Applications & Pathways
Optimising Renewable Generation Configurations of Off-grid Green Ammonia Production System Considering Haber-Bosch Flexibility
Feb 2023
Publication
Green ammonia has received increasing interest for its potential as an energy carrier in the international trade of renewable power. This paper considers the factors that contribute to producing cost-competitive green ammonia from an exporter’s perspective. These factors include renewable resource quality across potential sites operating modes for off-grid plants and seasonal complementarity with trade buyers. The study applies a mixed-integer programming model and uses Australia as a case study because of its excellent solar and wind resources and the potential for synergy between Southern Hemisphere supply and Northern Hemisphere demand. Although renewable resources are unevenly distributed across Australia and present distinct diurnal and seasonal variability modelling shows that most of the pre-identified hydrogen hubs in each state and territory of Australia can produce cost-competitive green ammonia providing the electrolysis and Haber-Bosch processes are partially flexible to cope with the variability of renewables. Flexible operation reduces energy curtailment and leads to lower storage capacity requirements using batteries or hydrogen storage which would otherwise increase system costs. In addition an optimised combination of wind and solar can reduce the magnitude of storage required. Providing that a partially flexible Haber Bosch plant is commercially available the modelling shows a levelised cost of ammonia (LCOA) of AU$756/tonne and AU$659/tonne in 2025 and 2030 respectively. Based on these results green ammonia would be cost-competitive with grey ammonia in 2030 given a feedstock natural gas price higher than AU$14/MBtu. For green ammonia to be cost-competitive with grey ammonia assuming a lower gas price of AU$6/MBtu a carbon price would need to be in place of at least AU$123/tonne. Given that there is a greater demand for energy in winter concurrent with lower solar power production there may be opportunities for solar-based Southern Hemisphere suppliers to supply the major industrial regions most of which are located in the Northern Hemisphere.
A Comparison between Fuel Cells and Other Alternatives for Marine Electric Power Generation
Mar 2016
Publication
The world is facing a challenge in meeting its needs for energy. Global energy consumption in the last half-century has increased very rapidly and is expected to continue to grow over the next 50 years. However it is expected to see significant differences between the last 50 years and the next. This paper aims at introducing a good solution to replace or work with conventional marine power plants. This includes the use of fuel cell power plant operated with hydrogen produced through water electrolysis or hydrogen produced from natural gas gasoline or diesel fuels through steam reforming processes to mitigate air pollution from ships.
Effects of Compression Ratios on Combustion and Emission Characteristics of SI Engine Fueled with Hydrogen-Enriched Biogas Mixture
Aug 2022
Publication
The effects of hydrogen-enriched biogas on combustion and emissions of a dual-fuel sparkignition engine with different hydrogen concentration ratios were studied numerically. A 1-cylinder spark ignition was used to perform a numerical simulation. To reveal the influence of the compression ratios on combustion and emissions of a gaseous engine the crankshaft of the engine was modified to generate different compression ratios of 8.5 9.0 9.4 10.0 and 10.4. The biogas contained 60 and 40% methane (CH4 ) and carbon dioxide (CO2 ) respectively while the hydrogen fractions used to enrich biogas were 10 20 and 30% of the mixture by volume. The ignition timing is fixed at 350 CA◦ . The results indicate that the in-cylinder pressure combustion temperature and combustion burning speed increase gradually with increasing hydrogen concentration due to the combustion characteristics of hydrogen in blends. As increasing the compression ratio NOx emissions increase proportionally while CO2 emissions decrease gradually. Almost no combustion process occurs as operating the compression ratio below 8.5 when using pure biogas. However adding 20% of hydrogen fraction could improve the combustion process significantly even at a low compression ratio.
Technical and Commercial Challenges of Proton-Exchange Membrane (PEM) Fuel Cells
Dec 2020
Publication
This review critically evaluates the latest trends in fuel cell development for portable and stationary fuel cell applications and their integration into the automotive industry. Fast start-up high efficiency no toxic emissions into the atmosphere and good modularity are the key advantages of fuel cell applications. Despite the merits associated with fuel cells the high cost of the technology remains a key factor impeding its widespread commercialization. Therefore this review presents detailed information into the best operating conditions that yield maximum fuel cell performance. The paper recommends future research geared towards robust fuel cell geometry designs as this determines the cell losses and material characterization of the various cell components. When this is done properly it will support a total reduction in the cost of the cell which in effect will reduce the total cost of the system. Despite the strides made by the fuel cell research community there is a need for public sensitization as some people have reservations regarding the safety of the technology. This hurdle can be overcome if there is a well-documented risk assessment which also needs to be considered in future research activities.
Optimal Incorporation of Intermittent Renewable Energy Storage Units and Green Hydrogen Production in the Electrical Sector
Mar 2023
Publication
This paper presents a mathematical programming approach for the strategic planning of hydrogen production from renewable energies and its use in electric power generation in conventional technologies. The proposed approach aims to determine the optimal selection of the different types of technologies electrolyzers and storage units (energy and hydrogen). The approach considers the implementation of an optimization methodology to select a representative data set that characterizes the total annual demand. The economic objective aims to determine the minimum cost which is composed of the capital costs in the acquisition of units operating costs of such units costs of production and transmission of energy as well as the cost associated with the emissions generated which is related to an environmental tax. A specific case study is presented in the Mexican peninsula and the results show that it is possible to produce hydrogen at a minimum sale price of 4200 $/tonH2 with a total cost of $5.1687 × 106 and 2.5243 × 105 tonCO2eq. In addition the financial break-even point corresponds to a sale price of 6600 $/tonH2 . The proposed model determines the trade-offs between the cost and the emissions generated.
Fuel Cell Electric Vehicles (FCEV): Policy Advances to Enhance Commercial Success
May 2021
Publication
Many initiatives and policies attempt to make our air cleaner by reducing the carbon foot imprint on our planet. Most of the existing and planned initiatives have as their objectives the reduction of carbon dependency and the enhancement of newer or better technologies in the near future. However numerous policies exist for electric vehicles (EVs) and only some policies address specific issues related to fuel cell electric vehicles (FCEV). The lack of a distinction between the policies for EVs and FCEVs provides obstacles for the advancement of FCEV-related technologies that may otherwise be successful and competitive in the attempt to create a cleaner planet. Unfortunately the lack of this distinction is not always based on intellectual or scientific evidence. Therefore governments may need to introduce clearer policy distinctions in order to directly address FCEV-related challenges that may not pertain to other EVs. Unfortunately lobbyism continues to exist that supports the maintenance of the status quo as new technologies may threaten traditional less sustainable approaches to provide opportunities for a better environment. This lobbyism has partially succeeded in hindering the advancement of new technologies partially because the development of new technologies may reduce profit and business opportunities for traditionalists. However these challenges are slowly overcome as the demand for cleaner air and lower carbon emissions has increased and a stronger movement toward newer and cleaner technologies has gained momentum. This paper will look at policies that have been either implemented or are in the process of being implemented to address the challenge of overcoming traditional obstacles with respect to the automobile industry. The paper reviewed synthesized and discussed policies in the USA Japan and the European Union that helped implement new technologies with a focus on FCEVs for larger mass markets. These regions were the focus of this paper because of their particular challenges. South Korea and China were not included in this discussion as these countries already have equal or even more advanced policies and initiatives in place.
Propulsion System Integration for a First-generation Hydrogen Civil Airliner?
May 2021
Publication
An unusual philosophical approach is proposed here to decarbonise larger civil aircraft that fly long ranges and consume a large fraction of civil aviation fuel. These inject an important amount of carbon emissions into the atmosphere and holistic decarbonising solutions must consider this sector. A philosophical–analytical investigation is reported here on the feasibility of an airliner family to fly over long ranges and assist in the elimination of carbon dioxide emissions from civil aviation. Backed by state-of-the-art correlations and engine performance integration analytical tools a family of large airliners is proposed based on the development and integration of the body of a very large two-deck four-engine airliner with the engines wings and flight control surfaces of a very long-range twin widebody jet. The proposal is for a derivative design and not a retrofit. This derivative design may enable a swifter entry to service. The main contribution of this study is a philosophical one: a carefully evaluated aircraft family that appears to have very good potential for first-generation hydrogen-fuelled airliners using gas turbine engines for propulsion. This family offers three variants: a 380-passenger aircraft with a range of 3300nm a 330-passenger aircraft with a range of 4800nm and a 230- passenger aircraft with a range of 5500nm. The latter range is crucially important because it permits travel from anywhere in the globe to anywhere else with only one stop. The jet engine of choice is a 450kN high-bypass turbofan.
Next for Net Zero Podcast: Transporting to a Greener World
Oct 2022
Publication
Decarbonisation will need a significant societal shift. The when why and how we travel is going to look very different within a decade. Joining us is Florentine Roy – a leading expert on electric vehicles and Innovation Project Lead at UK Power Networks and Matt Hindle - Head of Net Zero and Sustainability at Wales and West Utilities. Let’s talk about the energy system implications of this massive undertaking and how it can be enabled by innovation in a fair and just way.
The podcast can be found here.
The podcast can be found here.
Fuel Cells for Shipping: To Meet On-board Auxiliary Demand and Reduce Emissions
Feb 2021
Publication
The reduction of harmful emissions from the international shipping sector is necessary. On-board energy demand can be categorised as either: propulsion or auxiliary services. Auxiliary services contribute a significant proportion of energy demand with major loads including: compressors pumps and HVAC (heating ventilation and air-conditioning). Typically this demand is met using the same fuel source as the main propulsion (i.e. fossil fuels). This study has analysed whether emissions from large scale ships could feasibly be reduced by meeting auxiliary demand by installing a hydrogen fuel cell using data from an LNG tanker to develop a case study. Simulations have shown that for a capacity of 10 x 40ft containers of compressed hydrogen the optimal fuel cell size would be 3 MW and this could save 10600 MWh of fossil fuel use equivalent to 2343 t of CO2. Hence this could potentially decarbonise a significant proportion of shipping energy demand. Although there are some notable technical and commercial considerations such as fuel cell lifetime and capital expenditure requirements. Results imply that if auxiliary loads could be managed to avoid peaks in demand this could further increase the effectiveness of this concept.
The Potential Role of Flying Vehicles in Progressing the Energy Transition
Oct 2022
Publication
An energy transition is in progress around the globe notably led by an increase in the deployment of renewable energy and a shift toward less emissions-intense options notably in the transportation sector. This research investigates the potential role that new transportation options namely flying vehicles may play toward progressing the energy transition. As flying vehicles are a relatively new technology yet to penetrate the market it is also prudent to consider the ethical legal and social issues (ELSI) associated with their implementation alongside the potential energy and environmental impacts. Through a review of ELSI and energy and environmental literature we identify research gaps and identify how flying vehicles may impact upon the energy transition over time. Our research identifies several critical aspects of both ELSI and energy and environmental academia relevant to the future deployment of flying vehicles and describes a deployment timeline and the resultant societal outcomes. We find that flying vehicles could drive the energy transition and the hydrogen economy and that their widespread adoption could engender shared socio-environmental benefits. Our findings are relevant to transportation and environmental policymakers and identify critical considerations for the planned introduction of new shared transportation options to the market conducive to a sustainable energy transition.
Assessment of Hydrogen Fuel for Rotorcraft Applications
Jun 2022
Publication
This paper presents the application of a multidisciplinary approach for the preliminary design and evaluation of the potential improvements in performance and environmental impact through the utilization of compressed (CGH2) and liquefied (LH2) hydrogen fuel for a civil tilt-rotor modelled after the NASA XV-15. The methodology deployed comprises models for rotorcraft flight dynamics engine performance flight path analysis hydrogen tank and thermal management system sizing. Trade-offs between gravimetric efficiency energy consumption fuel burn CO2 emissions and cost are quantified and compared to the kerosene-fuelled rotorcraft. The analysis carried out suggests that for these vehicle scales gravimetric efficiencies of the order of 13% and 30% can be attained for compressed and liquid hydrogen storage respectively leading to reduced range capability relative to the baseline tilt-rotor by at least 40%. At mission level it is shown that the hydrogen-fuelled configurations result in increased energy consumption by at least 12% (LH2) and 5% (CGH2) but at the same time significantly reduced life-cycle carbon emissions compared to the kerosene counterpart. Although LH2 storage at cryogenic conditions has a higher gravimetric efficiency than CGH2 (at 700 bar) it is shown that for this class of rotorcraft the latter is more energy efficient when the thermal management system for fuel pressurization and heating prior to combustion is accounted for.
Sector Coupling and Migration towards Carbon-Neutral Power Systems
Feb 2023
Publication
There is increasing interest in migrating to a carbon-neutral power system that relies on renewable energy due to concerns about greenhouse gas emissions energy shortages and global warming. However the increasing share of renewable energy has added volatility and uncertainty to power system operations. Introducing new devices and using flexible resources may help solve the problem but expanding the domain of the problem can be another solution. Sector coupling which integrates production consumption conversion and storage by connecting various energy domains could potentially meet the needs of each energy sector. It can also reduce the generation of surplus energy and unnecessary carbon emissions. As a result sector coupling an integrated energy system increases the acceptance of renewable energy in the traditional power system and makes it carbon neutral. However difficulties in large-scale integration low conversion efficiency and economic feasibility remain obstacles. This perspective paper discusses the background definition and components of sector coupling as well as its functions and examples in rendering power systems carbon-neutral. The current limitations and outlook of sector coupling are also examined.
Everything About Hydrogen Podcast: Flying Hy!
Feb 2021
Publication
Decarbonizing aviation is a big challenge. It is one of the most carbon intensive business sectors in the modern world and change comes slowly to the aviation industry. Hydrogen and fuel cell technologies offer a pathway to decarbonize regional flights in the not-so-distant future and big names are looking at potential solutions for long-haul flights in the longer term. But even if we build the aircraft that can use hydrogen as a fuel how do we get the fuel to them in a timely reliable and cost-efficient way?
The podcast can be found on their website
The podcast can be found on their website
Study on the Effect of Second Injection Timing on the Engine Performances of a Gasoline/Hydrogen SI Engine with Split Hydrogen Direct Injecting
Oct 2020
Publication
Split hydrogen direct injection (SHDI) has been proved capable of better efficiency and fewer emissions. Therefore to investigate SHDI deeply a numerical study on the effect of second injection timing was presented at a gasoline/hydrogen spark ignition (SI) engine with SHDI. With an excess air ratio of 1.5 five different second injection timings achieved five kinds of hydrogen mixture distribution (HMD) which was the main factor affecting the engine performances. With SHDI since the HMD is manageable the engine can achieve better efficiency and fewer emissions. When the second injection timing was 105◦ crank angle (CA) before top dead center (BTDC) the Pmax was the highest and the position of the Pmax was the earliest. Compared with the single hydrogen direct injection (HDI) the NOX CO and HC emissions with SHDI were reduced by 20% 40% and 72% respectively.
Hydrogen Refueling Process: Theory, Modeling, and In-Force Applications
Mar 2023
Publication
Among the alternative fuels enabling the energy transition hydrogen-based transportation is a sustainable and efficient choice. It finds application both in light-duty and heavy-duty mobility. However hydrogen gas has unique qualities that must be taken into account when employed in such vehicles: high-pressure levels up to 900 bar storage in composite tanks with a temperature limit of 85 ◦C and a negative Joule–Thomson coefficient throughout a wide range of operational parameters. Moreover to perform a refueling procedure that is closer to the driver’s expectations a fast process that requires pre-cooling the gas to −40 ◦C is necessary. The purpose of this work is to examine the major phenomena that occur during the hydrogen refueling process by analyzing the relevant theory and existing modeling methodologies.
Influence of Hydrogen Enrichment Strategy on Performance Characteristics, Combustion and Emissions of a Rotary Engine for Unmanned Aerial Vehicles (UAVs)
Dec 2022
Publication
In recent years there has been great interest in Wankel-type rotary engines which are one of the most suitable power sources for unmanned aerial vehicle (UAV) applications due to their high power-to-size and power-to-weight ratios. The purpose of the present study was to investigate the potential of a hydrogen enrichment strategy for the improvement of the performance and reduction of the emissions of Wankel engines. The main motivation behind this study was to make Wankel engines which are already very advantageous for UAV applications even more advantageous by applying the hydrogen enrichment technique. In this study hydrogen addition was implemented in a spark-ignition rotary engine model operating at a constant engine speed of 6000 rpm. The mass fraction of hydrogen in the intake gradually increased from 0% to 10%. Simulation results revealed that addition of hydrogen to the fuel accelerated the flame propagation and increased the burning speed of the fuel the combustion temperature and the peak pressure in the working chamber. These phenomena had a very positive effect on the performance and emissions of the Wankel engine. The indicated mean effective pressure (IMEP) increased by 8.18% and 9.68% and the indicated torque increased by 6.15% and 7.99% for the 5% and 10% hydrogen mass fraction cases respectively compared to those obtained with neat gasoline. In contrast CO emissions were reduced by 33.35% and 46.21% and soot emissions by 11.92% and 20.06% for 5% and 10% hydrogen additions respectively. NOx emissions increased with the application of the hydrogen enrichment strategy for the Wankel engine.
Thermodynamic Performance and Creep Life Assessment Comparing Hydrogen- and Jet-Fueled Turbofan Aero Engine
Apr 2021
Publication
There is renewed interest in hydrogen as an alternative fuel for aero engines due to their perceived environmental and performance benefits compared to jet fuel. This paper presents a cycle thermal performance energy and creep life assessment of hydrogen compared with jet fuel using a turbofan aero engine. The turbofan cycle performance was simulated using a code developed by the authors that allows hydrogen and jet fuel to be selected as fuel input. The exergy assessment uses both conservations of energy and mass and the second law of thermodynamics to understand the impact of the fuels on the exergy destruction exergy efficiency waste factor ratio environmental effect factor and sustainability index for a turbofan aero engine. Finally the study looks at a top-level creep life assessment on the high-pressure turbine hot section influenced by the fuel heating values. This study shows performance (64% reduced fuel flow rate better SFC) and more extended blade life (15% increase) benefits using liquefied hydrogen fuel which corresponds with other literary work on the benefits of LH2 over jet fuel. This paper also highlights some drawbacks of hydrogen fuel based on previous research work and gives recommendations for future work aimed at maturing the hydrogen fuel concept in aviation.
Reliability Analysis of Pyrotechnic Igniter for Hydrogen-Oxygen Rocket Engine with Low Temperature Combustion Instability Failure Mode
Mar 2022
Publication
To evaluate the functional reliability of the pyrotechnic igniter in the failure mode of unstable combustion at low temperature a reliability and reliability sensitivity analysis method based on the combination of an interior ballistic model and Kriging reliability method is proposed. Through the deterministic interior ballistic simulation the failure mode of low temperature unstable combustion of the pyrotechnic igniter is examined while the random variables are introduced to establish the ignition nonlinear implicit function of the pyrotechnic igniter. The ignition display function of the pyrotechnic igniter is established by the Kriging model which avoids the repeated calculation of true limit state function values. This study provides an efficient approach to evaluate the ignition reliability of the pyrotechnic igniter and compared with the traditional Monte Carlo method to verify the accuracy of the results. Finally reliability-based sensitivity indices are presented to quantify the significance of random parameters. It is shown that the influence of the uncertainties can be precisely described and the diameter of the nozzle plays a dominant role in ignition reliability. Additionally ignition experiments of nozzles with different diameters were performed to verify the result of sensitivity. This can further support the detailed design of the pyrotechnic igniter
Numerical Simulation of the Transport and the Thermodynamic Properties of Imported Natural Gas Inected with Hydrogen in the Manifold
Nov 2023
Publication
Blending hydrogen with natural gas (NG) is an efficient method for transporting hydrogen on a large scale at a low cost. The manifold at the NG initial station is an important piece of equipment that enables the blending of hydrogen with NG. However there are differences in the components and component contents of imported NG from different countries. The components of hydrogen-blended NG can affect the safety and efficiency of transportation through pipeline systems. Therefore numerical simulations were performed to investigate the blending process and changes in the thermodynamic properties of four imported NGs and hydrogen in the manifold. The higher the heavy hydrocarbon content in the imported NG the longer the distance required for the gas to mix uniformly with hydrogen in the pipeline. Hydrogen blending reduces the temperature and density of NG. The gas composition is the main factor affecting the molar calorific value of a gas mixture and hydrogen blending reduces the molar calorific value of NG. The larger the content of high-molar calorific components in the imported NG the higher the molar calorific value of the gas after hydrogen blending. Increasing both the temperature and hydrogen mixing ratio reduces the Joule-Thomson coefficient of the hydrogen-blended NG. The results of this study provide technical references for the transport of hydrogen-blended NG.
Optimal Expansion of a Multi-domain Virtual Power Plant for Green Hydrogen Production to Decarbonise Seaborne Passenger Transportation
Nov 2023
Publication
Many industrialised nations recently concentrated their focus on hydrogen as a viable option for the decarbonisation of fossil-intensive sectors including maritime transportation. A sustainable alternative to the conventional production of hydrogen based on fossil hydrocarbons is water electrolysis powered by renewable energy sources. This paper presents a detailed techno-economic optimisation model for sizing an electrolyser and a hydrogen storage embedded in a multi-domain virtual power plant to produce green hydrogen for seaborne passenger transportation. We base our numerical analysis on three years of historical data from a renewable-dominated 60/10 kV substation on the Danish island of Bornholm and on data for ferries to the mainland of Sweden. Our analysis shows that an electrolyser system serves as a valuable flexibility asset on the electrical demand side while supporting the thermal management of the district heating system and contributing to meeting the ferries hydrogen demand. With a sized electrolyser of 9.63 MW and a hydrogen storage of 1.45 t the hydrogen assets are able to take up a large share of the local excess electricity generation. The waste heat of the electrolyser delivers a significant share of 21.4% of the annual district heating demand. Moreover the substation can supply 26% of the hydrogen demand of the ferries from local resources. We further examine the sensitivity of the asset sizing towards investment costs electrolyser efficiency and hydrogen market prices.
No more items...