Applications & Pathways

Conventional fuels for vehicular applications generate hazardous pollutants which have an adverse effect on the environment. Therefore there is a high demand to shift towards environment-friendly vehicles for the present mobility sector. This paper highlights sustainable mobility and specifically sustainable transportation as a solution to reduce GHG emissions. Thus hydrogen fuel-based vehicular technologies have started blooming and have gained significance following the zero-emission policy focusing on various types of sustainable motilities and their limitations. Serving an incredible deliverance of energy by hydrogen fuel combustion engines hydrogen can revolution various transportation sectors. In this study the aspects of hydrogen as a fuel for sustainable mobility sectors have been investigated. In order to reduce the GHG (Green House Gas) emission from fossil fuel vehicles researchers have paid their focus for research and development on hydrogen fuel vehicles and proton exchange fuel cells. Also its development and progress in all mobility sectors in various countries have been scrutinized to measure the feasibility of sustainable mobility as a future. This paper is an inclusive review of hydrogen-based mobility in various sectors of transportation in particular fuel cell cars that provides information on various technologies adapted with time to add more towards perfection. When compared to electric vehicles with a 200-mile range fuel cell cars have a lower driving cost in all of the 2035 and 2050 scenarios. To stimulate the use of hydrogen as a passenger automobile fuel the cost of a hydrogen fuel cell vehicle (FCV) must be brought down to at least the same level as an electric vehicle. Compared to gasoline cars fuel cell vehicles use 43% less energy and generate 40% less CO2.

This study presents a novel design and development of a 280000 m3 liquefied hydrogen tanker ship by implementing a set of 6 Flettner rotors as an assistance propulsion system in conjunction with a combined-cycle gas turbine fuelled by hydrogen as a prime mover. The study includes assessment of the technical and environmental aspects of the developed design. Furthermore an established method was applied to simulate the LH2 tanker in different voyages and conditions to investigate the benefits of harnessing wind energy to assist combined-cycle gas turbine in terms of performance and emission reduction based on engine behaviour for different voyages under loaded and unloaded normal as well as 6 % degraded engine and varying ambient conditions. The results indicate that implementing a set of 6 Flettner rotors for the LH2 tanker ship has the potential to positively impact the performance and lead to environmental benefits. A maximum contribution power of around 1.8 MW was achieved in the winter season owing to high wind speed and favourable wind direction. This power could save approximately 3.6 % of the combined-cycle gas turbine total output power (50 MW) and cause a 3.5 % reduction in NOx emissions.

Combustion of hybrid natural gas (methane) and hydrogen mixture in domestic swirl stoves has been characterized using hot-state experiments and numerical analysis. The detailed combustion mechanism of methane and hydrogen (GRI-Mech 3.0) has been simplified to obtain reduced number of chemical reactions involved (82 % reduction). The novel simplified combustion mechanism developed has been used to obtain combustion characteristics of hybrid methane-hydrogen mixture. The difference between the calculations from the detailed and the simplified mechanisms has been found to be Combustion of hybrid natural gas (methane) and hydrogen mixture in domestic swirl stoves has been characterized using hot-state experiments and numerical analysis. The detailed combustion mechanism of methane and hydrogen (GRI-Mech 3.0) has been simplified to obtain reduced number of chemical reactions involved (82 % reduction). The novel simplified combustion mechanism developed has been used to obtain combustion characteristics of hybrid methane-hydrogen mixture. The difference between the calculations from the detailed and the simplified mechanisms has been found to be <1 %. A numerical model based on the simplified combustion model is developed rigorously tested and validated against hot-state tests. The results depict that the maximum difference in combustion zone’s average temperature is <13 %. The investigations have then been extended to hybrid methane-hydrogen mixtures with varying volume fraction of hydrogen. The results show that for a mixture containing 15 % hydrogen the release of CO due to combustion reduces by 25 % while the combustion zone’s average temperature reduces by 6.7 %. The numerical results and hot-state tests both confirm that the temperature remains stable when hybrid methane-hydrogen mixture is used in domestic swirl gas stoves demonstrating its effectiveness in cooking processes.

In order to reduce the emission of carbon dioxide gas turbine power station will expect to use more clean fuels in the future especially those like hydrogen. Hydrogen-rich fuel(syngas) combustion characteristics of the novel counter dual-swirl gas turbine combustor under fixed calorific value input were studied by experiment and numerical simulation. PIV and temperature rake were used respectively to obtain the velocity and temperature distribution in the combustion chamber. The turbulence model of Reynolds stress and the kinetic model of detailed chemical syngas combustion were used simultaneously in the computational simulations. Based on the obtained results it was found that there is a reasonable agreement between the numerical results and the experimental data. The analysis shows that the flow field and temperature field of the combustor were almost unaffected by the change of hydrogen content and shows a nearly identical distribution structure under all conditions with hydrogen content below 90%; but when the H2 content reaches 90% the above characteristic plots were significantly changed. As the H2 content in the fuel increases on the center line of the combustor the jet velocity of the fuel decreased the temperature of the gas flow increased the recovery coefficient of total pressure decreased and the temperature distribution at the combustor outlet became more uniform. In addition it is also found that the syngas turbine with the same output power consumed less fuel than the gas turbine with hydrocarbon fuel. This paper provides reference for the study of hydrogen-rich syngas turbine and the application of hydrogen-rich fuel in combustor of energy system.

A novel carbon capture and utilization (CCU) process is described in which process-related carbon dioxide is captured from cement plant exhaust gas (10000 tons/year) and converted with green hydrogen in a Fischer Tropsch synthesis to liquid mainly paraffinic hydrocarbons (syncrude approx. 3000 tons/year) which is finally processed to polyolefins. This CCU process chain is simulated with the software package ASPEN Plus V12.1®. In a first step the influence of hydrogen production technology such as PEM and SOEC and reverse water-gas shift reactor (rWGS) technology (electrified and autothermal design) on plant specific efficiencies (Power-to-Liquid PtL carbon conversion) product volumes and investment operating and net production costs (NPC) is investigated. Furthermore process routes reducing the CO2 content in the Fischer Tropsch feed gas are elaborated implementing a CO2 separation unit or recycle streams back to the rWGS reactor. Unexpectedly CO2 capture and recycle streams back to the rWGS show no significant impact on the performance of each process scenario particularly in terms of the product quantity. However lower PtL efficiencies and higher NPC are noticeable for these cases. The techno-economic assessment reveals that the use of a SOEC and an electrified rWGS reactor offers the technologically best and economically most optimized process chain with NPC of 8.40 EUR/kgsyncrude a PtL efficiency of 54% and a carbon conversion of 85%.

The negative consequences of toxic emissions from internal combustion engines energy security climate change and energy costs have led to a growing demand for clean power sources in the automotive industry. The development of eco-friendly vehicle technologies such as electric and hydrogen vehicles has increased. This article investigates whether hydrogen vehicles will replace electric vehicles in the future. The results showed that fuel-cell cars are unlikely to compete with electric cars. This is due to the advancements in electric vehicles and charging infrastructure which are becoming more cost-effective and efficient. Additionally the technical progress in battery electric vehicles (BEVs) is expected to reduce the market share of fuel-cell electric vehicles (FCEVs) in passenger vehicles. However significant investments have been made in hydrogen cars. Many ongoing investments seem to follow the sunk cost fallacy where decision-makers continue to invest in an unprofitable project due to their already invested resources. Furthermore even with megawatt charging fuel-cell trucks cost more than battery-powered electric trucks. The use cases for fuel-cell electric trucks are also much more limited as their running expenses are higher compared to electric cars. Hydrogen vehicles may be beneficial for heavy transport in remote areas. However it remains to be seen if niche markets are large enough to support fuel-cell electric truck commercialization and economies of scale. In summary we believe that hydrogen vehicles will not replace electric cars and trucks at least before 2050.

Issues related to the reduction of the environmental impact of means of road transport by the use of electric motors powered by Proton Exchange Membrane (PEM) fuel cells are presented in this article. The overall functional characteristics of electric vehicles are presented as well as the essence of the operation of a fuel cell. On the basis of analyzing the energy conversion process significant advantages of electric drive are demonstrated especially in vehicles for urban and suburban applications. Moreover the analyzed literature indicated problems of controlling and maintaining fuel cell power caused by its highest dynamic and possible efficiency. This control was related to the variable load conditions of the fuel cell vehicle (FCV) engine. The relationship with the conventional dependencies in the field of vehicle dynamics is demonstrated. The final part of the study is related to the historical outline and examples of already operating fuel cell systems using hydrogen as an energy source for energy conversion to power propulsion vehicle’s engines. In conclusion the necessity to conduct research in the field of methods for controlling the power of fuel cells that enable their effective adaptation to the temporary load resulting from the conditions of vehicle motion is indicated.

Hydrogen is believed as a promising energy carrier that contributes to deep decarbonization especially for the sectors hard to be directly electrified. A grid-connected wind/hydrogen system is a typical configuration for hydrogen production. For such a system a critical barrier lies in the poor cost-competitiveness of the produced hydrogen. Researchers have found that flexible operation of a wind/hydrogen system is possible thanks to the excellent dynamic properties of electrolysis. This finding implies the system owner can strategically participate in day-ahead power markets to reduce the hydrogen production cost. However the uncertainties from imperfect prediction of the fluctuating market price and wind power reduce the effectiveness of the offering strategy in the market. In this paper we proposed a decision-making framework which is based on data-driven robust chance constrained programming (DRCCP). This framework also includes multi-layer perception neural network (MLPNN) for wind power and spot electricity price prediction. Such a DRCCP-based decision framework (DDF) is then applied to make the day-ahead decision for a wind/hydrogen system. It can effectively handle the uncertainties manage the risks and reduce the operation cost. The results show that for the daily operation in the selected 30 days offering strategy based on the framework reduces the overall operation cost by 24.36% compared to the strategy based on imperfect prediction. Besides we elaborate the parameter selections of the DRCCP to reveal the best parameter combination to obtain better optimization performance. The efficacy of the DRCCP method is also highlighted by the comparison with the chance-constrained programming method.

Hydrogen is seen as a future energy carrier since its chemical compounds make up a large part of the Earth’s surface. This study sought to analyze the impact related to the inclusion of hydrogen and oxygen gases produced on demand by an alkaline electrolyzer to the engine added directly through the fuel intake line. For this purpose performance parameters were monitored such as liquid fuel consumption and greenhouse gas emissions and correlated to any effect observed on the engine’s power output and combustion behavior. A 58 kVA nominal power motor-generator was used coupled with a resistive load bank (20 kW) where two fuel configurations were tested (diesel injection only and a mixture of diesel hydrogen and oxygen) and compared. A total of 42 tests were performed considering both the admission gases into the fuel intake line and also diesel supply only for baseline. A substantial decrease in fuel consumption was observed (7.59%) when the blend configuration was used despite a decrease in the engine’s work (1.07%). It was also possible to see a common pattern between NO and NO2 emissions for both fuel configurations while the behavior of the CO2 and CO emissions indicated a higher complete diesel burning fraction when using the gases on demand. Therefore we can verify that the use of hydrogen and oxygen gases produced on demand in the fuel intake line is a promising alternative to provide a decrease in liquid fuel consumption and an overall improvement in engine combustion.

Fuel transition can decarbonize shipping and help meet IMO 2050 goals. In this paper HFO with CCS LNG with CCS bio-methanol biodiesel hydrogen ammonia and electricity were studied using empirical ship design models from a fleet-level perspective and at the Tank-ToWake level to assist operators technology developers and policy makers. The cargo attainment rate CAR (i.e. cargo that must be displaced due to the low-C propulsion system) the ES (i.e. TTW energy needed per ton*n.m.) the CS (economic cost per ton*n.m.) and the carbon intensity index CII (gCO2 per ton*n.m.) were calculated so that the potential of the various alternatives can be compared quantitatively as a function of different criteria. The sensitivity of CAR towards ship type fuel type cargo type and voyage distance were investigated. All ship types had similar CAR estimates which implies that considerations concerning fuel transition apply equally to all ships (cargo containership tankers). Cargo type was the most sensitive factor that made a ship either weight or volume critical indirectly impacting on the CAR of different fuels; for example a hydrogen ship is weight-critical and has 2.3% higher CAR than the reference HFO ship at 20000 nm. Voyage distance and fuel type could result in up to 48.51% and 11.75% of CAR reduction. In addition to CAR the ES CS and CII for a typical mission were calculated and it was found that HFO and LNG with CCS gave about 20% higher ES and CS than HFO and biodiesel had twice the cost while ammonia methanol and hydrogen had 3–4 times the CS of HFO and electricity about 20 times suggesting that decarbonisation of the world’s fleet will come at a large cost. As an example of including all factors in an effort to create a normalized scoring system an equal weight was allocated to each index (CAR ES CS and CII). Biodiesel achieved the highest score (80%) and was identified as the alternative with the highest potential for a deep-seagoing containership followed by ammonia hydrogen bio-methanol and CCS. Electricity has the lowest normalized score of 33%. A total of 100% CAR is achievable by all alternative fuels but with compromises in voyage distance or with refuelling. For example a battery containership carrying an equal amount of cargo as an HFO-fuelled containership can only complete 13% of the voyage distance or needs refuelling seven times to complete 10000 n.m. The results can guide decarbonization strategies at the fleet level and can help optimise emissions as a function of specific missions.

Nowadays we face a series of global challenges including the growing depletion of fossil energy environmental pollution and global warming. The replacement of coal petroleum and natural gas by secondary energy resources is vital for sustainable development. Hydrogen (H2 ) energy is considered the ultimate energy in the 21st century because of its diverse sources cleanliness low carbon emission flexibility and high efficiency. H2 fuel cell vehicles are commonly the end-point application of H2 energy. Owing to their zero carbon emission they are gradually replacing traditional vehicles powered by fossil fuel. As the H2 fuel cell vehicle industry rapidly develops H2 fuel supply especially H2 quality attracts increasing attention. Compared with H2 for industrial use the H2 purity requirements for fuel cells are not high. Still the impurity content is strictly controlled since even a low amount of some impurities may irreversibly damage fuel cells’ performance and running life. This paper reviews different versions of current standards concerning H2 for fuel cell vehicles in China and abroad. Furthermore we analyze the causes and developing trends for the changes in these standards in detail. On the other hand according to characteristics of H2 for fuel cell vehicles standard H2 purification technologies such as pressure swing adsorption (PSA) membrane separation and metal hydride separation were analyzed and the latest research progress was reviewed.

The state of environmental pollution brought about as a result of the modern civilization has been monitored in the interests of the environment and human health since the seventies of the last century. Ensuring the energy security is one of the most basic existential requirements for a functional civilized society. The growing civilizational needs caused by broadly understood development generate demand for the production of all kinds of goods in all sectors of the economy as well as world-wide information transfer. The current energy demand is mostly covered using fossil fuels such as coal oil and natural gas. Some of the energy demand is covered by the energy generated in nuclear reactions and a small part of it comes from renewable energy sources. Energy derived from fossil fuels is inevitably associated with fuel oxidation processes. These processes in addition to generating heat are responsible for the emission of harmful compounds to the atmosphere: carbon monoxide carbon dioxide nitrogen oxides hydrocarbons and particulate matter. These pollutants pose a serious threat to the people as well as the environment in which they live. Due to the large share of fossil fuel energy generation in the process of combustion it becomes necessary to seek other means of obtaining the so-called "clean energy". Fuel cells may have a very high potential in this respect. Their development has enabled attempts to use them in all modes of transport. An important factor in the development of fuel cells is their relatively high efficiency and the coinciding strictening of the emission norms from internal combustion engines used to power maritime transport. Therefore the aim of this article has been to assess the potential of fuel cells as a main source of propulsion power source. A review of the designs of fuel cell systems and their use was performed. The article summarizes the assessment of the potential role of fuel cells as a power source of maritime transport.

Currently transitioning from fossil fuels to renewable sources of energy is needed considering the impact of climate change on the globe. From this point of view there is a need for development in several stages such as storage transmission and conversion of power. In this paper we demonstrate a simulation of a hybrid energy storage system consisting of a battery and fuel cell in parallel operation. The novelty in the proposed system is the inclusion of an electrolyser along with a switching algorithm. The electrolyser consumes electricity to intrinsically produce hydrogen and store it in a tank. This implies that the system consumes electricity as input energy as opposed to hydrogen being the input fuel. The hydrogen produced by the electrolyser and stored in the tank is later utilised by the fuel cell to produce electricity to power the load when needed. Energy is therefore stored in the form of hydrogen. A battery of lower capacity is coupled with the fuel cell to handle transient loads. A parallel control algorithm is developed to switch on/off the charging and discharging cycle of the fuel cell and battery depending upon the connected load. Electrically equivalent circuits of a polymer electrolyte membrane electrolyser polymer electrolyte membrane fuel cell necessary hydrogen oxygen water tanks and switching controller for the parallel operation were modelled with their respective mathematical equations in MATLAB® Simulink®. In this paper we mainly focus on the modelling and simulation of the proposed system. The results showcase the simulated system’s mentioned advantages and compare its ability to handle loads to a battery-only system.

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.

Appropriate climate change mitigation requires solutions for all actors of the energy system. The residential sector is a major part of the energy system and solutions for the implementation of a seasonal hydrogen storage system in residential houses has been increasingly discussed. A global analysis of prosumer systems including seasonal hydrogen storage with water electrolyser hydrogen compressor storage tank and a fuel cell studying the role of such a seasonal household storage in the upcoming decades is not available. This study aims to close this research gap via the improved LUT-PROSUME model which models a fully micro sector coupled residential photovoltaic prosumer system with linear optimisation for 145 regions globally. The modelling of the cost development of hydrogen storage components allows for the simulation of a residential system from 2020 until 2050 in 5-year steps in hourly resolution. The systems are cost-optimised for either on– or off-grid operation in eight scenarios including battery electric vehicles which can act as an additional vehicle-to-home electricity storage for the system. Results show that implementation of seasonal hydrogen systems only occurs in least cost solutions in high latitude countries when the system is forced to run in off-grid mode. In general a solar photovoltaic plus battery system including technologies that can cover the heat demand is the most economic choice and can even achieve lower cost than a full grid supply in off-grid operation for most regions until 2050. Additional parameters including the self-consumption ratio the demand cover ratio and the heat cover ratio can therefore not be improved by seasonal storage systems if economics is the main deciding factor for a respective system. Further research opportunities and possible limitations of the system are then identified.

In the modern world zero-carbon society has become a new buzzword of the era. Many projects have been initiated to develop alternatives not only to the environmental crisis but also to the shortage of fossil fuels. With successful projects in automobile technology hydrogen fuel is now being tested and utilized as a sustainable green fuel in the aviation sector which will lead to zero carbon emission in the future. From the mid-20th century to the early 21st numerous countries and companies have funded multimillion projects to develop hydrogen-fueled aircraft. Empirical data show positive results for various projects. Consequently large companies are investing in various innovations undertaken by researchers under their supervision. Over time the efficiency of hydrogen-fueled aircraft has improved but the lack of refueling stations large production cost and consolidated carbon market share have impeded the path of hydrogen fuel being commercialized. In addition the Unmanned Aerial Vehicle (UAV) is another important element of the Aviation industry Hydrogen started to be commonly used as an alternative fuel for heavy-duty drones using fuel cell technology. The purpose of this paper is to provide an overview of the chronological development of hydrogen-powered aircraft technology and potential aviation applications for hydrogen and fuel cell technology. Furthermore the major barriers to widespread adoption of hydrogen technology in aviation are identified as are future research opportunities.

The electrification of heavy-duty trucks stands as a critical and challenging cornerstone in the low-carbon transition of the transportation sector. This paper employs the total cost of ownership (TCO) as the economic evaluation metric framed within the context of China’s ambitious goals for heavy truck electrification by 2035. A detailed TCO model is developed encompassing not only the vehicles but also their related energy replenishing infrastructures. This comprehensive approach enables a sophisticated examination of the economic feasibility for different deployment contexts of both fuel cell and battery electric heavy-duty trucks emphasizing renewable energy utilization. This study demonstrates that in the context where both fuel cell components and hydrogen energy are costly fuel cell trucks (FCTs) exhibit a significantly higher TCO compared to battery electric trucks (BETs). Specifically for a 16 ton truck with a 500 km range the TCO for the FCT is 0.034 USD/tkm representing a 122% increase over its BET counterpart. In the case of a 49 ton truck designed for a 1000 km range the TCO for the FCT is 0.024 USD/tkm marking a 36% premium compared to the BET model. The technological roadmap suggests a narrowing cost disparity between FCTs and BETs by 2035. For the aforementioned 16 ton truck model the projected TCO for the FCT is expected to be 0.016 USD/tkm which is 58% above the BET and for the 49 ton variant it is anticipated at 0.012 USD per ton-kilometer narrowing the difference to just 4.5% relative to BET. Further analysis within this study on the influences of renewable energy pricing and operational range on FCT and BET costs highlights a pivotal finding: for the 49 ton truck achieving TCO parity between FCTs and BETs is feasible when renewable energy electricity prices fall to 0.022 USD/kWh or when the operational range extends to 1890 km. This underscores the critical role of energy costs and efficiency in bridging the cost gap between FCTs and BETs.

System durability is crucial for the successful commercialization of polymer electrolyte fuel cells (PEFCs) in fuel cell electric vehicles (FCEVs). Besides conventional electrochemical cycling durability during long-term operation the effect of operation in cold climates must also be considered. Ice formation during start up in sub-zero conditions may result in damage to the electrocatalyst layer and the polymer electrolyte membrane (PEM). Here we conduct accelerated cold start cycling tests on prototype fuel cell stacks intended for incorporation into commercial FCEVs. The effect of this on the stack performance is evaluated the resulting mechanical damage is investigated and degradation mechanisms are proposed. Overall only a small voltage drop is observed after the durability tests only minor damage occurs in the electrocatalyst layer and no increase in gas crossover is observed. This indicates that these prototype fuel cell stacks successfully meet the cold start durability targets for automotive applications in FCEVs.

Hydrogen is an emerging technology changing the context of heating with cleaner combustion than traditional fossil fuels. Studies indicate the potential to repurpose the existing natural gas infrastructure offering consumers a sustainable economically viable option in the future. The integration of hydrogen in combined heat and power systems could provide residential energy demand and reduce environmental emissions. However the widespread adoption of hydrogen will face several challenges such as carbon dioxide emissions from the current production methods and the need for infrastructure modification for transport and safety. Researchers indicated the viability of hydrogen in decarbonizing heat while some studies also challenged its long-term role in the future of heating. In this paper a comprehensive literature review is carried out by identifying the following key aspects which could impact the conclusion on the overall role of hydrogen in heat decarbonization: (i) a holistic view of the energy system considering factors such as renewable integration and system balancing; (ii) consumer-oriented approaches often overlook the broader benefits of hydrogen in emission reduction and grid stability; (iii) carbon capture and storage scalability is a key factor for large-scale production of low-emission blue hydrogen; (iv) technological improvements could increase the cost-effectiveness of hydrogen; (v) the role of hydrogen in enhancing resilience especially during extreme weather conditions raises the potential of hydrogen as a flexible asset in the energy infrastructure for future energy supply; and finally when considering the UK as a basis case (vi) incorporating factors such as the extensive gas network and unique climate conditions necessitates specific strategies.

Proton Exchange Membrane Fuel Cells (PEMFCs) are seen as an alternative for heavy-duty transportation electrification. Powered by a green hydrogen source they can provide high efficiency and low carbon emissions compared to traditional fuels. However to be competitive these systems require high reliability when operated in real-life conditions as well as safe and efficient operating management. In order to achieve these goals the X-in-the-loop (also called model-based design) methodology is well suited. It has been largely adopted for PEMFC system development and optimisation as they are complex multi-component systems. In this paper a systematic analysis of the scientific literature is conducted to review the methodology implementation for the design and improvement of the PEMFC systems. It exposes a precise definition of each development step in the methodology. The analysis shows that it can be employed in different ways depending on the subsystems considered and the objectives sought. Finally gaps in the literature and technical challenges for fuel cell systems that should be addressed are identified.

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.

Decarbonisation of heavy haul rail is an essential contributor to a zero-emissions future. However the transition from diesel to battery locomotives is not always practical given the unique characteristics of each haul. This paper demonstrates the limitations of state-of-the-art batteries using real-world data from multiple locomotives operating in Australian rail freight. An energy model was developed to assess each route’s required energy and potential regenerated energy. The tractive and regenerative battery energy mass and cost were determined using data from the energy model coupled with battery specifications. The feasibility of implementing lithium iron phosphate (LFP) nickel manganese cobalt (NMC) and lithium titanium oxide (LTO) chemistries was explored based on cost energy density cycle lifespan and locomotive data. LFP was identified as the most suitable current battery solution based on current chemistries. Further examination of the energy demands and associated mass/volume constraints concluded that three platforms are required for heavy haul rail decarbonisation i) a battery electric locomotive for low-energy demands which can be coupled with either ii) a battery electric tender for medium energy demands or iii) a hydrogen fuel cell electric tender for higher energy demands. A future-looking techno-economic assessment of battery and hydrogen fuel cell platforms concludes that the lowest cost solution for low-energy hauls is a battery-only system and for high-energy hauls a battery-hydrogen system.

Green liquid hydrogen (LH2) could play an essential role as a zero-carbon aircraft fuel to reach long-term sustainable aviation. Excluding challenges such as electrolysis transportation and use of renewable energy in setting up hydrogen (H2) fuel infrastructure this paper investigates the interface between refueling systems and aircraft and the impacts on fuel distribution at the airport. Furthermore it provides an overview of key technology design decisions for LH2 refueling procedures and their effects on the turnaround times as well as on aircraft design. Based on a comparison to Jet A-1 refueling new LH2 refueling procedures are described and evaluated. Process steps under consideration are connecting/disconnecting purging chill-down and refueling. The actual refueling flow of LH2 is limited to a simplified Reynolds term of v · d = 2.35 m2/s. A mass flow rate of 20 kg/s is reached with an inner hose diameter of 152.4 mm. The previous and subsequent processes (without refueling) require 9 min with purging and 6 min without purging. For the assessment of impacts on LH2 aircraft operation process changes on the level of ground support equipment are compared to current procedures with Jet A-1. The technical challenges at the airport for refueling trucks as well as pipeline systems and dispensers are presented. In addition to the technological solutions explosion protection as applicable safety regulations are analyzed and the overall refueling process is validated. The thermodynamic properties of LH2 as a real compressible fluid are considered to derive implications for airport-side infrastructure. The advantages and disadvantages of a subcooled liquid are evaluated and cost impacts are elaborated. Behind the airport storage tank LH2 must be cooled to at least 19 K to prevent two-phase phenomena and a mass flow reduction during distribution. Implications on LH2 aircraft design are investigated by understanding the thermodynamic properties including calculation methods for the aircraft tank volume and problems such as cavitation and two-phase flows. In conclusion the work presented shows that LH2 refueling procedure is feasible compliant with the applicable explosion protection standards and hence does not impact the turnaround procedure. A turnaround time comparison shows that refueling with LH2 in most cases takes less time than with Jet A-1. The turnaround at the airport can be performed by a fuel truck or a pipeline dispenser system without generating direct losses i.e. venting to the atmosphere.

The production storage and use of hydrogen for energy purposes will become increasingly important during the energy transition. One way to use hydrogen is to apply it to power vehicles. This green technological solution affects low-emissions transport which is beneficial and important especially in cities. The authors of this article analyzed the use of hydrogen production infrastructure for bus propulsion in the city of Katowice (Poland). The methods used in the study included a greedy algorithm and cost methods which were applied for the selection of vehicles and identification of the infrastructure for the production storage and refueling of hydrogen as well as to conduct the economic analysis during this term. The article presented the complexity of the techno-economic analysis of the infrastructure and its installation. The key element was the selection of the number of vehicles to the hydrogen production possibilities of an electrolyser and capabilities of the storage and charging infrastructure.

Power-to-X technologies that convert renewable electricity to chemically stored energy in “X” may provide a gaseous liquid or solid fuel that can be used in winter to provide both heat and electricity and thus replace fossil fuels that are currently used in many countries with cold winters. This contribution compares two options for power-to-X technologies for providing heat and electricity supply of buildings with high solar photovoltaic coverage at times of low solar availability. The option “compressed hydrogen” is based on water electrolysis that produces hydrogen on-site. This hydrogen is subsequently compressed and stored at high pressure (350 bar) for use in winter by a fuel cell. The option “aluminium redox-cycle” includes an inert electrode high temperature electrolysis process that is carried out at industrial scale. Produced aluminium is subseqeuntly transported to the site of use and converted to hydrogen and heat – and finally to electricity and heat - by aluminium-water reaction in combination with a fuel cell. Results of cost and LCA analysis show that the overall energetic efficiency of the compressed hydrogen process is slightly higher than for the aluminium redox cycle. However the aluminium redox-cycles needs far less on-site storage volume and is likely to become available at lower investment cost for the end user. Total annual cost of ownership and global warming potential of the two options are quite similar.