Publications

Progressing limits on pollutant emissions oblige ship owners to reduce the environmental impact of their operations. Fuel cells may provide a suitable solution since they are fuel efficient while they emit few hazardous compounds. Various choices can be made with regard to the type of fuel cell system and logistic fuel and it is unclear which have the best prospects for maritime application. An overview of fuel cell types and fuel processing equipment is presented and maritime fuel cell application is reviewed with regard to efficiency gravimetric and volumetric density dynamic behaviour environmental impact safety and economics. It is shown that low temperature fuel cells using liquefied hydrogen provide a compact solution for ships with a refuelling interval up to a tens of hours but may result in total system sizes up to five times larger than high temperature fuel cells and more energy dense fuels for vessels with longer mission requirements. The expanding infrastructure of liquefied natural gas and development state of natural gas-fuelled fuel cell systems can facilitate the introduction of gaseous fuels and fuel cells on ships. Fuel cell combined cycles hybridisation with auxiliary electricity storage systems and redundancy improvements are identified as topics for further study

Energy-related GHG emissions mainly from fossil fuels combustion account for around 70% of total emissions. Those emissions are the target of the recent sustainability policies. Indeed renewables exploitation is considered widely the weapon to deal with this challenge thanks to their carbon neutrality. But the biggest drawback is represented by the mismatching between their production and users consumption. The storage would be a possible solution but its viability consists of economic sustainability and energy process efficiency as well. The cutting edge technologies of batteries have not still solved these issues at the same time. So a paradigm shift towards the identification of an energy carrier as storage option the so called Power-to-Gas could be the viable solution. From viability to feasibility a mandatory step is required: the opportunity to integrate the new solution in the proven infrastructures system. Thus the recent studies on Hydrogen (H2) enrichment in Natural Gas demonstrating a lower environmental impact and an increase in energy performance are the base to build the hydrogen transition in the urban environment. The aim of this paper is to evaluate the environmental benefits at building and district scale.

The technological lock-in of the transportation and industrial sector can be largely attributed to the limited availability of alternative fuel infrastructures. Herein a countrywide supply chain analysis of Germany spanning until 2050 is applied to investigate promising infrastructure development pathways and associated hydrogen distribution costs for each analyzed hydrogen market. Analyzed supply chain pathways include seasonal storage to balance fluctuating renewable power generation with necessary purification as well as trailer- and pipeline-based hydrogen delivery. The analysis encompasses green hydrogen feedstock in the chemical industry and fuel cell-based mobility applications such as local buses non-electrified regional trains material handling vehicles and trucks as well as passenger cars. Our results indicate that the utilization of low-cost long-term storage and improved refueling station utilization have the highest impact during the market introduction phase. We find that public transport and captive fleets offer a cost-efficient countrywide renewable hydrogen supply roll-out option. Furthermore we show that at comparable effective carbon tax resulting from the current energy tax rates in Germany hydrogen is cost-competitive in the transportation sector by the year 2025. Moreover we show that sector-specific CO2 taxes are required to provide a cost-competitive green hydrogen supply in both the transportation and industrial sectors.

Hydrogen has been identified as a very promising vector for energy storage especially for heavy mobility applications. For this reason France is making significant investments in this field and use cases need to be evaluated as they are sprouting. In this paper the relevance of H2 in two storage applications is studied: a domestic renewable electricity production system connected to the grid and a collective hydrogen production for the daily bus refill. The investigation consists of the sizing of the system and then the evaluation of its performance according to several criteria depending on case. Optimizations are made using Bayesian and gradient-based methods. Several variations around a central case are explored for both cases to give insights on the impact of the different parameters (location pricing objective etc.) on the performance of the system.Our results show that domestic power-to-power applications (case 1) do not seem to be competitive with electrochemical storage. Meanwhile without any subsidies or incentives such configuration does not allow prosumers to save money (+16% spendings compared to non-equipped dwelling). It remains interesting when self-sufficiency is the main objective (up to 68% of energy is not exchanged). The power-to-gas application (case 2 central case) with a direct use of hydrogen for mobility seems to be more relevant according to our case study we could reach a production cost of green H2 around 5 €/kg similar to the 3–10 $/kg found in literature for 182 houses involved. In both cases H2 follows a yearly cycle charging in summer and discharging in winter (long term storage) due to low conversion efficiency.

Considering the current environmental restrictions particularly those imposed on fossil fuel exploitation hydrogen stands out as a very promising alternative for the power and transportation sectors. This paper investigates the effects of the employment of hydrogen in a K9K automotive diesel engine. Experiments were conducted at a speed of 2000 min−1 with various engine load levels of 40% 55% 70% and 85%; several quantities were monitored to evaluate the performance with hydrogen use in terms of brake-specific energetic consumption (BSEC) fuel economy maximum pressure and heat-release characteristics. It was found that at 55% engine load the engine efficiency increased by 5.3% with hydrogen addition achieving a diesel fuel economy of 1.32 kg/h. The rate of increase of the peak pressure and maximum pressure started to increase as a consequence of the higher fuel quantity that burned in the premixed combustion phase while still remaining within reliable operational limits. The accelerated combustion and augmented heat release rate resulted in a combustion duration that was reduced by 3◦ CA (crank angle degree) achieving a mass fraction burned percentage of 10% to 90% earlier in the cycle and the combustion variability was also influenced. Hydrogen use assured the decrease of CO2 HC NOx and smoke emission levels in comparison with classic fueling.

As a countermeasure to the greenhouse gas problem the world is focusing on alternative fuel vehicles (AFVs). The most prominent alternatives are battery electric vehicles (BEV) and fuel cell electric vehicles (FCEVs). This study examines FCEVs especially considering hydrogen refueling stations to fill the gap in the research. Many studies suggest the important impact that infrastructure has on the diffusion of AFVs but they do not provide quantitative preferences for the design of hydrogen refueling stations. This study analyzes and presents a consumer preference structure for hydrogen refueling stations considering the production method distance probability of failure to refuel number of dispensers and fuel costs as core attributes. For the analysis stated preference data are applied to choice experiments and mixed logit is used for the estimation. Results indicate that the supply stability of hydrogen refueling stations is the second most important attribute following fuel price. Consumers are willing to pay more for green hydrogen compared to gray hydrogen which is hydrogen produced by fossil fuels. Driver fuel type and perception of hydrogen energy influence structure preference. Our results suggest a specific design for hydrogen refueling stations based on the characteristics of user groups.

In this study the consequences of an accidental release of hydrogen within large scale (>15000 m3) facilities were modelled. To model the hydrogen release an LES Navier–Stokes CFD solver called fireFoam was used to calculate the dispersion and mixing of hydrogen within a large scale facility. The performance of the CFD modelling technique was evaluated through a validation study using experimental results from a 1/6 scale hydrogen release from the literature and a grid sensitivity study. Using the model a parametric study was performed varying release rates and enclosure sizes and examining the concentrations that develop. The hydrogen dispersion results were then used to calculate the corresponding pressure loads from hydrogen-air deflagrations in the facility.

In this study we model seven scenarios for the European power system in 2050 based on 100% renewable energy sources assuming different levels of future demand and technology availability and compare them with a scenario which includes low-carbon non-renewable technologies. We find that a 100% renewable European power system could operate with the same level of system adequacy as today when relying on European resources alone even in the most challenging weather year observed in the period from 1979 to 2015. However based on our scenario results realising such a system by 2050 would require: (i) a 90% increase in generation capacity to at least 1.9 TW (compared with 1 TW installed today) (ii) reliable cross-border transmission capacity at least 140GW higher than current levels (60 GW) (iii) the well-managed integration of heat pumps and electric vehicles into the power system to reduce demand peaks and biogas requirements (iv) the implementation of energy efficiency measures to avoid even larger increases in required biomass demand generation and transmission capacity (v) wind deployment levels of 7.5GWy−1 (currently 10.6GWy−1) to be maintained while solar photovoltaic deployment to increase to at least 15GWy−1 (currently 10.5GWy−1) (vi) large-scale mobilisation of Europe’s biomass resources with power sector biomass consumption reaching at least 8.5 EJ in the most challenging year (compared with 1.9 EJ today) and (vii) increasing solid biomass and biogas capacity deployment to at least 4GWy−1 and 6 GWy−1 respectively. We find that even when wind and solar photovoltaic capacity is installed in optimum locations the total cost of a 100% renewable power system (∼530 €bn y−1) would be approximately 30% higher than a power system which includes other low-carbon technologies such as nuclear or carbon capture and storage (∼410 €bn y−1). Furthermore a 100% renewable system may not deliver the level of emission reductions necessary to achieve Europe’s climate goals by 2050 as negative emissions from biomass with carbon capture and storage may still be required to offset an increase in indirect emissions or to realise more ambitious decarbonisation pathways.

The recent transport electrification trend is pushing governments to limit the future use of Internal Combustion Engines (ICEs). However the rationale for this strong limitation is frequently not sufficiently addressed or justified. The problem does not seem to lie within the engines nor with the combustion by themselves but seemingly rather with the rise in greenhouse gases (GHG) namely CO2 rejected to the atmosphere. However it is frequent that the distinction between fossil CO2 and renewable CO2 production is not made or even between CO2 emissions and pollutant emissions. The present revision paper discusses and introduces different alternative fuels that can be burned in IC Engines and would eliminate or substantially reduce the emission of fossil CO2 into the atmosphere. These may be non-carbon fuels such as hydrogen or ammonia or biofuels such as alcohols ethers or esters including synthetic fuels. There are also other types of fuels that may be used such as those based on turpentine or even glycerin which could maintain ICEs as a valuable option for transportation.

Hydrogen produced by solar and other clean energy sources is an essential alternative to fossil fuels. In this study a commercial alkaline electrolyzer with different cell numbers and electrode areas are simulated for different pressure temperature thermal resistance and electrical current. This alkaline electrolyzer is considered unsteady in simulations and different parameters such as temperature are obtained in terms of time. The obtained results are compared with similar results in the literature and good agreement is observed. Various characteristics of this alkaline electrolyzer as thermoneutral voltage faraday efficiency and cell voltage are calculated and displayed. The outlet heat rate and generated heat rate are obtained as well. The pressure and the temperature in the simulations are between 1 and 100 bar and between 300 and 360 Kelvin respectively. The results show that the equilibrium temperature is reached 2-3 hours after the time when the Alkaline electrolyzer starts to work.

The explosion venting is an effective way to reduce hydrogen-air explosion hazards but the explosion venting has been hardly touched in an obstructed container. Current experiments focused on the effects of different blockage ratios on the explosion venting in a small obstructed rectangular container. Experimental results show that three overpressure peaks are formed in the case with the obstacle while only two can be observed in the case of no obstacle. The obstacle blockage ratio has a significant influence on the peak overpressure induced by the obstacle-acoustic interactions but it has an ignorable effect on the peak overpressure caused by the rupture of the vent film. The obstacle-induced overpressure peak first increases and then decreases with the increase of the blockage ratio. In addition all overpressure peaks inside the container decreases with the increase of the vent area and its appearance time is relatively earlier for larger vent area.

In this report a 5 kW PEFC system running on dry hydrogen with an appropriately sized Balance of Plant (BoP) was used to conduct experimental studies and analyses of gas supply subsystems. The improper rating and use of BoP components has been found to increase parasitic loads which consequently has a direct effect on the polymer electrolyte fuel cell (PEFC) system efficiency. Therefore the minimisation of parasitic loads while maintaining desired performance is crucial. Nevertheless little has been found in the literature regarding experimental work on large stacks and BoP with the majority of papers concentrating on modelling. A particular interest of our study was the anode side of the fuel cell. Additionally the rationale behind the use of hydrogen anode recirculation was scrutinised and a novel anode purging strategy was developed and implemented. Through experimental modelling the use of cathode air blower was minimised since it was found to be the biggest contributor to the parasitic loads.

In December 2019 the European Commission unveiled an ambitious project the European Green Deal which aims to lead the European Union to climate neutrality by 2050. This is a significant challenge for all EU countries and especially for Poland. The role of hydrogen in the processes of decarbonization of the economy and transport is being discussed in many countries around the world to find rational solutions to this difficult and complex problem. There is an ongoing discussion about the hydrogen economy which covers the production of hydrogen its storage transport and conversion to the desired forms of energy primarily electricity mechanical energy and new fuels. The development of the hydrogen economy can significantly support the achievement of climate neutrality. The belief that hydrogen plays an important role in the transformation of the energy sector is widespread. There are many technical and economic challenges as well as legal and logistical barriers to deal with in the transition process. The development of hydrogen technologies and a global sustainable energy system that uses hydrogen offers a real opportunity to solve the challenges facing the global energy industry: meeting the need for clean fuels increasing the efficiency of fuel and energy production and significantly reducing greenhouse gas emissions. The paper provides an in-depth analysis of the Polish Hydrogen Strategy a document that sets out the directions for the development of hydrogen use (competences and technologies) in the energy transport and industrial sectors. This analysis is presented against the background of the European Commission’s document ‘A Hydrogen Strategy for a Climate-Neutral Europe’. The draft project presented is a good basis for further discussion on the directions of development of the Polish economy. The Polish Hydrogen Strategy although it was created later than the EU document does not fully follow its guidelines. The directions for further work on the hydrogen strategy are indicated so that its final version can become a driving force for the development of the country’s economy.

This paper proposes a current decoupling controller for a Doubly-fed Induction Generator (DFIG) based on floating offshore wind turbine and power to gas. The proposed controller realizes Maximum Power Point Tracking (MPPT) through integral sliding mode compensation. By using the internal model control strategy an open-loop controller is designed to ensure that the system has good dynamic performance. Furthermore using the integral Sliding Mode Control (SMC) strategy a compensator is designed to eliminate the parameter perturbation and external disturbance of the open-loop control. The parameters of the designed controller are designed through Grey Wolf Optimization (GWO). Simulation results show that the proposed control strategy has better response speed and smaller steady-state error than the traditional control strategy. This research is expected to be applied to the field of hydrogen production by floating offshore wind power.

Storing renewable energy in chemicals like hydrogen can bring various benefits like high energy density seasonal storability possible cost reduction of the final product and the potential to let renewable power penetrate other markets and to overcome their intermittent availability. In the last year’s production of this gas from renewable energy sources via electrolysis has grown its reputation as one feasible solution to satisfy future zero-emission energy demand. To extend the exploitation of Renewable Energy Source (RES) small-scale conversion plants seem to be an interesting option. In view of a possible widespread adoption of these types of plants the authors intend to present the experimental characterization of a small-scale hydrogen production and storage plant. The considered experimental plant is based on an alkaline electrolyser and an air-driven hydrogen compression and storage system. The results show that the hydrogen production-specific consumption is on average 77 kWh/kgH2 . The hydrogen compressor energy requirement is on average 15 kWh/kgH2 (data referred to the driving compressed air). The value is higher than data found in literature (4.4–9.3 kWh/kgH2 ) but the difference can be attributed to the small size of the considered compressor and the choice to limit the compression stages.

There is a large literature exploring possible hydrogen futures using various modelling and scenario approaches. This paper compares the rates of transition depicted in that literature with a set of historical analogies. These analogies are cases in which alternative-fuelled vehicles have penetrated vehicle markets. The paper suggests that the literature has tended to be optimistic about the possible rate at which hydrogen vehicles might replace oil-based transportation. The paper compares 11 historical adoptions of alternative fuel vehicles with 24 scenarios from 20 studies that depict possible hydrogen futures. All but one of the hydrogen scenarios show vehicle adoption faster than has occurred for hybrid electric vehicles in Japan the most successful market for hybrids. Several scenarios depict hydrogen transitions occurring at a rate faster than has occurred in any of the historic examples. The paper concludes that scenarios of alternative vehicle adoption should include more pessimistic scenarios alongside optimistic ones.

Gaseous fuels with low life-cycle emissions of greenhouse gases (GHG) play a prominent role in the European Union’s (EU) decarbonization plans. Renewable and low-GHG hydrogen are highlighted in the ambitious goals for a cross-sector hydrogen economy laid out in the European Commission’s Hydrogen Strategy. Renewable hydrogen and biomethane are given strong production incentives in the Commission’s proposed revision to the Renewable Energy Directive (REDII). The EU uses life-cycle analysis (LCA) to determine whether renewable gas pathways meet the GHG reduction thresholds for eligibility in the REDII. This study aims to support European policymakers with a better understanding of the uncertainties regarding gaseous fuels’ roles in meeting climate goals. Life-cycle GHG analysis is complex and differences in methodology as well as data inputs and assumptions can spell the difference between a renewable gas pathway qualifying or not for REDII eligibility at the 50% to 80% GHG reduction level. It is thus important for European policymakers to use robust LCA to ensure that policy only supports gas pathways consistent with a vision of deep decarbonization. For this purpose we conduct sensitivity analysis of the life-cycle GHG emissions of a number of low-GHG gas pathways including biomethane produced from four feedstocks: wastewater sludge manure landfill gas (LFG) and silage maize; and hydrogen produced from eight sources: natural gas combined with carbon capture and storage (CCS) coal with CCS biomass gasification renewable electricity 2030 EU grid electricity wastewater sludge biomethane manure biomethane and LFG biomethane. For each pathway we estimate the life-cycle GHG intensity using a default central case identify key parameters that strongly affect the fuel’s GHG intensity and conduct a sensitivity analysis by changing these key parameters according to the range of possible values collected from the literature. Figure ES1 summarizes the full range of possible GHG intensities for each gaseous pathway we analyzed in this study—biomethane is depicted in the top figure and hydrogen is shown in the bottom. The bars represent the GHG intensity of the central case and vertical error bars indicate the maximum and minimum GHG intensity of each pathway according to our sensitivity analysis. The dotted orange horizontal line illustrates the fossil comparator which is 94 grams of carbon dioxide equivalent per megajoule (gCO2e/MJ) for transport fuels in the REDII. The dotted yellow line represents the GHG intensity of a 65% GHG reduction goal for biomethane used in the transportation sector or 70% GHG reduction for hydrogen. Pathways are situated from left to right in increasing order of GHG intensity of the central case. Comparing the central cases of the four biomethane pathways the waste-based biomethane pathways generally have negative GHG intensity. However considering the uncertainty in these GHG intensities manure biomethane might have more limited carbon reduction potential in the 100-year timeframe if methane leakage from its production process is high. In contrast wastewater sludge biomethane and LFG biomethane even after accounting for uncertainties retain relatively low GHG emissions. On the other hand biomethane produced from silage maize can have much higher emissions; in the central case we find that silage maize biogas only reduces GHG emissions by 30% relative to the fossil comparator—the low carbon reduction potential is due to the significant emissions emerging from direct and indirect land use change involved in growing maize. Taking into account the variation in assumptions silage maize biomethane can be worse for the climate than fossil fuels.

Sustainability transportation is characterized by a positive externality on the environment health social security land use and social inclusion. The increasing interest in global warming has caused attention to be paid to the introduction of the hydrogen bus (H2B). When introducing new environmental technologies such as H2B it is often necessary to assess the environmental benefits related to this new technology. However such benefits are typically non-priced due to their public good nature. Therefore we have to address this problem using the contingent valuation (CV) method. This method has been developed within environmental economics as a means to economically assess environmental changes which are typically not traded in the market. So far several big cities have been analyzed to evaluate the perceived benefit related to H2B introduction but to the best of our knowledge no one has performed a CV analysis of a historical city where smog also damages historical buildings. This paper presents the results obtained using a multi-wave survey. We have investigated user preferences to elicit their willingness to pay for H2B introduction in Perugia taking into account all types of negative externalities due to the traffic pollution. The results confirm that residents in Perugia are willing to pay extra to support the introduction of H2B.

Alkaline water electrolysis powered by renewable energy sources is one of the most promising strategies for environmentally friendly hydrogen production. However wind and solar energy sources are highly dependent on weather conditions. As a result power fluctuations affect the electrolyzer and cause several negative effects. Considering these limiting effects which reduce the water electrolysis efficiency a novel operation strategy is proposed in this study. It is based on pumping the electrolyte according to the current density supplied by a solar PV module in order to achieve the suitable fluid dynamics conditions in an electrolysis cell. To this aim a mathematical model including the influence of electrode-membrane distance temperature and electrolyte flow rate has been developed and used as optimization tool. The obtained results confirm the convenience of the selected strategy especially when the electrolyzer is powered by renewable energies.

Hydrogen storage in the solid state represents one of the most attractive and challenging ways to supply hydrogen to a proton exchange membrane (PEM) fuel cell. Although in the last 15 years a large variety of material systems have been identified as possible candidates for storing hydrogen further efforts have to be made in the development of systems which meet the strict targets of the Fuel Cells and Hydrogen Joint Undertaking (FCH JU) and U.S. Department of Energy (DOE). Recent projections indicate that a system possessing: (i) an ideal enthalpy in the range of 20–50 kJ/mol H2 to use the heat produced by PEM fuel cell for providing the energy necessary for desorption; (ii) a gravimetric hydrogen density of 5 wt. % H2 and (iii) fast sorption kinetics below 110 ◦C is strongly recommended. Among the known hydrogen storage materials amide and imide-based mixtures represent the most promising class of compounds for on-board applications; however some barriers still have to be overcome before considering this class of material mature for real applications. In this review the most relevant progresses made in the recent years as well as the kinetic and thermodynamic properties experimentally measured for the most promising systems are reported and properly discussed.

The turbine-combined free-piston engine generator (TCFPEG) is a hybrid machine generating both mechanical work from the gas turbine and electricity from the linear electric generator for battery charging. In the present study the system performance of the designed TCFPEG system is predicted using a validated numerical model. A parametric analysis is undertaken based on the influence of the engine load valve timing the number of linear generators adopted and different fuels on the system performance. It is found that when linear electric generators are connected with the free-piston gas turbine the bottom dead centre the peak piston velocity and engine operation frequency are all reduced. Very minimal difference on the in-cylinder pressure and the compressor pressure is observed while the peak pressure in the bounce chamber is reduced. When coupled with a linear electric generator the system efficiency can be improved to nearly 50% by optimising engine load and the number of the linear generators adopted in the TCFPEG system. The system is able to be operated with different fuels as the piston is not limited by a mechanical system; the output power and system efficiency are highest when hydrogen is used as the fuel.

The effect of alcohol structure on photocatalytic production of H₂ from C-3 alcohols was studied on 0.5% Pt/TiO₂. A C-2 alcohol (ethanol) was also included for comparative purposes. For individual reactions from 10% v/v aqueous solutions of alcohols hydrogen production followed the order ethanol ≈ propan-2-ol > propan-1- ol > propane-123-triol > propane-12-diol > propane-13-diol. The process was found to be quite sensitive to the presence of additional alcohols in the reaction medium as evidenced by competitive reactions. Therefore propan-2-ol conversion was retarded in the presence of traces of the other alcohols this effect being particularly significant for vicinal diols. Additional experiments showed that adsorption of alcohols on Pt/TiO₂ followed the order propane-123-triol > propane-12-diol > propane-13-diol > propan-1-ol > ethanol > propan-2-ol. Adsorption studies (DRIFT) and monitoring of reaction products showed that the main photocatalyzed process for propan-2-ol and propan-1-ol transformation is dehydrogenation to the corresponding carbonyl compound (especially for propan-2-ol both in the liquid and the gas phase). In the case of liquid-phase transformation of propan-1-ol ethane was also detected which is indicative of the dissociative mechanism to lead to the corresponding C-1 alkane. All in all competitive reactions proved to be very useful for mechanistic studies.

This paper compares the well-to-wheel (WTW) greenhouse gas (GHG) emissions of representative vehicle types–internal combustion engine vehicle (ICEV) hybrid electric vehicle (HEV) plug-in hybrid electric vehicle (PHEV) battery electric vehicle (BEV) and fuel cell electric vehicle (FCEV)–in the future (2030) based on a WTW analysis for the present (2017) and an analysis of various energy policies that could affect future emissions. South Korea was selected as the target region because it has detailed energy policies related to alternative vehicles. The WTW analysis for the present was performed based on three sets of subordinate analyses: (1) life cycle analyses of eight base fuels; (2) life cycle analyses of electricity and hydrogen; and (3) analyses of the fuel economies of seven vehicle types. From the WTW analysis for the present the national average WTW GHG emissions of ICEV-gasoline ICEV-diesel ICEV-liquefied petroleum gas HEV PHEV BEV and FCEV were calculated as 225 233 201 159 133 109 and 55 g-CO₂-eq./km respectively. For calculating the WTW GHG emissions in the future two policies regarding electricity production and three policies regarding hydrogen production were analysed. Three cases with varying the degrees of improvements in fuel economies were considered. Six future scenarios were constructed and each scenario represented the case in which each energy policy is enacted. In the reference scenario for compact car the WTW GHG emissions of ICEVs-gasoline HEV PHEV BEV-200 mile FCEV were analysed as 161 110 97 86 and 91 g-CO₂-eq./km respectively. The differences between ICEV/HEV and BEV were predicted to decrease in the future mainly due to larger improvements of ICEV/HEV in fuel economies compared to that of BEV. The future life cycle GHG emissions of electricity and hydrogen were calculated according to energy policy. Both two policies regarding power generation were confirmed to increase the benefits of utilizing BEVs but current energy policy regarding hydrogen production were confirmed to decrease the benefits of utilizing FCEVs. Based on the comprehensive results of this study a framework was proposed to evaluate the impacts of an energy policy regarding electricity and hydrogen production on the benefits of using BEVs and FCEVs compared to using HEVs and ICEVs. This framework can also be utilized in other countries when they assess and establish their energy policies.

The upcoming stricter limitations on both pollutant and greenhouse gases emissions represent a challenge for the shipping sector. The entire ship design process requires an approach to innovation with a particular focus on both the fuel choice and the power generation system. Among the possible alternatives natural gas and hydrogen based propulsion systems seem to be promising in the medium and long term. Nonetheless natural gas and hydrogen storage still represents a problem in terms of cargo volume reduction. This paper focuses on the storage issue considering compressed gases and presents an innovative solution which has been developed in the European project GASVESSEL® that allows to store gaseous fuels with an energy density higher than conventional intermediate pressure containment systems. After a general overview of natural gas and hydrogen as fuels for shipping a case study of a small Roll-on/Rolloff passenger ferry retrofit is proposed. The study analyses the technical feasibility of the installation of a hybrid power system with batteries and polymer electrolyte membrane fuel cells fuelled by hydrogen. In particular a process simulation model has been implemented to assess the quantity of hydrogen that can be stored on board taking into account boundary conditions such as filling time on shore storage capacity and cylinder wall temperature. The simulation results show that if the fuel cells system is run continuously at steady state to cover the energy need for one day of operation 140 kg of hydrogen are required. Using the innovative pressure cylinder at a storage pressure of 300 bar the volume required by the storage system assessed on the basis of the containment system outer dimensions is resulted to be 15.2 m3 with a weight of 2.5 ton. Even if the innovative type of pressure cylinder allows to reach an energy density higher than conventional intermediate pressure cylinders the volume necessary to store a quantity of energy typical for the shipping sector is many times higher than that required by conventional fuels today used. The analysis points out as expected that the filling process is critical to maximize the stored hydrogen mass and that it is critical to measure the temperature of the cylinder walls in order not to exceed the material limits. Nevertheless for specific application such as the one considered in the paper the introduction of gaseous hydrogen as fuel can be considered for implementing zero local emission propulsion system in the medium term.

Hydrogen dispersion in stagnant environment resulting from blowdown of a vessel storing the gas at cryogenic temperature is simulated using different CFD codes and modelling strategies. The simulations are based on the DISCHA experiments that were carried out by Karlsruhe Institute of Technology (KIT) and Pro-Science (PS). The selected test for the current study involves hydrogen release from a 2.815 dm3 volume tank with an initial pressure of 200 barg and temperature 80 K. During the release the hydrogen pressure in the tank gradually decreased. A total of about 139 gr hydrogen is released through a 4 mm diameter. The temperature time series and the temperature decay rate of the minimum value predicted by the different codes are compared with each other and with the experimentally measured ones. Recommendations for future experimental setup and for modeling approaches for similar releases are provided based on the present analysis. The work is carried out within the EU-funded project PRESLHY.

Existing studies of financing efficiency concentrate on capital structure and a single external environment or internal management characteristic. Few of the studies include the internal and external financing environments at the same time for hydrogen energy industry financing efficiency. This paper used the data envelopment analysis (DEA) model and the Malmquist index to measure the financing efficiency of 70 hydrogen energy listed enterprises in China from 2014 to 2020 from both static and dynamic perspectives. Then a tobit model was constructed to explore the influence of external environment and internal factors on the financing efficiency. The contributions of this paper are studying the internal and external financing environments and integrating financing cost efficiency and capital allocation efficiency into the financing efficiency of hydrogen energy enterprises. The results show that firstly the financing efficiency of China’s hydrogen energy listed enterprises showed an upward trend during the years 2014–2020. Secondly China’s hydrogen energy enterprises mainly gather in the eastern coastal areas and their financing efficiency is more than that in western areas. Thirdly the regional economic development level enterprise scale financing structure capital utilization efficiency and profitability have significant effects on the financing efficiency. These results can promote the achievement of “carbon neutrality” in China.

Natural gas (Methane) is currently the primary source of catalytic hydrogen production accounting for three quarters of the annual global dedicated hydrogen production (about 70 M tons). Steam–methane reforming (SMR) is the currently used industrial process for hydrogen production. However the SMR process suffers with insufficient catalytic activity low long-term stability and excessive energy input mostly due to the handling of large amount of CO2 coproduced. With the demand for anticipated hydrogen production to reach 122.5 M tons in 2024 novel and upgraded catalytic processes are desired for more effective utilization of precious natural resources. In this review we summarized the major descriptors of catalyst and reaction engineering of the SMR process and compared the SMR process with its derivative technologies such as dry reforming with CO2 (DRM) partial oxidation with O2 autothermal reforming with H2O and O2. Finally we discussed the new progresses of methane conversion: direct decomposition to hydrogen and solid carbon and selective oxidation in mild conditions to hydrogen containing liquid organics (i.e. methanol formic acid and acetic acid) which serve as alternative hydrogen carriers. We hope this review will help to achieve a whole picture of catalytic hydrogen production from methane.

The actual start of the full-scale hydrogen energy infrastructure operations is scheduled to 2020 in Japan. The scope of factors and policy for the hydrogen infrastructure development in Japan is made. The paper provides observation for the major undergoing and already done projects for each link within hydrogen infrastructure chain – from production to end-user applications. Implications for the Russian energy policy are provided.

Green hydrogen will play a key role in building a climate-neutral energy-intensive industry as key technologies for defossilising the production of steel and basic chemicals depend on it. Thus policy-making needs to support the creation of a market for green hydrogen and its use in industry. However it is unclear how appropriate policies should be designed and a number of challenges need to be addressed. Based on an analysis of the ongoing German debate on hydrogen policies this paper analyses how policy-making for green hydrogen development may support industry defossilisation. For the assessment of policy instruments a simplified multi-criteria analysis (MCA) is used with an innovative approach that derives criteria from specific challenges. Four challenges and seven relevant policy instruments are identified. The results of the MCA reveal the potential of each of the selected instruments to address the challenges. The paper furthermore outlines how instruments might be combined in a policy package that supports industry defossilisation creates synergies and avoids trade-offs. The paper’s impact may reach beyond the German case as the challenges are not specific to the country. The results are relevant for policy-makers in other countries with energy-intensive industries aiming to set the course towards a hydrogen future.

Hot water and space heating account for about 80% of total energy consumption in the residential sector in the UK. It is thus crucial to decarbonise residential heating to achieve UK's 2050 greenhouse gas reduction targets. However the decarbonisation transitions determined by most techno-economic energy system models might be too optimistic or misleading for relying on cost minimisation alone and not considering households' preferences for different heating technologies. This study thus proposes a novel framework to incorporate heterogeneous households' (HHs) preferences into the modelling process of the UK TIMES model. The incorporated preferences for HHs are based on a nationwide survey on homeowners' choices of heating technologies. Preference constraints are then applied to regulate the HHs' choices of heating technologies to reflect the survey results. Consequently compared to the least cost transition pathway the preference-driven pathway adopts heating technologies gradually without abrupt increases of market shares. Heat pumps and electric heaters are deployed much less than in the cost optimal result. Extensive district heating using low-carbon fuels and conservation measures should thus be deployed to provide flexibility for decarbonisation. The proposed framework can also incorporate preferences for other energy consumption technologies and be applied to other linear programming based energy system models.

This paper deals with the main safety aspects of the EOS project. The partners of the project – Politecnico di Torino Gas Turbine Technologies (GTT Siemens group) Hysylab (Hydrogen System Laboratory) of Environment Park and Regione Piemonte – aim to create the main node of a regional fuel cell generator network. As a first step the Pennsylvania-based Stationary Fuel Cells division of Siemens Westinghouse Power Corporation (SWPC) supplied GTT with a CHP 100 kWe SOFC (Solide Oxide Fuel Cell) field unit fuelled by natural gas with internal reforming. The fuel cell is connected to the electricity national grid and provides part of the industrial district energy requirement. The thermal energy from the fuel cells is used for heating and air-conditioning of GTT offices bringing the total first Law efficiency of the plant to 70-80%. In the second phase of the EOS project (2007/2008) the maximum power produced by the SOFC systems installed in the GTT EOS test room will be increased to a total of about 225 kWe by means of an additional SOFC generator rated 125 kWe and up to 115 kWth. The paper provides information about the safety analysis which was performed during the main steps of the design of the system i.e. the HAZOP during the SOFC design by SWPC and the safety evaluations during the test hall design by GTT and Politecnico di Torino.

To quantify the risk of an accident in a liquid hydrogen system it is necessary to determine how often a leak may occur. To do this representative component leakage frequencies specific to liquid hydrogen can be determined as a function of the normalized leak size. Subsequently the system characteristics (e.g. system pressure) can be used to calculate accident consequences. Operating data (such as leak frequencies) for liquid hydrogen systems are very limited; rather than selecting a single leak frequency value from a literature source data from different sources can be combined using a Bayesian model. This approach provides leakage rates for different amounts of leakage distributions for leakage rates to propagate through risk assessment models to establish risk result uncertainty and a means for incorporating liquid hydrogen-specific leakage data with leakage frequencies from other fuels. Specifically other cryogenic fluids like liquefied natural gas are used as a baseline for the Bayesian analysis. This Bayesian update process is used to develop leak frequency distributions for different system component types and leak sizes. These leak frequencies can be refined as liquid hydrogen data becomes available and may then inform safety code requirements based on the likelihood of liquid hydrogen release for different systems.

Power-to-Methane (PtM) can provide flexibility to the electricity grid while aiding decarbonization of other sectors. This study focuses specifically on the methanation component of PtM in 2050. Scenarios with 80–95% CO₂ reduction by 2050 (vs. 1990) are analyzed and barriers and drivers for methanation are identified. PtM arises for scenarios with 95% CO₂ reduction no CO₂ underground storage and low CAPEX (75 €/kW only for methanation). Capacity deployed across EU is 40 GW (8% of gas demand) for these conditions which increases to 122 GW when liquefied methane gas (LMG) is used for marine transport. The simultaneous occurrence of all positive drivers for PtM which include limited biomass potential low Power-to-Liquid performance use of PtM waste heat among others can increase this capacity to 546 GW (75% of gas demand). Gas demand is reduced to between 3.8 and 14 EJ (compared to ∼20 EJ for 2015) with lower values corresponding to scenarios that are more restricted. Annual costs for PtM are between 2.5 and 10 bln€/year with EU28’s GDP being 15.3 trillion €/year (2017). Results indicate that direct subsidy of the technology is more effective and specific than taxing the fossil alternative (natural gas) if the objective is to promote the technology. Studies with higher spatial resolution should be done to identify specific local conditions that could make PtM more attractive compared to an EU scale.

Environmentally friendly and energy saving treatment of black liquor (BL) a massively produced waste in Kraft papermaking process still remains a big challenge. Here by adopting a Ni-CaO-Ca12Al14O33 bifunctional catalyst derived from hydrotalcite-like materials we demonstrate the feasibility of producing high-purity H2 (∼96%) with 0.9 mol H2 mol-1 C yield via the sorption enhanced steam reforming (SESR) of BL. The SESRBL performance in terms of H2 production maintained stable for 5 cycles but declined from the 6th cycle. XRD Raman spectroscopy elemental analysis and energy dispersive techniques were employed to rationalize the deactivation of the catalyst. It was revealed that gradual sintering and agglomeration of Ni and CaO and associated coking played important roles in catalyst deactivation and performance degradation of SESRBL while deposition of Na and K from the BL might also be responsible for the declined performance. On the other hand it was demonstrated that the SESRBL process could effectively reduce the emission of sulfur species by storing it as CaSO3. Our results highlight a promising alternative for BL treatment and H2 production thereby being beneficial for pollution control and environment governance in the context of mitigation of climate change.

Ethanol and palm oil biodiesel blended with diesel fuel have the potential to reduce greenhouse gas emissions such as carbon dioxide (CO2) and can gradually decrease dependence on fossil fuels. However the combustion products from these fuels such as oxides of nitrogen (NOx) total hydrocarbons (THC) and particulate matter (PM) require to be examined and any beneficial or detrimental effect to the environment needs to be assessed. This study investigates the hydrocarbon selective catalyst reduction (HC-SCR) activities by the effect of combustion using renewable fuels (biodiesel-ethanol-diesel) blends and the effect of hydrogen addition to the catalyst with the various diesel engine operating conditions. Lower values rate of heat released were recorded as the ethanol fraction increases resulting in trade-off where lower NOx was produced while greater concentration of carbon monoxide (CO) and THC was measured in the exhaust. Consequently increasing the THC/NOx promoting the NOx reduction activity (up to 43%). Additionally the HC-SCR performance was greatly heightened when hydrogen was added into the catalyst and able to improve the NOx reduction activity up to 73%. The experiment demonstrated plausible alternatives to improve the HC-SCR performance through the aids from fuel blends and hydrogen addition.

This study uses an online quasi-experiment with a national sample from Australia to evaluate public acceptance of hydrogen exports. It explores the complex communications environment that messaging about hydrogen exports is typically encountered in. We find that acceptance of green hydrogen exports is significantly higher than blue or brown hydrogen exports and acceptance of blue hydrogen exports higher than brown hydrogen exports. Additionally results show economic-framed benefit messages are associated with lesser public acceptance when encountered in communication contexts that outline differently-focused environmental downsides (competing contexts) but not same-focused economic downsides (conflicting contexts). In contrast environment-framed benefit messages are associated with lesser public acceptance when presented in communication contexts that outline same-focused environmental downsides (conflicting contexts) but not differentlyfocused economic downsides (competing contexts). Overall the study indicates message framing can impact acceptance of hydrogen exports and that organisations should consider the informational context within which their communications will be received.

Hydrogen represents a versatile energy carrier with net zero end use emissions. Power-to-Liquid (PtL) includes the combination of hydrogen with CO2 to produce liquid fuels and satisfy mostly transport demand. This study assesses the role of these pathways across scenarios that achieve 80–95% CO₂ reduction by 2050 (vs. 1990) using the JRC-EU-TIMES model. The gaps in the literature covered in this study include a broader spatial coverage (EU28+) and hydrogen use in all sectors (beyond transport). The large uncertainty in the possible evolution of the energy system has been tackled with an extensive sensitivity analysis. 15 parameters were varied to produce more than 50 scenarios. Results indicate that parameters with the largest influence are the CO₂ target the availability of CO₂ underground storage and the biomass potential.

Hydrogen demand increases from 7 mtpa today to 20–120 mtpa (2.4–14.4 EJ/yr) mainly used for PtL (up to 70 mtpa) transport (up to 40 mtpa) and industry (25 mtpa). Only when CO₂ storage was not possible due to a political ban or social acceptance issues was electrolysis the main hydrogen production route (90% share) and CO₂ use for PtL became attractive. Otherwise hydrogen was produced through gas reforming with CO₂ capture and the preferred CO₂ sink was underground. Hydrogen and PtL contribute to energy security and independence allowing to reduce energy related import cost from 420 bln€/yr today to 350 or 50 bln€/yr for 95% CO₂ reduction with and without CO₂ storage. Development of electrolyzers fuel cells and fuel synthesis should continue to ensure these technologies are ready when needed. Results from this study should be complemented with studies with higher spatial and temporal resolution. Scenarios with global trading of hydrogen and potential import to the EU were not included.

The effects of reaction parameters including reaction temperature and space velocity on hydrogen production via steam reforming of methane (SRM) were investigated using lab- and bench-scale reactors to identify critical factors for the design of large-scale processes. Based on thermodynamic and kinetic data obtained using the lab-scale reactor a series of SRM reactions were performed using a pelletized catalyst in the bench-scale reactor with a hydrogen production capacity of 10 L/min. Various temperature profiles were tested for the bench-scale reactor which was surrounded by three successive cylindrical furnaces to simulate the actual SRM conditions. The temperature at the reactor bottom was crucial for determining the methane conversion and hydrogen production rates when a sufficiently high reaction temperature was maintained (>800 ◦C) to reach thermodynamic equilibrium at the gas-hourly space velocity of 2.0 L CH4/(h·gcat). However if the temperature of one or more of the furnaces decreased below 700 ◦C the reaction was not equilibrated at the given space velocity. The effectiveness factor (0.143) of the pelletized catalyst was calculated based on the deviation of methane conversion between the lab- and bench-scale reactions at various space velocities. Finally an idling procedure was proposed so that catalytic activity was not affected by discontinuous operation.

Last year the Prime Minister set out his 10 point plan for a green industrial revolution laying the foundations for a green economic recovery from the impact of COVID-19 with the UK at the forefront of the growing global green economy.

This strategy builds on that approach to keep us on track for UK carbon budgets our 2030 Nationally Determined Contribution and net zero by 2050. It includes:

• our decarbonisation pathways to net zero by 2050 including illustrative scenarios 
• policies and proposals to reduce emissions for each sector 
• cross-cutting action to support the transition. 

The government response to the 2021 Committee on Climate Change (CCC) progress report to Parliament in reducing UK emissions is published alongside this strategy. It will set out our progress over the last 12 months and addresses the latest CCC recommendations. The Net Zero Strategy will be submitted to the United Nations Framework Convention on Climate Change (UNFCCC) as the UK’s second Long-Term Low Greenhouse Gas Emission Development Strategy under the Paris Agreement.

Power to gas (PtG) is an emerging technology that allows to overcome the issues due to the increasingly widespread use of intermittent renewable energy sources (IRES). Via water electrolysis power surplus on the electric grid is converted into hydrogen or into synthetic natural gas (SNG) that can be directly injected in the natural gas network for long-term energy storage. The core units of the Power to synthetic natural gas (PtSNG) plant are the electrolyzer and the methanation reactors where the renewable electrolytic hydrogen is converted to synthetic natural gas by adding carbon dioxide. A technical issue of the PtSNG plant is the different dynamics of the electrolysis unit and the methanation unit. The use of a hydrogen storage system can help to decouple these two subsystems and to manage the methanation unit for assuring long operation time and reducing the number of shutdowns. The purpose of this paper is to evaluate the energy storage potential and the technical feasibility of the PtSNG concept to store intermittent renewable sources. Therefore different plant sizes (1 3 and 6 MW) have been defined and investigated by varying the ratio between the renewable electric energy sent to the plant and the total electric energy generated by the renewable energy source (RES) facility based on a 12 MW wind farm. The analysis has been carried out by developing a thermochemical and electrochemical model and a dynamic model. The first allows to predict the plant performance in steady state. The second allows to forecast the annual performance and the operation time of the plant by implementing the control strategy of the storage unit. The annual overall efficiencies are in the range of 42–44% low heating value (LHV basis). The plant load factor i.e. the ratio between the annual chemical energy of the produced SNG and the plant capacity results equal to 60.0% 46.5% and 35.4% for 1 3 and 6 MW PtSNG sizes respectively.

Before the Covid-19 pandemic UK passed net-zero emission law legislation to become the first major economy in the world to end its contribution to global warming by 2050. Following the UK’s legislation to reach net-zero emissions a long-term strategy for transition to a net-zero target was published in 2021. The strategy is a technology-led and with a top-down approach. The intention is to reach the target over the next three decades. The document targets seven sectors to reduce emissions and include a wide range of policies and innovations for decarbonization. This paper aims to accomplish a much needed review of the strategy in heat and buildings part and cover the key related areas in future buildings standard heat pumps and use of hydrogen as elaborated in the strategy. For that purpose this research reviews key themes in the policy challenges recent advancement and future possibilities. It provides an insight on the overall development toward sustainability and decarbonization of built environment in the UK by 2050. A foresight model Future Wheels is also used to visualize the findings from the review and provide a clear picture of the potential impact of the policy.

In this study an energy exergy and environmental (3E) analyses of a plasma-assisted hydrogen production process from microalgae is investigated. Four different microalgal biomass fuels namely raw microalgae (RM) and three torrefied microalgal fuels (TM200 TM250 and TM300) are used as the feedstock for steam plasma gasification to generate syngas and hydrogen. The effects of steam-tobiomass (S/B) ratio on the syngas and hydrogen yields and energy and exergy efficiencies of plasma gasification _{(hEn;PG hEx;PG)} and hydrogen production_{(hEn;H2 hEx;H2 )} are taken into account. Results show that the optimal S/B ratios of RM TM200 TM250 and TM300 are 0.354 0.443 0.593 and 0.760 respectively occurring at the carbon boundary points (CBPs) where the maximum values of _{hEn;PG hEx;PG hEn;H2} and _hEx;H2 are also achieved. At CBPs torrefied microalgae as feedstock lower the_{hEn;PG hEx;PG hEn;H2} and _hEx;H2 because of their improved calorific value after undergoing torrefaction and the increased plasma energy demand compared to the RM. However beyond CBPs the torrefied feedstock displays better performance. A comparative life cycle analysis indicates that TM300 exhibits the highest greenhouse gases (GHG) emissions and the lowest net energy ratio (NER) due to the indirect emissions associated with electricity consumption.

This paper analyzes the economic potential of Power-to-Gas (PtG) as a source of flexibility in electricity markets with both high shares of renewables and high external demand for hydrogen. The contribution of this paper is that it develops and applies a short-term (hourly) partial equilibrium model of integrated electricity and hydrogen markets including markets for green certificates while using a welfare-economic framework to assess the market outcomes. We find that strongly increasing the share of renewable electricity makes electricity prices much more volatile while the presence of PtG reduces this price volatility. However a large demand for hydrogen from outside the electricity sector reduces the impact of PtG on the volatility of electricity prices. In a scenario with a high external hydrogen demand PtG can deliver positive benefits for some groups as it can provide hydrogen at lower costs than Steam Methane Reforming (SMR) during hours when electricity prices are low but these positive welfare effects are outweighed by the fixed costs of PtG assets plus the costs of replacing a less expensive energy carrier (natural gas) with a more expensive one (hydrogen). Investments in PtG are profitable from a social-welfare perspective when the induced reduction in carbon emissions is valued at 150–750 euro/ton. Hence at lower carbon prices PtG can only become a valuable provider of flexibility when installation costs are significantly reduced and conversion efficiencies of electrolysers increased.

This paper reviews state-of-the-art developments in hydrogen energy systems which integrate fuel cells with metal hydride-based hydrogen storage. The 187 reference papers included in this review provide an overview of all major publications in the field as well as recent work by several of the authors of the review. The review contains four parts. The first part gives an overview of the existing types of fuel cells and outlines the potential of using metal hydride stores as a source of hydrogen fuel. The second part of the review considers the suitability and optimisation of different metal hydrides based on their energy efficient thermal integration with fuel cells. The performances of metal hydrides are considered from the viewpoint of the reversible heat driven interaction of the metal hydrides with gaseous H2. Efficiencies of hydrogen and heat exchange in hydrogen stores to control H2 charge/discharge flow rates are the focus of the third section of the review and are considered together with metal hydride – fuel cell system integration issues and the corresponding engineering solutions. Finally the last section of the review describes specific hydrogen-fuelled systems presented in the available reference data.

Continuous developments in Proton Exchange Membrane Fuel Cells (PEMFC) make them a promising technology to achieve zero emissions in multiple applications including mobility. Incremental advancements in fuel cells materials and manufacture processes make them now suitable for commercialization. However the complex operation of fuel cell systems in automotive applications has some open issues yet. This work develops and compares three different controllers for PEMFC systems in automotive applications. All the controllers have a cascade control structure where a generator of setpoints sends references to the subsystems controllers with the objective to maximize operational efficiency. To develop the setpoints generators two techniques are evaluated: off-line optimization and Model Predictive Control (MPC). With the first technique the optimal setpoints are given by a map obtained off-line of the optimal steady state conditions and corresponding setpoints. With the second technique the setpoints time profiles that maximize the efficiency in an incoming time horizon are continuously computed. The proposed MPC architecture divides the fast and slow dynamics in order to reduce the computational cost. Two different MPC solutions have been implemented to deal with this fast/slow dynamics separation. After the integration of the setpoints generators with the subsystems controllers the different control systems are tested and compared using a dynamic detailed model of the automotive system in the INN-BALANCE project running under the New European Driving Cycle.

The thermochemical water‐splitting method is a promising technology for efficiently con verting renewable thermal energy sources into green hydrogen. This technique is primarily based on recirculating an active material capable of experiencing multiple reduction‐oxidation (redox) steps through an integrated cycle to convert water into separate streams of hydrogen and oxygen. The thermochemical cycles are divided into two main categories according to their operating temperatures namely low‐temperature cycles (<1100 °C) and high‐temperature cycles (<1100 °C). The copper chlorine cycle offers relatively higher efficiency and lower costs for hydrogen production among the low‐temperature processes. In contrast the zinc oxide and ferrite cycles show great potential for developing large‐scale high‐temperature cycles. Although several challenges such as energy storage capacity durability cost‐effectiveness etc. should be addressed before scaling up these technologies into commercial plants for hydrogen production. This review critically examines various aspects of the most promising thermochemical water‐splitting cycles with a particular focus on their capabilities to produce green hydrogen with high performance redox pairs stability and the technology maturity and readiness for commercial use.

This study aims to reduce greenhouse gas emissions to the atmosphere and effectively utilize wasted resources by converting methane the main component of biogas into hydrogen. Therefore a reactor was developed to decompose methane into carbon and hydrogen using solar thermal sources instead of traditional energy sources such as coal and petroleum. The optical distributions were analyzed using TracePro a Monte Carlo ray-tracing-based program. In addition Fluent a computational fluid dynamics program was used for the heat and mass transfer and chemical reaction. The cylindrical indirect heating reactor rotates at a constant speed to prevent damage by the heat source concentrated at the solar furnace. The inside of the reactor was filled with a porous catalyst for methane decomposition and the outside was surrounded by insulation to reduce heat loss. The performance of the reactor according to the cavity model was calculated when solar heat was concentrated on the reactor surface and methane was supplied into the reactor in an environment with a solar irradiance of 700 W/m2 wind speed of 1 m/s and outdoor temperature of 25 °C. As a result temperature methane mass fraction distribution and heat loss amounts for the two cavities were obtained and it was found that the effect on the conversion rate was largely dependent on a temperature over 1000 °C in the reactor. Moreover the heat loss of the full-cavity model decreased by 12.5% and the methane conversion rate increased by 33.5% compared to the semi-cavity model. In conclusion the high-temperature environment of the reactor has a significant effect on the increase in conversion rate with an additional effect of reducing heat loss.

This US Hydrogen Road Map was created through the collaboration of executives and technical industry experts in hydrogen across a broad range of applications and sectors who are committed to improving the understanding of hydrogen and how to increase its adoption across many sectors of the economy. For the first time this coalition of industry leaders has convened to develop a targeted holistic approach for expanding the use of hydrogen as an energy carrier. Due to great variation among national and state policies infrastructure needs and community interests each state and region of the US will likely have its own specific policies and road maps for implementing hydrogen infrastructure. The West Coast for example has traditionally had progressive policies on reducing transportation emissions so it is likely that hydrogen will scale sooner for vehicles in this region especially California. Experts also acknowledge the role that hydrogen in combination with renewables can play in supplying microgrid-type power to communities with the highest risk of shut-offs during seasonal weather-related issues such as high temperatures or wildfire-related power interruptions. Some states have emphasized the need to decarbonize the gas grid so blending hydrogen in natural gas networks and using hydrogen as feedstock may advance more quickly in these regions. Other states are interested in hydrogen as a means to address power grid issues enable the deployment of renewables and support competitive nuclear power. The launch of hydrogen technologies in some states or regions will help to scale hydrogen in various applications across the country laying the foundation for energy security grid resiliency economic growth and the reduction of both greenhouse gas (GHG) emissions and air pollutants. This report outlines the benefits and impact of fuel cell technologies and hydrogen as a viable solution to the energy challenges facing the US through 2030 and beyond. As such it can serve as the latest comprehensive industry-driven national road map to accelerate and scale up hydrogen in the economy across North America

The main objective of this work is the Large Eddy Simulation (LES) of hydrogen subsonic jets in order to evaluate modelling strategies and to provide guidelines for similar simulations. The ADREAHF code and the experiments conducted by Sandia National Laboratories are used for that purpose. These experiments are particularly ideal for LES studies because turbulent fluctuations have been measured which is something rare in hydrogen experiments. Hydrogen is released vertically from a small orifice of 1.91 mm diameter into an unconfined stagnant environment. Three experimental cases are simulated with different inlet velocity (49.7 76.0 and 133.9 m/s) which corresponds to transitional or turbulent flows. Hydrogen mass fraction and velocity mean values and fluctuations are compared against the experimental data. The Smagorinsky subgrid-scale model is mainly used. In the 49.7 m/s case the RNG LES is also evaluated. Several grid resolutions are used to assess the effect on the results. The amount of the resolved by the LES turbulence and velocity spectra are presented. Finally the effect of the release modelling is discussed.

Safe practices in the production storage distribution and use of hydrogen are essential for the widespread acceptance of hydrogen and fuel cell technologies. A significant safety incident in any project could damage public perception of hydrogen and fuel cells. A recent incident involving a hydrogen mobile storage trailer in the United States has brought attention to the potential impacts of mobile hydrogen storage and transport. Road transport of bulk hydrogen presents unique hazards that can be very different from those for stationary equipment and new equipment developers may have less experience and expertise than seasoned gas providers. In response to the aforementioned incident and in support of hydrogen and fuel cell activities in California the Hydrogen Safety Panel (HSP) has investigated the safety of mobile hydrogen and fuel cell applications (mobile auxiliary/emergency fuel cell power units mobile fuellers multi-cylinder trailer transport unmanned aircraft power supplies and mobile hydrogen generators). The HSP examined the applications requirements and performance of mobile applications that are being used extensively outside of California to understand how safety considerations are applied. This paper discusses the results of the HSP’s evaluation of hydrogen and fuel cell mobile applications along with recommendations to address relevant safety issues.