to their carbon neutrality. But the biggest drawback is represented by the mismatching between their production and users consumption. The storage would be a possible solution but its viability consists of economic sustainability and energy process efficiency as well. The cutting edge technologies of batteries have not still solved these issues at the same time. So a paradigm shift towards the identification of an energy carrier as storage option the so called Power-to-Gas could be the viable solution. From viability to feasibility a mandatory step is required: the opportunity to integrate the new solution in the proven infrastructures system. Thus the recent studies on Hydrogen (H2) enrichment in Natural Gas demonstrating a lower environmental impact and an increase in energy performance are the base to build the hydrogen transition in the urban environment. The aim of this paper is to evaluate the environmental benefits at building and district scale.
An Evaluation of Turbocharging and Supercharging Options for High-Efficiency Fuel Cell Electric Vehicles
Dec 2018
Publication
Mass-produced off-the-shelf automotive air compressors cannot be directly used for boosting a fuel cell vehicle (FCV) application in the same way that they are used in internal combustion engines since the requirements are different. These include a high pressure ratio a low mass flow rate a high efficiency requirement and a compact size. From the established fuel cell types the most promising for application in passenger cars or light commercial vehicle applications is the proton exchange membrane fuel cell (PEMFC) operating at around 80 ◦C. In this case an electric-assisted turbocharger (E-turbocharger) and electric supercharger (single or two-stage) are more suitable than screw and scroll compressors. In order to determine which type of these boosting options is the most suitable for FCV application and assess their individual merits a co-simulation of FCV powertrains between GT-SUITE and MATLAB/SIMULINK is realised to compare vehicle performance on the Worldwide Harmonised Light Vehicle Test Procedure (WLTP) driving cycle. The results showed that the vehicle equipped with an E-turbocharger had higher performance than the vehicle equipped with a two-stage compressor in the aspects of electric system efficiency (+1.6%) and driving range (+3.7%); however for the same maximal output power the vehicle’s stack was 12.5% heavier and larger. Then due to the existence of the turbine the E-turbocharger led to higher performance than the single-stage compressor for the same stack size. The solid oxide fuel cell is also promising for transportation application especially for a use as range extender. The results show that a 24-kWh electric vehicle can increase its driving range by 252% due to a 5 kW solid oxide fuel cell (SOFC) stack and a gas turbine recovery system. The WLTP driving range depends on the charge cycle but with a pure hydrogen tank of 6.2 kg the vehicle can reach more than 600 km.
Design Challenges in Hydrogen-Fueled Rotary Engine-A Review
Jan 2023
Publication
The rotary engine (RE) is a potential power plant for unmanned aerial vehicles (UAVs) and automobiles because of its structural and design merits. However it has some serious drawbacks such as frequent maintenance requirements and excessive fuel consumption. This review paper presents the current status of hydrogen-fueled rotary engine (HRE) technology and identifies the existing research and development gaps in combustion efficiency and performance of this engine that might benefit transportation sector. Focusing primarily on the research from past ten years the crucial challenges encountered in hydrogen-powered rotary engines have been reviewed in terms of knock hydrocarbon (HC) emissions and seal leakages. The paper identifies the recent advances in design concepts and production approaches used in hydrogen-fueled rotary engines such as geometric models of trochoid profiles port configurations fuel utilization systems and currently available computational fluid dynamics (CFD) tools. This review article is an attempt to collect and organize literature on existing design methods up to date and provide recommendations for further improvements in RE technology.
A Quantitative Study of Policy-driven Changes and Forecasts in the Development of the Hydrogen Transportation Industry
Feb 2022
Publication
Through data mining and analysis of the word frequency and occurrence position of industrial policy keywords the main policy parameters affecting industrial development are determined and the functional relationship between industrial policy and industrial development is obtained through multi-parameter non-linear regression: Yit−1 (y1 y2 y3 y4 y5) = β1it X1 + β2it ln X2 + β3it ln X3 + β4it X1it ∗ ln X3 + εit . The time series function of the industrial development index: Y (t) = 0.174 ∗ e (0.256∗t) is established and the industrial development under the influence of next year’s policy is predicted. It is concluded from the mathematical expression of the statistical model that there is a certain coupling effect between different policies and that industrial development is influenced by the joint effect on the parent and sub-industries. This ultimately proves that there is a clear correlation between policy and industry development.
Van der Waals Heterostructures - Recent Progress in Electrode Materials for Clean Energy Applications
Jul 2021
Publication
The unique layered morphology of van der Waals (vdW) heterostructures give rise to a blended set of electrochemical properties from the 2D sheet components. Herein an overview of their potential in energy storage systems in place of precious metals is conducted. The most recent progress on vdW electrocatalysis covering the last three years of research is evaluated with an emphasis on their catalytic activity towards the oxygen reduction reaction (ORR) oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). This analysis is conducted in pair with the most active Pt-based commercial catalyst currently utilized in energy systems that rely on the above-listed electrochemistry (metal–air battery fuel cells and water electrolyzers). Based on current progress in HER catalysis that employs vdW materials several recommendations can be stated. First stacking of the two types vdW materials with one being graphene or its doped derivatives results in significantly improved HER activity. The second important recommendation is to take advantage of an electronic coupling when stacking 2D materials with the metallic surface. This significantly reduces the face-to-face contact resistance and thus improves the electron transfer from the metallic surface to the vdW catalytic plane. A dual advantage can be achieved from combining the vdW heterostructure with metals containing an excess of d electrons (e.g. gold). Despite these recent and promising discoveries more studies are needed to solve the complexity of the mechanism of HER reaction in particular with respect to the electron coupling effects (metal/vdW combinations). In addition more affordable synthetic pathways allowing for a well-controlled confined HER catalysis are emerging areas.
High Energy Density Storage of Gaseous Marine Fuels: An Innovative Concept and its Application to a Hydrogen Powered Ferry
Apr 2020
Publication
The upcoming stricter limitations on both pollutant and greenhouse gases emissions represent a challenge for the shipping sector. The entire ship design process requires an approach to innovation with a particular focus on both the fuel choice and the power generation system. Among the possible alternatives natural gas and hydrogen based propulsion systems seem to be promising in the medium and long term. Nonetheless natural gas and hydrogen storage still represents a problem in terms of cargo volume reduction. This paper focuses on the storage issue considering compressed gases and presents an innovative solution which has been developed in the European project GASVESSEL® that allows to store gaseous fuels with an energy density higher than conventional intermediate pressure containment systems. After a general overview of natural gas and hydrogen as fuels for shipping a case study of a small Roll-on/Rolloff passenger ferry retrofit is proposed. The study analyses the technical feasibility of the installation of a hybrid power system with batteries and polymer electrolyte membrane fuel cells fuelled by hydrogen. In particular a process simulation model has been implemented to assess the quantity of hydrogen that can be stored on board taking into account boundary conditions such as filling time on shore storage capacity and cylinder wall temperature. The simulation results show that if the fuel cells system is run continuously at steady state to cover the energy need for one day of operation 140 kg of hydrogen are required. Using the innovative pressure cylinder at a storage pressure of 300 bar the volume required by the storage system assessed on the basis of the containment system outer dimensions is resulted to be 15.2 m3 with a weight of 2.5 ton. Even if the innovative type of pressure cylinder allows to reach an energy density higher than conventional intermediate pressure cylinders the volume necessary to store a quantity of energy typical for the shipping sector is many times higher than that required by conventional fuels today used. The analysis points out as expected that the filling process is critical to maximize the stored hydrogen mass and that it is critical to measure the temperature of the cylinder walls in order not to exceed the material limits. Nevertheless for specific application such as the one considered in the paper the introduction of gaseous hydrogen as fuel can be considered for implementing zero local emission propulsion system in the medium term.
Hydrogen and Fuel Cell Demonstrations in Turkey
Nov 2012
Publication
As a non-profit UNIDO project funded 100% by the Turkish Ministry of Energy and Natural Resources International Center for Hydrogen Energy Technologies (ICHET) has been implementing pilot demonstration projects providing applied R&D funding; organizing workshops education and training activities in Turkey and other developing countries to show potential benefits of “hydrogen and fuel cell systems”. It is important to leap-frog developing countries to hydrogen for eliminating detrimental effect of fossil fuels. To achieve its mission ICHET implements pilot demonstration projects in combination with renewable energy systems to encourage local industry to manufacture similar systems and explore market potential for such use. Support is provided to selected industrial partners in Turkey for developing products or for early demonstrations including a fuel cell forklift a fuel cell boat a fuel cell passenger cart with PV integrated roof-top renewable integrated mobile house fuel cell based UPS installations. As more and more systems demonstrated public awareness on applications of hydrogen and fuel cell technologies will increase and viability of such systems will be realized to change public perception.
Power-to-Steel: Reducing CO2 through the Integration of Renewable Energy and Hydrogen into the German Steel Industry
Apr 2017
Publication
This paper analyses some possible means by which renewable power could be integrated into the steel manufacturing process with techniques such as blast furnace gas recirculation (BF-GR) furnaces that utilize carbon capture a higher share of electrical arc furnaces (EAFs) and the use of direct reduced iron with hydrogen as reduction agent (H-DR). It is demonstrated that these processes could lead to less dependence on—and ultimately complete independence from—coal. This opens the possibility of providing the steel industry with power and heat by coupling to renewable power generation (sector coupling). In this context it is shown using the example of Germany that with these technologies reductions of 47–95% of CO2 emissions against 1990 levels and 27–95% of primary energy demand against 2008 can be achieved through the integration of 12–274 TWh of renewable electrical power into the steel industry. Thereby a substantial contribution to reducing CO2 emissions and fuel demand could be made (although it would fall short of realizing the German government’s target of a 50% reduction in power consumption by 2050).
Climate Impact Reduction Potentials of Synthetic Kerosene and Green Hydrogen Powered Mid-Range Aircraft Concepts
Jun 2022
Publication
One of aviation’s major challenges for the upcoming decades is the reduction in its climate impact. As synthetic kerosene and green hydrogen are two promising candidates their potentials in decreasing the climate impact is investigated for the mid-range segment. Evolutionary advancements for 2040 are applied first with an conventional and second with an advanced low-NOx and low-soot combustion chamber. Experts and methods from all relevant disciplines are involved starting from combustion turbofan engine overall aircraft design fleet level and climate impact assessment allowing a sophisticated and holistic evaluation. The main takeaway is that both energy carriers have the potential to strongly reduce the fleet level climate impact by more than 75% compared with the reference. Applying a flight-level constraint of 290 and a cruise Mach number of 0.75 causing 5% higher average Direct Operating Costs (DOC) the reduction is even more than 85%. The main levers to achieve this are the advanced combustion chamber an efficient contrail avoidance strategy in this case a pure flight-level constraint and the use of CO2 neutral energy carrier in a descending priority order. Although vehicle efficiency gains only lead to rather low impact reduction they are very important to compensate the increased costs of synthetic fuels or green hydrogen.
CO2 Emissions Reduction Measures for RO-RO Vessels on Non-Profitable Coastal Liner Passenger Transport
Jun 2021
Publication
Reducing CO2 emissions from ships in unprofitable coastline transport using electricity and hydrogen has potential for island development to improve transport and protect biodiversity and nature. New technologies are a challenge for shipping companies and their introduction should be accompanied by a system of state aid for alternative energy sources. The energy requirements of an electric ferry for a route of up to 6 km were considered as well as the amount of hydrogen needed to generate the electricity required to charge the ferry batteries to enable a state aid scheme. For a daily ferry operation a specific fuel consumption of 60.6 g/kWh of liquid hydrogen is required in the system fuel cell with a total of 342.69 kg of hydrogen. Compared to marine diesel the use of electric ferries leads to a reduction of CO2 emissions by up to 90% including significantly lower NOx Sox and particulate matter (PM) emissions and operating costs by up to 80%.
Hydrogen Station Location Planning via Geodesign in Connecticut: Comparing Optimization Models and Structured Stakeholder Collaboration
Nov 2021
Publication
Geodesign is a participatory planning approach in which stakeholders use geographic information systems to develop and vet alternative design scenarios in a collaborative and iterative process. This study is based on a 2019 geodesign workshop in which 17 participants from industry government university and non-profit sectors worked together to design an initial network of hydrogen refueling stations in the Hartford Connecticut metropolitan area. The workshop involved identifying relevant location factors rapid prototyping of station network designs and developing consensus on a final design. The geodesign platform which was designed specifically for facility location problems enables breakout groups to add or delete stations with a simple point-and-click operation view and overlay different map layers compute performance metrics and compare their designs to those of other groups. By using these sources of information and their own expert local knowledge participants recommended six locations for hydrogen refueling stations over two distinct phases of station installation. We quantitatively and qualitatively compared workshop recommendations to solutions of three optimal station location models that have been used to recommend station locations which minimize travel times from stations to population and traffic or maximize trips that can be refueled on origin–destination routes. In a post-workshop survey participants rated the workshop highly for facilitating mutual understanding and information sharing among stakeholders. To our knowledge this workshop represents the first application of geodesign for hydrogen refueling station infrastructure planning.
Optimization of Hydrogen Cost and Transport Technology in France and Germany for Various Production and Demand Scenarios
Jan 2021
Publication
Green hydrogen for mobility represents an alternative to conventional fuel to decarbonize the transportation sector. Nevertheless the thermodynamic properties make the transport and the storage of this energy carrier at standard conditions inefficient. Therefore this study deploys a georeferenced optimal transport infrastructure for four base case scenarios in France and Germany that differs by production distribution based on wind power potential and demand capacities for the mobility sector at different penetration shares for 2030 and 2050. The restrained transport network to the road infrastructure allows focusing on the optimum combination of trucks operating at different states of aggregations and storage technologies and its impact on the annual cost and hydrogen flow using linear programming. Furthermore four other scenarios with production cost investigate the impact of upstream supply chain cost and eight scenarios with daily transport and storage optimization analyse the modeling method sensitivity. The results show that compressed hydrogen gas at a high presser level around 500 bar was on average a better option. However at an early stage of hydrogen fuel penetration substituting compressed gas at low to medium pressure levels by liquid organic hydrogen carrier minimizes the transport and storage costs. Finally in France hydrogen production matches population distribution in contrast to Germany which suffers from supply and demand disparity.
Why Can’t We Just Burn Hydrogen? Challenges When Changing Fuels in an Existing Infrastructure
Feb 2021
Publication
The current global consumption of natural gas as a fuel is roughly 4 trillion cubic meters per year. In terms of energy the demand for natural gas exceeds the global demand for fossil fuels for transportation. Despite this observation the challenges to natural gas end use that arise when changing the composition of the fuel are largely absent from public policy and research agendas whereas for transportation fuels the issues are more appreciated. Natural gas is delivered via complex networks of interconnected pipelines to end users for direct and indirect heating in household and industrial sectors and for power generation. This interconnectedness is a crucial aspect of the challenge for introducing new fuels.<br/>In this paper we discuss the issues that arise from changing fuel properties for an existing population of end-use equipment. To illustrate the issues we will consider the changes in (combustion) performance of domestic combustion equipment and gas engines for power generation in response to substituting natural gas by hydrogen or hydrogen/natural gas blends. During the discussion we shall also indicate methods for characterizing the properties of the fuel and identify the combustion challenges that must be addressed for a successful transition from the current fuel mix to whatever the future mix may be.
Hydrogen for Australia’s Future
Aug 2018
Publication
The Hydrogen Strategy Group chaired by Australia’s Chief Scientist Dr Alan Finkel has today released a briefing paper on the potential domestic and export opportunities of a hydrogen industry in Australia.
Like natural gas hydrogen can be used to heat buildings and power vehicles. Unlike natural gas or petrol when hydrogen is burned there are no CO2 emissions. The only by-products are water vapour and heat.
Hydrogen is the most abundant element in the universe not freely available as a gas on Earth but bound into many common substances including water and fossil fuels.
Hydrogen was first formally presented as a credible alternative energy source in the early 1970s but never proved competitive at scale as an energy source – until now. We find that the worldwide demand for hydrogen is set to increase substantially over coming decades driven by Japan’s decision to put imported hydrogen at the heart of its economy. Production costs are falling technologies are progressing and the push for non-nuclear low-emissions fuels is building momentum. We conclude that Australia is remarkably well-positioned to benefit from the growth of hydrogen industries and markets.
Like natural gas hydrogen can be used to heat buildings and power vehicles. Unlike natural gas or petrol when hydrogen is burned there are no CO2 emissions. The only by-products are water vapour and heat.
Hydrogen is the most abundant element in the universe not freely available as a gas on Earth but bound into many common substances including water and fossil fuels.
Hydrogen was first formally presented as a credible alternative energy source in the early 1970s but never proved competitive at scale as an energy source – until now. We find that the worldwide demand for hydrogen is set to increase substantially over coming decades driven by Japan’s decision to put imported hydrogen at the heart of its economy. Production costs are falling technologies are progressing and the push for non-nuclear low-emissions fuels is building momentum. We conclude that Australia is remarkably well-positioned to benefit from the growth of hydrogen industries and markets.
Modeling Hydrogen Refueling Infrastructure to Support Passenger Vehicles
May 2018
Publication
The year 2014 marked hydrogen fuel cell electric vehicles (FCEVs) first becoming commercially available in California where significant investments are being made to promote the adoption of alternative transportation fuels. A refueling infrastructure network that guarantees adequate coverage and expands in line with vehicle sales is required for FCEVs to be successfully adopted by private customers. In this paper we provide an overview of modelling methodologies used to project hydrogen refueling infrastructure requirements to support FCEV adoption and we describe in detail the National Renewable Energy Laboratory’s scenario evaluation and regionalization analysis (SERA) model. As an example we use SERA to explore two alternative scenarios of FCEV adoption: one in which FCEV deployment is limited to California and several major cities in the United States; and one in which FCEVs reach widespread adoption becoming a major option as passenger vehicles across the entire country. Such scenarios can provide guidance and insights for efforts required to deploy the infrastructure supporting transition toward different levels of hydrogen use as a transportation fuel for passenger vehicles in the United States.
Everything About Hydrogen Podcast: Toyota's global hydrogen ambitions
Feb 2020
Publication
On this weeks episode the team are talking all things hydrogen with Craig Scott the Group Manager for Toyota North America a global automotive giant and a recognised pioneer in the field of fuel cell mobility. On the show we get into the story of Toyota’s roll out of fuel cell mobility solutions in North America the challenges and opportunities that fuel cell vehicles can offer in the hydrogen market and the challenges around infrastructure. Importantly we also dive into the scaling up work that Toyota is undertaking and some of its plans for next steps on the mission to become the world’s leader in fuel cell mobility solutions. All this and more on the show!
The podcast can be found on their website
The podcast can be found on their website
Comparing e-Fuels and Electrification for Decarbonization of Heavy-Duty Transports
Oct 2022
Publication
The freight sector is expected to keep or even increase its fundamental role for the major modern economies and therefore actions to limit the growing pressure on the environment are urgent. The use of electricity is a major option for the decarbonization of transports; in the heavy-duty segment it can be implemented in different ways: besides full electric-battery powertrains electricity can be used to supply catenary roads or can be chemically stored in liquid or gaseous fuels (e-fuels). While the current EU legislation adopts a tailpipe Tank-To-Wheels approach which results in zero emissions for all direct uses of electricity a Well-To-Wheels (WTW) method would allow accounting for the potential benefits of using sustainable fuels such as e-fuels. In this article we have performed a WTW-based comparison and modelling of the options for using electricity to supply heavy-duty vehicles: e-fuels eLNG eDiesel and liquid Hydrogen. Results showed that the direct use of electricity can provide high Greenhouse Gas (GHG) savings and also in the case of the e-fuels when low-carbonintensity electricity is used for their production. While most studies exclusively focus on absolute GHG savings potential considerations of the need for new infrastructures and the technological maturity of some options are fundamental to compare the different technologies. In this paper an assessment of such technological and non-technological barriers has been conducted in order to compare alternative pathways for the heavy-duty sector. Among the available options the flexibility of using drop-in energy-dense liquid fuels represents a clear and substantial immediate advantage for decarbonization. Additionally the novel approach adopted in this paper allows us to quantify the potential benefits of using e-fuels as chemical storage able to accumulate electricity from the production peaks of variable renewable energies which would otherwise be wasted due to grid limitations.
A Review of Renewable Hydrogen Generation and Proton Exchange Membrane Fuel Cell Technology for Sustainable Energy Development
Mar 2023
Publication
Beyond its typical usage as an economical fuel for creating ammonia methanol and petroleum refineries hydrogen has become a modern form of energy. Energy-scarce advanced countries like Japan and Korea are concerned about energy privacy and environmental responsibility. Many wealthy countries have been fervently building hydrogen networks and renewable energy sources to fulfil their main goals or the growing requirement for energy. In this study we concentrate on proton-exchange membrane fuel cells (PEMFCs) generally viewed as financially viable for vehicle industries especially for automobiles demanding less hydrogen infrastructure facilities like fleets of cabs buses and logistical automobiles. This overview includes all of the significant PEMFC components focusing on the reaction gas diffusion and polymer. Without question the equipment necessary for a consistent supply of ultra-pure hydrogen is essential for the effectiveness of PEMFC in extensive requests.
Simulation and Study of PEMFC System Directly Fueled by Ammonia Decomposition Gas
Mar 2022
Publication
Ammonia can be stored as a liquid under relatively easy conditions (Ambient temperature by applying 10 bar or Ambient pressure with the temperature of 239 K). At the same time liquid ammonia has a high hydrogen storage density and is therefore a particularly promising carrier for hydrogen storage. At the same time the current large-scale industrial synthesis of ammonia has long been mature and in the future it will be possible to achieve a zero-emission ammonia regeneration cycle system by replacing existing energy sources with renewable ones. Ammonia does not contain carbon and its use in fuel cells can avoid NOx production during energy release. high temperature solid oxide fuel cells can be directly fueled by ammonia and obtain good output characteristics but the challenges inherent in high temperature solid oxide fuel cells greatly limit the implementation of this option. Whereas PEMFC has gained initial commercial use however for PEMFC ammonia is a toxic gas so the general practice is to convert ammonia to pure hydrogen. Ammonia to hydrogen requires decomposition under high temperature and purification which increases the complexity of the fuel system. In contrast PEMFC that can use ammonia decomposition gas directly can simplify the fuel system and this option has already obtained preliminary experimental validation studies. The energy efficiency of the system obtained from the preliminary validation experiments is only 34–36% which is much lower than expected. Therefore this paper establishes a simulation model of PEMFC directly using ammonia decomposition gas as fuel to study the maximum efficiency of the system and the effect of the change of system parameters on the efficiency and the results show that the system efficiency can reach up to 45% under the condition of considering certain heat loss. Increasing the ammonia decomposition reaction temperature decreases the system efficiency but the effect is small and the system efficiency can reach 44% even at a temperature of 850°C. The results of the study can provide a reference for a more scientific and quantitative assessment of the potential value of direct ammonia decomposition gas-fueled PEMFC.
Assessment of Paper Industry Decarbonization Potential via Hydrogen in a Multi-energy System Scenario: A Case Study
Jul 2023
Publication
Green hydrogen is currently regarded as a key catalyst for the decarbonization of energy-intensive industries. In this context the pulp and paper industry stands out as one of the most demanding given the simultaneous need for large amounts of heat and electricity usually satisfied via cogeneration systems. Given the urgent need for cost-effective solutions in response to the climate crisis it is crucial to analyze the feasibility of retrofitting existing power plants to operate carbon-neutral. The aim of this work is to provide a techno-economic analysis for the conversion of a conventional cogeneration system to run on locally produced hydrogen. Building on the energy consumption of the paper mill the operation of a hydrogen-fuelled gas turbine is modelled in detail. Based on these results a multi-energy system model for the production of green fuel is presented considering production via solar-powered PEM electrolyzers storage in tanks and final use in the gas turbine. An optimal configuration for the system is defined leading to the definition of a solution that ensures a cost of 6.41 /kg for the production of green hydrogen. Finally a sensitivity analysis highlights the close dependence of the economic profitability of the Power-to-X system on the natural gas price. The results indicate that although positive performance is achieved the cost of investment remains still prohibitive for systems of this size and the high initial capital expenditure needs to be supported by incentive policies that facilitate the adoption of hydrogen in industrial applications making it competitive in the short term.
Hydrogenerally - Episode 8: Hydrogen for Combustion
Jan 2023
Publication
In this episode Steffan Eldred Hydrogen Knowledge Transfer Manager and Debra Jones Chemistry Knowledge Transfer Manager from Innovate UK KTN talk about hydrogen combustion with special guest Duncan Engeham European Research and Development Director at Cummins Inc.
The podcast can be found on their website.
The podcast can be found on their website.
Hydrogen-Powered Aviation—Design of a Hybrid-Electric Regional Aircraft for Entry into Service in 2040
Mar 2023
Publication
Over the past few years the rapid growth of air traffic and the associated increase in emissions have created a need for sustainable aviation. Motivated by these challenges this paper explores how a 50-passenger regional aircraft can be hybridized to fly with the lowest possible emissions in 2040. In particular the use of liquid hydrogen in this aircraft is an innovative power source that promises to reduce CO2 and NOx emissions to zero. Combined with a fuel-cell system the energy obtained from the liquid hydrogen can be used efficiently. To realize a feasible concept in the near future considering the aspects of performance and security the system must be hybridized. In terms of maximized aircraft sustainability this paper analyses the flight phases and ground phases resulting in an aircraft design with a significant reduction in operating costs. Promising technologies such as a wingtip propeller and electric green taxiing are discussed in this paper and their potential impacts on the future of aviation are highlighted. In essence the hybridization of regional aircraft is promising and feasible by 2040; however more research is needed in the areas of fuel-cell technology thermal management and hydrogen production and storage.
Hydrogen Fuel Cell Power System—Development Perspectives for Hybrid Topologies
Mar 2023
Publication
In recent years the problem of environmental pollution especially the emission of greenhouse gases has attracted people’s attention to energy infrastructure. At present the fuel consumed by transportation mainly comes from fossil energy and the strong traffic demand has a great impact on the environment and climate. Fuel cell electric vehicles (FCEVs) use hydrogen energy as a clean alternative to fossil fuels taking into account the dual needs of transportation and environmental protection. However due to the low power density and high manufacturing cost of hydrogen fuel cells their combination with other power supplies is necessary to form a hybrid power system that maximizes the utilization of hydrogen energy and prolongs the service life of hydrogen fuel cells. Therefore the hybrid power system control mode has become a key technology and a current research hotspot. This paper first briefly introduces hydrogen fuel cells then summarizes the existing hybrid power circuit topology categorizes the existing technical solutions and finally looks forward to the future for different scenarios of hydrogen fuel cell hybrid power systems. This paper provides reference and guidance for the future development of renewable hydrogen energy and hydrogen fuel cell hybrid electric vehicles.
Concepts for Hydrogen Internal Combustion Engines and Their Implications on the Exhaust Gas Aftertreatment System
Dec 2021
Publication
Hydrogen as carbon-free fuel is a very promising candidate for climate-neutral internal combustion engine operation. In comparison to other renewable fuels hydrogen does obviously not produce CO2 emissions. In this work two concepts of hydrogen internal combustion engines (H2 -ICEs) are investigated experimentally. One approach is the modification of a state-of-the-art gasoline passenger car engine using hydrogen direct injection. It targets gasoline-like specific power output by mixture enrichment down to stoichiometric operation. Another approach is to use a heavy-duty diesel engine equipped with spark ignition and hydrogen port fuel injection. Here a diesel-like indicated efficiency is targeted through constant lean-burn operation. The measurement results show that both approaches are applicable. For the gasoline engine-based concept stoichio-metric operation requires a three-way catalyst or a three-way NOX storage catalyst as the primary exhaust gas aftertreatment system. For the diesel engine-based concept state-of-the-art selective catalytic reduction (SCR) catalysts can be used to reduce the NOx emissions provided the engine calibration ensures sufficient exhaust gas temperature levels. In conclusion while H2 -ICEs present new challenges for the development of the exhaust gas aftertreatment systems they are capable to realize zero-impact tailpipe emission operation.
An MILP Approach for the Optimal Design of Renewable Battery-hydrogen Energy Systems for Off-grid Insular Communities
Jul 2021
Publication
The optimal sizing of stand-alone renewable H2-based microgrids requires the load demand to be reliably satisfied by means of local renewable energy supported by a hybrid battery/hydrogen storage unit while minimizing the system costs. However this task is challenging because of the high number of components that have to be installed and operated. In this work an MILP optimization framework has been developed and applied to the off-grid village of Ginostra (on the Stromboli island Italy) which is a good example of several other insular sites throughout the Mediterranean area. A year-long time horizon was considered to model the seasonal storage which is necessary for off-grid areas that wish to achieve energy independence by relying on local renewable sources. The degradation costs of batteries and H2-based devices were included in the objective function of the optimization problem i.e. the annual cost of the system. Efficiency and investment cost curves were considered for the electrolyzer and fuel cell components in order to obtain a more detailed and precise techno-economic estimation. The design optimization was also performed with the inclusion of a general demand response program (DRP) to assess its impact on the sizing results. Moreover the effectiveness of the proposed MILP-based method was tested by comparing it with a more traditional approach based on a metaheuristic algorithm for the optimal sizing complemented with ruled-based strategies for the system operation. Thanks to its longer-term storage capability hydrogen is required for the optimal system configuration in order to reach energy self-sufficiency. Finally considering the possibility of load deferral the electricity generation cost can be reduced to an extent that depends on the amount of load that is allowed to participate in the DRP scheme. This cost reduction is mainly due to the decreased capacity of the battery storage system.
Performance Analysis of a Zero-Energy Building Using Photovoltaics and Hydrogen Storage
Mar 2023
Publication
The exploitation of renewable energy sources in the building sector is a challenging aspect of achieving sustainability. The incorporation of a proper storage unit is a vital issue for managing properly renewable electricity production and so to avoid the use of grid electricity. The present investigation examines a zero-energy residential building that uses photovoltaics for covering all its energy needs (heating cooling domestic hot water and appliances-lighting needs). The building uses a reversible heat pump and an electrical heater so there is not any need for fuel. The novel aspect of the present analysis lies in the utilization of hydrogen as the storage technology in a power-to-hydrogen-to-power design. The residual electricity production from the photovoltaics feeds an electrolyzer for hydrogen production which is stored in the proper tank under high pressure. When there is a need for electricity and the photovoltaics are not enough the hydrogen is used in a fuel cell for producing the needed electricity. The present work examines a building of 400 m2 floor area in Athens with total yearly electrical demand of 23656 kWh. It was found that the use of 203 m2 of photovoltaics with a hydrogen storage capacity of 34 m3 can make the building autonomous for the year period.
Drop-in and Hydrogen-based Biofuels for Maritime Transport: Country-based Assessment of Climate Change Impacts in Europe up to 2050
Nov 2022
Publication
Alternative fuels are crucial to decarbonize the European maritime transport but their net climate benefits vary with the type of fuel and production country. In this study we assess the energy potential and climate change mitigation benefits of using agricultural and forest residues in different European countries for drop-in (Fast Pyrolysis Hydrothermal Liquefaction and Gasification to Fischer-Tropsch fuels or Bio-Synthetic Natural Gas) and hydrogen-based biofuels (hydrogen ammonia and methanol) with or without carbon capture and storage (CCS). Our results show the combinations of countries and biofuel options that successfully achieve the decarbonization targets set by the FuelEU Maritime initiative for the next years including a prospective analysis that include technological changes projected for the biofuel supply chains until 2050. With the current technologies the largest greenhouse gas (GHG) mitigation potential per year at a European scale is obtained with bio-synthetic natural gas and hydrothermal liquefaction. Among carbon-free biofuels ammonia currently has higher mitigation but hydrogen can achieve a lower GHG intensity per unit of energy with the projected decarbonization of the electricity mixes until 2050. The full deployment of CCS can further accelerate the decarbonization of the maritime sector. Choosing the most suitable renewable fuels requires a regional perspective and a transition roadmap where countries coordinate actions to meet ambitious climate targets.
Analysis of Hydrogen-powered Propulsion System Alternatives for Diesel-electric Regional Trains
Aug 2022
Publication
Non-electrified regional railway lines with typically employed diesel-electric multiple units require alternative propulsion systems to meet increasingly strict emissions regulations. With the aim to identify an optimal alternative to conventional diesel traction this paper presents a model-based assessment of hydrogen-powered propulsion systems with an internal combustion engine or fuel cells as the prime mover combined with different energy storage system configurations based on lithium-ion batteries and/or double-layer capacitors. The analysis encompasses technology identification design modelling and assessment of alternative powertrains explicitly considering case-related constraints imposed by the infrastructure technical and operational requirements. Using a regional railway network in the Netherlands as a case we investigate the possibilities in converting a conventional benchmark vehicle and provide the railway undertaking and decision-makers with valuable input for planning of future rolling stock investments. The results indicate the highest fuel-saving potential for fuel cell-based hybrid propulsion systems with lithium-ion battery or a hybrid energy storage system that combines both energy storage system technologies. The two configurations also demonstrate the highest reduction of greenhouse gas emissions compared to the benchmark diesel-driven vehicle by about 25% for hydrogen produced by steam methane reforming and about 19% for hydrogen obtained from electrolysis of water with grey electricity.
Thermodynamic and Emission Analysis of a Hydrogen/Methane Fueled Gas Turbine
May 2023
Publication
The importance of hydrogen in the effort to decarbonize the power sector has grown immensely in recent years. Previous studies have investigated the effects of mixing hydrogen into natural gas for gas turbine combustors but limited studies have examined the resulting effects hydrogen addition has on the entire system. In this work a thermodynamic model of a gas turbine with combustion chemical kinetics integrated is created and the effects hydrogen addition (0-100 volume percent addition) has on the system performance emissions and combustion kinetics are analyzed. The maximum system performance is achieved when the maximum turbine inlet temperature is reached and the resulting optimal fuel/air equivalence ratio is determined. As hydrogen is added to the fuel mixture the optimal equivalence ratio shifts leaner causing non-linearity in emissions and system performance at optimal conditions. An analysis of variance is conducted and it is shown that isentropic efficiencies of the turbine and compressor influences the system performance the most out of any system parameter. While isentropic efficiencies of the turbine and compressor increase towards 100% an operating regime where the optimal system efficiency cannot be achieved is discovered due to the lower flammability limit of the fuel being reached. This can be overcome by mixing hydrogen into the fuel.
Review of Life Cycle Assessments for Steel and Environmental Analysis of Future Steel Production Scenarios
Oct 2022
Publication
The steel industry is focused on reducing its environmental impact. Using the life cycle assessment (LCA) methodology the impacts of the primary steel production via the blast furnace route and the scrap-based secondary steel production via the EAF route are assessed. In order to achieve environmentally friendly steel production breakthrough technologies have to be implemented. With a shift from primary to secondary steel production the increasing steel demand is not met due to insufficient scrap availability. In this paper special focus is given on recycling methodologies for metals and steel. The decarbonization of the steel industry requires a shift from a coal-based metallurgy towards a hydrogen and electricity-based metallurgy. Interim scenarios like the injection of hydrogen and the use of pre-reduced iron ores in a blast furnace can already reduce the greenhouse gas (GHG) emissions up to 200 kg CO2/t hot metal. Direct reduction plants combined with electrical melting units/furnaces offer the opportunity to minimize GHG emissions. The results presented give guidance to the steel industry and policy makers on how much renewable electric energy is required for the decarbonization of the steel industry
Reduction of Iron Oxides with Hydrogen - A Review
Aug 2019
Publication
This review focuses on the reduction of iron oxides using hydrogen as a reducing agent. Due to increasing requirements from environmental issues a change of process concepts in the iron and steel industry is necessary within the next few years. Currently crude steel production is mainly based on fossil fuels and emitting of the climate-relevant gas carbon dioxide is integral. One opportunity to avoid or reduce greenhouse gas emissions is substituting hydrogen for carbon as an energy source and reducing agent. Hydrogen produced via renewable energies allows carbon-free reduction and avoids forming harmful greenhouse gases during the reduction process. The thermodynamic and kinetic behaviors of reduction with hydrogen are summarized and discussed in this review. The effects of influencing parameters such as temperature type of iron oxide grain size etc. are shown and compared with the reduction behavior of iron oxides with carbon monoxide. Different methods to describe the kinetics of the reduction progress and the role of the apparent activation energy are shown and proofed regarding their plausibility.
Double Compression-Expansion Engine (DCEE) Fueled with Hydrogen: Preliminary Computational Assessment
Jan 2022
Publication
Hydrogen (H2 ) is currently a highly attractive fuel for internal combustion engines (ICEs) owing to the prospects of potentially near-zero emissions. However the production emissions and cost of H2 fuel necessitate substantial improvements in ICE thermal efficiency. This work aims to investigate a potential implementation of H2 combustion in a highly efficient double compression-expansion engine (DCEE). DICI nonpremixed H2 combustion mode is used for its superior characteristics as concluded in previous studies. The analysis is performed using a 1D GT-Power software package where different variants of the DICI H2 and diesel combustion cycles obtained experimentally and numerically (3D CFD) are imposed in the combustion cylinder of the DCEE. The results show that the low jet momentum free jet mixing dominated variants of the DICI H2 combustion concept are preferred owing to the lower heat transfer losses and relaxed requirements on the fuel injection system. Insulation of the expander and removal of the intercooling improve the engine efficiency by 1.3 and 0.5 %-points respectively but the latter leads to elevated temperatures in the high-pressure tank which makes the selection of its materials harder but allows the use of cheaper oxidation catalysts. The results also show that the DCEE performance is insensitive to combustion cylinder temperatures making it potentially suitable for other high-octane fuels such as methane methanol ammonia etc. Finally a brake thermal efficiency of 56 % is achieved with H2 combustion around 1 %-point higher than with diesel. Further efficiency improvements are also possible with a fully optimized H2 combustion system.
Towards Deep Decarbonisation of Energy-Intensive Industries: A Review of Current Status, Technologies and Policies
Apr 2021
Publication
Industries account for about 30% of total final energy consumption worldwide and about 20% of global CO2 emissions. While transitions towards renewable energy have occurred in many parts of the world in the energy sectors the industrial sectors have been lagging behind. Decarbonising the energy-intensive industrial sectors is however important for mitigating emissions leading to climate change. This paper analyses various technological trajectories and key policies for decarbonising energy-intensive industries: steel mining and minerals cement pulp and paper and refinery. Electrification fuel switching to low carbon fuels together with technological breakthroughs such as fossil-free steel production and CCS are required to bring emissions from energy-intensive industry down to net-zero. A long-term credible carbon price support for technological development in various parts of the innovation chain policies for creating markets for low-carbon materials and the right condition for electrification and increased use of biofuels will be essential for a successful transition towards carbon neutrality. The study focuses on Sweden as a reference case as it is one of the most advanced countries in the decarbonisation of industries. The paper concludes that it may be technically feasible to deep decarbonise energy-intensive industries by 2045 given financial and political support.
Repurposing Fischer-Tropsch and Natural Gas as Bridging Technologies for the Energy Revolution
Jun 2022
Publication
Immediate and widespread changes in energy generation and use are critical to safeguard our future on this planet. However while the necessity of renewable electricity generation is clear the aviation transport and mobility chemical and material sectors are challenging to fully electrify. The age-old Fischer-Tropsch process and natural gas industry could be the bridging solution needed to accelerate the energy revolution in these sectors – temporarily powering obsolete vehicles acting as renewable energy’s battery supporting expansion of hydrogen fuel cell technologies and the agricultural and waste sectors as they struggle to keep up with a full switch to biofuels. Natural gas can be converted into hydrogen synthetic natural gas or heat during periods of low electricity demand and converted back to electricity again when needed. Moving methane through existing networks and converting it to hydrogen on-site at tanking stations also overcomes hydrogen distribution storage problems and infrastructure deficiencies. Useful co-products include carbon nanotubes a valuable engineering material that offset emissions in the carbon nanotube and black industries. Finally excess carbon can be converted back into syngas if desired. This flexibility and the compatibility of natural gas with both existing and future technologies provides a unique opportunity to rapidly decarbonise sectors struggling with complex requirements.
The Trajectory of Hybrid and Hydrogen Technologies in North American Heavy Haul Operations
Jul 2021
Publication
The central aim of this paper is to provide an up-to-date snapshot of hybrid and hydrogen technology-related developments and activities in the North American heavy haul railway setting placed in the context of the transportation industry more broadly. An overview of relevant alternative propulsion technologies is provided including a discussion of applicability to the transportation sector in general and heavy haul freight rail specifically. This is followed by a discussion of current developments and research in alternative and blended fuels discussed again in both general and specific settings. Key factors and technical considerations for heavy haul applications are reviewed followed by a discussion of non-technical and human factors that motivate a move toward clean energy in North American Heavy Haul systems. Finally current project activities are described to provide a clear understanding of both the status and trajectory of hybrid and hydrogen technologies in the established context.
A Preliminary Study on an Alternative Ship Propulsion System Fueled by Ammonia: Environmental and Economic Assessments
Mar 2020
Publication
The shipping industry is becoming increasingly aware of its environmental responsibilities in the long-term. In 2018 the International Maritime Organization (IMO) pledged to reduce greenhouse gas (GHG) emissions by at least 50% by the year 2050 as compared with a baseline value from 2008. Ammonia has been regarded as one of the potential carbon-free fuels for ships based on these environmental issues. In this paper we propose four propulsion systems for a 2500 Twenty-foot Equivalent Unit (TEU) container feeder ship. All of the proposed systems are fueled by ammonia; however different power systems are used: main engine generators polymer electrolyte membrane fuel cell (PEMFC) and solid oxide fuel cell (SOFC). Further these systems are compared to the conventional main engine propulsion system that is fueled by heavy fuel oil with a focus on the economic and environmental perspectives. By comparing the conventional and proposed systems it is shown that ammonia can be a carbon-free fuel for ships. Moreover among the proposed systems the SOFC power system is the most eco-friendly alternative (up to 92.1%) even though it requires a high lifecycle cost than the others. Although this study has some limitations and assumptions the results indicate a meaningful approach toward solving GHG problems in the maritime industry.
An Energy Systems Model of a Large Commercial Liquid Hydrogen Aircraft in a Low-carbon Future
Apr 2023
Publication
Liquid hydrogen (LH2) aircraft have the potential to achieve carbon neutrality. However if the hydrogen is produced using electricity grids that utilise fossil fuel they have a non-zero carbon dioxide (CO2) emission associated with their well-to-wing pathway. To assess the potential of LH2 in aviation decarbonisation an energy systems comparison of large commercial LH2 liquified natural gas (LNG) conventional Jet-A and LH2 dual-fuel aircraft is presented. The performance of each aircraft is compared towards 2050 over which three system changes occur: (1) LH2 aircraft technology develops; (2) both world average and region-specific grid electricity which is used to produce the hydrogen decarbonises; and (3) the International Air Transportation Association (IATA) emissions targets which are used to restrict the passenger-range performance of each aircraft tighten. In 2050 the emissions of all aircraft are thus constrained to 0.063 kg-CO2/p-km relative to 0.110 kg-CO2/p-km for the unconstrained Jet A fuelled Boeing 787-8. It is estimated that in this year an LH2 aircraft powered by fuel cells and sourcing world average electricity can travel 6000 km 20% further than the conventional Jet A aircraft that is also constrained to meet the IATA targets but not as far as the LNG aircraft. At its maximum range the LH2 aircraft carries 84% of the Jet A passenger demand. Analysis using region-specific hydrogen indicates that LH2 aircraft can travel further than LNG aircraft in North America only accounting for 17% of the global demand. 1.59 times the current aviation energy consumption is required if all conventional aircraft are replaced with LH2 designs. Under stricter emissions constraints than those outlined by the IATA LH2 outperforms LNG in Europe and the Americas accounting for 41% of the global demand. Also in these regions the range energy consumption and passenger capacity of LH2 aircraft can be improved upon by combining the advantages of LH2 with LNG in dual-fuel aircraft concepts. The use of LH2 is therefore advantageous within several prominent niches of a future decarbonising aviation system.
Techno-Economic Analysis of a Hydrogen-Based Power Supply Backup System for Tertiary Sector Buildings: A Case Study in Greece
May 2023
Publication
In view of the European Union’s strategy on hydrogen for decarbonization and buildings’ decarbonization targets the use of hydrogen in buildings is expected in the future. Backup power in buildings is usually provided with diesel generators (DGs). In this study the use of a hydrogen fuel cell (HFC) power supply backup system is studied. Its operation is compared to a DG and a techno-economic analysis of the latter’s replacement with an HFC is conducted by calculating relevant key performance indicators (KPIs). The developed approach is presented in a case study on a school building in Greece. Based on the school’s electricity loads which are calculated with a dynamic energy simulation and power shortages scenarios the backup system’s characteristics are defined and the relevant KPIs are calculated. It was found that the HFC system can reduce the annual CO2 emissions by up to 400 kg and has a lower annual operation cost than a DG. However due to its high investment cost its levelized cost of electricity is higher and the replacement of an existing DG is unviable in the current market situation. The techno-economic study reveals that subsidies of around 58–89% are required to foster the deployment of HFC backup systems in buildings.
Process of Transformation to Net Zero Steelmaking: Decarbonisation Scenarios Based on the Analysis of the Polish Steel Industry
Apr 2023
Publication
The European steel industry is experiencing new challenges related to the market situation and climate policy. Experience from the period of pandemic restrictions and the effects of Russia’s armed invasion of Ukraine has given many countries a basis for including steel along with raw materials (coke iron ore electricity) in economic security products (CRMA). Steel is needed for economic infrastructure and construction development as well as a material for other industries (without steel factories will not produce cars machinery ships washing machines etc.). In 2022 steelmakers faced a deepening energy crisis and economic slowdown. The market situation prompted steelmakers to impose restrictions on production volumes (worldwide production fell by 4% compared to the previous year). Despite the difficult economic situation of the steel industry (production in EU countries fell by 11% in 2022 compared to the previous year) the EU is strengthening its industrial decarbonisation policy (“Fit for 55”). The decarbonisation of steel production is set to accelerate by 2050. To sharply reduce carbon emissions steel mills need new steelmaking technologies. The largest global steelmakers are already investing in new technologies that will use green hydrogen (produced from renewable energy sources). Reducing iron ore with hydrogen plasma will drastically reduce CO2 emissions (steel production using hydrogen could emit up to 95% less CO2 than the current BF + BOF blast furnace + basic oxygen furnace integrated method). Investments in new technologies must be tailored to the steel industry. A net zero strategy (deep decarbonisation goal) may have different scenarios in different EU countries. The purpose of this paper was to introduce the conditions for investing in low-carbon steelmaking technologies in the Polish steel market and to develop (based on expert opinion) scenarios for the decarbonisation of the Polish steel industry.
Review of Fuel Cell Technologies and Applications for Sustainable Microgrid Systems
Aug 2020
Publication
The shift from centralized to distributed generation and the need to address energy shortage and achieve the sustainability goals are among the important factors that drive increasing interests of governments planners and other relevant stakeholders in microgrid systems. Apart from the distributed renewable energy resources fuel cells (FCs) are a clean pollution-free highly efficient flexible and promising energy resource for microgrid applications that need more attention in research and development terms. Furthermore they can offer continuous operation and do not require recharging. This paper examines the exciting potential of FCs and their utilization in microgrid systems. It presents a comprehensive review of FCs with emphasis on the developmental status of the different technologies comparison of operational characteristics and the prevailing techno-economic barriers to their progress and the future outlook. Furthermore particular attention is paid to the applications of the FC technologies in microgrid systems such as grid-integrated grid-parallel stand-alone backup or emergency power and direct current systems including the FC control mechanisms and hybrid designs and the technical challenges faced when employing FCs in microgrids based on recent developments. Microgrids can help to strengthen the existing power grid and are also suitable for mitigating the problem of energy poverty in remote locations. The paper is expected to provide useful insights into advancing research and developments in clean energy generation through microgrid systems based on FCs.
Progress in Energy Storage Technologies and Methods for Renewable Energy Systems Application
May 2023
Publication
This paper provides a comprehensive review of the research progress current state-ofthe-art and future research directions of energy storage systems. With the widespread adoption of renewable energy sources such as wind and solar power the discourse around energy storage is primarily focused on three main aspects: battery storage technology electricity-to-gas technology for increasing renewable energy consumption and optimal configuration technology. The paper employs a visualization tool (CiteSpace) to analyze the existing works of literature and conducts an in-depth examination of the energy storage research hotspots in areas such as electrochemical energy storage hydrogen storage and optimal system configuration. It presents a detailed overview of common energy storage models and configuration methods. Based on the reviewed articles the future development of energy storage will be more oriented toward the study of power characteristics and frequency characteristics with more focus on the stability effects brought by transient shocks. This review article compiles and assesses various energy storage technologies for reference and future research.
Effects of Hydrogen Mixture Ratio and Scavenging Air Temperature on Combustion and Emission Characteristics of a 2-stroke Marine Engine
Nov 2022
Publication
A numerical study was conducted to investigate the effects of hydrogen and scavenging air temperature (SAT) on the combustion and emission characteristics of a 2-stroke heavy-duty dual-fuel (DF) marine engine at full load. The engine had a 700 mm bore fuelled with hydrogen–methane (H2-CH4) mixtures. Three-dimensional simulations of the combustion and emission formation inside the engine cylinder with various H2 contents in the H2-CH4 mixture were performed. ANSYS FLUENT simulation software was used to analyse the engine performance in-cylinder pressure temperature and emission characteristics. The CFD models were validated against the measured data recorded from the engine experiments. The results showed that an increase in the in-cylinder peak pressure increased the engine power when the H2 content in the H2-CH4 mixture increased. Notably CO2 and soot emissions decreased (up to more than 65%) when the H2 content in the gaseous mixture increased to 50%. Specific NO emissions in the DF modes were lower than that of the diesel mode when the H2 content in the gaseous mixture was lower than 40%. However they increased compared to the diesel mode when the H2 content continued to increase. This limits the H2 amount that should be used in a gaseous mixture creating NO emissions. The results also showed that the SAT cooling method can further reduce emission problems while enhancing engine power. In particular reducing the SAT to 28 ◦C in the gaseous mixture with 10% H2 ensured that the DF mode emitted the lowest NO emissions compared to the diesel mode. This reduced NO emissions by 37.92% compared to the measured NO emissions of the research engine (a Tier II marine engine). This study successfully analysed the benefits of using an H2-CH4 mixture as the primary fuel and the SAT cooling method in a 2-stroke ME-GI heavy-duty marine engine.
Hydrogen-Fuel Cell Hybrid Powertrain: Conceptual Layouts and Current Applications
Nov 2022
Publication
Transportation is one of the largest sources of CO2 emissions accounting for more than 20% of worldwide emissions. However it is one of the areas where decarbonization presents the greatest hurdles owing to its capillarity and the benefits that are associated with the use of fossil fuels in terms of energy density storage and transportation. In order to accomplish comprehensive decarbonization in the transport sector it will be required to encourage a genuine transition to low-carbon fuels and the widespread deployment of the necessary infrastructures to allow for a large-scale innovation. Renewable hydrogen shows potential for sustainable transportation applications whether in fuel cell electric vehicles (FCEVs) such as automobiles trucks and trains or as a raw material for ship and airplane synthetic fuels. The present paper aims to present how hydrogen-fuel cell hybrid powertrains for road vehicles work in terms of conceptual layouts and operating strategies. A comprehensive overview of real and current applications is presented concerning existing prototypes and commercially available vehicles with a focus on the main key performance indicators such as efficiency mileage and energy consumption.
Integrated Demand Response Design of Integrated Energy System with Mobile Hydrogen Energy Storage in Time-Domain Two-Port Model
Dec 2022
Publication
With the development of energy integration technology demand response (DR) has gradually evolved into integrated demand response (IDR). In this study for the integrated energy system (IES) on the distribution grid side with electricity heat natural gas network and hydrogen energy equipment the analogy relationship between the thermal and mobile hydrogen energy storage networks is proposed. Moreover a unified model that reflects network commonalities across different energy forms is established. Then considering the time delay of the IES in the nontransient network a time-domain two-port model of the IES considering the time delay is established. This model shows the joint effect of time and space on system parameters. Finally this study validates the model in the application of DR. The verification results show that in DR the time-domain two-port model can accurately “cut peaks and fill valleys” for the IES and effectively reduce the operating cost of the IES system.
Multi-Objective Optimization-Based Health-Conscious Predictive Energy Management Strategy for Fuel Cell Hybrid Electric Vehicles
Feb 2022
Publication
The Energy Management Strategy (EMS) in Fuel Cell Hybrid Electric Vehicles (FCHEVs) is the key part to enhance optimal power distribution. Indeed the most recent works are focusing on optimizing hydrogen consumption without taking into consideration the degradation of embedded energy sources. In order to overcome this lack of knowledge this paper describes a new health-conscious EMS algorithm based on Model Predictive Control (MPC) which aims to minimize the battery degradation to extend its lifetime. In this proposed algorithm the health-conscious EMS is normalized in order to address its multi-objective optimization. Then weighting factors are assigned in the objective function to minimize the selected criteria. Compared to most EMSs based on optimization techniques this proposed approach does not require any information about the speed profile which allows it to be used for real-time control of FCHEV. The achieved simulation results show that the proposed approach reduces the economic cost up to 50% for some speed profile keeping the battery pack in a safe range and significantly reducing energy sources degradation. The proposed health-conscious EMS has been validated experimentally and its online operation ability clearly highlighted on a PEMFC delivery postal vehicle.
Global Green Hydrogen-based Steel Opportunities Surrounding High Quality Renewable Energy and Iron Ore Deposits
May 2023
Publication
The steel sector currently accounts for 7% of global energy-related CO2 emissions and requires deep reform to disconnect from fossil fuels. Here we investigate the market competitiveness of one of the widely considered decarbonisation routes for primary steel production: green hydrogen-based direct reduction of iron ore followed by electric arc furnace steelmaking. Through analysing over 300 locations by combined use of optimisation and machine learning we show that competitive renewables-based steel production is located nearby the tropic of Capricorn and Cancer characterised by superior solar with supplementary onshore wind in addition to high-quality iron ore and low steelworker wages. If coking coal prices remain high fossil-free steel could attain competitiveness in favourable locations from 2030 further improving towards 2050. Large-scale implementation requires attention to the abundance of suitable iron ore and other resources such as land and water technical challenges associated with direct reduction and future supply chain configuration.
Synergistic Value in Vertically Integrated Power-to-Gas Energy Systems
Oct 2019
Publication
In vertically integrated energy systems integration frequently entails operational gains that must be traded off against the requisite cost of capacity investments. In the context of the model analyzed in this study the operational gains are subject to inherent volatility in both the price and the output of the intermediate product transferred within the vertically integrated structure. Our model framework provides necessary and sufficient conditions for the value (NPV) of an integrated system to exceed the sum of two optimized subsystems on their own. We then calibrate the model in Germany and Texas for systems that combine wind energy with Power-to-Gas (PtG) facilities that produce hydrogen. Depending on the prices for hydrogen in different market segments we find that a synergistic investment value emerges in some settings. In the context of Texas for instance neither electricity generation from wind power nor hydrogen production from PtG is profitable on its own in the current market environment. Yet provided both subsystems are sized optimally in relative terms the attendant operational gains from vertical integration more than compensate for the stand-alone losses of the two subsystems.
Alternative Vehicular Fuels for Environmental Decarbonization: A Critical Review of Challenges in Using Electricity, Hydrogen, and Biofuels as a Sustainable Vehicular Fuel
Jan 2023
Publication
Using vehicles powered by alternative fuels such as electricity hydrogen and biofuels have been envisioned as the ideal way to curb noxious vehicular emissions. However the availability of resources for the sustainable use of these alternative fuels the possible risks and their fate at the end of their life are frequently questioned necessitating a detailed assessment of factors influencing the use of all three alternative fuels for vehicular use. Though the vehicles powered by batteries and fuel cells are “locally” zero-emission vehicles (ZEVs) they have resource scarcity infrastructure limitations and are relatively expensive thus restricting their market penetration and consumer acceptance. Biofuels though can be used in the existing vehicles procuring the required amounts of feedstock and mitigating food-versus-fuel issues is still a challenge. Overcoming these challenges is a crucial and critical step for the sustained use of these alternative fuels as primary vehicular fuels. To accomplish this all these challenges need to be categorized and a comparative analysis among them is necessary to address them. This work can therefore serve as a ready reference for researchers and policy makers to take appropriate and informed decisions for long-term action to achieve the goals of the Paris agreement to reduce global temperature.
Artificial Intelligence/Machine Learning in Energy Management Systems, Control, and Optimization of Hydrogen Fuel Cell Vehicles
Mar 2023
Publication
Environmental emissions global warming and energy-related concerns have accelerated the advancements in conventional vehicles that primarily use internal combustion engines. Among the existing technologies hydrogen fuel cell electric vehicles and fuel cell hybrid electric vehicles may have minimal contributions to greenhouse gas emissions and thus are the prime choices for environmental concerns. However energy management in fuel cell electric vehicles and fuel cell hybrid electric vehicles is a major challenge. Appropriate control strategies should be used for effective energy management in these vehicles. On the other hand there has been significant progress in artificial intelligence machine learning and designing data-driven intelligent controllers. These techniques have found much attention within the community and state-of-the-art energy management technologies have been developed based on them. This manuscript reviews the application of machine learning and intelligent controllers for prediction control energy management and vehicle to everything (V2X) in hydrogen fuel cell vehicles. The effectiveness of data-driven control and optimization systems are investigated to evolve classify and compare and future trends and directions for sustainability are discussed.
Reduction in Greenhouse Gas and Other Emissions from Ship Engines: Current Trends and Future Options
Nov 2022
Publication
The impact of ship emission reductions can be maximised by considering climate health and environmental effects simultaneously and using solutions fitting into existing marine engines and infrastructure. Several options available enable selecting optimum solutions for different ships routes and regions. Carbon-neutral fuels including low-carbon and carbon-negative fuels from biogenic or non-biogenic origin (biomass waste renewable hydrogen) could resemble current marine fuels (diesel-type methane and methanol). The carbon-neutrality of fuels depends on their Well-to-Wake (WtW) emissions of greenhouse gases (GHG) including carbon dioxide (CO2) methane (CH4) and nitrous oxide emissions (N2O). Additionally non-gaseous black carbon (BC) emissions have high global warming potential (GWP). Exhaust emissions which are harmful to health or the environment need to be equally removed using emission control achieved by fuel engine or exhaust aftertreatment technologies. Harmful emission species include nitrogen oxides (NOx) sulphur oxides (SOx) ammonia (NH3) formaldehyde particle mass (PM) and number emissions (PN). Particles may carry polyaromatic hydrocarbons (PAHs) and heavy metals which cause serious adverse health issues. Carbon-neutral fuels are typically sulphur-free enabling negligible SOx emissions and efficient exhaust aftertreatment technologies such as particle filtration. The combinations of carbon-neutral drop-in fuels and efficient emission control technologies would enable (near-)zero-emission shipping and these could be adaptable in the short- to mid-term. Substantial savings in external costs on society caused by ship emissions give arguments for regulations policies and investments needed to support this development.
Multi-layer Coordinated Optimization of Integrated Energy System with Electric Vehicles Based on Feedback Correction
Sep 2022
Publication
The integrated energy system with electric vehicles can realize multi-energy coordination and complementarity and effectively promote the realization of low-carbon environmental protection goals. However the temporary change of vehicle travel plan will have an adverse impact on the system. Therefore a multi-layer coordinated optimization strategy of electric-thermal-hydrogen integrated energy system including vehicle to grid (V2G) load feedback correction is proposed. The strategy is based on the coordination of threelevel optimization. The electric vehicle charging and discharging management layer comprehensively considers the variance of load curve and the dissatisfaction of vehicle owners and the charging and discharging plan is obtained through multi-objective improved sparrow search algorithm which is transferred to the model predictive control rolling optimization layer. In the rolling optimization process according to the actual situation selectively enter the V2G load feedback correction layer to update V2G load so as to eliminate the impact of temporary changes in electric vehicle travel plans. Simulation results show that the total operating cost with feedback correction is 4.19% lower than that without feedback correction and tracking situation of tie-line planned value is improved which verifies the proposed strategy.
Use of Sustainable Fuels in Aviation—A Review
Mar 2022
Publication
As the push for carbon-neutral transport continues the aviation sector is facing increasing pressure to reduce its carbon footprint. Furthermore commercial air traffic is expected to resume the continuous growth experienced until the pandemic highlighting the need for reduced emissions. The use of alternative fuels plays a key role in achieving future emission goals while also lowering the dependency on fossil fuels. The so-called sustainable aviation fuels (SAF) which encompass bio and synthetic fuels are currently the most viable option but hydrogen is also being considered as a long-term solution. The present paper reviews the production methods logistical and technological barriers and potential for future mass implementation of these alternative fuels. In general biofuels currently present higher technological readiness levels than other alternatives. Sustainable mass production faces critical feedstock-related challenges that synthetic fuels together with other solutions can overcome. All conventional fuel replacements though with different scopes will be important in meeting long-term goals. Government support will play an important role in accelerating and facilitating the transition towards sustainable aviation.
Everything About Hydrogen Podcast: Plotting the Course for a Decarbonized Global Maritime Industry
Jan 2023
Publication
On this episode of EAH we sat down with Dr. Bo Cerup-Simonsen Chief Executive Officer of the Maersk Mc-Kinney Møller Center for Zero Carbon Shipping. Bo holds a PHD in Naval Architecture and Mechanical Engineering and spent seven years as a research engineer at MIT.
Bo explains the Center's work and we discuss decarbonization of shipping using hydrogen derived green fuels.
The podcast can be found on their website.
Bo explains the Center's work and we discuss decarbonization of shipping using hydrogen derived green fuels.
The podcast can be found on their website.
Optimal Energy Management for Hydrogen Economy in a Hybrid Electric Vehicle
Feb 2023
Publication
Fuel cell hybrid electric vehicles (FCEVs) are mainly electrified by the fuel cell (FC) system. As a supplementary power source a battery or supercapacitor (SC) is employed (besides the FC) to enhance the power response due to the slow dynamics of the FC. Indeed the performance of the hybrid power system mainly depends on the required power distribution manner among the sources which is managed by the energy management strategy (EMS). This paper considers an FCEV based on the proton exchange membrane FC (PEMFC)/battery/SC. The energy management strategy is designed to ensure optimum power distribution between the sources considering hydrogen consumption. Its main objective is to meet the electric motor’s required power with economic hydrogen consumption and better electrical efficiency. The proposed EMS combines the external energy maximization strategy (EEMS) and the bald eagle search algorithm (BES). Simulation tests for the Extra-Urban Driving Cycle (EUDC) and New European Driving Cycle (NEDC) profiles were performed. The test is supposed to be performed in typical conditions t = 25 ◦C on a flat road without no wind effect. In addition this strategy was compared with the state machine control strategy classic PI and equivalent consumption minimization strategy. In terms of optimization the proposed approach was compared with the original EEMS particle swarm optimization (PSO)-based EEMS and equilibrium optimizer (EO)-based EEMS. The results confirm the ability of the proposed strategy to reduce fuel consumption and enhance system efficiency. This strategy provides 26.36% for NEDC and 11.35% for EUDC fuel-saving and efficiency enhancement by 6.74% for NEDC and 36.19% for EUDC.
Optimal Design and Operation of Dual-Ejector PEMFC Hydrogen Supply and Circulation System
Jul 2022
Publication
A proton exchange membrane fuel cell (PEMFC) system requires an adequate hydrogen supply and circulation to achieve its expected performance and operating life. An ejector-based hydrogen circulation system can reduce the operating and maintenance costs noise and parasitic power consumption by eliminating the recirculation pump. However the ejector’s hydrogen entrainment capability restricted by its geometric parameters and flow control variability can only operate properly within a relatively narrow range of fuel cell output power. This research introduced the optimal design and operation control methods of a dual-ejector hydrogen supply/circulation system to support the full range of PEMFC system operations. The technique was demonstrated on a 70 kW PEMFC stack with an effective hydrogen entrainment ratio covering 8% to 100% of its output power. The optimal geometry design ensured each ejector covered a specific output power range with maximized entrainment capability. Furthermore the optimal control of hydrogen flow and the two ejectors’ opening and closing times minimized the anode gas pressure fluctuation and reduced the potential harm to the PEMFC’s operation life. The optimizations were based on dedicated computational fluid dynamics (CFD) and system dynamics models and simulations. Bench tests of the resulting ejector-based hydrogen supply/circulation system verified the simulation and optimization results.
How to Reduce the Greenhouse Gas Emissions and Air Pollution Caused by Light and Heavy Duty Vehicles with Battery-electric, Fuel Cell-electric and Catenary Trucks
Mar 2021
Publication
The reduction of greenhouse gas emissions is one of the greatest global challenges through 2050. Besides greenhouse gas emissions air pollution such as nitrogen oxide and particulate matter emissions has gained increasing attention in agglomerated areas with transport vehicles being one of the main sources thereof. Alternative fuels that fulfill the greenhouse gas reduction goals also offer the possibility of solving the challenge of rising urban pollution. This work focuses on the electric drive option for heavy and light duty vehicle freight transport. In this study fuel cell-electric vehicles battery-electric vehicles and overhead catenary line trucks were investigated taking a closer look at their potential to reduce greenhouse gas emissions and air pollution and also considering the investment and operating costs of the required infrastructure. This work was conducted using a bottom-up transport model for the federal state of North Rhine-Westphalia in Germany. Two scenarios for reducing these emissions were analyzed at a spatial level. In the first of these selected federal highways with the highest traffic volume were equipped with overhead catenary lines for the operation of diesel-hybrid overhead trucks on them. For the second spatial scenario the representative urban area of the city of Cologne was investigated in terms of air pollution shifting articulated trucks to diesel-hybrid overhead trucks and rigid trucks trailer trucks and light duty vehicles to battery-electric or fuel cell-electric drives. For the economic analysis the building up of a hydrogen infrastructure in the cases of articulated trucks and all heavy duty vehicles were also taken into account. The results showed that diesel-hybrid overhead trucks are only a cost-efficient solution for highways with high traffic volume whereas battery overhead trucks have a high uncertainty in terms of costs and technical feasibility. In general the broad range of costs for battery overhead trucks makes them competitive with fuel cell-electric trucks. Articulated trucks have the highest potential to be operated as overhead trucks. However the results indicated that air pollution is only partially reduced by switching conventional articulated trucks to electric drive models. The overall results show that a comprehensive approach such as fuel cell-electric drives for all trucks would most likely be more beneficial.
Advancements in Hydrogen Production, Storage, Distribution and Refuelling for a Sustainable Transport Sector: Hydrogen Fuel Cell Vehicles
Jul 2023
Publication
Hydrogen is considered as a promising fuel in the 21st century due to zero tailpipe CO2 emissions from hydrogen-powered vehicles. The use of hydrogen as fuel in vehicles can play an important role in decarbonising the transport sector and achieving net-zero emissions targets. However there exist several issues related to hydrogen production efficient hydrogen storage system and transport and refuelling infrastructure where the current research is focussing on. This study critically reviews and analyses the recent technological advancements of hydrogen production storage and distribution technologies along with their cost and associated greenhouse gas emissions. This paper also comprehensively discusses the hydrogen refuelling methods identifies issues associated with fast refuelling and explores the control strategies. Additionally it explains various standard protocols in relation to safe and efficient refuelling analyses economic aspects and presents the recent technological advancements related to refuelling infrastructure. This study suggests that the production cost of hydrogen significantly varies from one technology to others. The current hydrogen production cost from fossil sources using the most established technologies were estimated at about $0.8–$3.5/kg H2 depending on the country of production. The underground storage technology exhibited the lowest storage cost followed by compressed hydrogen and liquid hydrogen storage. The levelised cost of the refuelling station was reported to be about $1.5–$8/kg H2 depending on the station's capacity and country. Using portable refuelling stations were identified as a promising option in many countries for small fleet size low-to-medium duty vehicles. Following the current research progresses this paper in the end identifies knowledge gaps and thereby presents future research directions.
Sustainable Public Transport Strategies—Decomposition of the Bus Fleet and Its Influence on the Decrease in Greenhouse Gas Emissions
Mar 2022
Publication
The COVID pandemic has caused a major exodus of passengers who chose urban and suburban transport. In many countries especially in the European Union there is a tendency to choose individual means of transport causing damage to the environment and contributing significantly to greenhouse gas emissions. One method to promote urban transport is replacing bus fleets with newer ones thus making public transport more attractive and reducing the emission of harmful exhaust fume components into the atmosphere. The aim of this study was to show a methodology for calculating CO2e for bus fleets. When determining CO2e the principal greenhouse gases such as CO2 CH4 and N2O are usually considered. However CO emissions also have indirect effects on climate through enhanced levels of tropospheric O3 and increased lifetime of CH4; therefore CO2 CH4 N2O and CO emissions were determined for CO2e emission calculations. Two bus fleet variant scenarios were analysed; the first non-investment variant assumed passenger transport using the old fleet without any P&R parking zones. The second scenario was based on the current state which includes the purchase of new low-emission buses and the construction of P&R infrastructure. The calculations were performed using the COPERT emission model with real data from 52 buses running on 13 lines. For the analysed case study of the Rzeszow agglomeration and neighbouring communes implementing the urban and suburban transport modernisation project resulted in a reduction in estimated CO2e emissions of about 450 t. The methodology presented which also considers the impact of CO emissions on the greenhouse effect is a new element of the study that has not been presented in previous works and may serve as a model for other areas in the field of greenhouse gas emission analyses. The future research scope includes investigation of other fuels and powertrain supplies such as hydrogen and hybrid vehicles.
An Integrated Demand Response Dispatch Strategy for Low-carbon Energy Supply Park Considering Electricity-Hydrogen-Carbon Coordination
Apr 2023
Publication
Driven by the goal of ‘carbon peak carbon neutrality’ an integrated demand response strategy for integrated electricity– hydrogen energy systems is proposed for low-carbon energy supply parks considering the multi-level and multi-energy characteristics of campus-based microgrids. Firstly considering the spatial and temporal complementary nature of wind and photovoltaic generation and energy utilization the energy flow framework of the park is built based on the electricity and hydrogen energy carriers. Clean energy is employed as the main energy supply and power heat cooling and gas loads are considered energy consumption. Secondly the operation mechanism of coupled hydrogen storage hydrogen fuel cell and carbon capture equipment is analyzed in the two-stage power-to-gas conversion process. Thirdly considering the operating costs and environmental costs of the park an integrated demand response dispatch model is constructed for the coupled electricity– hydrogen–carbon system while satisfying the system equipment constraints network constraints and energy balance constraints of the park system. Finally Case study in an energy supply park system is implemented. The dispatch results of the integrated demand response with customer participation in the conventional electricity–hydrogen and electricity–hydrogen–carbon modes are compared to verify the effectiveness of the proposed strategy in renewable accommodation environmental protection and economic benefits.
Efficiency and Optimal Load Capacity of E-Fuel-Based Energy Storage Systems
Apr 2023
Publication
This work evaluates the effectiveness of chemical-based solutions for storing large amounts of renewable electricity. Four “Power-to-X-to-Power” pathways are examined comprising hydrogen methane methanol and ammonia as energy carriers. The pathways are assessed using a model scenario where they are produced with electricity from an onshore wind farm stored in suitable facilities and then reconverted to electricity to meet the energy demand of a chemical site. An energy management and storage capacity estimation tool is used to calculate the annual load coverage resulting from each pathway. All four pathways offer a significant increase in load coverage compared to a scenario without storage solution (56.19%). The hydrogen-based pathway has the highest load coverage (71.88%) and round-trip efficiency (36.93%) followed by the ammonia-based (69.62% 31.37%) methanol-based (67.85% 27.00%) and methane-based (67.64% 26.47% respectively) pathways. The substantially larger storage capacity required for gaseous energy carriers to ensure a steady supply to the consumer could be a decisive factor. The hydrogen pathway requires a storage volume up to 10.93 times larger than ammonia and 16.87 times larger than methanol. Notably ammonia and methanol whose load coverages are only 2.26 and 4.03 percentage points lower than that of hydrogen offer the possibility of implementing site-specific storage solutions avoiding potential bottlenecks due to limited pipeline and cavern capacities.
An Energy Balance and Multicriteria Approach for the Sizing of a Hybrid Renewable Energy System with Hydrogen Storage
Mar 2023
Publication
As the clamour for a Net Zero carbon energy economy increases it is necessary to harness the potential of renewable energies in powering buildings to lower fossil power plants' contributions to the overall energy mix. This paper aims to present an energy balance load sensitivity analysis and multi-criteria method for sizing a green energy system for powering two office complexes that house space research laboratories. The energy component considered includes battery storage (BAT) captive diesel generator (DG) fuel cell (FC) hydrogen storage (H2T) solar photovoltaic (PV) and wind turbine. Using HOMER the techno-economic features and the hourly operational details of the energy components were obtained. The efficacy of Entropy- Additive Ratio Assessment was deployed on the outputs from HOMER to obtain the most preferred energy system based on more than one criterion. The result of the study indicates that the most preferred energy system for Abuja is a PV WD FC DG and BAT having a total net present cost (TNPC) of $220930. In contrast the most suitable energy system for the energy in the Anyigba office consists of PV FC and BAT with its TNPC at $106955.
Low-Carbon Strategic Planning of Integrated Energy Systems
Mar 2022
Publication
With the rapid promotion of renewable energy technologies and the trend to a low-carbon society the positive impacts of an integrated energy system that realizes various forms of energy-utilizing improvement and carbon reduction have fully emerged. Hydrogen with a decarbonized characteristic being integrated into the integrated energy system has become a viable option to offset the intermittency of renewables and decline the fossil fuel usage. An optimal planning model of a wind–photovoltaic–hydrogen storage-integrated energy system with the objective of total economic and environmental cost minimization by considering various energy technology investments is proposed. Case studies are developed to compare the economic and environmental benefits of different energy investment scenarios especially hydrogen applications. The cost–benefit analysis was carried out to prove that hydrogen investment is not a cost-competitive option but can alleviate the burden of carbon emissions somehow. Finally sensitivity analysis of key parameters of sale capacity carbon tax and renewable penetration level was performed to indicate the rational investment for a wind–photovoltaic–hydrogen storage-integrated energy system.
A Theoretical Study Using the Multiphase Numerical Simulation Technique for Effective Use of H2 as Blast Furnaces Fuel
Jun 2017
Publication
We present a numerical simulation procedure for analyzing hydrogen oxygen and carbon dioxide gases injections mixed with pulverized coals within the tuyeres of blast furnaces. Effective use of H2 rich gas is highly attractive into the steelmaking blastfurnace considering the possibility of increasing the productivity and decreasing the specific emissions of carbon dioxide becoming the process less intensive in carbon utilization. However the mixed gas and coal injection is a complex technology since significant changes on the inner temperature and gas flow patterns are expected beyond to their effects on the chemical reactions and heat exchanges. Focusing on the evaluation of inner furnace status under such complex operation a comprehensive mathematical model has been developed using the multi interaction multiple phase theory. The BF considered as a multiphase reactor treats the lump solids (sinter small coke pellets granular coke and iron ores) gas liquids metal and slag and pulverized coal phases. The governing conservation equations are formulated for momentum mass chemical species and energy and simultaneously discretized using the numerical method of finite volumes. We verified the model with a reference operational condition using pulverized coal of 215 kg per ton of hot metal (kg thm−1). Thus combined injections of varying concentrations of gaseous fuels with H2 O2 and CO2 are simulated with 220 kg thm−1 and 250 kg thm−1 coals injection. Theoretical analysis showed that stable operations conditions could be achieved with productivity increase of 60%. Finally we demonstrated that the net carbon utilization per ton of hot metal decreased 12%.
Efficient Use of Low-Emission Power Supply for Means of Transport
Apr 2023
Publication
The paper presents the possibilities of low-emission-powered vehicles based mainly on compressed hydrogen. It shows currently used forms of powering vehicles based on their genesis process of obtention and popularity. They are also compared to each other presenting the advantages and disadvantages of a given solution. The share of electricity in transport its forecasts for the future and the possibilities of combination with conventional energy sources are also described. Based on current technological capabilities hydrogen plays a crucial role as presented in the above work constituting a fundamental basis for future transport solutions.
Electric Aircraft Fueled by Liquid Hydrogen and Liquefied Natural Gas
Jul 2021
Publication
The paper is a review of the opportunities and challenges of cryogenic power devices of electric aircraft and the ongoing research and development efforts of the government agencies and the industry. Liquid Hydrogen (LH2) and Liquefied Natural Gas (LNG) are compared to support high temperature superconducting (HTS) and normal metal devices respectively. The power devices were assumed to operate at the normal boiling point of the fuel used. The efficiencies of the electrical devices are estimated based on state-of-the-art technology. The mass flow rates and total fuel requirements for both the cryogenic fuels required to maintain the operating temperatures of the devices were simulated using thermal network models. A twin-aisle 300 passenger aircraft with a 5.5 h flight duration was used for the models. The results show that the required masses of LH2 and LNG are 744 kg and 13638 kg respectively for the cooling requirement. The corresponding volumes of LH2 and LNG required are 9760 and 30300 L respectively. In both cases the estimated mass of the fuel needed for the aircraft is more than what is needed to maintain the cryogenic environment of the power devices. It was concluded that an electric aircraft with LNG cooled normal metal devices is feasible. However an aircraft with HTS devices and cooled with LH2 is more attractive if the ongoing R&D efforts on HTS devices and LH2 infrastructure are successful. The emission reductions would be substantially higher with LH2 particularly when H2 is produced using renewable energy sources.
Frequency Regulation of an Islanded Microgrid Using Hydrogen Energy Storage Systems: A Data-Driven Control Approach
Nov 2022
Publication
Hydrogen energy storage (HES) systems have recently received attention due to their potential to support real-time power balancing in a power grid. This paper proposes a data-driven model predictive control (MPC) strategy for HES systems in coordination with distributed generators (DGs) in an islanded microgrid (MG). In the proposed strategy a data-driven model of the HES system is developed to reflect interactive operations of an electrolyzer hydrogen tank and fuel cell and hence the optimal power sharing with DGs is achieved to support real-time grid frequency regulation (FR). The MG-level controller cooperates with a device-level controller of the HES system that overrides the FR support based on the level of hydrogen. Small-signal analysis is used to evaluate the contribution of FR support. Simulation case studies are also carried out to verify the accuracy of the data-driven model and the proposed strategy is effective for improving the real-time MG frequency regulation compared with the conventional PI-based strategy.
Numerical 1-D Simulations on Single-Cylinder Stationary Spark Ignition Engine using Micro-Emulsions, Gasoline, and Hydrogen in Dual Fuel Mode
Mar 2022
Publication
This work is contributing towards reducing the emissions from stationary spark ignition engine single cylinder by adopting the state of the Art Technology Hydrogen fuel and H2O based Emulsion fuel in dual fuel mode. In addition comparing its combustion emissions and performance with conventional 100% Gasoline fuel. This research work has been done on 1-D AVL Boost Simulation Software by using the single cylinder engine model setup. The main objectives of this research work is to comply with the strict emission rules Euro VII. This work predicted the overall combustion parameters NOx CO and HC emissions as well as several performance measures like power torque BSFC and BMEP of stationary spark ignition engine test rig. Since Hydrogen is zero carbon emission based fuel so it is not creating any carbon-based emissions and has shown to be the most efficient source of energy. Although Hydrogen fuel showed no carbon emissions but NOx emissions were slightly higher than micro-emulsion fuel. Since Hydrogen fuel burns at very high temperature so it produced slightly more NOx emissions. The NOx emissions were 20% higher than emulsion fuel and 10% higher than Gasoline 100% fuel. The H2O based emulsion fuel is also investigated which helped in reducing the emissions and improved the performance of single-cylinder stationary spark Gasoline+ Micro-Emulsion +Hydrogen fuel Lower CO HC and NOx Emissions Improved Power Torque Bsfc & Pressure Constant Speed & variable Load ignition test rig. The Brake power BSFC BMEP & Torque were also investigated power and showed greater improvement for emulsion fuel. At 60% load the Hydrogen fuel showed 50% increase in power as compared to emulsion fuel and 38% more power than Gasoline fuel. Exhaust emissions CO HC were compared for gasoline and emulsion fuel. The CO emissions are 18% lower for micro-emulsion as compared to Gasoline 100% and HC emissions are 12.5% lower than gasoline 100% fuel at 20% load.
Optimal Configuration of Multi-Energy Storage in an Electric–Thermal–Hydrogen Integrated Energy System Considering Extreme Disaster Scenarios
Mar 2024
Publication
Extreme disasters have become increasingly common in recent years and pose significant dangers to the integrated energy system’s secure and dependable energy supply. As a vital part of an integrated energy system the energy storage system can help with emergency rescue and recovery during major disasters. In addition it can improve energy utilization rates and regulate fluctuations in renewable energy under normal conditions. In this study the sizing scheme of multienergy storage equipment in the electric–thermal–hydrogen integrated energy system is optimized; economic optimization in the regular operating scenario and resilience enhancement in extreme disaster scenarios are also considered. A refined model of multi-energy storage is constructed and a two-layer capacity configuration optimization model is proposed. This model is further enhanced by the integration of a Markov two-state fault transmission model which simulates equipment defects and improves system resilience. The optimization process is solved using the tabu chaotic quantum particle swarm optimization (TCQPSO) algorithm to provide reliable and accurate optimization results. The results indicate that addressing severe disaster situations in a capacity configuration fully leverages the reserve energy function of energy storage and enhances system resilience while maintaining economic efficiency; furthermore adjusting the load loss penalty coefficients offers a more targeted approach to the balancing of the system economy and resilience. Thus new algorithmic choices and planning strategies for future research on enhancing the resilience of integrated energy systems under extreme disaster scenarios are provided.
The Hydrogen Fuel Cell Battery: Replacing the Combustion Engine in Heavy Vehicles
Nov 2022
Publication
This opinion piece describes how the optimal integration of hydrogen-fuel-cell with battery in a heavy highly-utilised vehicle can extend vehicle range while cutting refuelling time and reducing cost compared to a pure battery electric vehicle.
Towards Climate-neutral Aviation: Assessment of Maintenance Requirements for Airborne Hydrogen Storage and Distribution Systems
Apr 2023
Publication
Airlines are faced with the challenge of reducing their environmental footprint in an effort to push for climate-neutral initiatives that comply with international regulations. In the past the aviation industry has followed the approach of incremental improvement of fuel efficiency while simultaneously experiencing significant growth in annual air traffic. With the increase in air traffic negating any reduction in Greenhouse Gas (GHG) emissions more disruptive technologies such as hydrogen-based onboard power generation are required to reduce the environmental impact of airline operations. However despite initial euphoria and first conceptual studies for hydrogen-powered aircraft several decades ago there still has been no mass adoption to this day. Besides the challenges of a suitable ground infrastructure this can partly be attributed to uncertainties with the associated maintenance requirements and the expected operating costs to demonstrate the economic viability of this technology. With this study we address this knowledge gap by estimating changes towards scheduled maintenance activities for an airborne hydrogen storage and distribution system. In particular we develop a detailed system design for a hydrogen-powered fuel-cell-based auxiliary power generation and perform a comparative analysis with an Airbus A320 legacy system. That analysis allows us to (a) identify changes for the expected maintenance effort to enhance subsequent techno-economic assessments (b) identify implications of specific design assumptions with corresponding maintenance activities while ensuring regulatory compliance and (c) describe the impact on the resulting task execution. The thoroughly examined interactions between system design and subsequent maintenance requirements of this study can support practitioners in the development of prospective hydrogen-powered aircraft. In particular it allows the inclusion of maintenance implications in early design stages of corresponding system architectures. Furthermore since the presented methodology is transferable to different design solutions it provides a blueprint for alternative operating concepts such as the complete substitution of kerosene by hydrogen to power the main engines.
Computational Analysis of Liquid Hydrogen Storage Tanks for Aircraft Applications
Mar 2023
Publication
During the last two decades the use of hydrogen (H2 ) as fuel for aircraft applications has been drawing attention; more specifically its storage in liquid state (LH2 ) which is performed in extreme cryogenic temperatures (−253 ◦C) is a matter of research. The motivation for this effort is enhanced by the predicted growth of the aviation sector; however it is estimated that this growth could be sustainable only if the strategies and objectives set by global organizations for the elimination of greenhouse gas emissions during the next decades such as the European Green Deal are taken into consideration and consequently technologies such as hydrogen fuel are promoted. Regarding LH2 in aircraft substantial effort is required to design analyze and manufacture suitable tanks for efficient storage. Important tools in this process are computational methods provided by advanced engineering software (CAD/CAE). In the present work a computational study with the finite element method is performed in order to parametrically analyze proper tanks examining the effect of the LH2 level stored as well as the tank geometric configuration. In the process the need for powerful numerical models is demonstrated owing to the highly non-linear dependence on temperature of the involved materials. The present numerical models’ efficiency could be further enhanced by integrating them as part of a total aircraft configuration design loop.
Performance Analysis of a Stand-alone Integrated Solar Hydrogen Energy System for Zero Energy Buildings
Oct 2022
Publication
This study analyzes the optimal sizing design of a stand-alone solar hydrogen hybrid energy system for a house in Afyon Turkey. The house is not connected to the grid and the proposed hybrid system meets all its energy demands; therefore it is considered a zero-energy building. The designed system guarantees uninterrupted and reliable power throughout the year. Since the reliability of the power supply is crucial for the house optimal sizing of the components photovoltaic (PV) panels electrolyzer storage tank and fuel cell stack is critical. Determining the sufficient number of PV panels suitable electrolyzer model and size number of fuel cell stacks and the minimum storage tank volume to use in the proposed system can guarantee an uninterrupted energy supply to the house. In this study a stand-alone hybrid energy system is proposed. The system consists of PV panels a proton exchange membrane (PEM) electrolyzer a storage tank and a PEM fuel cell stack. It can meet the continuous energy demand of the house is sized by using 10 min of averaged solar irradiation and temperature data of the site and consumption data of the house. Present results show that the size of each component in a solar hydrogen hybrid energy system in terms of power depends on the size of each other components to meet the efficiency requirement of the whole system. Choosing the nominal electrolyzer power is critical in such energy systems
Optimization of a Hydrogen-based Hybrid Propulsion System Under Aircraft Performance Constraints
Aug 2021
Publication
This paper addresses the topic of the conceptual design of a regional aircraft with hybrid electric propulsion based on hydrogen fuel cells. It aims at providing an optimization-based method to design a hybrid propulsive system comprising two power sources (jet fuel and hydrogen) for the generation of the required propulsive power and at studying the impact of fuel cell technologies on the aircraft performances. Indeed by performing optimizations for two hybrid propulsive systems using either low temperature or high temperature Proton-exchange membrane fuel cells this study provides a preliminary assessment of the impact of the fuel cell operating temperature on the system design and the overall aircraft performance. First this paper gives a description of the baseline turboprop regional aircraft with a focus on its high speed and low speed flight performances which will serve as requirements for the design of the hybrid aircraft. Then the hybrid electric architecture and the sizing models of the propulsion system are presented. Finally optimizations are performed to design two parallel hybrid propulsive systems based on different fuel cells technologies and aimed at minimizing the block fuel per passenger over a mission of 200 nm. Results show how the proposed methodology and models lead to design two propulsive systems capable of reducing the fuel consumption per passenger by more than 30% compared to the baseline aircraft. The study also shows that the choice of fuel cell operating temperature has a first-order impact on the total mass of the propulsive system due to the higher cooling requirement of the low temperature fuel cells.
Transition to a Low-carbon Building Stock. Techno-economic and Spatial Optimization of Renewables‑hydrogen Strategies in Spain
Oct 2022
Publication
Europe has set ambitious targets to reduce the final energy consumption of buildings in concerning the degree of electrification energy efficiency and penetration of renewable energy sources (RES). So far hydrogen is becoming an increasingly important energy vector offering huge opportunities to promote the share of intermittent RES. Thus this manuscript proposes an energy model for the complete decarbonization of the estimated electricity consumed by the Spanish building stock in 2030 and 2050 scenarios; the model is based on the combination of photovoltaic and wind primary sources and hydrogen technologies considering both distributed and centralized configurations applying also geospatial criteria for their optimal allocation. Large-scale RES generation centralized hydrogen production and re-electrification along with underground hydrogen storage result in the lowest levelized cost of energy (LCOE) hydrogen production costs (HPC) and the highest overall efficiency (μSYS). Wind energy is mainly harvested in the north of Spain while large PV farms are deployed in the mid-south. Furthermore reinforcement of underground hydrogen storage enhances the overall system performance reducing surplus energy and the required RES generation capacity. Finally all the considered scenarios achieve LCOE below the Spanish utility grid benchmark apart from accomplishing the decarbonization goals established for the year 2030.
On the Design and Optimization of Distributed Energy Resources for Sustainable Grid-integrated Microgrid in Ethiopia
Apr 2023
Publication
This paper presents a study that focuses on alleviating the impacts of grid outages in Ethiopia. To deal with grid outages most industrial customers utilize backup diesel generators (DG) which are environmentally unfriendly and economically not viable. Grid integration of hybrid renewable energy systems (HRES) might be a possible solution to enhance grid reliability and reduce environmental and economic impacts of utilizing DG. In this study an optimization of grid integrated HRES is carried out for different dispatch and control strategies. The optimal power supply option is determined by performing comparative analysis of the different configurations of grid integrated HRES. The result of the study shows that grid integrated HRES consisting of photovoltaic and wind turbine as renewable energy sources and battery and hydrogen as hybrid energy storage systems is found to be the optimal system to supply the load demand. From the hydrogen produced on-site the FC generator and FCEVs consume 143 620 kg/yr of hydrogen which is equivalent to 394 955 kg/yr gasoline fuel consumption. This corresponds to saving 1 184 865 kg/yr of CO2 emissions and 605 703 $/yr revenue. Besides this system yields 547 035.4 $/yr revenue by injecting excess electricity to the grid. The study clearly shows the economic and environmental viability of this new technology for implementation.
Deep Decarbonisation Pathways of the Energy System in Times of Unprecedented Uncertainty in the Energy Sector
May 2023
Publication
Unprecedented investments in clean energy technology are required for a net-zero carbon energy system before temperatures breach the Paris Agreement goals. By performing a Monte-Carlo Analysis with the detailed ETSAPTIAM Integrated Assessment Model and by generating 4000 scenarios of the world’s energy system climate and economy we find that the uncertainty surrounding technology costs resource potentials climate sensitivity and the level of decoupling between energy demands and economic growth influence the efficiency of climate policies and accentuate investment risks in clean energy technologies. Contrary to other studies relying on exploring the uncertainty space via model intercomparison we find that the CO2 emissions and CO2 prices vary convexly and nonlinearly with the discount rate and climate sensitivity over time. Accounting for this uncertainty is important for designing climate policies and carbon prices to accelerate the transition. In 70% of the scenarios a 1.5 ◦C temperature overshoot was within this decade calling for immediate policy action. Delaying this action by ten years may result in 2 ◦C mitigation costs being similar to those required to reach the 1.5 ◦C target if started today with an immediate peak in emissions a larger uncertainty in the medium-term horizon and a higher effort for net-zero emissions.
Decarbonisation of Heavy-duty Diesel Engines Using Hydrogen Fuel: A Review of the Potential Impact NOx Emissions
Jul 2022
Publication
As countries seek ways to meet climate change commitments hydrogen fuel offers a low-carbon alternative for sectors where battery electrification may not be viable. Blending hydrogen with fossil fuels requires only modest technological adaptation however since combustion is retained nitrogen oxides (NOx) emissions remain a potential disbenefit. We review the potential air quality impacts arising from the use of hydrogen–diesel blends in heavy-duty diesel engines a powertrain which lends itself to hydrogen co-fuelling. Engine load is identified as a key factor influencing NOx emissions from hydrogen–diesel combustion in heavy-duty engines although variation in other experimental parameters across studies complicates this relationship. Combining results from peer-reviewed literature allows an estimation to be made of plausible NOx emissions from hydrogen–diesel combustion relative to pure-diesel combustion. At 0–30% engine load which encompasses the average load for mobile engine applications NOx emissions changes were in the range 59 to +24% for a fuel blend with 40 e% hydrogen. However at 50–100% load which approximately corresponds to stationary engine applications NOx emissions changes were in the range 28 to +107%. Exhaust gas recirculation may be able to reduce NOx emissions at very high and very low loads when hydrogen is blended with diesel and existing exhaust aftertreatment technologies are also likely to be effective. Recent commercial reporting on the development of hydrogen and hydrogen–diesel dual fuel combustion in large diesel engines are also summarised. There is currently some disconnection between manufacturer reported impacts of hydrogen-fuelling on NOx emissions (always lower emissions) and the conclusions drawn from the peer reviewed literature (frequently higher emissions).
Sustainable Power Generation Expansion in Island Systems with Extensive RES and Energy Storage
Oct 2023
Publication
Insular networks constitute ideal fields for investment in renewables and storage due to their excellent wind and solar potential as well the high generation cost of thermal generators in such networks. Nevertheless in order to ensure the stability of insular networks network operators impose strict restrictions on the expansion of renewables. Storage systems render ideal solutions for overcoming the aforementioned restrictions unlocking additional renewable capacity. Among storage technologies hybrid battery-hydrogen demonstrates beneficial characteristics thanks to the complementary features that battery and hydrogen exhibit regarding efficiency self-discharge cost etc. This paper investigates the economic feasibility of a private investment in renewables and hybrid hydrogen-battery storage realized on the interconnected island of Crete Greece. Specifically an optimization formulation is proposed to optimize the capacity of renewables and hybrid batteryhydrogen storage in order to maximize the profit of investment while simultaneously reaching a minimum renewable penetration of 80% in accordance with Greek decarbonization goals. The numerical results presented in this study demonstrate that hybrid hydrogen-battery storage can significantly reduce electricity production costs in Crete potentially reaching as low as 64 EUR/MWh. From an investor’s perspective even with moderate compensation tariffs the energy transition remains profitable due to Crete’s abundant wind and solar resources. For instance with a 40% subsidy and an 80 EUR/MWh compensation tariff the net present value can reach EUR 400 million. Furthermore the projected cost reductions for electrolyzers and fuel cells by 2030 are expected to enhance the profitability of hybrid renewable-battery-hydrogen projects. In summary this research underscores the sustainable and economically favorable prospects of hybrid hydrogen-battery storage systems in facilitating Crete’s energy transition with promising implications for investors and the wider renewable energy sector.
Towards Sustainable Transport: Techno-Economic Analysis of Investing in Hydrogen Buses in Public Transport in the Selected City of Poland
Dec 2022
Publication
The production storage and use of hydrogen for energy purposes will become increasingly important during the energy transition. One way to use hydrogen is to apply it to power vehicles. This green technological solution affects low-emissions transport which is beneficial and important especially in cities. The authors of this article analyzed the use of hydrogen production infrastructure for bus propulsion in the city of Katowice (Poland). The methods used in the study included a greedy algorithm and cost methods which were applied for the selection of vehicles and identification of the infrastructure for the production storage and refueling of hydrogen as well as to conduct the economic analysis during this term. The article presented the complexity of the techno-economic analysis of the infrastructure and its installation. The key element was the selection of the number of vehicles to the hydrogen production possibilities of an electrolyser and capabilities of the storage and charging infrastructure.
Numerical Study on Hydrogen–Gasoline Dual-Fuel Spark Ignition Engine
Nov 2022
Publication
Hydrogen as a suitable and clean energy carrier has been long considered a primary fuel or in combination with other conventional fuels such as gasoline and diesel. Since the density of hydrogen is very low in port fuel-injection configuration the engine’s volumetric efficiency reduces due to the replacement of hydrogen by intake air. Therefore hydrogen direct in-cylinder injection (injection after the intake valve closes) can be a suitable solution for hydrogen utilization in spark ignition (SI) engines. In this study the effects of hydrogen direct injection with different hydrogen energy shares (HES) on the performance and emissions characteristics of a gasoline port-injection SI engine are investigated based on reactive computational fluid dynamics. Three different injection timings of hydrogen together with five different HES are applied at low and full load on a hydrogen– gasoline dual-fuel SI engine. The results show that retarded hydrogen injection timing increases the concentration of hydrogen near the spark plug resulting in areas with higher average temperatures which led to NOX emission deterioration at −120 Crank angle degree After Top Dead Center (CAD aTDC) start of injection (SOI) compared to the other modes. At −120 CAD aTDC SOI for 50% HES the amount of NOX was 26% higher than −140 CAD aTDC SOI. In the meanwhile an advanced hydrogen injection timing formed a homogeneous mixture of hydrogen which decreased the HC and soot concentration so that −140 CAD aTDC SOI implied the lowest amount of HC and soot. Moreover with the increase in the amount of HES the concentrations of CO CO2 and soot were reduced. Having the HES by 50% at −140 CAD aTDC SOI the concentrations of particulate matter (PM) CO and CO2 were reduced by 96.3% 90% and 46% respectively. However due to more complete combustion and an elevated combustion average temperature the amount of NOX emission increased drastically.
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