Publications

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.

The large-amplitude sloshing behavior of liquid hydrogen in a tank for heavy-duty trucks may have adverse effects on the safety and stability of driving. With successful application of liquid hydrogen in the field of new energy vehicles the coupled thermodynamic performance during liquid hydrogen large-amplitude sloshing becomes more attractive. In this paper a three-dimensional numerical model is established to simulate the thermodynamic coupling characteristics during liquid hydrogen sloshing in a horizontal tank for heavy-duty trucks. The calculation results obtained by the developed model are in good agreement with experimental data for liquid hydrogen. Based on the established 3D model the large-amplitude sloshing behavior of liquid hydrogen under extreme acceleration as well as the effects of acceleration magnitude and duration on liquid hydrogen sloshing is numerically determined. The simulation results show that under the influence of liquid hydrogen large-amplitude sloshing the convective heat transfer of fluid in the tank is greatly strengthened resulting in a decrease in the vapor temperature and an increase in the liquid temperature. In particular the vapor condensation caused by the sloshing promotes a rapid reduction of pressure in the tank. When the acceleration magnitude is 5 g with a duration of 200 ms the maximum reduction of ullage pressure is 1550 Pa and the maximum growth of the force on the right wall is 3.89 kN. Moreover the acceleration magnitude and duration have a remarkable influence on liquid hydrogen sloshing. With the increase in acceleration magnitude or duration there is a larger sloshing amplitude for the liquid hydrogen. When the duration of acceleration is 200 ms compared with the situation at the acceleration magnitude of 5 g the maximum reductions of ullage pressure decrease by 9.46% and 55.02% and the maximum growth of forces on the right wall decrease by 80.57% and 99.53% respectively at 2 g and 0.5 g. Additionally when the acceleration magnitude is 5 g in contrast with the situation at a duration of acceleration of 200 ms the maximum-ullage-pressure drops decrease by 8.17% and 21.62% and the maximum increase in forces on the right wall decrease by 71.80% and 88.63% at 100 ms and 50 ms respectively. These results can provide a reference to the safety design of horizontal liquid hydrogen tanks for heavy-duty trucks.

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.

As the world looks to implement the Energy Transition repurposing existing fossil fuel infrastructure to produce or distribute “clean” energy will be critical. The most promising is using natural gas pipelines for moving hydrogen. This is the cheapest and fastest method of transport and reducing the cost of transporting hydrogen is a key step in making it economically viable. However while there are technical challenges the greater challenge is in the legal arena. This paper seeks to outline the numerous legal — treaty statutory and contractual — and regulatory obstacles to repurposing natural gas pipelines for hydrogen transport. Gas pipelines exist in a complex microclimate of international public and private law and domestic law and contracts. Ownership is often layered and tangled; financing doubly so; and myriad state interests compound the private interests including national security concerns energy supply imperatives and geopolitical balance. State aid — investment subsidies and tax breaks — may encumber the project with additional legal obligations. And the contracts that control the development of a pipeline project may inject further legal complexity such as dispute mediation procedures and fora and applicable law. This paper seeks to map all the likely areas of future conflict or difficulty so that work on developing the requisite legal regime and remedies to permit use of natural gas pipelines for hydrogen transport can begin now. For policy and lawmakers as well as the private sector evaluating these known unknowns is a good starting point for reconsidering legislation regulation contracts and project risk in preparation for the future probability of hydrogen pipelines.

Unignited hydrogen release in underground parking could be considered inherently safer if the safety strategy to avoid the formation of the flammable hydrogen-air mixture under a ceiling is followed. This strategy excludes destructive deflagrative combustion and associated pressure and thermal effects in the case of ignition. This paper aims at understanding the effects of the thermally activated pressure relieve device (TPRD) diameter and direction of release on the build-up of hydrogen flammable concentration under the ceiling in the presence of mechanical ventilation required for underground parking. The study employs the similarity law for hydrogen jet concentration decay in a free under-expanded jet to find the lower limit of TPRD diameter that excludes the formation of a flammable mixture under the ceiling during upward release. This approach is conservative and does not include the effect of mechanical ventilation providing flow velocity around a few meters per second which is significantly below velocities in hydrogen momentum-dominated under-expanded jets. Hydrogen releases downwards under a vehicle at different angles and with different air velocities due to mechanical ventilation were investigated using computational fluid dynamics (CFD). The joint effect of TPRD diameter release direction and mechanical ventilation is studied. TPRD diameters for the release of hydrogen upwards and downwards preventing the creation of flammable hydrogen-air mixture under the parking ceiling are defined for different ceiling heights and locations of TPRD above the floor. Recommendations to the design of TPRD devices to underpin the safe introduction of hydrogen fuelled vehicles in currently existing underground parking and infrastructure are formulated."

This research studies the current state of the Colombian industrial sector which is focused on self-generation processes. The study’s objective is to search for viable technological strategies that strengthen this particular sector’s competitiveness and sustainable development. The analysis shows that internal combustion engines represent 49% of the technologies used for self-generation. The main fuel used in the sector is natural gas with a percentage of 56%. The lack of strategies for the use of residual heat and technological inefficiencies caused a loss of 36% in the energy used in the Colombian industrial sector. Thermoelectric generators are a feasible way to recover energy from exhaust gases in engines used for self-generation. Additionally they allow a 4% reduction in fuel consumption and an improvement in the engine’s energy efficiency. The use of hydrogen as fuel allows a 30% reduction in polluting emissions such as CO2 CO HC and particulate matter. Hydrogen production processes such as water electrolysis allow the participation of Colombia’s solar energy potential leading to sustainable hydrogen production efficiency (60–80%) and a lower economic cost. In general the application of thermoelectric generators and the use of hydrogen gas allow the improvement of the Colombian industrial sector’s environmental social and economic aspects due to greater competitiveness and the reduction in emissions and operating costs.

Green hydrogen via renewable powered electrolysis has a high relevance in decarbonization and supply security. Achieving economically competitive hydrogen production costs is a major challenge in times of an energy price crisis. Our objective is to show the economically optimal installed capacity of electrolysers in relation to wind and solar power so swift and credible statements can be made regarding the system design. The ratio between renewable generation and electrolysis power as well as scaling effects operating behaviour and development of costs are considered. Hydrogen production costs are calculated for four exemplary real PV and wind sites and different ratios of electrolysis to renewable power for the year 2020. The ideal ratio for PV systems is between 14% and 73% and for wind between 3.3% and 143% for low and high full load hours. The lowest hydrogen production costs are identified at 2.53 €/kg for 50 MW wind power and 72 MW electrolysis power. The results provide plant constructors the possibility to create a cost-optimized design via an optimum ratio of electrolysis to renewable capacity. Therefore the procedures for planning and dimensioning of selected systems can be drastically simplified.

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 successful and fast start-up of proton exchange membrane fuel cells (PEMFCs) at subfreezing temperatures (cold start) is very important for the use of PEMFCs as energy sources for automotive applications. The effective thermal management of PEMFCs is of major importance. When hydrogen is stored in hydride-forming intermetallics significant amounts of heat are released due to the exothermic nature of the reaction. This excess of heat can potentially be used for PEMFC thermal management and to accelerate the cold start. In the current work this possibility is extensively studied. Three hydride-forming intermetallics are introduced and their hydrogenation behavior is evaluated. In addition five thermal management scenarios of the metal hydride beds are studied in order to enhance the kinetics of the hydrogenation. The optimum combination of the intermetallic hydrogenation behavior weight and complexity of the thermal management system was chosen for the study of thermal coupling with the PEMFCs. A 1D GT-SUITE model was built to stimulate the thermal coupling of a 100 kW fuel cell stack with the metal hydride. The results show that the use of the heat from the metal hydride system was able to reduce the cold start by up to 8.2%.

As the clamour for a Net Zero carbon energy economy increases it is necessary to harness the potential of renewable energies in powering buildings to lower fossil power plants' contributions to the overall energy mix. This paper aims to present an energy balance load sensitivity analysis and multi-criteria method for sizing a green energy system for powering two office complexes that house space research laboratories. The energy component considered includes battery storage (BAT) captive diesel generator (DG) fuel cell (FC) hydrogen storage (H2T) solar photovoltaic (PV) and wind turbine. Using HOMER the techno-economic features and the hourly operational details of the energy components were obtained. The efficacy of Entropy- Additive Ratio Assessment was deployed on the outputs from HOMER to obtain the most preferred energy system based on more than one criterion. The result of the study indicates that the most preferred energy system for Abuja is a PV WD FC DG and BAT having a total net present cost (TNPC) of $220930. In contrast the most suitable energy system for the energy in the Anyigba office consists of PV FC and BAT with its TNPC at $106955.

This study proposed two concepts for ammonia fuel storage for an ammonia-fueled ammonia carrier and evaluated these concepts in terms of economics. The first concept was to use ammonia in the cargo tank as fuel and the second concept was to install an additional independent fuel tank in the vessel. When more fuel tanks were installed there was no cargo loss. However there were extra costs for fuel tanks. The target ship was an 84000 m3 ammonia carrier (very large gas carrier VLGC). It traveled from Kuwait to South Korea. The capacity of fuel tanks was 4170 m3 which is the required amount for the round trip. This study conducted an economic evaluation to compare the two proposed concepts. Profits were estimated based on sales and life cycle cost (LCC). Results showed that sales were USD 1223 million for the first concept and USD 1287 million for the second concept. Profits for the first and second concepts were USD 684.3 million and USD 739.5 million respectively. The second concept showed a USD 53.1 million higher profit than the first concept. This means that the second concept which installed additional independent fuel tanks was better than the first concept in terms of economics. Sensitivity analysis was performed to investigate the influence of given parameters on the results. When the ammonia fuel price was changed by ±25% there was a 15% change in the profits and if the ammonia (transport) fee was changed by ±25% there was a 45% change in the profits. The ammonia fuel price and ammonia (cargo) transport fee had a substantial influence on the business of ammonia carriers.

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 expected to play a key role in the future as a clean energy source that can mitigate global warming. It can also contribute significantly to reducing the imbalance between energy supply and demand posed by deploying renewable energy. However the infrastructure is not ready for the direct use of hydrogen and largescale storage facilities are needed to store the excess hydrogen production. Geological formations particularly salt caverns seem to be a practical option for this large-scale storage as there is already good experience storing hydrocarbons in caverns worldwide. Salt is known to be ductile impermeable and inert to natural gas. Some cases of hydrogen storage in salt caverns in the United States the United Kingdom and Germany reinforce the idea that salt caverns could be a viable option for underground hydrogen storage especially when the challenges and uncertainties associated with hydrogen storage in porous media are considered. However cavern con struction and management can be challenging when salt deposits are not completely pure and mixed with nonsoluble strata. This review summarises the challenges associated with hydrogen storage in salt caverns and suggests some potential mitigation strategies linked to geomechanical and geochemical interactions. The Zechstein salt group in Northern Europe seems to be a feasible geological site for hydrogen storage but the effect of salt impurity particularly at deep offshore sites such as in the Norwegian North Sea should be carefully analysed. It appears that mechanical integrity geochemical reactions hydrogen loss by halophilic bacteria leaching issues and potential hydrogen diffusion are among the major issues when the internal structure of the salt is not pure.

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.

Fossil fuels continue to exacerbate climate change due to large carbon emissions resulting from their use across a number of sectors. An energy transition away from fossil fuels seems inevitable and energy sources such as renewables and hydrogen may provide a low carbon alternative for the future energy system particularly in large emitting nations such as the United States. This research quantifies and maps potential hydrogen fuel distribution pathways for the continental US reflecting technological changes barriers to deployment and end-use-cases from 2020 to 2100 clarifying the potential role of hydrogen in the US energy transition. The methodology consists of two parts a linear optimization of the global energy system constrained by carbon reduction targets and system cost followed by a projection of hydrogen infrastructure development. Key findings include the emergence of trade pattern diversification with a greater variety of end-uses associated with imported fuels and greater annual hydrogen consumption over time. Further sensitivity analysis identified the influence of complementary technologies including nuclear power and carbon capture and storage technologies. We conclude that hydrogen penetration into the US energy system is economically viable and can contribute toward achieving Paris Agreement and more aggressive carbon reduction targets in the future.

We investigate the role of offshore wind in a hybrid system comprising solar PV offshore wind electrical storage (pumped hydro energy storage or battery) and an electrolyser in an off-grid hydrogen production system. Further we capture a wide range of future cost reduction scenarios for offshore wind power and solar PV generation in addition to accounting for future projected falls in electrolyser costs allowing future hydrogen costs to be estimated with a variety of different assumptions. The empirical setting of Australia and incorporation of solar PV as an additional potential source of electricity enables us to examine the contribution of offshore wind to renewable hydrogen production when an low-cost renewable alternative is available. This study complements a small number of studies on opportunities for offshore wind power in the Australian setting (Briggs et al. 2021; Golestani et al. 2021; Aryai et al. 2021) and contributes to research on the potential for offshore wind to contribute to green hydrogen production focused on the crucial Asia-Pacific region (Kim and Kim 2017; Song et al. 2021).<br/>In the following sections we describe the optimization model and the process used for selecting sites used in the study. We then summarize the modelling scenarios and assumptions before outlining the modelling results. We conclude by discussing the implications of the findings.

The main goal stated at the Paris agreement is to limit the global temperature rise well below 2 °C above pre-industrial levels. Limiting the increase of global average temperature to 1.5 °C is striven since risks and impacts of the climate change would be reduced drastically. To face these challenges the European Green Deal was invented by the European Commission. The “Green Deal” is a growth strategy which aims to transform the economy of the EU into a resource-efficient modern and competitive one [1-1 1-2]. Figure 1: The key elements of the European Green Deal [1-2] In this context the European Commission proposed that the amount of renewable energy within the EU’s overall energy mix should reach 20 % by 2020 and therefore producing energy by solar and wind plants become even more important. For example the cumulative installed wind farm capacity increased from 117.3 GW in 2013 to a total capacity of 182.163 GW in 2018 within the EU [1-4-1-6]. Due to the fluctuations in energy produced by wind farms storage of electricity is crucial. One possibility for storage is the production of hydrogen via electrolysis using renewable energy sources like wind farms. The hydrogen is then either directly added to the gas distribution grid or is converted to methane with external CO or CO2 which is then added to the gas distribution grid as a substitute [1-4]. Increasing the knowledge about the impact of renewable gases on available gas meters in terms of accuracy and durability is the main object of the EMPIR NEWGASMET project. Therefore in activity A3.1.1 a literature study was performed to provide information on which technologies can be used to calibrate gas meters when using renewable gases.

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.

Green hydrogen allows coupling renewable electricity to hard-to-decarbonize sectors such as long-distance transport and carbon-intensive industries in order to achieve net zero emissions. Evaluating the cost and value of power-to-gas is a major challenge owing to the spatial distribution and temporal variability of renewable electricity CO2 and energy demand. Here we propose a method based on geographic information system (GIS) and techno-economic modeling to: (i) compare the levelized cost and levelized value of power-to-gas across locations; (ii) identify potential hotspots for their future implementation in Switzerland; and (iii) set cost improvement targets as well as smart deployment strategies. Our method accounts for the spatial and temporal (both hourly and seasonal) availability of renewable electricity and CO2 sources as well as the presence of gas infrastructure heating networks oxygen and gas demand centers. We find that only green hydrogen plants connected directly to run-of-river hydropower plants are currently profitable in Switzerland (with NPV per CAPEX ranging between 2.3-5.6). However considering technological progress by 2050 a few green hydrogen plants deployed in the demand centers and powered by rooftop PV electricity will also become economically attractive. Moreover a few synthetic methane plants connected to run-of-river hydropower plants currently show slight profitability (NPV per CAPEX reaching values up to 1.3) and in 2050 (NPV per CAPEX up to 3.1) whereas those connected to rooftop PV will remain uneconomical even in 2050. Based on our findings we devise a long-term roadmap for policy makers and project developers to plan future green hydrogen projects. The proposed methodology which is applied to Switzerland can be extended to other countries.

On 20 December 2021 the Department for Business Energy and Industrial Strategy (BEIS) launched a Call for Evidence (CfE) on enabling or requiring hydrogen-ready industrial boiler equipment. The aim was to gather evidence from a broad range of UK manufacturers industrial end-users supply chain participants and other experts to enable the development of proposals. The CfE was open for 12 weeks closing on 14 March 2022. The CfE followed the publication of the UK Hydrogen Strategy on 17 August 2021. In the Strategy government committed to run a CfE on hydrogen-ready industrial equipment by theend of 2022. The published CfE focussed on industrial boilers due to their widespread use and because BEIS analysis indicates a significant proportion of the demand for hydrogen in industry will come from this equipment category. Furthermore the technology required for hydrogen boilers is relatively advanced and more standardised than for other types of industrial<br/>equipment. For these reasons industrial boiler equipment presents a good test case for hydrogen-ready industrial equipment more broadly.<br/>The CfE contained the following three sections:<br/>• The opportunity for hydrogen-ready industrial boilers<br/>• The role for government to support hydrogen-ready industrial boiler equipment<br/>• The role of the supply chain and economic opportunities for the UK<br/>Respondents were asked to support their answers with evidence relating to their business product or sector published literature studies or to their broader expertise. To raise awareness of the CfE BEIS officials held two online webinars on 1 February 2022 and 3 February 2022. These were open to boiler manufacturers industrial end-users supply chain participants trade associations professional bodies and any other person(s) with an interest in the area.<br/>To build on evidence gathered through the CfE BEIS commissioned an independent study from Arup and Kiwa Gastec to further examine whether government should enable or require hydrogen-ready industrial boiler equipment. This study investigated the following topics:<br/>• definitions of hydrogen-readiness for industrial boilers<br/>• comparisons of the cost and resource requirement to install and convert hydrogen-ready industrial boiler equipment<br/>• industrial boiler supply chain capacity for conversion to hydrogen<br/>• estimates of the UK industrial boiler population<br/>The final report for this study has been published alongside the government response to the call for evidence. The conclusions and recommendations of that report do not necessarily represent the view of BEIS.

A new electrically driven gas booster is described as an alternative to the classical air-driven gas boosters known for their poor energetic efficiency. These boosters are used in small scale Hydrogen storage facilities and in refueling stations for Hydrogen vehicles. In such applications the overall energy count is of significance and must include the efficiency of the compression stage. The proposed system uses an electric motor instead of the pneumatic actuator and increases the total efficiency of the compression process. Two mechanical principles are studied for the transformation of the rotational motion of the motor to the linear displacement of the compressor pistons. The strongly fluctuating power of the compressor is smoothed by an active capacitive auxiliary storage device connected to the DC circuit of the power converter. The proposed system has been verified by numeric simulation including the thermodynamic phenomena the kinetics of the new compressor drive and the the operation of the circuits of the power smoothing system.

Hybrid electric vehicles are currently one of the most effective ways to increase the efficiency and reduce the pollutant emissions of internal combustion engines. Green hydrogen produced with renewable energies is an excellent alternative to fossil fuels in order to drastically reduce engine pollutant emissions. In this work the author proposes the implementation of a hydrogen-fueled engine in a hybrid vehicle; the investigated hybrid powertrain is the power-split type in which the engine two electric motor/generators and the drive shaft are coupled together by a planetary gear set; this arrangement allows the engine to operate independently from the wheels and thus to exploit the best efficiency operating points. A set of numeric simulations were performed in order to compare the gasoline-fueled engine with the hydrogen-fueled one in terms of the thermal efficiency and total energy consumed during a driving cycle. The simulation results show a mean engine efficiency increase of around 17% when fueled with hydrogen with respect to gasoline and an energy consumption reduction of around 15% in a driving cycle.

Although climate change can be efficiently curbed by shifting to low-carbon (blue) hydrogen as an energy carrier to achieve carbon neutrality current hydrogen production mainly proceeds via the gray pathway i.e. generates large amounts of CO2 as a byproduct. To address the need for cleaner hydrogen production we herein propose novel CO2 capture processes based on the integration of vacuum pressure swing adsorption into a gray hydrogen production process and perform retrofitting to a blue hydrogen production process for on-site hydrogen refueling stations. Techno-economic analysis reveals that the implementation of the proposed capture processes allows one to significantly reduce CO2 emission while preserving thermal efficiency and the economic feasibility of this implementation in different scenarios is determined by computing the levelized cost of hydrogen. As a result blue hydrogen is shown to hold great promise for the realization of sustainable energy usage and the net-zero transition.