Applications & Pathways
Emission Reduction and Cost-benefit Analysis of the Use of Ammonia and Green Hydrogen as Fuel for Marine Applications
Dec 2023
Publication
Increasingly stringent emission standards have led shippers and port operators to consider alternative energy sources which can reduce emissions while minimizing capital investment. It is essential to understand whether there is a certain economic investment gap for alternative energy. The present work mainly focuses on the simulation study of ships using ammonia and hydrogen fuels arriving at Guangzhou Port to investigate the emission advantages and cost-benefit analysis of ammonia and hydrogen as alternative fuels. By collecting actual data and fuel consumption emissions of ships arriving at Guangzhou Port the present study calculated the pollutant emissions and cost of ammonia and hydrogen fuels substitution. As expected it is shown that with the increase of NH3 in fuel mixed fuels will effectively reduce CO and CO2 emissions. Compared to conventional fuel the injection of NH3 increases the NOx emission. However the cost savings of ammonia fuel for CO2 SOx and PM10 reduction are higher than that for NOx. In terms of pollutants ammonia is less expensive than conventional fuels when applied to the Guangzhou Port. However the cost of fuel supply is still higher than conventional energy as ammonia has not yet formed a complete fuel supply and storage system for ships. On the other hand hydrogen is quite expensive to store and transport resulting in higher overall costs than ammonia and conventional fuels even if no pollutants are produced. At present conventional fuels still have advantage in terms of cost. With the promotion of ammonia fuel technology and application the cost of supply will be reduced. It is predicted that by 2035 ammonia will not only have emission reduction benefits but also will have a lower overall economic cost than conventional fuels. Hydrogen energy will need longer development and technological breakthroughs due to the limitation of storage conditions.
Greenhouse Gas Emissions Performance of Electric, Hydrogen and Fossil-Fuelled Freight Trucks with Uncertainty Estimates Using a Probabilistic Life-Cycle Assessment (pLCA)
Jan 2024
Publication
This research conducted a probabilistic life-cycle assessment (pLCA) into the greenhouse gas (GHG) emissions performance of nine combinations of truck size and powertrain technology for a recent past and a future (largely decarbonised) situation in Australia. This study finds that the relative and absolute life-cycle GHG emissions performance strongly depends on the vehicle class powertrain and year of assessment. Life-cycle emission factor distributions vary substantially in their magnitude range and shape. Diesel trucks had lower life-cycle GHG emissions in 2019 than electric trucks (battery hydrogen fuel cell) mainly due to the high carbon-emission intensity of the Australian electricity grid (mainly coal) and hydrogen production (mainly through steam–methane reforming). The picture is however very different for a more decarbonised situation where battery electric trucks in particular provide deep reductions (about 75–85%) in life-cycle GHG emissions. Fuel-cell electric (hydrogen) trucks also provide substantial reductions (about 50–70%) but not as deep as those for battery electric trucks. Moreover hydrogen trucks exhibit the largest uncertainty in emissions performance which reflects the uncertainty and general lack of information for this technology. They therefore carry an elevated risk of not achieving the expected emission reductions. Battery electric trucks show the smallest (absolute) uncertainty which suggests that these trucks are expected to deliver the deepest and most robust emission reductions. Operational emissions (on-road driving and vehicle maintenance combined) dominate life-cycle emissions for all vehicle classes. Vehicle manufacturing and upstream emissions make a relatively small contribution to life-cycle emissions from diesel trucks (
Comparative Analysis of Marine Alternative Fuels for Offshore Supply Vessels
Nov 2024
Publication
This paper provides an in-depth analysis of alternative fuels including liquefied natural gas (LNG) hydrogen ammonia and biofuels assessing their feasibility based on operational requirements availability safety concerns and the infrastructure needed for large-scale adoption. Moreover it examines hybrid and fully electric propulsion systems considering advancements in battery technology and the integration of renewable energy sources such as wind and solar power to further reduce SOV emissions. Key findings from this research indicate that LNG serves as a viable short- to medium-term solution for reducing GHG emissions in the SOV sector due to its relatively lower carbon content compared to MDO and HFO. This paper finally insists that while LNG presents an immediate opportunity for emission reduction in the SOV sector a combination of hydrogen ammonia and hybrid propulsion systems will be necessary to meet long-term decarbonisation goals. The findings underscore the importance of coordinated industry efforts technological innovation and supportive regulatory frameworks to overcome the technical economic and infrastructural challenges associated with decarbonising the maritime industry.
Batteries or Hydrogen or Both for Grid Electricity Storage Upon Full Electrification of 145 Countries with Wind-Water-Solar?
Jan 2024
Publication
Grids require electricity storage. Two emerging storage technologies are battery storage (BS) and green hydrogen storage (GHS) (hydrogen produced and compressed with clean-renewable electricity stored then returned to electricity with a fuel cell). An important question is whether GHS alone decreases system cost versus BS alone or BS+GHS. Here energy costs are modeled in 145 countries grouped into 24 regions. Existing conventional hydropower (CH) storage is used along with new BS and/or GHS. A method is developed to treat CH for both baseload and peaking power. In four regions only CH is needed. In five CH+BS is lowest cost. Otherwise CH+BS+GHS is lowest cost. CH+GHS is never lowest cost. A metric helps estimate whether combining GHS with BS reduces cost. In most regions merging (versus separating) grid and non-grid hydrogen infrastructure reduces cost. In sum worldwide grid stability may be possible with CH+BS or CH+BS+GHS. Results are subject to uncertainties.
Literature Review on Life Cycle Assessment of Transportation Alternative Fuels
Aug 2023
Publication
Environmental concerns such as global warming and human health damage are intensifying and the transportation sector significantly contributes to carbon and harmful emissions. This review examines the life cycle assessment (LCA) of alternative fuels (AF) evaluating current research on fuel types LCA framework development life cycle inventory (LCI) and impact selection. The objectives of this paper are: (1) to compare various AF LCA frameworks and develop a comprehensive framework for the transportation sector; (2) to identify emission hotspots of different AFs through simulations and real-world cases; (3) to review AF LCA research; (4) to extract valuable information for potential future research directions. The analysis reveals that all stages except for hydrogen use have an environmental impact. LCA boundaries and LCIs vary considerably depending on the raw materials production processes and products involved leading to different emission hotspots. Due to knowledge or data limitations some stages remain uncalculated in the current study emphasizing the need for further refinement of the AF LCI. Future research should also explore the various impacts of widespread adoption of alternative fuels in transportation encompassing social economic and environmental aspects. Lastly the review provides structured recommendations for future research directions.
Comparative Study of Electric and Hydrogen Mobility Infrastructures for Sustainable Public Transport: A PyPSA Optimization for a Remote Island Context
Jul 2024
Publication
Decarbonizing road transportation is vital for addressing climate change given that the sector currently contributes to 16% of global GHG emissions. This paper presents a comparative analysis of electric and hydrogen mobility infrastructures in a remote context i.e. an off-grid island. The assessment includes resource assessment and sizing of renewable energy power plants to facilitate on-site self-production. We introduce a comprehensive methodology for sizing the overall infrastructure and carry out a set of techno-economic simulations to optimize both energy performance and cost-effectiveness. The levelized cost of driving at the hydrogen refueling station is 0.40 e/km i.e. 20% lower than the electric charging station. However when considering the total annualized cost the battery-electric scenario (110 ke/year) is more favorable compared to the hydrogen scenario (170 ke/year). To facilitate informed decision-making we employ a multi-criteria decision-making analysis to navigate through the techno-economic findings. When considering a combination of economic and environmental criteria the hydrogen mobility infrastructure emerges as the preferred solution. However when energy efficiency is taken into account electric mobility proves to be more advantageous.
Toward Green Steel: Modelling and Environmental Economic Analysis of Iron Direct Reduction with Different Reducing Gases
Sep 2023
Publication
The objective of the paper is to simulate the whole steelmaking process cycle based on Direct Reduced Iron and Electric Arc Furnace technologies by modeling for the first time the reduction furnace based on kinetic approach to be used as a basis for the environmental and techno-economic plant analysis by adopting different reducing gases. In addition the impact of carbon capture section is discussed. A complete profitability analysis has been conducted for the first time adopting a Monte Carlo simulation approach.<br/>In detail the use of syngas from methane reforming syngas and hydrogen from gasification of municipal solid waste and green hydrogen from water electrolysis are analyzed. The results show that the Direct Reduced Iron process with methane can reduce CO2 emissions by more than half compared to the blast furnace based-cycle and with the adoption of carbon capture greenhouse gas emissions can be reduced by an additional 40%. The use of carbon capture by amine scrubbing has a limited economic disadvantage compared to the scenario without it becoming profitable once carbon tax is included in the analysis. However it is with the use of green hydrogen from electrolyzer that greenhouse gas emissions can be cut down almost completely. To have an environmental benefit compared with the methane-based Direct Reduced Iron process the green hydrogen plant must operate for at least 5136 h per year (64.2% of the plant's annual operating hours) on renewable energy.<br/>In addition the use of syngas and separated hydrogen from municipal solid waste gasification is evaluated demonstrating its possible use with no negative effects on the quality of produced steel. The results show that hydrogen use from waste gasification is more economic with respect to green hydrogen from electrolysis but from the environmental viewpoint the latter results the best alternative. Comparing the use of hydrogen and syngas from waste gasification it can be stated that the use of the former reducing gas results preferable from both the economic and environmental viewpoint.
Opportunities and Challenges of Hydrogen Ports: An Empirical Study in Australia and Japan
Jul 2024
Publication
This paper investigated the opportunities and challenges of integrating ports into hydrogen (H2 ) supply chains in the context of Australia and Japan because they are leading countries in the field and are potential leaders in the upcoming large-scale H2 trade. Qualitative interviews were conducted in the two countries to identify opportunities for H2 ports necessary infrastructure and facilities key factors for operations and challenges associated with the ports’ development followed by an online survey investigating the readiness levels of H2 export and import ports. The findings reveal that there are significant opportunities for both countries’ H2 ports and their respective regions which encompass business transition processes and decarbonisation. However the ports face challenges in areas including infrastructure training standards and social licence and the sufficiency and readiness levels of port infrastructure and other critical factors are low. Recommendations were proposed to address the challenges and barriers encountered by H2 ports. To optimise logistics operations within H2 ports and facilitate effective integration of H2 applications this paper developed a user-oriented working process framework to provide guidance to ports seeking to engage in the H2 economy. Its findings and recommendations contribute to filling the existing knowledge gap pertaining to H2 ports.
Explainable Prognostics-optimization of Hydrogen Carrier Biogas Engines in an Integrated Energy System using a Hybrid Game-theoretic Approach with XGBoost and Statistical Methods
Jul 2025
Publication
Biogas is a renewable fuel source that helps the circular economy by turning organic waste into energy. This study tackles existing research gaps by exploring the use of biogas as a hydrogen carrier in dual-fuel engine systems. It additionally employs explainable machine learning techniques for predictive modelling and interpretive analysis. The dual-fuel engine was powered with biogas as main fuel while biodiesel-diesel blend was used as pilot fuel. The engine was tested at different Compression Ratios (CR) and Brake Powers (BP). The generated data from testing was used to develop the mathematical models and parametric optimization of engine performance and emissions using Response Surface Methodology (RSM). Desirability-based optimization identified optimal results: a Peak Cylinder Pressure (Pmax) of 54.97 bar and a brake thermal efficiency (BTE) of 24.35 % achieved at a CR of 18.3 and a BP of 3.3 kW. The predictive machine learning approach Extreme Gradient Boosting (XGBoost) was employed to develop predictive models. XGBoost precisely forecasted engine performance and emissions with Coefficient of Determination (R2 ) values (up to 0.9960) and minimal Mean Absolute Percentage Error (MAPE) values (1.47–4.89 %) for all parameters. SHapley Additive exPlanations (SHAP) based analysis identified BP as the predominant feature with a normalized importance score reaching up to 0.9 surpassing that of CR. These findings underscore the potential of biogas as a viable sustainable fuel and highlight the role of explainable prediction–optimization frameworks can play in achieving optimal engine performance and emission control.
Thermal Design of a System for Mobile Powersupply
Sep 2023
Publication
Ever more stringent emission regulations for vehicles encourage increasing numbers of battery electric vehicles on the roads. A drawback of storing electric energy in a battery is the comparable low energy density low driving range and the higher propensity to deplete the energy storage before reaching the destination especially at low ambient temperatures. When the battery is depleted stranded vehicles can either be towed or recharged with a mobile recharging station. Several technologies of mobile recharging stations already exist however most of them use fossil fuels to recharge battery electric vehicles. The proposed novel zero emission solution for mobile charging is a combined high voltage battery and hydrogen fuel cell charging station. Due to the thermal characteristics of the fuel cell and high voltage battery (which allow only comparable low coolant temperatures) the thermal design for this specific application (available heat exchanger area zero vehicle speed air flow direction) becomes challenging and is addressed in this work. Experimental methods were used to obtain reliable thermal and electric power measurement data of a 30 kW fuel cell system which is used in the Mobile Hydrogen Powersupply. Subsequently simulation methods were applied for the thermal design and optimisation of the coolant circuits and heat exchangers. It is shown that an battery electric vehicle charging power of 22 kW requires a heat exchanger area of 1 m2 of which 60 % is used by the fuel cell heat exchanger and the remainder by the battery heat exchanger to achieve steady state operation at the highest possible ambient temperature of 436 °C. Furthermore the simulation showed that when the charging power of 22 kW is solely provided by the high voltage battery the highest possible ambient temperature is 42 °C. When the charging power is decreased operation up to the maximum ambient temperatures of 45 °C can be achieved. The results of maximum charging power and limiting ambient temperature give insights for further system improvements which are: sizing of fuel cell or battery trailer design and heat exchanger area operation strategy of the system (power split between high voltage battery and fuel cell) as well as possible dynamic operation scenarios.
Internal Combustion Engines and Carbon-Neutral Fuels: A Perspective on Emission Neutrality in the European Union
Mar 2024
Publication
Nowadays there is an intense debate in the European Union (EU) regarding the limits to achieve the European Green Deal to make Europe the first climate-neutral continent in the world. In this context there are also different opinions about the role that thermal engines should play. Furhermore there is no clear proposal regarding the possibilities of the use of green hydrogen in the transport decarbonization process even though it should be a key element. Thus there are still no precise guidelines regarding the role of green hydrogen with it being exclusively used as a raw material to produce E-fuels. This review aims to evaluate the possibilities of applying the different alternative technologies available to successfully complete the process already underway to achieve Climate Neutrality by about 2050 depending on the maturity of the technologies currently available and those anticipated to be available in the coming decades.
Energy Management Strategy Based on Reinforcement Learning and Frequency Decoupling for Fuel Cell Hybrid Powertrain
Apr 2024
Publication
This study presents a Two-Layer Deep Deterministic Policy Gradient (TL-DDPG) energy management strategy for Hydrogen fuel cell hybrid train that aims to solve the problem that traditional reinforcement learning strategies require high initial values and are difficult to optimize global variables. Augmenting the optimization capabilities of the inner layer a frequency decoupling algorithm integrates into the outer layer furnishing a fitting initial value for strategy optimization. This addition aims to bolster the stability of fuel cell output thereby enhancing the overall efficiency of the hybrid power system. In comparison with the traditional reinforcement learning algorithm the proposed approach demonstrates notable improvements: a reduction in hydrogen consumption per 100 km by 16.3 kg a 9.7% increase in the output power stability of the fuel cell and a 1.8% enhancement in its efficiency.
Numerical Study on the Use of Ammonia/Hydrogen Fuel Blends for Automotive Sparking-ignition Engines
Jun 2023
Publication
The importance of new alternative fuels has assumed great relevance in the last decades to face the issues of global warming and pollutant emissions from energy production. The scientific community is responsible for developing solutions to achieve the necessary environmental restriction policies. In this context ammonia appears as a potential fuel candidate and energy vector that may solve the technological difficulties of using hydrogen (H2 ) directly in internal combustion engines. Its high hydrogen content per unit mass higher energy density than liquid hydrogen well-developed infrastructure and experience in handling and storage make it suitable to be implemented as a long-term solution. In this work a virtual engine model was developed to perform prospective simulations of different operating conditions using ammonia and H2 -enriched ammonia as fuel in a spark-ignition (SI) engine integrating a chemical kinetics model and empirical correlations for combustion prediction. In addition specific conditions were evaluated to consider and to understand the governing parameters of ammonia combustion using computational fluid dynamics (CFD) simulations. Results revealed similar thermal efficiency than methane fuel with considerable improvements after appropriate H2 - enrichment. Moreover increasing the intake temperature and the turbulence intensity inside the cylinder evinced significant reductions in combustion duration. Finally higher compression ratios ensure efficiency gains with no evidence of abnormal combustion (knocking) even at high compression ratios (above 16:1) and low engine speeds (800 rpm). Numerical simulations showed the direct influence of the flame front surface area and the turbulent combustion velocity on efficiency reflecting the need for optimizing the SI engines design paradigm for ammonia applications.
Environmental-economic Sustainability of Hydrogen and Ammonia Fuels for Short Sea Shipping Operations
Jan 2024
Publication
Alternative fuels of low or zero carbon content can decarbonise the shipping operations. This study aims at assessing the lifetime environmental-economic sustainability of ammonia and hydrogen as alternatives to diesel fuel for short sea shipping cargo vessels. A model is employed to calculate key performance indicators representing the lifetime financial sustainability and environmental footprint of the case ship using a realistic operating profile and considering several scenarios with different diesel substitution rates. Scenarios meeting the carbon emissions reduction targets set by the International Maritime Organisation (IMO) for 2030 are identified whereas policy measures for their implementation including the emissions taxation are discussed. The derived results demonstrate that the future implementation of carbon emissions taxation in the ranges of 136–965 €/t for hydrogen and 356–2647 €/t for ammonia can support these fuels financial sustainability in shipping. This study provides insights for adopting zero-carbon fuels and as such impacts the de-risking of shipping decarbonisation.
Multi-Objective Robust Optimization of Integrated Energy System with Hydrogen Energy Storage
Feb 2024
Publication
A novel multi-objective robust optimization model of an integrated energy system with hydrogen storage (HIES) considering source–load uncertainty is proposed to promote the low-carbon economy operation of the integrated energy system of a park. Firstly the lowest total system cost and carbon emissions are selected as the multi-objective optimization functions. The Pareto front solution set of the objective function is applied by compromise planning and the optimal solution among them is obtained by the maximum–minimum fuzzy method. Furthermore the robust optimization (RO) approach is introduced to cope with the source–load uncertainty effectively. Finally it is demonstrated that the illustrated HIES can significantly reduce the total system cost carbon emissions and abandoned wind and solar power. Meanwhile the effectiveness of the proposed model and solution method is verified by analyzing the influence of multi-objective solutions and a robust coefficient on the Chongli Demonstration Project in Hebei Province.
A Review of the Research Progress and Application of Key Components in the Hydrogen Fuel Cell System
Jan 2024
Publication
The hydrogen cycle system one of the main systems used for hydrogen fuel cells has many advantages. It can improve the efficiency the water capacity and the management of thermal fuel cells. It can also enhance the safety of the system. Therefore it is widely used in hydrogen fuel cell vehicles. We introduce the structure and principles of hydrogen cycle pumps ejectors and steam separators and analyze and summarize the advantages of the components as well as reviewing the latest research progress and industrialization status of hydrogen cycle pumps and ejectors. The technical challenges in hydrogen circulation systems and the development direction of key technologies in the future are discussed. This paper aims to provide a reference for research concerning hydrogen energy storage application technology in hydrogen fuel cell systems.
The Possibility of Using Hydrogen as a Green Alternative to Traditional Marine Fuels on an Offshore Vessel Serving Wind Farms
Nov 2024
Publication
Achieving the required decarbonisation targets by the shipping industry requires a transition to technologies with zero or near-zero greenhouse gas (GHG) emissions. One promising shipping fuel with zero emission of exhaust gases (including CO2) is green hydrogen. This type of fuel recognised as a 100% clean solution is being investigated for feasible use on a service offshore vessel (SOV) working for offshore wind farms. This study aims to examine whether hydrogen may be used on an SOV in terms of the technical and economic challenges associated with the design process and other factors. In the analyses a reference has been made to the current International Maritime Organization (IMO) guidelines and regulations. In this study it was assumed that hydrogen would be directly combusted in a reciprocating internal combustion engine. This engine type was reviewed. In further research hydrogen fuel cell propulsion systems will also be considered. The hydrogen demand was calculated for the assumed data of the SOV and then the volume and number of highpressure tanks were estimated. The analyses revealed that the SOV cannot undertake 14-day missions using hydrogen fuel stored in cylinders on board. These cylinders occupy 66% of the ship’s current volume and their weight including the modular system accounts for 62% of its deadweight. The costs are over 100% higher compared to MDO and LNG fuels and 30% higher than methanol. The actual autonomy of the SOV with hydrogen fuel is 3 days.
Experimental Investigations of the Hydrogen Injectors on the Combustion Characteristics and Performance of a Hydrogen Internal Combustion Engine
Feb 2024
Publication
Hydrogen is regarded as an ideal zero-carbon fuel for an internal combustion engine. However the low mass flow rate of the hydrogen injector and the low volume heat value of the hydrogen strongly restrict the enhancement of the hydrogen engine performance. This experimental study compared the effects of single-injectors and double-injectors on the engine performance combustion pressure heat release rate and the coefficient of variation (CoVIMEP) based on a singlecylinder 0.5 L port fuel injection hydrogen engine. The results indicated that the number of hydrogen injectors significantly influences the engine performance. The maximum brake power is improved from 4.3 kW to 6.12 kW when adding the injector. The test demonstrates that the utilization of the double-injector leads to a reduction in hydrogen obstruction in the intake manifold consequently minimizing the pumping losses. The pump mean effective pressure decreased from −0.049 MPa in the single-injector condition to −0.029 MPa in the double-injector condition with the medium loads. Furthermore the double-injector exhibits excellent performance in reducing the coefficient of variation. The maximum CoVIMEP decreased from 2.18% in the single-injector configuration to 1.92% in the double-injector configuration. This result provides new insights for optimizing hydrogen engine injector design and optimizing the combustion process.
Energy Efficiency Analysis of a Fuel Cell Bus Model Using Real Scenarios Generated by Data Collection
Feb 2024
Publication
Modernizing public transportation is crucial given the ongoing call for sustainable mobility. Growing concerns about climate change and the increasingly stringent emissions standards have compelled public transport operators to embrace alternative propulsion vehicles on a broader scale. For the past years the Battery Electric Buses (BEBs) have been the vehicle of choice for public transportation. However an emerging contender in this sector is the Fuel Cell Electric Bus (FCEB). This paper aims to evaluate the way one such vehicle would perform in terms of energy efficiency while being exploited in an urban scenario generated from collected data.
Comparative Analysis of Solar Cells and Hydrogen Fuels: A Mini Review
Jul 2024
Publication
The aim of this mini-review is to compare the effectiveness and potential of solar cells and hydrogen fuel technologies in clean energy generation. Key aspects such as efficiency scalability environmental footprint and technological maturity are examined. Solar cells are analyzed for their ability to convert sunlight into electricity efficiently and their potential for widespread deployment with minimal environmental impact. Hydrogen fuel technologies are assessed based on their efficiency in hydrogen production scalability and overall environmental footprint from production to end use. The review identifies significant challenges including high costs infrastructure needs and policy requirements as well as opportunities for innovation and market growth. The findings provide insights to guide decision-making towards a sustainable energy future.
Comprehensive Techno-economic Assessment of Power Technologies and Synthetic Fuels under Discussion for Ship Applications
Jun 2023
Publication
The decarbonization of the global ship traffic is one of the industry’s greatest challenges for the next decades and will likely only be achieved with the introduction of synthetic fuels. Until now however not one single best technology solution emerged to ideally fit this task. Instead different energy carriers including hydrogen ammonia methanol methane and synthetic diesel are subject of discussion for usage in either internal combustion engines or fuel cells. In order to drive the selection procedure a case study for the year 2030 with all eligible combinations of power technologies and fuels is conducted. The assessment quantifies the technologies’ economic performances for cost-optimized system designs and in dependence of a ship’s mission characteristics. Thereby the influence of trends for electrofuel prices and shipboard volume opportunity costs are examined. Even if gaseous hydrogen is often considered not suitable for large ship applications due to its low volumetric energy density both the comparatively small fuel price and the high efficiency of fuel cells lead to the overall smallest system costs for passages up to 21 days depending on assumed cost parameters. Only for missions longer than seven days fuel cells operating on methanol or ammonia can compete with gaseous hydrogen economically.
Distributionally Robust Optimal Scheduling of Integrated Energy Systems Including Hydrogen Fuel Cells Considering Uncertainties
Aug 2023
Publication
The economic operation of the integrated energy system faces the problems of coupling between energy production and conversion equipment in the system and the imbalance of various energy demands. Therefore taking system safety as the constraint and minimum economic cost as the objective function including fuel cost operation and maintenance cost this paper proposes the operation dispatching model of the integrated energy system based on hydrogen fuel cell (HFC) including HFC photovoltaic wind turbine electric boiler electric chiller absorption chiller electric energy storage and thermal energy storage equipment. On this basis a distributionally robust optimization (DRO) model is introduced to deal with the uncertainty of wind power and photovoltaic output. In the distributionally robust optimization model Kullback–Leibler (KL) divergence is used to construct an ambiguity set which is mainly used to describe the prediction errors of renewable energy output. Finally the DRO economic dispatching model of the HFC integrated energy system (HFCIES) is established. Besides based on the same load scenario the economic benefits of hybrid energy storage equipment are discussed. The dispatching results show that compared with the scenario of only electric energy storage and only thermal energy storage the economic cost of the scenario of hybrid electric and thermal storage can be reduced by 3.92% and 7.55% respectively and the use of energy supply equipment can be reduced and the stability of the energy storage equipment can be improved.
A Review of Current Advances in Ammonia Combustion from the Fundamentals to Applications in Internal Combustion Engines
Aug 2023
Publication
The energy transition from hydrocarbon-based energy sources to renewable and carbon-free energy sources such as wind solar and hydrogen is facing increasing demands. The decarbonization of global transportation could come true via applying carbon-free fuel such as ammonia especially for internal combustion engines (ICEs). Although ammonia has advantages of high hydrogen content high octane number and safety in storage it is uninflammable with low laminar burning velocity thus limiting its direct usage in ICEs. The purpose of this review paper is to provide previous studies and current research on the current technical advances emerging in assisted combustion of ammonia. The limitation of ammonia utilization in ICEs such as large minimum ignition energy lower flame speed and more NOx emission with unburned NH3 could be solved by oxygen-enriched combustion ammonia–hydrogen mixed combustion and plasma-assisted combustion (PAC). In dual-fuel or oxygen-enriched NH3 combustion accelerated flame propagation speeds are driven by abundant radicals such as H and OH; however NOx emission should be paid special attention. Furthermore dissociating NH3 in situ hydrogen by non-noble metal catalysts or plasma has the potential to replace dual-fuel systems. PAC is able to change classical ignition and extinction S-curves to monotonic stretching which makes low-temperature ignition possible while leading moderate NOx emissions. In this review the underlying fundamental mechanism under these technologies are introduced in detail providing new insight into overcoming the bottleneck of applying ammonia in ICEs. Finally the feasibility of ammonia processing as an ICE power source for transport and usage highlights it as an appealing choice for the link between carbon-free energy and power demand.
Challenges and Solutions of Hydrogen Fuel Cells in Transportation Systems: A Review and Prospects
Jun 2023
Publication
Conventional transportation systems are facing many challenges related to reducing fuel consumption noise and pollutants to satisfy rising environmental and economic criteria. These requirements have prompted many researchers and manufacturers in the transportation sector to look for cleaner more efficient and more sustainable alternatives. Powertrains based on fuel cell systems could partially or completely replace their conventional counterparts used in all modes of transport starting from small ones such as scooters to large mechanisms such as commercial airplanes. Since hydrogen fuel cells (HFCs) emit only water and heat as byproducts and have higher energy conversion efficiency in comparison with other conventional systems it has become tempting for many scholars to explore their potential for resolving the environmental and economic concerns associated with the transportation sector. This paper thoroughly reviews the principles and applications of fuel cell systems for the main transportation schemes including scooters bicycles motorcycles cars buses trains and aerial vehicles. The review showed that fuel cells would soon become the powertrain of choice for most modes of transportation. For commercial long-rage airplanes however employing fuel cells will be limited due to the replacement of the axillary power unit (APU) in the foreseeable future. Using fuel cells to propel such large airplanes would necessitate redesigning the airplane structure to accommodate the required hydrogen tanks which could take a bit more time.
Assessment of a Coupled Electricity and Hydrogen Sector in the Texas Energy System in 2050
Oct 2024
Publication
Due to its ability to reduce emissions in the hard-to-abate sectors hydrogen is expected to play a significant role in future energy systems. This study modifies a sector-coupled dynamic modeling framework for electricity and hydrogen by including policy constraints carbon prices and possible hydrogen pathways and applies it to Texas in 2050. The impact of financial policies including the US clean hydrogen production tax credit on required infrastructure and costs are explored. Due to low natural gas prices financial levers are necessary to promote low-carbon hydrogen production as the optimized solution. The Levelized Costs of Hydrogen are found to be $1.50/kg in the base case (primarily via steam methane reformation production) and lie between $2.10 - 3.10/kg when production is via renewable electrolysis. The supporting infrastructure required to supply those volumes of renewable hydrogen is immense. The hydrogen tax credit was found to be enough to drive production via electrolysis.
Modelling and Operation Strategy Approaches for On-site Hydrogen Refuelling Stations
Aug 2023
Publication
The number of Fuel Cell Electric Vehicles (FCEVs) in circulation has undergone a significant increase in recent years. This trend is foreseen to be stronger in the near future. In correlation with the FCEVs market increase the hydrogen delivery infrastructure must be developed. With this aim many countries have announced ambitious projects. For example Spain has the objective of increasing the number of Hydrogen Refuelling Stations (HRS) with public access from three units in operation currently to about 150 by 2030. HRSs are complex systems with high variability in terms of layout design size of components operational strategy hydrogen generation method or hydrogen generation location. This paper is focused on on-site HRS with electrolysis-based hydrogen production which provides interesting advantages when renewable energy is utilized compared to off-site hydrogen production despite their complexity. To optimize HRS design and operation a simulation model must be implemented. This paper describes a generic on-site HRS with electrolysis-based hydrogen production a cascaded multi-tank storage system with multiple compressors renewable energy sources and multiple types of dispensing formats. A modelling approach of the layout is presented and tested with real-based parameters of an HRS currently under development which is capable of producing 11.34 kg/h of green H2 with irradiation at 1000 W/m2. For the operation an operational strategy is proposed. The modelled system is tested through several simulations. A sensitivity analysis of the effects of hydrogen demand and day-ahead hydrogen production objective on emissions demand satisfaction and variable costs is performed. Simulation results show how the operational strategy has achieved service up to 310 FCEVs refuelling events of heavy duty and light duty FCEVs bringing the total H2 sold up to almost 7200 H2kg in one month of winter. Additionally considering variable costs of the energy from the utility grid the model shows a profit in the range of 21–50 k€ for a daily demand of 60 H2kg/day and 100 H2kg/day respectively. In terms of emissions a year simulation with 60 H2kg/day of demand shows specific emissions in the production of H2 in Spain of 6.26 kgCO2eq/H2kg which represents a greenhouse gas emission intensity of 52.26 kgCO2eq/H2MJ.
Performance Evaluation of a Fuel Cell mCHP System under Different Configurations of Hydrogen Origin and Heat Recovery
Sep 2023
Publication
Motivated by the growing importance of fuel cell systems as the basis for distributed energy generation systems this work considers a micro-combined heat and power (mCHP) generation system based on a fuel cell integrated to satisfy the (power and thermal) energy demands of a residential application. The main objective of this work is to compare the performance of several CHP configurations with a conventional alternative in terms of primary energy consumption greenhouse gas (GHG) emissions and economic viability. For that a simulation tool has been developed to easily estimate the electrical and thermal energy generated by a hydrogen fuel cell and all associated results related to the hydrogen production alternatives: excess or shortfall of electrical and thermal energy CO2 emission factor overall performance operating costs payback period etc. A feasibility study of different configuration possibilities of the micro-CHP generation system has been carried out considering different heat-to-power ratios (HPRs) in the possible demands and analyzing primary energy savings CO2 emissions savings and operating costs. An extensive parametric study has been performed to analyze the effect of the fuel cell’s electric power and number of annual operation hours as parameters. Finally a study of the influence of the configuration parameters on the final results has been carried out. Results show that in general configurations using hydrogen produced from natural gas save more primary energy than configurations with hydrogen production from electricity. Furthermore it is concluded that the best operating points are those in which the generation system and the demand have similar HPR. It has also been estimated that a reduction in renewable hydrogen price is necessary to make these systems profitable. Finally it has been determined that the most influential parameters on the results are the fuel cell electrical efficiencies hydrogen production efficiency and hydrogen cost.
Socio-technical Imaginaries of Climate-neutral Aviation
May 2024
Publication
Limiting global warming to 1.5 ◦C is crucial to prevent the worst effects of climate change. This entails also the decarbonization of the aviation sector which is considered to be a “hard-to-abate” sector and thus requires special attention regarding its sustainability transition. However transition pathways to a potentially climateneutral aviation sector are unclear with different stakeholders having diverse imaginations of the sector's future. This paper aims to analyze socio-technical imaginaries of climate-neutral aviation as different perceptions of various stakeholders on this issue have not been sufficiently explored so far. In that sense this work contributes to the current scientific debate on socio-technical imaginaries of energy transitions for the first time studying the case of the aviation sector. Drawing on six decarbonization reports composed by different interest groups (e.g. industry academia and environmental associations) three imaginaries were explored following the process of a thematic analysis: rethinking travel and behavioral change (travel innovation) radical modernization and technological progress (fleet innovation) and transition to alternative fuels and renewable energy sources (fuel innovation). The results reveal how different and partly conflicting socio-technical imaginaries are co-produced and how the emergence and enforceability of these imaginaries is influenced by the situatedness of their creators indicating that the sustainability transition of aviation also raises political issues. Essentially as socio-technical imaginaries act as a driver for change policymakers should acknowledge the existence of alternative and counter-hegemonic visions created by actors from civil society settings to take an inclusive and equitable approach to implementing pathways towards climate-neutral aviation.
Capacity Expansion Planning of Hydrogen-Enabled Industrial Energy Systems for Carbon Dioxide Peaking
Jul 2024
Publication
As the main contributor of carbon emissions the low-carbon transition of the industrial sector is important for achieving the goal of carbon dioxide peaking. Hydrogen-enabled industrial energy systems (HIESs) are a promising way to achieve the low-carbon transition of industrial energy systems since the hydrogen can be well coordinated with renewable energy sources and satisfy the high and continuous industrial energy demand. In this paper the long-term capacity expansion planning problem of the HIES is formulated from the perspective of industrial parks and the targets of carbon dioxide peaking and the gradual decommissioning of existing equipment are considered as constraints. The results show that the targets of carbon dioxide peaking before different years or with different emission reduction targets can be achieved through the developed method while the economic performance is ensured to some extent. Meanwhile the overall cost of the strategy based on purchasing emission allowance is three times more than the cost of the strategy obtained by the developed method while the emissions of the two strategies are same. In addition long-term carbon reduction policies and optimistic expectations for new energy technologies will help industrial parks build more new energy equipment for clean transformation.
Low-carbon Economic Dispatch of Hydrogen-containing Integrated Energy System Considering Stepped Demand Response
Apr 2024
Publication
Vigorously developing an integrated energy system (IES) centered on the utilization of hydrogen energy is a crucial strategy to achieve the goal of carbon peaking and carbon neutrality. During the energy conversion process a hydrogen storage system releases a large amount of heat. By integrating a heat recovery mechanism we have developed a sophisticated hydrogen energy utilization model that accommodates multiple operational conditions and maximizes heat recovery thereby enhancing the efficiency of energy use on the supply side. To harness the potential of load-side response an integrated demand response (IDR) model accounting for price and incentives is established and a ladder-type subsidy incentive mechanism is proposed to deeply unlock load-side response capacity. Considering system economics and low carbon an IES source-load coordinated optimal scheduling model is proposed optimizing source-load coordinated operation for optimally integrated economy factoring in reward and punishment ladder-type carbon trading. Demonstrations reveal that the proposed methodology not only improves the efficiency of energy utilization but also minimizes wind energy wastage activates consumer engagement and reduces both system costs and carbon emissions thus proving the effectiveness of our optimization approach.
Co-Combustion of Hydrogen with Diesel and Biodiesel (RME) in a Dual-Fuel Compression-Ignition Engine
Jun 2023
Publication
The utilization of hydrogen for reciprocating internal combustion engines remains a subject that necessitates thorough research and careful analysis. This paper presents a study on the co-combustion of hydrogen with diesel fuel and biodiesel (RME) in a compression-ignition piston engine operating at maximum load with a hydrogen content of up to 34%. The research employed engine indication and exhaust emissions measurement to assess the engine’s performance. Engine indication allowed for the determination of key combustion stages including ignition delay combustion time and the angle of 50% heat release. Furthermore important operational parameters such as indicated pressure thermal efficiency and specific energy consumption were determined. The evaluation of dual-fuel engine stability was conducted by analyzing variations in the coefficient of variation in indicated mean effective pressure. The increase in the proportion of hydrogen co-combusted with diesel fuel and biodiesel had a negligible impact on ignition delay and led to a reduction in combustion time. This effect was more pronounced when using biodiesel (RME). In terms of energy efficiency a 12% hydrogen content resulted in the highest efficiency for the dual-fuel engine. However greater efficiency gains were observed when the engine was powered by RME. It should be noted that the hydrogen-powered engine using RME exhibited slightly less stable operation as measured by the COVIMEP value. Regarding emissions hydrogen as a fuel in compression ignition engines demonstrated favorable outcomes for CO CO2 and soot emissions while NO and HC emissions increased.
Technology Pathways, Efficiency Gains and Price Implications of Decarbonising Residential Heat in the UK
Jun 2023
Publication
The UK government’s plans to decarbonise residential heating will mean major changes to the energy system whatever the specific technology pathway chosen driving a range of impacts on users and suppliers. We use an energy system model (UK TIMES) to identify the potential energy system impacts of alternative pathways to low or zero carbon heating. We find that the speed of transitioning can affect the network investment requirements the overall energy use and emissions generated while the primary heating fuel shift will determine which sectors and networks require most investment. Crucially we identify that retail price differences between heating fuels in the UK particularly gas and electricity could erode or eliminate bill savings from switching to more efficient heating systems.
Feasibility Assessment of Alternative Clean Power Systems onboard Passenger Short-Distance Ferry
Sep 2023
Publication
In order to promote low-carbon fuels such as hydrogen to decarbonize the maritime sector it is crucial to promote clean fuels and zero-emission propulsion systems in demonstrative projects and to showcase innovative technologies such as fuel cells in vessels operating in local public transport that could increase general audience acceptability thanks to their showcase potential. In this study a short sea journey ferry used in the port of Genova as a public transport vehicle is analyzed to evaluate a ”zero emission propulsion” retrofitting process. In the paper different types of solutions (batteries proton exchange membrane fuel cell (PEMFC) solid oxide fuel cell (SOFC)) and fuels (hydrogen ammonia natural gas and methanol) are investigated to identify the most feasible technology to be implemented onboard according to different aspects: ferry daily journey and scheduling available volumes and spaces propulsion power needs energy storage/fuel tank capacity needed economics etc. The paper presents a multi-aspect analysis that resulted in the identification of the hydrogen-powered PEMFC as the best clean power system to guarantee for this specific case study a suitable retrofitting of the vessel that could guarantee a zero-emission journey
Feasibility of Green Hydrogen-Based Synthetic Fuel as a Carbon Utilization Option: An Economic Analysis
Sep 2023
Publication
Singapore has committed to achieving net zero emissions by 2050 which requires the pursuit of multiple decarbonization pathways. CO2 utilization methods such as fuel production may provide a fast interim solution for carbon abatement. This paper evaluates the feasibility of green hydrogen-based synthetic fuel (synfuel) production as a method for utilizing captured CO2. We consider several scenarios: a baseline scenario with no changes local production of synfuel with hydrogen imports and overseas production of synfuel with CO2 exports. This paper aims to determine a CO2 price for synfuel production evaluate the economic viability of local versus overseas production and investigate the effect of different cost parameters on economic viability. Using the current literature we estimate the associated production and transport costs under each scenario. We introduce a CO2 utilization price (CUP) that estimates the price of utilizing captured CO2 to produce synfuel and an adjusted CO2 utilization price (CCUP) that takes into account the avoided emissions from crude oil-based fuel production. We find that overseas production is more economically viable compared to local production with the best case CCUP bounds giving a range of 142–148 $/tCO2 in 2050 if CO2 transport and fuel shipping costs are low. This is primarily due to the high cost of hydrogen feedstock especially the transport cost which can offset the combined costs of CO2 transport and fuel shipping. In general we find that any increase in the hydrogen feedstock cost can significantly affect the CCUP for local production. Sensitivity analysis reveals that hydrogen transport cost has a significant impact on the viability of local production and if this cost is reduced significantly local production can be cheaper than overseas production. The same is true if the economies of scale for local production is significantly better than overseas production. A significantly lower carbon capture cost can also the reduce the CCUP significantly.
Techno-economic Modelling of Zero-emission Marine Transport with Hydrogen Fuel and Superconducting Propulsion System: Case Study of a Passenger Ferry
Mar 2023
Publication
This paper proposes a techno-economic model for a high-speed hydrogen ferry. The model can describe the system properties i.e. energy demand weight and daily operating expenses of the ferry. A novel aspect is the consideration of superconductivity as a measure for cost saving in the setting where liquid hydrogen (LH2) can be both coolant and fuel. We survey different scenarios for a high-speed ferry that could carry 300 passengers. The results show that despite higher energy demand compressed hydrogen gas is more economical compared with LH2 for now; however constructing large-scale hydrogen liquefaction plants make it competitive in the future. Moreover compressed hydrogen gas is restricted to a shorter distance while LH2 makes longer distances possible and whenever LH2 is accessible using a superconducting propulsion system has a beneficial impact on both energy and cost savings. These effects strengthen if the operational time or the weight of the ferry increases.
Technology Roadmap for Hydrogen-fuelled Transportation in the UK
Apr 2023
Publication
Transportation is the sector responsible for the largest greenhouse gas emission in the UK. To mitigate its impact on the environment and move towards net-zero emissions by 2050 hydrogen-fuelled transportation has been explored through research and development as well as trials. This article presents an overview of relevant technologies and issues that challenge the supply use and marketability of hydrogen for transportation application in the UK covering on-road aviation maritime and rail transportation modes. The current development statutes of the different transportation modes were reviewed and compared highlighting similarities and differences in fuel cells internal combustion engines storage technologies supply chains and refuelling characteristics. In addition common and specific future research needs in the short to long term for the different transportation modes were suggested. The findings showed the potential of using hydrogen in all transportation modes although each sector faces different challenges and requires future improvements in performance and cost development of innovative designs refuelling stations standards and codes regulations and policies to support the advancement of the use of hydrogen.
Techno-Economic Assessment of Power-to-Liquids (PtL) Fuels Production and Global Trading Based on Hybrid PV-Wind Power Plants
Nov 2016
Publication
This paper introduces a value chain design for transportation fuels and a respective business case taking into account hybrid PV-Wind power plants electrolysis and hydrogen-to-liquids (H2tL) based on hourly resolved full load hours (FLh). The value chain is based on renewable electricity (RE) converted by power-to-liquids (PtL) facilities into synthetic fuels mainly diesel. Results show that the proposed RE-diesel value chains are competitive for crude oil prices within a minimum price range of about 79 - 135 USD/barrel (0.44 – 0.75 €/l of diesel production cost) depending on the chosen specific value chain and assumptions for cost of capital available oxygen sales and CO2 emission costs. A sensitivity analysis indicates that the RE-PtL value chain needs to be located at the best complementing solar and wind sites in the world combined with a de-risking strategy and a special focus on mid to long-term electrolyser and H2tL efficiency improvements. The substitution of fossil fuels by hybrid PV-Wind power plants could create a PV-wind market potential in the order of terawatts.
Optimal Operation Strategy of PV-Charging-Hydrogenation Composite Energy Station Considering Demand Response
Apr 2023
Publication
Traditional charging stations have a single function which usually does not consider the construction of energy storage facilities and it is difficult to promote the consumption of new energy. With the gradual increase in the number of new energy vehicles (NEVs) to give full play to the complementary advantages of source-load resources and provide safe efficient and economical energy supply services this paper proposes the optimal operation strategy of a PV-charging-hydrogenation composite energy station (CES) that considers demand response (DR). Firstly the operation mode of the CES is analyzed and the CES model including a photovoltaic power generation system fuel cell hydrogen production hydrogen storage hydrogenation and charging is established. The purpose is to provide energy supply services for electric vehicles (EVs) and hydrogen fuel cell vehicles (HFCVs) at the same time. Secondly according to the travel law of EVs and HFCVs the distribution of charging demand and hydrogenation demand at different periods of the day is simulated by the Monte Carlo method. On this basis the following two demand response models are established: charging load demand response based on the price elasticity matrix and interruptible load demand response based on incentives. Finally a multi-objective optimal operation model considering DR is proposed to minimize the comprehensive operating cost and load fluctuation of CES and the maximum–minimum method and analytic hierarchy process (AHP) are used to transform this into a linearly weighted single-objective function which is solved via an improved moth–flame optimization algorithm (IMFO). Through the simulation examples operation results in four different scenarios are obtained. Compared with a situation not considering DR the operation strategy proposed in this paper can reduce the comprehensive operation cost of CES by CNY 1051.5 and reduce the load fluctuation by 17.8% which verifies the effectiveness of the proposed model. In addition the impact of solar radiation and energy recharge demand changes on operations was also studied and the resulting data show that CES operations were more sensitive to energy recharge demand changes.
Scatter Search for Optimal Sizing of a Hybrid Renewable Energy System for Scheduling Green Hydrogen Production
Dec 2024
Publication
At present energy demands are mainly covered by the use of fossil fuels. The process of fossil fuel production increases pollution from oil extraction transport to processing centers treatment to obtain lighter fractions and delivery and use by the final consumers. Such polluting circumstances are aggravated in the case of accidents involving fossil fuels. They are also linked to speculative markets. As a result the trend is towards the decarbonization of lifestyles in advanced societies. The present paper addresses the problem of the optimal sizing of a hybrid renewable energy system for scheduling green hydrogen production. A local system fully powered by renewable energies is designed to obtain hydrogen from seawater. In order to monetize excess energy the grid connection of the system is considered under realistic energy market constraints designing an hourly purchasing strategy. This crucial problem which has not been taken into account in the literature is solved by the specific dispatch strategy designed. Several optimization methods have been used to solve this problem; however the scatter search method has not previously been employed. In this paper the problem is faced with a novel implementation of this method. The implementation is competitive in terms of performance when compared to on the one hand the genetic algorithm and differential evolution methods which are well-known state-of-the-art evolutionary algorithms and on the other hand the optimal foraging algorithm (OFA) a more recent algorithm. Furthermore scatter search outperformed all other methods in terms of computational cost. This is promising for real-world applications that require quick responses.
Decarbonization with Induced Technical Change: Exploring the Niche Potential of Hydrogen in Heavy Transportation
Jan 2024
Publication
Fuel cells and electric batteries are competing technologies for the energy transition in heavy transportation. We explore the conditions for the survival of a unique technology in the long term. Learning by doing suggests focusing on a single technology while differentiation and decreasing return to scale (cost convexity) favor diversification. Exogenous technical change also plays a role. The interaction between these factors is analyzed in a general model. It is proved that in absence of convexity and exogenous technical change only one technology is used for the whole transition. We then apply this framework to analyze the competition between fuel-cell electric buses (FCEBs) and battery electric buses (BEB) in the European bus sector. There are both learning by doing and exogenous technical change. The model is calibrated and solved. It is shown that the existence of a niche for FCEBs critically depends on the speed at which cost reductions are achieved. The speed depends both on the size of the niche and the rate of learning by doing for FCEBs. Public policies to decentralize the socially optimal trajectory in terms of taxes (carbon) and subsidies (learning by doing) are derived.
Assessing Techno-economic Feasibility of Cogeneration and Power to Hydrogen Plants: A Novel Dynamic Simulation Model
Aug 2023
Publication
Green hydrogen technologies are crucial for decarbonization purposes while cogeneration offers efficient heat and power generation. Integrating green hydrogen and cogeneration brings numerous benefits optimizing energy utilization reducing emissions and supporting the transition to a sustainable future. While there are numerous studies examining the integration of combined heat and power with Power to Gas certain aspects still requires a more detailed analysis especially for internal combustion engines fuelled by natural gas due to their widespread adoption as one of the primary technologies in use. Therefore this paper presents a comprehensive numerical 0-D dynamic simulation model implemented within the TRNSYS environment considering internal combustion engines fuelled by natural gas. Specifically the study focuses on capturing CO2 from exhaust gases and producing green hydrogen from electrolysis. Based on these considerations two configurations are proposed: the first involves the methanation reaction while the second entails the production of a hydromethane mixture. The aim is to evaluate the technical and economic feasibility of these configurations and compare their performance within the Power to Gas framework. Self-sufficiency from the national electricity grid has been almost achieved for the two configurations considering an industrial case. The production of hydromethane allows smaller photovoltaic plant (81 kWp) compared to the production of synthetic methane (670 kWp) where a high quantity of hydrogen is required especially if all the carbon dioxide captured is used in the methanation process. Encouraging economic results with payback times below ten years have been obtained with the use of hydromethane. Moreover hydromethane shows potential residential applications with small required photovoltaic sizes.
The Possibility of Powering a Light Aircraft by Releasing the Energy Stored in Hydrogen within a Fuel Cell Stack
Jun 2024
Publication
In this work we examine the possibility of converting a light propeller-driven aircraft powered by a spark-ignition reciprocating piston and internal combustion engine running on AVGAS into one powered by an electric motor driven by a proton exchange membrane fuel cell stack running on hydrogen. Our studies suggest that storing hydrogen cryogenically is a better option than storing hydrogen under pressure. In comparison to cryogenic tanks high-pressure tanks are extremely heavy and unacceptable for light aircraft. We show that the modified aircraft (including batteries) is no heavier than the original and that the layout of the major components results in lower movement of the aircraft center-of-gravity as the aircraft consumes hydrogen. However we acknowledge that our fuel cell aircraft cannot store the same amount of energy as the original running on AVGAS. Therefore despite the fact that the fuel cell stack is markedly more efficient than an internal combustion engine there is a reduction in the range of the fuel cell aircraft. One of our most important findings is that the quantity of energy that we need to dissipate to the surroundings via heat transfer is significantly greater from a fuel cell stack than from an internal combustion engine. This is particularly the case when we attempt to run the fuel cell stack at high current densities. To control this problem our strategy during the cruise phase is to run the fuel cell stack at its maximum efficiency where the current density is low. We size the fuel cell stack to produce at least enough power for cruise and when we require excess power we add the energy stored in batteries to make up the difference.
Renewable Hydrogen in Industrial Production: A Bibliometric Analysis of Current and Future Applications
Dec 2024
Publication
Renewable hydrogen is widely considered a key technology to achieve net zero emissions in industrial production processes. This paper presents a structured bibliometric analysis examining current and future applications of hydrogen as feedstock and fuel across industries quantifying demand for different industrial processes and identifying greenhouse gas emissions reduction potential against the context of current fossil-based practices. The findings highlight significant focus on hydrogen as feedstock for steel ammonia and methanol production and its use in high-to medium-temperature processes and a general emphasis on techno-economic and technological evaluations of hydrogen applications across industries. However gaps exist in research on hydrogen use in sectors like cement glass waste pulp and paper ceramics and aluminum. Additionally the analysis reveals limited attention in the identified literature to hydrogen supply chain efficiencies including conversion and transportation losses as well as geopolitical and raw material challenges. The analysis underscores the need for comprehensive and transparent data to align hydrogen use with decarbonization goals optimize resource allocation and inform policy and investment decisions for strategic deployment of renewable hydrogen.
The Economic Impact and Carbon Footprint Dependence of Energy Management Strategies in Hydrogen-Based Microgrids
Sep 2023
Publication
This paper presents an economic impact analysis and carbon footprint study of a hydrogenbased microgrid. The economic impact is evaluated with respect to investment costs operation and maintenance (O&M) costs as well as savings taking into account two different energy management strategies (EMSs): a hydrogen-based priority strategy and a battery-based priority strategy. The research was carried out in a real microgrid located at the University of Huelva in southwestern Spain. The results (which can be extrapolated to microgrids with a similar architecture) show that although both strategies have the same initial investment costs (EUR 52339.78) at the end of the microgrid lifespan the hydrogen-based strategy requires higher replacement costs (EUR 74177.4 vs. 17537.88) and operation and maintenance costs (EUR 35254.03 vs. 34877.08) however it provides better annual savings (EUR 36753.05 vs. 36282.58) and a lower carbon footprint (98.15% vs. 95.73% CO2 savings) than the battery-based strategy. Furthermore in a scenario where CO2 emission prices are increasing the hydrogen-based strategy will bring even higher annual cost savings in the coming years.
Energy and Greenhouse Gases Life Cycle Assessment of Electric and Hydrogen Buses: A Real-world Case Study in Bolzano Italy
May 2023
Publication
The transportation sector plays an important role in the current effort towards the control of global warming. Against this backdrop electrification is currently attracting attention as the life cycle environmental performance of different powertrain technologies is critically assessed. In this study a life cycle analysis of the public transportation buses was performed. The scope of the analysis is to compare the energy and global warming performances of the different powertrain technologies in the city fleet: diesel full electric and hydrogen buses. Real world monitored data were used in the analysis for the energy consumptions of the buses and to produce hydrogen in Bolzano. Compared to the traditional diesel buses the electric vehicles showed a 43% reduction of the non-renewable primary energy demand and a 33% of the global warming potential even in the worst consequential scenario considered. The switch to hydrogen buses leads to very different environmental figures: from very positive if it contributes to a further penetration of renewable electricity to hardly any difference if hydrogen from steam-methane reforming is used to clearly negative ones (approximately doubling the impacts) if a predominantly fossil electricity mix is used in the electrolysis.
The Use of Hydrogen as Alternative Fuel for Ship Propulsion: A Case Study of Full and Partial Retrofitting of Roll-on/Roll-off Vessels for Short Distance Routes
Oct 2023
Publication
Roll-on/Roll-Off (Ro-Ro) vessels including those without and with passenger accommodation Roll-on/roll-off passenger (Ro-Pax) can be totally or partially retrofitted to reduce the greenhouse gas (GHG) emissions in maritime transport not only during hoteling operation at the dock but also during service. This study is based on data of the vessel routes connecting the Port of Piombino to the Elba Island in Italy. Three retrofitting scenarios have been considered: replacement of the main and auxiliary engines with fuel cells (FC) (full retrofitting) replacement of the auxiliary engines with FCs (partial retrofitting) and replacement of the auxiliary engines with FCs and hoteling only with auxiliary engines for one specific vessel. The amount of hydrogen the filling time and the energy needed for production compression and pre-cooling of hydrogen have been calculated for the different scenarios.
The Role of Electricity-based Hydrogen in the Emerging Power-to-X Economy
Aug 2023
Publication
As energy system research into high shares of renewables has developed so have the perspectives of the fundamental nature of a highly renewable economy. Early energy system transition research suggested that current fossil fuel energy systems would transition to a ‘Hydrogen Economy’ whereas more recent insights suggest that a ‘Power-to-X Economy’ may be a more appropriate term as renewable electricity will become both the most important primary and final energy carrier through various Power-to-X conversion routes across the energy system. This paper provides a detailed overview on research insights of recent years on the core elements of the Power-to-X Economy and the role of hydrogen based on latest research results. These results suggest that by 2050 upwards of 61737 TWhLHV of hydrogen will be required to fully defossilise the global energy-industry system. Hydrogen therefore emerges as a central intermediate energy carrier and its relevance is driven by significant cost reductions in renewable electricity especially of solar photovoltaics and wind power. Efficiency and cost drivers position direct electrification as the primary solution for defossilisation of the global energy-industry system; however electron-to-molecule routes are essential for the large subset of remaining energy-related demands including chemical production marine and aviation fuels and steelmaking.
Design and Optimization of a Type-C Tank for Liquid Hydrogen Marine Transport
May 2023
Publication
As one of the most promising renewable energy sources hydrogen has the excellent environmental benefit of producing zero emissions. A key technical challenge in using hydrogen across sectors is placed on its storage technology. The storage temperature of liquid hydrogen (20 K or 253 C) is close to absolute zero so the storage materials and the insulation layers are subjected to extremely stringent requirements against the cryogenic behaviour of the medium. In this context this research proposed to design a large liquid hydrogen type-C tank with AISI (American Iron and Steel Institution) type 316 L stainless steel as the metal barrier using Vapor-Cooled Shield (VCS) and Rigid Polyurethane Foams (RPF) as the insulation layer. A parametric study on the design of the insulation layer was carried out by establishing a thermodynamic model. The effects of VCS location on heat ingress to the liquid hydrogen transport tank and insulation temperature distribution were investigated and the optimal location of the VCS in the insulation was identified. Research outcomes finally suggest two optimal design schemes: (1) when the thickness of the insulation layer is determined Self-evaporation Vapor-Cooled Shield (SVCS) and Forcedevaporation Vapor-Cooled Shield (FVCS) can reduce heat transfer by 47.84% and 85.86% respectively; (2) when the liquid hydrogen evaporation capacity is determined SVCS and FVCS can reduce the thickness of the insulation layer by 50% and 67.93% respectively.
A Web-based Decision Support System (DSS) for Hydrogen Refueling Station Location and Supply Chain Optimisation
Jun 2023
Publication
This study presents a novel web-based decision support system (DSS) that optimizes the locations of hydrogen refueling stations (HRSs) and hydrogen supply chains (HSCs). The system is developed with a design science approach that identifies key design requirements and features through interviews and literature reviews. Based on the findings a system architecture and data model were designed incorporating scenario management optimization model visualization and data management components. The DSS provides a two-stage solution model that links demand to HRSs and production facilities to HRSs. A prototype is demonstrated with a plan for 2025 and 2030 in the Republic of Korea where 450 to 660 stations were deployed nationwide and linked to production facilities. User evaluation confirmed the effectiveness of the DSS in solving optimization problems and its potential to assist the government and municipalities in planning hydrogen infrastructure.
Inter-Zone Optimal Scheduling of Rural Wind–Biomass-Hydrogen Integrated Energy System
Aug 2023
Publication
To solve the problems of low utilization of biomass and uncertainty and intermittency of wind power (WP) in rural winter an interval optimization model of a rural integrated energy system with biogas fermentation and electrolytic hydrogen production is constructed in this paper. Firstly a biogas fermentation kinetic model and a biogas hydrogen blending model are developed. Secondly the interval number is used to describe the uncertainty of WP and an interval optimization scheduling model is developed to minimize daily operating cost. Finally a rural integrated energy system in Northeast China is taken as an example and a sensitivity analysis of electricity price gas production and biomass price is conducted. The simulation results show that the proposed strategy can significantly reduce the wind abandonment rate and improve the economy by 3.8–22.3% compared with conventional energy storage under optimal dispatch.
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