Netherlands

There is growing interest in using hydrogen (H2) as a long-duration energy storage resource in a future electric grid dominated by variable renewable energy (VRE) generation. Modeling H2 use exclusively for grid-scale energy storage often referred to as ‘‘power-to-gas-to-power (P2G2P)’’ overlooks the cost-sharing and CO2 emission benefits from using the deployed H2 assets to decarbonize other end-use sectors where direct electrification is challenging. Here we develop a generalized framework for co-optimizing infrastructure investments across the electricity and H2 supply chains accounting for the spatio-temporal variations in energy demand and supply. We apply this sector-coupling framework to the U.S. Northeast under a range of technology cost and carbon price scenarios and find greater value of power-to-H2 (P2G) vs. P2G2P routes. Specifically P2G provides grid flexibility to support VRE integration without the round-trip efficiency penalty and additional cost incurred by P2G2P routes. This form of sector coupling leads to: (a) VRE generation increase by 13–56% and (b) total system cost (and levelized costs of energy) reduction by 7–16% under deep decarbonization scenarios. Both effects increase as H2 demand for other end-uses increases more than doubling for a 97% decarbonization scenario as H2 demand quadruples. We also find that the grid flexibility enabled by sector coupling makes deployment of carbon capture and storage (CCS) for power generation less cost-effective than its use for low-carbon H2 production. These findings highlight the importance of using an integrated energy system framework with multiple energy vectors in planning cost-effective energy system decarbonization

In this work a novel reactor concept referred to as Membrane-Assisted Chemical Looping Reforming (MA-CLR) has been demonstrated at lab scale under different operating conditions for a total working time of about 100 h. This reactor combines the advantages of Chemical Looping such as CO₂ capture and good thermal integration with membrane technology for a better process integration and direct product separation in a single unit which in its turn leads to increased efficiencies and important benefits compared to conventional technologies for H₂ production. The effect of different operating conditions (i.e. temperature steam-to-carbon ratio or oxygen feed in the reactor) has been evaluated in a continuous chemical looping reactor and methane conversions above 90% have been measured with (ultra-pure) hydrogen recovery from the membranes. For all the cases a maximum recovery factor of around 30% has been measured which could be increased by operating the concept at higher pressures and with more membranes. The optimum conditions have been found at temperatures around 600°C for a steam-to-carbon ratio of 3 and diluted air in the air reactor (5% O₂). The complete demonstration has been carried out feeding up to 1 L/min of CH4 (corresponding to 0.6 kW of thermal input) while up to 1.15 L/min of H2 was recovered. Simultaneously a phenomenological model has been developed and validated with the experimental results. In general good agreement is observed with overall deviations below 10% in terms of methane conversion H₂ recovery and separation factor. The model allows better understanding of the behavior of the MA-CLR concept and the optimization and design of scaled-up versions of the concept.

This paper analyses the feasibility of power-to-gas in electricity markets dominated by renewables. The business case of a power-to-gas plant that is producing hydrogen is evaluated by determining the willingness to pay for electricity and by comparing this to the level and volatility of electricity prices in a number of European day-ahead markets. The short-term willingness to pay for electricity depends on the marginal costs and revenues of the plant while the long-term willingness to pay for electricity also takes into account investment and yearly fixed operational costs and therefore depends on the expected number of operating hours. The latter ultimately determines whether or not large-scale investments in the power-to-gas technology will take place.<br/>We find that power-to-gas plants are not profitable under current market conditions: even under the most optimistic assumptions for the cost and revenue parameters power-to-gas plants need to run for many hours during the year at very low prices (i.e. the long-term willingness to pay for electricity is very low) that do not currently exist in Europe. In an optimistic future scenario regarding investment costs efficiency and revenues of power-to-gas however the long-term willingness to pay for electricity is higher than the lowest recently observed day-ahead electricity prices. When prices remain at this low level investments in power-to-gas can thus become profitable.

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.

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.

Fuel cell electric vehicles convert chemical energy of hydrogen into electricity to power their motor. Since cars are used for transport only during a small part of the time energy stored in the on-board hydrogen tanks of fuel cell vehicles can be used to provide power when cars are parked. In this paper we present a community microgrid with photovoltaic systems wind turbines and fuel cell electric vehicles that are used to provide vehicle-to-grid power when renewable power generation is scarce. Excess renewable power generation is used to produce hydrogen which is stored in a refilling station. A central control system is designed to operate the system in such a way that the operational costs are minimized. To this end a hybrid model for the system is derived in which both the characteristics of the fuel cell vehicles and their traveling schedules are considered. The operational costs of the system are formulated considering the presence of uncertainty in the prediction of the load and renewable energy generation. A robust minmax model predictive control scheme is developed and finally a case study illustrates the performance of the designed system.

This work discusses the design and demonstration of an in-situ test setup for testing pipeline steels in a high pressure gaseous hydrogen (H2 ) environment. A miniature hollow pipe-like tensile specimen was designed that acts as the gas containment volume during the test. Specific areas of the specimen can be forced to fracture by selective notching as performed on the weldment. The volume of H2 used was minimised so the test can be performed safely without the need of specialised equipment. The setup is shown to be capable of characterising Hydrogen Embrittlement (HE) in steels through testing an X60 pipeline steel and its weldment. The percentage elongation (%El) of the base metal was found to be reduced by 40% when tested in 100 barg H2 . Reduction of cross-sectional area (%RA) was found to decrease by 28% and 11% in the base metal and weld metal respectively when tested in 100 barg H2 . Benchmark test were performed at 100 barg N2 pressure. SEM fractography further indicated a shift from normal ductile fracture mechanisms to a brittle transgranular (TG) quasi-cleavage (QC) type fracture that is characteristic of HE.

The first applications of hydrogen in a natural gas grid will be the admixing of low concentrations in an existing distribution grid. For easy quality and process control it is essential to monitor the hydrogen concentration in real time preferably using cost effective monitoring solutions. In this paper we introduce the use of a platinum based hydrogen sensor that can accurately (at 0.1 vol%) and reversibly monitor the concentration of hydrogen in a carrier gas. This carrier gas that can be nitrogen methane or natural gas has no influence on the accuracy of the hydrogen detection. The hydrogen sensor consists of an interdigitated electrode on a chip coated with a platinum nanocomposite layer that interacts with the gas. This chip can be easily added to a gas sensor for natural gas and biogas that was already developed in previous research. Just by the addition of an extra chip we extended the applicability of the natural gas sensor to hydrogen admixing. The feasibility of the sensor was demonstrated in our own (TNO) laboratory and at a field test location of the HyDeploy program at Keele University in the U.K

A large deployment of energy storage solutions will be required by the stochastic and non-controllable nature of most renewable energy sources when planning for higher penetration of renewable electricity into the energy mix. Various solutions have been suggested for dealing with medium- and long-term energy storage. Hydrogen and ammonia are two of the most frequently discussed as they are both carbon-free fuels. In this paper the authors analyse the energy and cost efficiency of hydrogen and ammonia-based pathways for the storage transportation and final use of excess electricity from an offshore wind farm. The problem is solved as a linear programming problem simultaneously optimising the size of each problem unit and the respective time-dependent operational conditions. As a case study we consider an offshore wind farm of 1.5 GW size located in a reference location North of Scotland. The energy efficiency and cost of the whole chain are evaluated and compared with competitive alternatives namely batteries and liquid hydrogen storage. The results show that hydrogen and ammonia storage can be part of the optimal solution. Moreover their use for long-term energy storage can provide a significant cost-effective contribution to an extensive penetration of renewable energy sources in national energy systems.

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

Meeting the Paris Agreement will most likely require the combination of CO2 capture and biomass in the industrial sector resulting in net negative emissions. CO2 capture within the industry has been extensively investigated. However biomass options have been poorly explored with literature alluding to technical and economic barriers. In addition a lack of consistency among studies makes comparing the performance of CO2 capture and/or biomass use between studies and sectors difficult. These inconsistencies include differences in methodology system boundaries level of integration costs greenhouse gas intensity of feedstock and energy carriers and capital cost estimations. Therefore an integrated evaluation of the techno-economic performance regarding CO2 capture and biomass use was performed for five energy-intensive industrial sub-sectors. Harmonization results indicate that CO2 mitigation potentials vary for each sub-sector resulting in reductions of 1.4–2.7 t CO2/t steel (77%–149%) 0.7 t CO2/t cement (92%) 0.2 t CO2/t crude oil (68%) 1.9 t CO2/t pulp (1663%–2548%) and 34.9 t CO2/t H2 (313%). Negative emissions can be reached in the steel paper and H2 sectors. Novel bio-based production routes might enable net negative emissions in the cement and (petro) chemical sectors as well. All the above-mentioned potentials can be reached for 100 €/t CO2 or less. Implementing mitigation options could reduce industrial CO2 emissions by 10 Gt CO2/y by 2050 easily meeting the targets of the 2 ◦C scenario by the International Energy Agency (1.8 Gt CO2/y reduction) for the industrial sector and even the Beyond 2 ◦C scenario (4.2 Gt CO2/y reduction).

We consider a profit-maximizing renewable energy producer operating in a rural area with limited electricity distribution capacity to the grid. While maximizing profits the energy producer is responsible for the electricity supply of a local community that aims to be self-sufficient. Energy storage is required to deal with the energy productions' uncertain and intermittent character. A promising new solution is to use strategic hydrogen reserves. This provides a long-term storage option to deal with seasonal mismatches in energy production and the local community's demand. Using a Markov decision process we provide a model that determines optimal daily decisions on how much energy to store as hydrogen and buy or sell from the power grid. We explicitly consider the seasonality and uncertainty of production demand and electricity prices. We show that ignoring seasonal demand and production patterns is suboptimal and that introducing hydrogen storage transforms loss-making operations into profitable ones. Extensive numerical experiments show that the distribution capacity should not be too small to prevent local grid congestion. A higher storage capacity increases the number of buying actions from the grid thereby causing more congestion which is problematic for the grid operator. We conclude that a profit-maximizing hydrogen storage operation alone is not an alternative to grid expansion to solve congestion which is essential knowledge for policy-makers and grid operators.

This paper examines the prospect of PEM (Proton Exchange Membrane) electrolyzers and fuel cells to partake in European electrical ancillary services markets. First the current framework of ancillary services is reviewed and discussed emphasizing the ongoing European harmonization plans for future frequency balancing markets. Next the technical characteristics of PEM hydrogen technologies and their potential uses within the electrical power system are discussed to evaluate their adequacy to the requirements of ancillary services markets. Last a case study based on a realistic representation of the transmission grid in the north of the Netherlands for the year 2030 is presented. The main goal of this case study is to ascertain the effectiveness of PEM electrolyzers and fuel cells for the provision of primary frequency reserves. Dynamic generic models suitable for grid simulations are developed for both technologies including the required controllers to enable participation in ancillary services markets. The obtained results show that PEM hydrogen technologies can improve the frequency response when compared to the procurement with synchronous generators of the same reserve value. Moreover the fast dynamics of PEM electrolyzers and fuel cells can help mitigate the negative effects attributed to the reduction of inertia in the system.

This review provides a comprehensive overview of the dynamics of low-temperature water electrolyzers and their influence on coupling the three major technologies alkaline Proton Exchange Membrane (PEM) and Anion Exchange Membrane (AEM) with photovoltaic (PV) systems. Hydrogen technology is experiencing considerable interest as a way to accelerate the energy transition. With no associated CO2 emissions and fast response water electrolyzers are an attractive option for producing green hydrogen on an industrial scale. This can be seen by the ambitious goals and large-scale projects being announced for hydrogen especially with solar energy dedicated entirely to drive the process. The electrical response of water electrolyzers is extremely fast making the slower variables such as temperature and pressure the limiting factors for variable operation typically associated with PV-powered electrolysis systems. The practical solar-to-hydrogen efficiency of these systems is in the range of 10% even with a very high coupling factor exceeding 99% for directly coupled systems. The solar-to-hydrogen efficiency can be boosted with a battery potentially sacrificing the cost. The intermittency of solar irradiance rather than its variability is the biggest challenge for PV-hydrogen systems regarding operation and degradation.

Countries with high energy demand but limited renewable energy potential are planning to meet part of their future energy needs by importing green hydrogen. For potential exporting countries in addition to sufficient renewable resources industrial preconditions are also relevant for the successful implementation of green hydrogen production value chains. A list of 36 “Green H2 Products” needed for stand-alone hydrogen production plants was defined and their economic complexity was analyzed using international trade data from 1995 to 2019. These products were found to be comparatively complex to produce and represent an opportunity for countries to enter new areas of the product space through green diversification. Large differences were revealed between countries in terms of industrial preconditions and their evolution over time. A detailed analysis of nine MENA countries showed that Turkey and Tunisia already possess industrial know-how in various green hydrogen technology components and perform only slightly worse than potential European competitors while Algeria Libya and Saudi Arabia score the lowest in terms of calculated hydrogen-related green complexity. These findings are supported by statistical tests showing that countries with a higher share of natural resources rents in their gross domestic product score significantly lower on economic and green complexity. The results thus provide new perspectives for assessing the capabilities of potential hydrogen-producing countries which may prove useful for policymakers and investors. Simultaneously this paper contributes to the theory of economic complexity by applying its methods to a new subset of products and using a dataset with long-term coverage.

Hydrogen is a promising avenue for decarbonising energy systems and providing flexibility. In this paper the JRC-EU-TIMES model – a bottom-up technology-rich model of the EU28 energy system – is used to assess the role of hydrogen in a future decarbonised Europe under two climate scenarios current policy initiative (CPI) and long-term decarbonisation (CAP). Our results indicate that hydrogen could become a viable option already in 2030 – however a long-term CO₂ cap is needed to sustain the transition. In the CAP scenario the share of hydrogen in the final energy consumption of the transport and industry sectors reaches 5% and 6% by 2050. Low-carbon hydrogen production technologies dominate and electrolysers provide flexibility by absorbing electricity at times of high availability of intermittent sources. Hydrogen could also play a significant role in the industrial and transport sectors while the emergence of stationary hydrogen fuel cells for hydrogen-to-power would require significant cost improvements over and above those projected by the experts.

Magnesium hydride owns the largest share of publications on solid materials for hydrogen storage. The “Magnesium group” of international experts contributing to IEA Task 32 “Hydrogen Based Energy Storage” recently published two review papers presenting the activities of the group focused on magnesium hydride based materials and on Mg based compounds for hydrogen and energy storage. This review article not only overviews the latest activities on both fundamental aspects of Mg-based hydrides and their applications but also presents a historic overview on the topic and outlines projected future developments. Particular attention is paid to the theoretical and experimental studies of Mg-H system at extreme pressures kinetics and thermodynamics of the systems based on MgH₂ nanostructuring new Mg-based compounds and novel composites and catalysis in the Mg based H storage systems. Finally thermal energy storage and upscaled H storage systems accommodating MgH₂ are presented.

A larger adoption of hydrogen fuel-cell electric vehicles (FCEVs) is typically included in the strategies to decarbonize the transportation sector. This inclusion is supported by life-cycle assessments (LCAs) which show the potential greenhouse gas (GHG) emission benefit of replacing internal combustion engine vehicles with their fuel cell counterpart. However the literature review performed in this study shows that the effects of durability and performance losses of fuel cells on the life-cycle environmental impact of the vehicle have rarely been assessed. Most of the LCAs assume a constant fuel consumption (ranging from 0.58 to 1.15 kgH2/100 km) for the vehicles throughout their service life which ranges in the assessments from 120000 to 225000 km. In this study the effect of performance losses on the life-cycle GHG emissions of the vehicles was assessed based on laboratory experiments. Losses have the effect of increasing the life-cycle GHG emissions of the vehicle up to 13%. Moreover this study attempted for the first time to investigate via laboratory analyses the GHG implications of replacing the hydrophobic polymer for the gas diffusion medium (GDM) of fuel cells to increase their durability. LCA showed that when the service life of the vehicle was fixed at 150000 km the GHG emission savings of using an FC with lower performance losses (i.e. FC coated with fluorinated ethylene propylene (FEP) instead of polytetrafluoroethylene (PTFE)) are negligible compared to the overall life-cycle impact of the vehicle. Both the GDM coating and the amount of hydrogen saved account for less than 2% of the GHG emissions arising during vehicle operation. On the other hand when the service life of the vehicle depends on the operability of the fuel cell the global warming potential per driven km of the FEP-based FCEV reduces by 7 to 32%. The range of results depends on several variables such as the GHG emissions from hydrogen production and the initial fuel consumption of the vehicle. Higher GHG savings are expected from an FC vehicle with high consumption of hydrogen produced with fossil fuels. Based on the results we recommend the inclusion of fuel-cell durability in future LCAs of FCEVs. We also advocate for more research on the real-life performance of fuel cells employing alternative materials.

The development of the temperature field in hydrogen tanks during the filling process has been investigated with Computational Fluid Dynamics (CFD). Measurements from experiments undertaken at the JRC GasTef facility have been used to develop and validate the CFD modelling strategy; by means of the CFD calculations the effect of the injector direction on the temperature distribution has been analysed. It has been found that the dynamics of the temperature field including the development of potentially detrimental phenomena like thermal stratification and temperature inhomogeneity e.g. hot spots can be significantly affected by the injector orientation.

Transitioning from fossil fuels to sustainable and green energy sources in mobile applications is a difficult challenge and demands sustained and highly multidisciplinary efforts in R&D. Liquid organic hydrogen carriers (LOHC) offer several advantages over more conventional energy storage solutions but have not been yet demonstrated at scale. Herein we describe the development of an integrated and compact 25 kW formic acid-to-power system by a team of BSc and MSc students. We highlight a number of key engineering challenges encountered during scale-up of the technology and discuss several aspects commonly overlooked by academic researchers. Conclusively we provide a critical outlook and suggest a number of developmental areas currently inhibiting further implementation of the technology.

As Europe moves towards decarbonising its energy infrastructure new measurement needs will arise that require collaborative efforts between European National Metrology Institutes and Designated Institutes to tackle. Such measurement needs include flow metering of hydrogen or hydrogen enriched natural gas in the gas grid for billing quality assurance of hydrogen at refuelling stations and equations of state for carbon dioxide in carbon capture and storage facilities. The European metrology network for energy gases for the first time provides a platform where metrology institutes can work together to develop a harmonised strategy prioritise new challenges and share expertise and capabilities to support the European energy gas industry to meet stringent EU targets for climate change and emissions reductions

The supply storage and (international) transport of green hydrogen (H2) are essential for the decarbonization of the energy sector. The goal of this study was to assess the final cost-price and carbon footprint of imported green H2 in the market via maritime shipping of liquid organic hydrogen carriers (LOHCs) including dibenzyl toluene-perhydro-dibenzyltoluene (DBTPDBT) and toluene-methylcyclohexane (TOL-MCH) systems. The study focused on logistic steps in intra-European supply chains in different scenarios of future production in Portugal and demand in the Netherlands and carbon tariffs between 2030 and 2050. The case study is based on a formally accepted agreement between Portugal and the Netherlands within the Strategic Forum on Important Projects of Common European Interest (IPCEI). Under the following assumptions the results show that LOHCs are a viable technical-economic solution with logistics costs from 2030 to 2050 varying between 0.30-0.37 €/kg-H2 for DBT-PDBT and 0.28-0.34 €/kg-H2 for TOL-MCH. The associated CO2 emissions of these international H2 supply chains are between 0.46 and 2.46 kg-CO2/GJ (LHV) and 0.55-2.95 kg-CO2/GJ (LHV) for DBT-PDBT and TOL-MCH respectively.

With a growing need for replacing fossil fuels with cleaner alternatives hydrogen has emerged as a viable candidate for providing heat and power. However stable and safe combustion of hydrogen is not simple and as such a number of key issues have been identified that need to be understood for a safe design of combustion chambers. One such issue is the higher propensity of hydrogen flames to flashback compared to that for methane flames. The flashback problem is coupled with higher burner temperatures that could cause strong thermal stresses in burners and could hinder their performance. In order to systematically investigate flashback in premixed hydrogen-air flames for finding a global flashback criteria in this study we use numerical simulations as a basic tool to study flashback limits of slit burners. Flashback limits are found for varying geometrical parameters and equivalence ratios and the sensitivity of each parameter on the flashback limit and burner temperatures are identified and analyzed. It is shown that the conventional flashback correlation with critical velocity gradient does not collapse the flashback data as it does not take into account stretch induced preferential diffusion effects. A new Karlovitz number definition is introduced with physical insights that collapses the flashback data at all tested conditions in an excellent manner.

Subsurface geological formations can be utilized to safely store large-scale (TWh) renewable energy in the form of green gases such as hydrogen. Successful implementation of this technology involves estimating feasible storage sites including rigorous mechanical safety analyses. Geological formations are often highly heterogeneous and entail complex nonlinear inelastic rock deformation physics when utilized for cyclic energy storage. In this work we present a novel scalable computational framework to analyse the impact of nonlinear deformation of porous reservoirs under cyclic loading. The proposed methodology includes three diferent time-dependent nonlinear constitutive models to appropriately describe the behavior of sandstone shale rock and salt rock. These constitutive models are studied and benchmarked against both numerical and experimental results in the literature. An implicit time-integration scheme is developed to preserve the stability of the simulation. In order to ensure its scalability the numerical strategy adopts a multiscale fnite element formulation in which coarse scale systems with locally-computed basis functions are constructed and solved. Further the efect of heterogeneity on the results and estimation of deformation is analyzed. Lastly the Bergermeer test case—an active Dutch natural gas storage feld—is studied to investigate the infuence of inelastic deformation on the uplift caused by cyclic injection and production of gas. The present study shows acceptable subsidence predictions in this feld-scale test once the properties of the fnite element representative elementary volumes are tuned with the experimental data.

Recently smart energy hubs with hydrogen conversion and storage have received increased attention in the Netherlands. The hydrogen is to be used for vehicle filling stations industrial processes and heating. The scientific problem addressed in this paper is the proper sizing of capacities for renewable energy generation hydrogen conversion and storage in relation to a feasible business case for the energy hub while achieving security of supply. Scenario analysis is often used during the early stages of the energy planning process and for this an easy-to-use analysis model is required. This paper investigates available modelling approaches and develops an algorithmic modelling method which is worked out in Microsoft Excel and offers ease of use for scenario analysis purposes. The model is applied to case study which leads to important insights such as the expected price of hydrogen and the proper sizing of electrolyser and hydrogen storage for that case. The model is made available open-source. Future work is proposed in the direction of application of the model for other project cases and comparison of results with other available modelling tools.

Mg attracts much research interest as anode material for Ni-MH batteries thanks to its lightweight cost-effectiveness and high theoretical capacity (2200 mA h g⁻¹). However its practical application is tremendously challenged by the poor hydrogen sorption kinetics passivation from aggressive aqueous electrolytes and insulating nature of MgH₂. Mg-based alloys exhibit enhanced hydrogen sorption kinetics and electrical conductivity but significant amount of costly transition metal elements are required. In this work we have for the first time utilized non-alloyed but catalyzed Mg as anode for Ni-MH batteries. 5 mol.% TiF3 was added to nanosized Mg for accelerating the hydrogen sorption kinetics. Several strategies for preventing the problematic passivation of Mg have been studied including protective encapsulation of the electrode and utilizing room-temperature/high-temperature ionic liquids and an alkaline polymer membrane as working electrolyte. Promising electrochemical performance has been achieved in this Mg–TiF₃ composite anode based Ni-MH batteries with room for further improvements.

Synthetic ammonia manufactured by the Haber–Bosch process and its variants is the key to securing global food security. Hydrogen is the most important feedstock for all synthetic ammonia processes. Renewable ammonia production relies on hydrogen generated by water electrolysis using electricity generated from hydropower. This was used commercially as early as 1921. In the present work we discuss how renewable ammonia production subsequently emerged in those countries endowed with abundant hydropower and in particular in regions with limited or no oil gas and coal deposits. Thus renewable ammonia played an important role in national food security for countries without fossil fuel resources until after the mid-20th century. For economic reasons renewable ammonia production declined from the 1960s onward in favor of fossil-based ammonia production. However renewable ammonia has recently gained traction again as an energy vector. It is an important component of the rapidly emerging hydrogen economy. Renewable ammonia will probably play a significant role in maintaining national and global energy and food security during the 21st century.

Owing to the complexity of the sector industrial activities are often represented with limited technological resolution in integrated energy system models. In this study we enriched the technological description of industrial activities in the integrated energy system analysis optimisation (IESA-Opt) model a peer-reviewed energy system optimisation model that can simultaneously provide optimal capacity planning for the hourly operation of all integrated sectors. We used this enriched model to analyse the industrial decarbonisation of the Netherlands for four key activities: high-value chemicals hydrocarbons ammonia and steel production. The analyses performed comprised 1) exploring optimality in a reference scenario; 2) exploring the feasibility and implications of four extreme industrial cases with different technological archetypes namely a bio-based industry a hydrogen-based industry a fully electrified industry and retrofitting of current assets into carbon capture utilisation and storage; and 3) performing sensitivity analyses on key topics such as imported biomass hydrogen and natural gas prices carbon storage potentials technological learning and the demand for olefins. The results of this study show that it is feasible for the energy system to have a fully bio-based hydrogen-based fully electrified and retrofitted industry to achieve full decarbonisation while allowing for an optimal technological mix to yield at least a 10% cheaper transition. We also show that owing to the high predominance of the fuel component in the levelled cost of industrial products substantial reductions in overnight investment costs of green technologies have a limited effect on their adoption. Finally we reveal that based on the current (2022) energy prices the energy transition is cost-effective and fossil fuels can be fully displaced from industry and the national mix by 2050

Aviation is the backbone of our modern society. In 2019 around 4.5 billion passengers travelled through the air. However at the same time aviation was also responsible for around 5% of anthropogenic causes of global warming. The impact of the COVID-19 pandemic on the aviation sector in the short term is clearly very high but the long-term effects are still unknown. However with the increase in global GDP the number of travelers is expected to increase between three- to four-fold by the middle of this century. While other sectors of transportation are making steady progress in decarbonizing aviation is falling behind. This paper explores some of the various options for energy carriers in aviation and particularly highlights the possibilities and challenges of using cryogenic fuels/energy carriers such as liquid hydrogen (LH2) and liquefied natural gas (LNG).

In the pathway towards decarbonization hydrogen can provide valid support in different sectors such as transportation iron and steel industries and domestic heating concurrently reducing air pollution. Thanks to its versatility hydrogen can be produced in different ways among which steam reforming of natural gas is still the most commonly used method. Today less than 0.7% of global hydrogen production can be considered low-carbon-emission. Among the various solutions under investigation for low-carbon hydrogen production membrane reactor technology has the potential especially at a small scale to efficiently convert biogas into green hydrogen leading to a substantial process intensification. Fluidized bed membrane reactors for autothermal reforming of biogas have reached industrial maturity. Reliable modelling support is thus necessary to develop their full potential. In this work a mathematical model of the reactor is used to provide guidelines for their design and operations in off-design conditions. The analysis shows the influence of temperature pressures catalyst and steam amounts and inlet temperature. Moreover the influence of different membrane lengths numbers and pitches is investigated. From the results guidelines are provided to properly design the geometry to obtain a set recovery factor value and hydrogen production. For a given reactor geometry and fluidization velocity operating the reactor at 12 bar and the permeate-side pressure of 0.1 bar while increasing reactor temperature from 450 to 500 °C leads to an increase of 33% in hydrogen production and about 40% in HRF. At a reactor temperature of 500 °C going from 8 to 20 bar inside the reactor doubled hydrogen production with a loss in recovery factor of about 16%. With the reactor at 12 bar a vacuum pressure of 0.5 bar reduces hydrogen production by 43% and HRF by 45%. With the given catalyst it is sufficient to have only 20% of solids filled into the reactor being catalytic particles. With the fixed operating conditions it is worth mentioning that by adding membranes and maintaining the same spacing it is possible to increase hydrogen production proportionally to the membrane area maintaining the same HRF.

The envisioned role of hydrogen in the energy transition – or the concept of a hydrogen economy – has varied through the years. In the past hydrogen was mainly considered a clean fuel for cars and/or electricity production; but the current renewed interest stems from the versatility of hydrogen in aiding the transition to CO2 neutrality where the capability to tackle emissions from distributed applications and complex industrial processes is of paramount importance. However the hydrogen economy will not materialise without strong political support and robust infrastructure design. Hydrogen deployment needs to address multiple barriers at once including technology development for hydrogen production and conversion infrastructure co-creation policy market design and business model development. In light of these challenges we have brought together a group of hydrogen researchers who study the multiple interconnected disciplines to offer a perspective on what is needed to deploy the hydrogen economy as part of the drive towards net-zero-CO2 societies. We do this by analysing (i) hydrogen end-use technologies and applications (ii) hydrogen production methods (iii) hydrogen transport and storage networks (iv) legal and regulatory aspects and (v) business models. For each of these we provide key take home messages ranging from the current status to the outlook and needs for further research. Overall we provide the reader with a thorough understanding of the elements in the hydrogen economy state of play and gaps to be filled.

An increasing demand in the marine industry to reduce emissions led to investigations into more efficient power conversion using fuels with sustainable production pathways. Solid Oxide Fuel Cells (SOFCs) are under consideration for long-range shipping because of its high efficiency low pollutant emissions and fuel flexibility. SOFC systems also have great potential to cater for the heat demand in ships but the heat integration is not often considered when assessing its feasibility. This study evaluates the electrical and heat efficiency of a 100 kW SOFC system for marine applications fuelled with methane methanol diesel ammonia or hydrogen. In addition cathode off-gas recirculation (COGR) is investigated to tackle low oxygen utilisation and thus improve heat regeneration. The software Cycle Tempo is used to simulate the power plant which uses a 1D model for the SOFCs. At nominal conditions the highest net electrical efficiency (LHV) was found for methane (58.1%) followed by diesel (57.6%) and ammonia (55.1%). The highest heat efficiency was found for ammonia (27.4%) followed by hydrogen (25.6%). COGR resulted in similar electrical efficiencies but increased the heat efficiency by 11.9% to 105.0% for the different fuels. The model was verified with a sensitivity analysis and validated by comparison with similar studies. It is concluded that COGR is a promising method to increase the heat efficiency of marine SOFC systems.

Renewable energy sources like solar-PV and wind and the electrification of heating demand lead to more variability in the generation and demand of electricity. The need for flexibility in the electricity supply system e.g. by energy storage will therefore increase. Hydrogen has been a long-serving CO2-free energy carrier apt to store energy over a long period of time without significant losses.

There is worldwide interest in transporting hydrogen using both new pipelines and pipelines converted from natural gas service. Laboratory tests investigating the effect of hydrogen on the mechanical properties of pipeline steels have shown that even low partial pressures of hydrogen can substantially reduce properties such as reduction in area and fracture toughness and increase fatigue crack growth rates. However qualitative arguments suggest that the effects on pipelines may not be as severe as predicted from the small scale tests. If the trends seen in laboratory tests do occur in service there are implications for the assessment of damage such as volumetric corrosion dents and mechanical interference. Most pipeline damage assessment methods are semi-empirical and have been calibrated with data from full scale tests that did not involve hydrogen. Hence the European Pipeline Research Group (EPRG) commissioned a study to investigate damage assessment methods in the presence of hydrogen. Two example pipeline designs were considered both were assessed assuming a modern high performance material and an older material. From these analyses the numerical results show that the high toughness material will tolerate damage even if the properties are degraded by hydrogen exposure. However low toughness materials may not be able to tolerate some types of severe damage. If the predictions are realistic operators may have to repair more damage or reduce operating pressures. Furthermore damage involving cracking may not Page 2 of 22 satisfy the ASME B31.12 requirements for preventing time dependent crack growth. Further work is required to determine if the effects predicted using small scale laboratory test data will occur in practice.

Recent advances in technologies for the decentralized islanded ammonia economy are reviewed with an emphasis on feasibility for long-term practical implementation. The emphasis in this review is on storage systems in the size range of 1–10 MW. Alternatives for hydrogen production nitrogen production ammonia synthesis ammonia separation ammonia storage and ammonia combustion are compared and evaluated. A conceptual process design based on the optimization of temperature and pressure levels of existing and recently proposed technologies is presented for an islanded ammonia energy system. This process design consists of wind turbines and solar panels for electricity generation a battery for short-term energy storage an electrolyzer for hydrogen production a pressure swing adsorption unit for nitrogen production a novel ruthenium-based catalyst for ammonia synthesis a supported metal halide for ammonia separation and storage and an ammonia fueled proton-conducting solid oxide fuel cell for electricity generation. In a generic location in northern Europe it is possible to operate the islanded energy system at a round-trip efficiency of 61% and at a cost of about 0.30–0.35 € kWh−1 .

Fuel cell electric vehicles (FCEV) currently have the challenge of high CAPEX mainly associated to the fuel cell. This study investigates strategies to promote FCEV deployment and overcome this initial high cost by combining a detailed simulation model of the passenger transport sector with an energy system model. The focus is on an energy system with 95% CO2 reduction by 2050. Soft-linking by taking the powertrain shares by country from the simulation model is preferred because it considers aspects such as car performance reliability and safety while keeping the cost optimization to evaluate the impact on the rest of the system. This caused a 14% increase in total cost of car ownership compared to the cost before soft-linking. Gas reforming combined with CO₂ storage can provide a low-cost hydrogen source for FCEV in the first years of deployment. Once a lower CAPEX for FCEV is achieved a higher hydrogen cost from electrolysis can be afforded. The policy with the largest impact on FCEV was a purchase subsidy of 5 k€ per vehicle in the 2030–2034 period resulting in 24.3 million FCEV (on top of 67 million without policy) sold up to 2050 with total subsidies of 84 bln€. 5 bln€ of R&D incentives in the 2020–2024 period increased the cumulative sales up to 2050 by 10.5 million FCEV. Combining these two policies with infrastructure and fuel subsidies for 2030–2034 can result in 76 million FCEV on the road by 2050 representing more than 25% of the total car stock. Country specific incentives split of demand by distance or shift across modes of transport were not included in this study.

Nowadays nearly 50% of the hydrogen produced worldwide comes from Steam Methane Reforming (SMR) at an environmental burden of 10.5 t_CO2 eq/t_H2 accelerating the consequences of global warming. One way to produce clean hydrogen is via methane pyrolysis using melts of metals and salts. Compared to SMR significant less CO₂ is produced due to conversion of methane into hydrogen and carbon making this route more sustainable to generate hydrogen. Hydrogen is produced with high purity and solid carbon is segregated and deposited on the molten bath. Carbon may be sold as valuable co-product making industrial scale promising. In this work methane pyrolysis was performed in a quartz bubble column using molten gallium as heat transfer agent and catalyst. A maximum conversion of 91% was achieved at 1119 °C and ambient pressure with a residence time of the bubbles in the liquid of 0.5 s. Based on in-depth analysis of the carbon it can be characterized as carbon black. Techno-economic and sensitivity analyses of the industrial concept were done for different scenarios. The results showed that if co-product carbon is saleable and a CO₂ tax of 50 euro per tonne is imposed to the processes the molten metal technology can be competitive with SMR.

One alternative for the storage and transport of hydrogen is blending a low amount of hydrogen (up to 15 or 20%) into existing natural gas grids. When demanded hydrogen can be then separated close to the end users using membranes. In this work composite alumina carbon molecular sieves membranes (Al-CMSM) supported on tubular porous alumina have been prepared and characterized. Single gas permeation studies showed that the H₂/CH₄ separation properties at 30 °C are well above the Robeson limit of polymeric membranes. H₂ permeation studies of the H2–CH4 mixture gases containing 5–20% of H2 show that the H2 purity depends on the H₂ content in the feed and the operating temperature. In the best scenario investigated in this work for samples containing 10% of H₂ with an inlet pressure of 7.5 bar and permeated pressure of 0.01 bar at 30 °C the H₂ purity obtained was 99.4%.

LCAs of electric cars and electrolytic hydrogen production are governed by the consumption of electricity. Therefore LCA benchmarking is prone to choices on electricity data. There are four issues: (1) leading Life Cycle Impact (LCI) databases suffer from inconvenient uncertainties and inaccuracies (2) electricity mix in countries is rapidly changing year after year (3) the electricity mix is strongly fluctuating on an hourly and daily basis which requires time-based allocation approaches and (4) how to deal with nuclear power in benchmarking. This analysis shows that: (a) the differences of the GHG emissions of the country production mix in leading databases are rather high (30%) (b) in LCA a distinction must be made between bundled and unbundled registered electricity certificates (RECs) and guarantees of origin (GOs); the residual mix should not be applied in LCA because of its huge inaccuracy (c) time-based allocation rules for renewables are required to cope with periods of overproduction (d) benchmarking of electricity is highly affected by the choice of midpoints and/or endpoint systems and (e) there is an urgent need for a new LCI database based on measured emission data continuously kept up-to-date transparent and open access.

Bi-directional solid oxide cell systems (Bi-SOC) are being increasingly considered as an electrical energy storage method and consequently as a means to boost the penetration of renewable energy (RE) and to improve the grid flexibility by power-to-gas electrochemical conversion. A major advantage of these systems is that the same SOC stack operates as both energy storage device (SOEC) and energy producing device (SOFC) based on the energy demand and production. SOEC and SOFC systems are now well-optimised as individual systems; this work studies the effect of using the bi-directionality of the SOC at a system level. Since the system performance is highly dependent on the cell-stack operating conditions this study improves the stack parameters for both operation modes. Moreover the year-round cumulative exergy method (CE) is introduced in the solid oxide cell (SOC) context for estimating the system exergy efficiencies. This method is an attempt to obtain more insightful exergy assessments since it takes into account the operational hours of the SOC system in both modes. The CE method therefore helps to predict more accurately the most efficient configuration and operating parameters based on the power production and consumption curves in a year. Variation of operating conditions configurations and SOC parameters show a variation of Bi-SOC system year-round cumulative exergy efficiency from 33% to 73%. The obtained thermodynamic performance shows that the Bi-SOC when feasible can prove to be a highly efficient flexible power plant as well as an energy storage system.

A 100 MW stand-alone wind power to methanol process has been evaluated to determine the capital requirement and power to methanol efficiency. Power available for electrolysis determines the amount of hydrogen produced. The stoichiometric amount of CO₂– required for the methanol synthesis – is produced using direct air capture. Integration of utilities for CO₂ air capture hydrogen production from co-harvested water and methanol synthesis is incorporated and capital costs for all process steps are estimated. Power to methanol efficiency is determined to be around 50%. The cost of methanol is around 300€ ton−1 excluding and 800€ ton−1 including wind turbine capital cost. Excluding 300 M€ investment cost for 100 MW of wind turbines total plant capital cost is around 200 M€. About 45% of the capital cost is reserved for the electrolysers 50% for the CO₂ air capture installation and 5% for the methanol synthesis system. The conceptual design and evaluation shows that renewable methanol produced from air captured CO₂ water and renewable electricity is becoming a realistic option at reasonable costs of 750–800 € ton−1.

Tensile and fatigue tests were performed on an AA2198 aluminum alloy in the T851 condition in ambient air and liquid hydrogen (LH2). All fatigue tests were performed under load control at a frequency of 20 Hz and a stress ratio of R=0.1. The Gecks-Och-Function [1] was fitted on the measured cyclic lifetimes.<br/><br/>The tensile strength in LH2 was measured to be 46 % higher compared to the value determined at ambient conditions and the fatigue limit was increased by approximately 60 %. Both S-N curves show a distinct S-shape but also significant differences. Under LH2 environment the transition from LCF- to HCF-region as well as the transition to the fatigue limit is shifted to higher cyclic lifetimes compared to ambient test results. The investigation of the crack surfaces showed distinct differences between ambient and LH2 conditions. These observed differences are important factors in the fatigue behavior change.

A rapid transition towards a CO2-neutral steel industry is required to limit climate change. Such a transition raises questions of justice as it entails positive and negative impacts unevenly distributed across societal stakeholders. To enable stakeholders to address such concerns this paper assesses the justice implications of three options that reduce emissions: CO2 capture and storage (CCS) on steel (up to 70%) bio-based steelmaking (up to 50%) and green hydrogen-based steel production (up to 100%). We select justice indicators from the energy climate labour and environmental justice literature and assess these indicators qualitatively for each of the technological routes based on literature and desk research. We find context-dependent differences in justness between the different technological routes. The impact on stakeholders varies across regions. There are justice concerns for local communities because of economic dependence on and environmental impact of the industry. Communities elsewhere are impacted through the siting of infrastructure and feedstock production. CCS and bio-based steelmaking routes can help retain industry and associated economic benefits on location while hydrogen-based steelmaking may deal better with environmental concerns. We conclude that besides techno-economic and environmental information transparency on sector-specific justice implications of transforming steel industries is essential for decision-making on technological routes

Hydrogen fuelled vehicles can play a key role in the decarbonisation of transport and reducing emissions. To ensure the durability of fuel cells a specification has been developed (ISO 14687) setting upper limits to the amount fraction of a series of impurities. Demonstrating conformity with this standard requires demonstrating by measurement that the actual levels of the impurities are below the thresholds. Currently the industry is unable to do so for measurement standards and sensitive dedicated analytical methods are lacking. In this work we report on the development of such measurement standards and methods for four reactive components: formaldehyde formic acid hydrogen chloride and hydrogen fluoride. The primary measurement standard is based on permeation and the analytical methods on highly sensitive and selective laser-based spectroscopic techniques. Relative expanded uncertainties at the ISO 14687 threshold level in hydrogen of 4% (formaldehyde) 8% (formic acid) 5% (hydrogen chloride) and 8% (hydrogen fluoride) have been achieved.

The design and operation of integrated multi-energy systems require models that adequately describe the behavior of conversion and storage technologies. Typically linear conversion performance or fixed data from technology manufacturers are employed especially for new or advanced technologies. This contribution provides a new modeling framework for electrochemical devices that bridges first-principles models to their simplified implementation in the optimization routine. First thermodynamic models are implemented to determine the on/off-design performance and dynamic behavior of different types of fuel cells and of electrolyzers. Then as such nonlinear models are intractable for use in the optimization of integrated systems different linear approximations are developed. The proposed strategies for the synthesis of reduced order models are compared to assess the impact of modeling approximations on the optimal design of multi-energy systems including fuel cells and electrolyzers. This allows to determine the most suitable level of detail for modeling the underlying electrochemical technologies from an integrated system perspective. It is found that the approximation methodology affects both the design and operation of the system with a significant effect on system costs and violation of the thermal energy demand. Finally the optimization and technology modeling framework is exploited to determine guidelines for the installation of the most suitable fuel cell technology in decentralized multi-energy systems. We show how the installation costs of PEMFC SOFC and MCFC their electrical and thermal efficiencies their conversion dynamics and the electricity price affect the system design and technology selection.

This paper presents the results of a demonstration project including building-integrated photovoltaic (BIPV) solar panels a residential building and a hydrogen fuel cell electric vehicle (FCEV) for combined mobility and power generation aiming to achieve a net zero-energy residential building target. The experiment was conducted as part of the Car as Power Plant project at The Green Village in the Netherlands. The main objective was to assess the end-user’s potential of implementing FCEVs in vehicle-to-grid operation (FCEV2G) to act as a local energy source. FCEV2G field test performance with a Hyundai ix35 FCEV are presented. The car was adapted using a power output socket capable of delivering up to 10 kW direct current (DC) to the alternating current (AC) national grid when parked via an off-board (grid-tie) inverter. A Tank-To-AC-Grid efficiency (analogous to Tank- To-Wheel efficiency when driving) of 44% (measured on a Higher Heating Value basis) was obtained when the car was operating in vehicle-to-grid (V2G) mode at the maximum power output. By collecting and analysing real data on the FCEV power production in V2G mode and on BIPV production and household consumption two different operating modes for the FCEV offering balanced services to a residential microgrid were identified namely fixed power output and load following. Based on the data collected one-year simulations of a microgrid consisting of 10 all-electric dwellings and 5 cars with the different FCEV2G modes of operation were performed. Simulation results were evaluated on the factors of autonomy self-consumption of locally produced energy and net-energy consumption by implementing different energy indicators. The results show that utilizing an FCEV working in V2G mode can reduce the annual imported electricity from the grid by approximately 71% over one year and aiding the buildings in the microgrid to achieve a net zero-energy building target. Furthermore the simulation results show that utilizing the FCEV2G setup in both modes analysed could be economically beneficial for the end-user if hydrogen prices at the pump fall below 8.24 €/kg.

Photoelectrochemical splitting of water is potentially a sustainable and affordable solution to produce hydrogen from sun light. Given the infancy stage of technology development it is important to compare the different experimental concepts and identify the most promising routes. The performance of photoelectrochemical devices is typically measured and reported under ideal irradiation conditions i.e. 1 sun. However real-life operating conditions are very different and are varying in time according to daily and seasonal cycles. In this work we present an equivalent circuit model for computing the steady state performance of photoelectrochemical cells. The model allows for a computationally efficient yet precise prediction of the system performance and a comparison of different devices working in real operating conditions. To this end five different photo-electrochemical devices are modeled using experimental results from literature. The calculated performance shows good agreement with experimental data of the different devices. Furthermore the model is extended to include the effect of illumination and tilt angle on the hydrogen production efficiency. The resulting model is used to compare the devices for different locations with high and low average illumination and different tilt angles. The results show that including real illumination data has a considerable impact on the efficiency of the PV-EC device. The yearly average solar-to-hydrogen efficiency is significantly lower than the ideal one. Moreover it is dependent on the tilt angle whose optimal value for European-like latitude is around 40. Notably we also show that the most performing device through the whole year might not necessarily be the one with highest sun-to-hydrogen efficiency for one-sun illumination.

Rapid industrial development vehicles domestic activities and mishandling of garbage are the main sources of pollutants which are destroying the atmosphere. There is a need to continuously monitor these pollutants for the safety of the environment and human beings. Conventional instruments for monitoring of toxic gases are expensive bigger in size and time-consuming. Hybrid materials containing organic and inorganic components are considered potential candidates for diverse applications including gas sensing. Gas sensors convert the information regarding the analyte into signals. Various polymeric/inorganic nanohybrids have been used for the sensing of toxic gases. Composites of different polymeric materials like polyaniline (PANI) poly (4-styrene sulfonate) (PSS) poly (34-ethylene dioxythiophene) (PEDOT) etc. with various metal/metal oxide nanoparticles have been reported as sensing materials for gas sensors because of their unique redox features conductivity and facile operation at room temperature. Polymeric nanohybrids showed better performance because of the larger surface area of nanohybrids and the synergistic effect between polymeric and inorganic materials. This review article focuses on the recent developments of emerging polymeric/inorganic nanohybrids for sensing various toxic gases including ammonia hydrogen nitrogen dioxide carbon oxides and liquefied petroleum gas. Advantages disadvantages operating conditions and prospects of hybrid composites have also been discussed.

Long-haul heavy-duty vehicles including trucks and coaches contribute to a substantial portion of the modern-day European carbon footprint and pose a major challenge in emissions reduction due to their energy-intensive usage. Depending on the hydrogen fuel source the use of fuel cell electric vehicles (FCEV) for long-haul applications has shown significant potential in reducing road freight CO2 emissions until the possible maturity of future long-distance battery-electric mobility. Fuel cell heavy-duty (HD) propulsion presents some specific characteristics advantages and operating constraints along with the notable possibility of gains in powertrain efficiency and usability through improved system design and intelligent onboard energy and thermal management. This paper provides an overview of the FCEV powertrain topology suited for long-haul HD applications their operating limitations cooling requirements waste heat recovery techniques state-of-the-art in powertrain control energy and thermal management strategies and over-the-air route data based predictive powertrain management including V2X connectivity. A case study simulation analysis of an HD 40-tonne FCEV truck is also presented focusing on the comparison of powertrain losses and energy expenditures in different subsystems while running on VECTO Regional delivery and Long-haul cycles. The importance of hydrogen fuel production pathways onboard storage approaches refuelling and safety standards and fleet management is also discussed. Through a comprehensive review of the H2 fuel cell powertrain technology intelligent energy management thermal management requirements and strategies and challenges in hydrogen production storage and refuelling this article aims at helping stakeholders in the promotion and integration of H2 FCEV technology towards road freight decarbonisation.

The deployment of low-emission alternative fuels is crucial to decarbonise the transport sector. A number of alternatives like hydrogen or dimethyl ether/methanol synthesised using CO2 as feedstock for fuel production (hereafter refer to “CO2-based fuels”) have been proposed to combat climate change. However the decarbonisation potential of CO2-based fuels is under debate because CO2 is re-emitted to the atmosphere when the fuel is combusted; and the majority of hydrogen still relies on fossil resources which makes its prospects of being a low-carbon fuel dependent on its manufacturing process. First this paper investigates the relative economic and environmental performance of hydrogen (produced from conventional steam methane reforming and produced via electrolysis using renewable energy) and CO2- based fuels (dimethyl ether and methanol) considering the full carbon cycle. The results reveal that hydrogen produced from steam methane reforming is the most economical option and that hydrogen produced via electrolysis using renewables has the best environmental profile. Whereas the idea of CO2-based fuels has recently gained much interest it has for the foreseeable future rather limited practical relevance since there is no favourable combination of cost and environmental performance. This will only change in the long run and requires that CO2 is of non-fossil origin i.e. from biomass combustion or captured from air. Second this paper address unresolved methodological issues in the assessment of CO2-based fuels such as the possible allocation of emissions to the different sectors involved. The outcomes indicate that implementing different allocation approaches substantially influences the carbon footprint of CO2-based fuels. To avoid allocation issues expanding the boundaries including the entire system and is therefore recommended.