Austria

Hydrogen embrittlement (HE) is one of the main limitations in the use of advanced high-strength steels in the automotive industry. To have a better understanding of the interaction between hydrogen (H) and a complex phase steel an in-situ method with plasma charging was applied in order to provide continuous H supply during mechanical testing in order to avoid H outgassing. For such fast-H diffusion materials only direct observation during in-situ charging allows for addressing H effects on materials. Different plasma charging conditions were analysed yet there was not a pronounced effect on the mechanical properties. The H concentration was calculated while using a simple analytical model as well as a simulation approach resulting in consistent low H values below the critical concentration to produce embrittlement. However the dimple size decreased in the presence of H and with increasing charging time the crack propagation rate increased. The rate dependence of flow properties of the material was also investigated proving that the material has no strain rate sensitivity which confirmed that the crack propagation rate increased due to H effects. Even though the H concentration was low in the experiments that are presented here different technological alternatives can be implemented in order to increase the maximum solute concentration.

To avoid failures due to hydrogen embrittlement it is important to know the amount of hydrogen absorbed by certain steel grades under service conditions. When a critical hydrogen content is reached the material properties begin to deteriorate. The hydrogen uptake and embrittlement of three different carbon steels (API 5CT L80 Type 1 P110 and 42CrMo4) was investigated in autoclave tests with hydrogen gas (H₂) at elevated pressure and in ambient pressure tests with hydrogen sulfide (H₂S). H₂ gas with a pressure of up to 100 bar resulted in an overall low but still detectable hydrogen absorption which did not cause any substantial hydrogen embrittlement in specimens under a constant load of 90% of the specified minimum yield strength (SMYS). The amount of hydrogen absorbed under conditions with H₂S was approximately one order of magnitude larger than under conditions with H₂ gas. The high hydrogen content led to failures of the 42CrMo4 and P110 specimens.

The proof of concept for the production of pure pressurized hydrogen from hydrocarbons in combination with the sequestration of a pure stream of carbon dioxide with the reformer steam iron cycle is presented. The iron oxide based oxygen carrier (95% Fe₂O₃ 5% Al₂O₃) is reduced with syngas and oxidized with steam at 1023 K. The carbon dioxide separation is achieved via partial reduction of the oxygen carrier from Fe₂O₃ to Fe₃O₄ yielding thermodynamically to a product gas only containing CO₂ and H₂O. By the subsequent condensation of steam pure CO₂ is sequestrated. After each steam oxidation phase an air oxidation was applied to restore the oxygen carrier to hematite level. Product gas pressures of up to 30.1 bar and hydrogen purities exceeding 99% were achieved via steam oxidations. The main impurities in the product gas are carbon monoxide and carbon dioxide which originate from solid carbon depositions or from stored carbonaceous molecules inside the pores of the contact mass. The oxygen carrier samples were characterized using elemental analysis BET surface area measurement XRD powder diffraction SEM and light microscopy. The maximum pressure of 95 bar was demonstrated for hydrogen production in the steam oxidation phase after the full oxygen carrier reduction significantly reducing the energy demand for compressors in mobility applications.

To reduce loss of hydrogen in storage vessels with high energy-to-weight-ratio new materials especially polymers have to be developed as barrier materials. Very established methods for characterization of barrier materials with permeation measurements are the time-lag and flow rate method along with the differential pressure method which resembles the nature of hydrogen vessel systems very well. Long measurement durations are necessary to gain suitable measurement data for these evaluation methods and often restrictive conditions have to be fulfilled. For these reasons common models for hydrogen permeation through single-layer and multi-layer membranes as well as models for hydrogen gas properties were collected and reviewed. Using current computer power together with these models can reduce measurement time for characterization of the barrier properties of materials while additional information about the quality of the measurement results is obtained.

To achieve the Paris Agreement’s long-term temperature goal current energy systems must be transformed. Australia represents an interesting case for energy system transformation modelling: with a power system dominated by fossil fuels and specifically with a heavy coal component there is at the same time a vast potential for expansion and use of renewables. We used the multi-sectoral Australian Energy Modelling System (AUSeMOSYS) to perform an integrated analysis of implications for the electricity transport and selected industry sectors to the mid-century. The state-level resolution allows representation of regional discrepancies in renewable supply and the quantification of inter-regional grid extensions necessary for the physical integration of variable renewables. We investigated the impacts of different CO₂ budgets and selected key factors on energy system transformation. Results indicate that coal-fired generation has to be phased out completely by 2030 and a fully renewable electricity supply achieved in the 2030s according to the cost-optimal pathway implied by the 1.5 °C Paris Agreement-compatible carbon budget. Wind and solar PV can play a dominant role in decarbonizing Australia’s energy system with continuous growth of demand due to the strong electrification of linked energy sectors.

This contribution places emphasis on tuning pore architecture and film thickness of mesoporous Pd–Cu–Si thin films sputtered on Si/SiO2 substrates for enhanced electrocatalytic and hydrogen sorption/desorption activity and their comparison with the state-of-the-art thin film electrocatalysts. Small Tafel slope of 43 mV dec–1 for 1250 nm thick coatings with 2 µm diameter pores with 4.2 µm interspacing (H2) electrocatalyst with comparable hydrogen overpotentials to the literature suggests its use for standard fuel cells. The largest hydrogen sorption has been attained for the 250 nm thick electrocatalyst on 5 µm pore diameter and 12 µm interspacing (2189 µC cm–2 per CV cycle) making it possible for rapid storage systems. Moreover the charge transfer resistance described by an equivalent circuit model has an excellent correlation with Tafel slopes. Along with its very low Tafel slope of 42 mV dec–1 10 nm thick H2 pore design electrocatalyst has the highest capacitive response of ∼0.001 S sn cm–2 and is promising to be used as a nano-charger and hydrogen sensor.

Energy management is a critical issue for the advancement of fuel cell vehicles because it significantly influences their hydrogen economy and lifetime. This paper offers a comprehensive investigation of the energy management of heavy-duty fuel cell vehicles for road freight transportation. An important and unique contribution of this study is the development of an extensive and realistic representation of the vehicle operation which includes 1750 hours of real-world driving data and variable truck loading conditions. This framework is used to analyze the potential benefits and drawbacks of heuristic optimal and predictive energy management strategies to maximize the hydrogen economy and system lifetime of fuel cell vehicles for road freight transportation. In particular the statistical evaluation of the effectiveness and robustness of the simulation results proves that it is necessary to consider numerous and realistic driving scenarios to validate energy management strategies and obtain a robust design. This paper shows that the hydrogen economy can be maximized as an individual target using the available driving information achieving a negligible deviation from the theoretical limit. Furthermore this study establishes that heuristic and optimal strategies can significantly reduce fuel cell transients to improve the system lifetime while retaining high hydrogen economies. Finally this investigation reveals the potential benefits of predictive energy management strategies for the multi-objective optimization of the hydrogen economy and system lifetime.

A polyethylene (PE) liner is the basic element in high-pressure type 4 composite vessels designed for hydrogen or compressed natural gas (CNG) storage systems. Liner defects may result in the elimination of the whole vessel from use which is very expensive both at the manufacturing and exploitation stage. The goal is therefore the development of efficient non-destructive testing (NDT) methods to test a liner immediately after its manufacturing before applying a composite reinforcement. It should be noted that the current regulations codes and standards (RC&S) do not specify liner testing methods after manufacturing. It was considered especially important to find a way of locating and assessing the size of air bubbles and inclusions and the field of deformations in liner walls. It was also expected that these methods would be easily applicable to mass-produced liners. The paper proposes the use of three optical methods namely visual inspection digital image correlation (DIC) and optical fiber sensing based on Bragg gratings (FBG). Deformation measurements are validated with finite element analysis (FEA). The tested object was a prototype of a hydrogen liner for high-pressure storage (700 bar). The mentioned optical methods were used to identify defects and measure deformations.

Hydrogen absorption into steel during atmospheric corrosion has been of a strong concern during last decades. It is technically important to investigate if hydrogen absorbed under atmospheric exposure conditions can significantly affect mechanical properties of steels. The present work studies changes of mechanical properties of dual phase (DP) advanced high strength steel specimens with sodium chloride deposits during corrosion in humid air using Slow Strain Rate Test (SSRT). Additional annealed specimens were used as reference in order to separate the possible effect of absorbed hydrogen from that of corrosion deterioration. Hydrogen entry was monitored in parallel experiments using hydrogen electric resistance sensor (HERS) and thermal desorption mass spectrometry (TDMS). SSRT results showed a drop in elongation and tensile strength by 42% and 6% respectively in 27 days of atmospheric exposure. However this decrease cannot be attributed to the effect of absorbed hydrogen despite the increase in hydrogen content with time of exposure. Cross-cut analysis revealed considerable pitting which was suggested to be the main reason for the degradation of mechanical properties

The maritime shipping sector is a major contributor to CO₂ emissions and this figure is expected to rise in coming decades. With the intent of reducing emissions from this sector this research proposes the utilization of the jet stream to transport a combination of cargo and hydrogen using airships or balloons at altitudes of 10–20 km. The jet streams flow in the mid-latitudes predominantly in a west–east direction reaching an average wind speed of 165 km/h. Using this combination of high wind speeds and reliable direction hydrogen-filled airships or balloons could carry hydrogen with a lower fuel requirement and shorter travel time compared to conventional shipping. Jet streams at different altitudes in the atmosphere were used to identify the most appropriate circular routes for global airship travel. Round-the-world trips would take 16 days in the Northern Hemisphere and 14 in the Southern Hemisphere. Hydrogen transport via the jet stream due to its lower energy consumption and shorter cargo delivery time access to cities far from the coast could be a competitive alternative to maritime shipping and liquefied hydrogen tankers in the development of a sustainable future hydrogen economy.

Due to its environmental impact the mobility system is increasingly under pressure. The challenges to cope with climate change air quality depleting fossil resources imply the need for a transition of the current mobility system towards a more sustainable one. Expectations and visions have been identified as crucial in the guidance of such transitions and more specifically of actor strategies. Still it remained unclear why the actors involved in transition activities appear to change their strategies frequently and suddenly. The empirical analysis of the expectations and strategies of three actors in the field of hydrogen and fuel cell technology indicates that changing actor strategies can be explained by rather volatile expectations related to different levels. Our case studies of the strategies of two large car manufacturers and the German government demonstrate that the car manufacturers refer strongly to expectations about the future regime while expectations related to the socio-technical landscape level appear to be crucial for the strategy of the German government.

High-strength steels with yield strength of 960 MPa are susceptible to hydrogen-assisted cracking (HAC) during welding processing. In the present paper the implant test is used to study HAC in a quenched and tempered steel S960QL and a high-strength steel produced by thermo-mechanical controlled process S960MC. Welding is performed using the gas-metal arc welding process. Furthermore diffusible hydrogen concentration (H_D) in arc weld metal is determined. Based on the implant test results lower critical stress (LCS) for complete fracture critical implant stress (σ_krit) for crack initiation and embrittlement index (EI) are determined. At HD of 1.66 ml/100 g LCS is 605 MPa and 817 MPa for S960QL and S960MC respectively. EI is 0.30 and 0.46 for S960QL and S960MC respectively. Fracture surfaces of S960QL show higher degradation with reduced deformation. Both higher EI of S960MC and fractography show better resistance to HAC in the HAZ of S960MC compared to S960QL.

Hydrogen when based on renewable electricity can play a key role in the transition towards CO2-neutral industrial production since its use as an energy carrier as well as a feedstock in various industrial process routes is promising. At the same time a large-scale roll-out of hydrogen for industrial use would entail substantial impacts on the energy system which can only be assessed if the regional distribution of future hydrogen demand is considered. Here we assess the technical potential of hydrogen-based technologies for energy-intensive industries in Germany. The site-specific and process-specific bottom-up calculation considers 615 individual plants at 367 sites and results in a total potential hydrogen demand of 326 TWh/a. The results are available as an open dataset. Using hydrogen for non-energy-intensive sectors as well increases the potential hydrogen demand to between 482 and 534 TWh/a for Germany - based on today’s industrial structure and production output. This assumes that fossil fuels are almost completely replaced by hydrogen for process heating and feedstocks. The resulting hydrogen demand is very unevenly distributed: a few sites account for the majority of the overall potential and similarly the bulk of demand is concentrated in a few regions with steel and chemical clusters.

This paper presents a beneficial combination of biomass gasification and pyrolysis oil hydrodeoxygenation for advanced biofuel production. Hydrogen for hydrodeoxygenation (HDO) of liquid phase pyrolysis oil (LPP oil) was generated by gasification of softwood. The process merges dual fluidized bed (DFB) steam gasification which produces a hydrogen rich product gas and the HDO of LPP oil. Synthesis gas was used directly without further cleaning and upgrading by making use of the water gas-shift (WGS) reaction. The water needed for the water gas-shift reaction was provided by LPP oil. HDO was successfully performed in a lab scale over 36 h time on stream (TOS). Competing reactions like the Boudouard reaction and Sabatier reaction were not observed. Product quality was close to Diesel fuel specification according to EN 590 with a carbon content of 85.4 w% and a residual water content of 0.28 w%. The water-gas shift reaction was confirmed by CO/CO₂-balance high water consumption and 28% less hydrogen consumption during HDO.

Determination of the optimal design of experiments that enables efficient parametrisation of fuel cell (FC) model with a minimum parametrisation data-set is one of the key prerequisites for minimizing costs and effort of the parametrisation procedure. To efficiently tackle this challenge the paper present an innovative methodology based on the electrochemical FC model parameter sensitivity analysis and application of D-optimal design plan. Relying on this consistent methodological basis the paper answers fundamental questions: a) on a minimum required data-set to optimally parametrise the FC model and b) on the impact of reduced space of operational points on identifiability of individual calibration parameters. Results reveal that application of D-optimal DoE enables enhancement of calibration parameters information resulting in up to order of magnitude lower relative standard errors on smaller data-sets. In addition it was shown that increased information and thus identifiability inherently leads to improved robustness of the FC electrochemical model.

To limit the global temperature change to no more than 2 ◦C by reducing global emissions the European Union (EU) set up a goal of a 20% improvement on energy efficiency a 20% cut of greenhouse gas emissions and a 20% share of energy from renewable sources by 2020 (10% share of renewable energy (RE) specifically in the transport sector). By 2030 the goal is a 27% improvement in energy efficiency a 40% cut of greenhouse gas emissions and a 27% share of RE. However the integration of RE in energy system faces multiple challenges. The geographical distribution of energy supply changes significantly the availability of the primary energy source (wind solar water) and is the determining factor rather than where the consumers are. This leads to an increasing demand to match supply and demand for power. Especially intermittent RE like wind and solar power face the issue of energy production unrelated to demand (issue of excess energy production beyond demand and/or grid capacity) and forecast errors leading to an increasing demand for grid services like balancing power. Megawatt electrolyzer units (beyond 3 MW) can provide a technical solution to convert large amounts of excess electricity into hydrogen for industrial applications substitute for natural gas or the decarbonization of the mobility sector. The demonstration of successful MW electrolyzer operation providing grid services under dynamic conditions as request by the grid can broaden the opportunities of new business models that demonstrate the profitability of an electrolyzer in these market conditions. The aim of this work is the demonstration of a technical solution utilizing Pressurized Alkaline Electrolyzer (PAE) technology for providing grid balancing services and harvesting Renewable Energy Sources (RES) under realistic circumstances. In order to identify any differences between local market and grid requirements the work focused on a demonstration site located in Austria deemed as a viable business case for the operation of a largescale electrolyzer. The site is adapted to specific local conditions commonly found throughout Europe. To achieve this this study uses a market-based solution that aims at providing value-adding services and cash inflows stemming from the grid balancing services it provides. Moreover the work assesses the viability of various business cases by analyzing (qualitatively and quantitatively) additional business models (in terms of business opportunities/energy source potential grid service provision and hydrogen demand) and analyzing the value and size of the markets developing recommendations for relevant stakeholder to decrease market barriers.

Hydrogen sulfide (H₂S) is an important mediator of inflammatory processes. However controversial findings also exist and its underlying molecular mechanisms are largely unknown. Recently the byproducts of H₂S per-/polysulfides emerged as biological mediators themselves highlighting the complex chemistry of H₂S. In this study we characterized the biological effects of P* a slow-releasing H₂S and persulfide donor. To differentiate between H₂S and polysulfide-derived effects we decomposed P* into polysulfides. P* was further compared to the commonly used fast-releasing H₂S donor sodium hydrogen sulfide (NaHS). The effects on oxidative stress and interleukin-6 (IL-6) expression were assessed in ATDC5 cells using superoxide measurement qPCR ELISA and Western blotting. The findings on IL-6 expression were corroborated in primary chondrocytes from osteoarthritis patients. In ATDC5 cells P* not only induced the expression of the antioxidant enzyme heme oxygenase-1 via per-/polysulfides but also induced activation of Akt and p38 MAPK. NaHS and P* significantly impaired menadione-induced superoxide production. P* reduced IL-6 levels in both ATDC5 cells and primary chondrocytes dependent on H₂Srelease. Taken together P* provides a valuable research tool for the investigation of H₂S and per-/polysulfide signalling. These data demonstrate the importance of not only H₂S but also per-/polysulfides as bioactive signaling molecules with potent anti-inflammatory and in particular antioxidant properties.

Renewable hydrogen is considered key in the transition towards a carbon-neutral future. This is due to its spatio-temporal storage and sector coupling potential which has seen it referred to as energy vector. However many unresolved issues remain regarding hydrogen's large-scale deployment e.g. least-cost production optimal facility siting and overall implications on power and energy systems. Expansion planning provides an option to study these issues in the holistic context of energy systems. To this end this article presents a comprehensive review on state-of-the-art expansion planning models that consider integrated power natural gas and hydrogen systems. We cluster the existing literature in terms of modelling themes and scope study the applied systematic modelling characteristics and conduct an in-depth analysis of the technical model features regarding hydrogen technologies and natural gas infrastructure. Finally we identify and discuss research gaps in the existing literature.

Achieving climate neutrality requires a massive transformation of current energy systems. Fossil energy sources must be replaced with renewable ones. Renewable energy sources with reasonable potential such as photovoltaics or wind power provide electricity. However since chemical energy carriers are essential for various sectors and applications the need for renewable gases comes more and more into focus. This paper determines the Austrian green hydrogen potential produced exclusively from electricity surpluses. In combination with assumed sustainable methane production the resulting renewable gas import demand is identified based on two fully decarbonised scenarios for the investigated years 2030 2040 and 2050. While in one scenario energy efficiency is maximised in the other scenario significant behavioural changes are considered to reduce the total energy consumption. A techno-economic analysis is used to identify the economically reasonable national green hydrogen potential and to calculate the averaged levelised cost of hydrogen (LCOH2) for each scenario and considered year. Furthermore roll-out curves for the necessary expansion of national electrolysis plants are presented. The results show that in 2050 about 43% of the national gas demand can be produced nationally and economically (34 TWh green hydrogen 16 TWh sustainable methane). The resulting national hydrogen production costs are comparable to the expected import costs (including transport costs). The most important actions are the quick and extensive expansion of renewables and electrolysis plants both nationally and internationally

Fuel starvation is a major cause of anode corrosion in low temperature polymer electrolyte fuel cells. The fuel cell start-up is a critical step as hydrogen may not yet be evenly distributed in the active area leading to local starvation. The present work investigates the hydrogen distribution and risk for starvation during start-up and after nitrogen purge by extending an existing computational fluid dynamic model to capture transient behavior. The results of the numerical model are compared with detailed experimental analysis on a 25 cm2 triple serpentine flow field with good agreement in all aspects and a required time step size of 1 s. This is two to three orders of magnitude larger than the time steps used by other works resulting in reasonably quick calculation times (e.g. 3 min calculation time for 1 s of experimental testing time using a 2 million element mesh).

Green hydrogen presents a promising solution for transitioning from fossil fuels to a clean energy future particularly with the application of fuel cell electric vehicles (FCEVs). However the hydrogen refuelling process for FCEVs requires extensive pre-cooling to achieve fast filling times. This study presents experiments and simulations of a hydrogen refuelling station equipped with an adaptable cold-fill unit aiming to maximize fuelling efficiencies. For this purpose we developed and experimentally validated simulation models for a hydrogen tank and an aluminium block heat exchanger. Different pre-cooling parameters affect the final tank temperatures during the parallel filling of three 350 L type IV tanks. The results indicate significant potential for optimizing the required cooling energy with achievable savings of over 50 % depending on the pre-cooling strategy. The optimized pre-cooling strategies and energy savings aid in advancing the refuelling process for FCEVs effectively contributing to the transition to clean energy.

The world is undergoing a substantial energy transition with an increasing share of intermittent sources of energy on the grid which is increasing the challenges to operate the power grid reliably. An option that has been receiving much focus after the COVID pandemic is the development of a hydrogen economy. Challenges for a hydrogen economy are the high investment costs involved in compression storage and long-distance transportation. This paper analyses an innovative proposal for the creation of hydrogen ocean links. It intends to fill existing gaps in the creation of a hydrogen economy with the increase in flexibility and viability for hydrogen production consumption compression storage and transportation. The main concept behind the proposals presented in this paper consists of using the fact that the pressure in the deep sea is very high which allows a thin and cheap HDPE tank to store and transport large amounts of pressurized hydrogen in the deep sea. This is performed by replacing seawater with pressurized hydrogen and maintaining the pressure in the pipes similar to the outside pressure. Hydrogen Deep Ocean Link has the potential of increasing the interconnectivity of different regional energy grids into a global sustainable interconnected energy system.

The number of demonstration projects with fuel cell buses has been increasing worldwide. The goal of this paper is to analyse prospects and barriers for fuel cell buses focusing on their economic- technical- and environmental performance. Our results show that the prices of fuel cell buses although decreasing over time are still about 40% higher than those of diesel buses. With the looming ban of diesel vehicles and current limitations of battery electric vehicles fuel cell buses could become a viable alternative in the mid-to long-term. With the requirements for a better integration of renewable energy sources in the transport system interest in hydrogen is rising. Hydrogen produced from renewables used in fuel cell buses has the potential to save about 93% of CO2 emissions in comparison to diesel buses. Yet from environmental point-of-view it has to be ensured that hydrogen is produced from renewables. Currently the major barrier for a faster penetration of fuel cell buses are their high purchase prices which could be significantly reduced with the increasing number of buses through technological learning. The final conclusion is that a tougher transport policy framework is needed which fully reflects the environmental impact of different buses used.

Hydrogen is widely considered as the energy carrier of the future but the rather high energy losses for its production are often neglected. The major current hydrogen production technology is steam methane reforming of fossil gas but there is a growing interest in producing hydrogen sustainably from water using electrolysis. This article examines four main hydrogen production chains and two transportation options (pipeline and ship) from North Africa to Europe analyzing the costs and environmental impacts of each. The core objective is to determine the most promising hydrogen provision method and location from an economic and ecological point of view including the required transport. An important finding of this analysis is that both options importing green hydrogen and producing it in Europe may be relevant for a decarbonized energy system. The emphasis should be on green hydrogen to achieve carbon emission reductions. If blue hydrogen is also considered attention should be paid to the often-neglected methane emissions upstream.

Hydrogen is among the energy carriers which are most often considered for bringing about a sustainable energy system. Yet so far hydrogen has not delivered as an energy carrier. The core objective of this paper is to provide a comprehensive analysis of the state-of-the-art and the future prospects of green hydrogen in the European energy system from economic energetic and CO2 emissions point-of-view. The analysis shows that there are some increasing opportunities for hydrogen use in industry and in the transport sector when electrification is not possible or is too expensive as well as a storage in the European electricity system. However a hydrogen-based energy system will remain a vision at least over the next decades. The major reason for this is the unfavorable economics mostly due to high investment costs in the whole supply chain. In addition the overall efficiencies in the hydrogen chains are moderate in general. The full environmental benignity of hydrogen as an energy carrier is only provided when renewable energy sources are used for hydrogen production. However in Europe the potentials for green hydrogen are very limited due to the insufficient expansion of renewable electricity generation. For this reason many European countries are considering options for green hydrogen import. The future of hydrogen is highly dependent on the supporting policy framework. To reduce the risk in the investment in hydrogen infrastructure as well as to justify the promotion of green hydrogen it is very important that Europe works out a very clear and realistic long-term implementation strategy.

Hydrogen uptake and embrittlement characteristics of a cold-drawn austenitic stainless steel wire were investigated. Slow strain rate testing and fracture surface analysis were applied to determine the hydrogen embrittlement resistance providing an apparent decrease in resistance to hydrogen embrittlement for a 50% degree of cold deformation. The hydrogen content was assessed by thermal desorption and laser-induced breakdown spectroscopy establishing a correlation between the total absorbed hydrogen and the intensity of near-surface hydrogen. The sub-surface hydrogen content of the hot-rolled specimen was determined to be 791 wt.ppm.

A transition towards zero-emission fuels is required in the mobility sector in order to reach the climate goals. Here (green) renewable hydrogen for use in fuel cells will play an important role especially for heavy duty applications such as trucks. However there are still challenges to overcome regarding efficient storage infrastructure integration and optimization of the refuelling process. A key aspect is to reduce the refuelling duration as much as possible while staying below the maximum allowed temperature of 85 C. Experimental tests for the refuelling of a 320 l type III tank were conducted at different operating conditions and the tank gas temperature measured at the front and back ends. The results indicate a strongly inhomogeneous temperature field where measuring and verifying the actual maximum temperatures proves difficult. Furthermore a simulation approach is provided to calculate the average tank gas temperature at the end of the refuelling process.

This research conducted a probabilistic life-cycle assessment (pLCA) into the greenhouse gas (GHG) emissions performance of nine combinations of truck size and powertrain technology for a recent past and a future (largely decarbonised) situation in Australia. This study finds that the relative and absolute life-cycle GHG emissions performance strongly depends on the vehicle class powertrain and year of assessment. Life-cycle emission factor distributions vary substantially in their magnitude range and shape. Diesel trucks had lower life-cycle GHG emissions in 2019 than electric trucks (battery hydrogen fuel cell) mainly due to the high carbon-emission intensity of the Australian electricity grid (mainly coal) and hydrogen production (mainly through steam–methane reforming). The picture is however very different for a more decarbonised situation where battery electric trucks in particular provide deep reductions (about 75–85%) in life-cycle GHG emissions. Fuel-cell electric (hydrogen) trucks also provide substantial reductions (about 50–70%) but not as deep as those for battery electric trucks. Moreover hydrogen trucks exhibit the largest uncertainty in emissions performance which reflects the uncertainty and general lack of information for this technology. They therefore carry an elevated risk of not achieving the expected emission reductions. Battery electric trucks show the smallest (absolute) uncertainty which suggests that these trucks are expected to deliver the deepest and most robust emission reductions. Operational emissions (on-road driving and vehicle maintenance combined) dominate life-cycle emissions for all vehicle classes. Vehicle manufacturing and upstream emissions make a relatively small contribution to life-cycle emissions from diesel trucks (

This work investigates the cost-efficient integration of renewable hydrogen into steelworks for the production of methane and methanol as an efficient way to decarbonize the steel industry. Three case studies that utilize a mixture of steelworks off-gases (blast furnace gas coke oven gas and basic oxygen furnace gas) which differ on the amount of used off-gases as well as on the end product (methane and/or methanol) are analyzed and evaluated in terms of their economic performance. The most influential cost factors are identified and sensitivity analyses are conducted for different operating and economic parameters. Renewable hydrogen produced by PEM electrolysis is the most expensive component in this scheme and responsible for over 80% of the total costs. Progress in the hydrogen economy (lower electrolyzer capital costs improved electrolyzer efficiency and lower electricity prices) is necessary to establish this technology in the future.

In order to eliminate the local CO2 emissions from vehicles and to combat the associated climate change the classic internal combustion engine can be replaced by an electric motor. The two most advantageous variants for the necessary electrical energy storage in the vehicle are currently the purely electrochemical storage in batteries and the chemical storage in hydrogen with subsequent conversion into electrical energy by means of a fuel cell stack. The two variants can also be combined in a battery electric vehicle with a fuel cell range extender so that the vehicle can be refuelled either purely electrically or using hydrogen. The air compressor a key component of a PEM fuel cell system can be operated at different air excess and pressure ratios which influence the stack as well as the system efficiency. To asses the steady state behaviour of a PEM fuel cell range extender system a system test bench utilising a commercially available 30 kW stack (96 cells 409 cm2 cell area) was developed. The influences of the operating parameters (air excess ratio 1.3 to 1.7 stack temperature 20 °C–60 °C air compressor pressure ratio up to 1.67 load point 122 mA/cm2 to 978 mA/cm2) on the fuel cell stack voltage level (constant ambient relative humidity of 45%) and the corresponding system efficiency were measured by utilising current voltage mass flow temperature and pressure sensors. A fuel cell stack model was presented which correlates closely with the experimental data (0.861% relative error). The air supply components were modelled utilising a surface fit. Subsequently the system efficiency of the validated model was optimised by varying the air mass flow and air pressure. It is shown that higher air pressures and lower air excess ratios increase the system efficiency at high loads. The maximum achieved system efficiency is 55.21% at the lowest continuous load point and 43.74% at the highest continuous load point. Future work can utilise the test bench or the validated model for component design studies to further improve the system efficiency.

The energy supply in Austria is significantly based on fossil natural gas. Due to the necessary decarbonization of the heat and energy sector a switch to a green substitute is necessary to limit CO2 emissions. Especially innovative concepts such as power-to-gas establish the connection between the storage of volatile renewable energy and its conversion into green gases. In this paper different methanation strategies are applied on syngas from biomass gasification. The investigated syngas compositions range from traditional steam gasification sorption-enhanced reforming to the innovative CO2 gasification. As the producer gases show different compositions regarding the H2/COx ratio three possible methanation strategies (direct sub-stoichiometric and over-stoichiometric methanation) are defined and assessed with technological evaluation tools for possible future large-scale set-ups consisting of a gasification an electrolysis and a methanation unit. Due to its relative high share of hydrogen and the high technical maturity of this gasification mode syngas from steam gasification represents the most promising gas composition for downstream methanation. Sub-stoichiometric operation of this syngas with limited H2 dosage represents an attractive methanation strategy since the hydrogen utilization is optimized. The overall efficiency of the sub-stoichiometric methanation lies at 59.9%. Determined by laboratory methanation experiments a share of nearly 17 mol.% of CO2 needs to be separated to make injection into the natural gas grid possible. A technical feasible alternative avoiding possible carbon formation in the methanation reactor is the direct methanation of sorption-enhanced reforming syngas with an overall process efficiency in large-scale applications of 55.9%.

Hydrogen plays a vital role in decarbonizing the mobility sector. With the number of hydrogen vehicles expected to drastically increase a network of refuelling stations needs to be built to keep up with the hydrogen demand. However further research and development on hydrogen refuelling infrastructure storage and standardization is required to overcome technical and economic barriers. Simulation tools can reduce time and costs during the design phase but existing models do not fully support calculations of complete and arbitrary system layouts. Therefore a flexible simulation toolbox for rapid investigations of hydrogen refuelling and extraction processes as well as development of refuelling infrastructure vehicle tank systems and refuelling protocols for non-standardized applications was developed. Our model library H2VPATT comprises of typical components found in refuelling infrastructure. The key component is the hydrogen tank model. The simulation model was successfully validated with measurement data from refuelling tests of a 320 l type III tank.

The valorization of integrated steelworks process off-gases as feedstock for synthesizing methane and methanol is in line with European Green Deal challenges. However this target can be generally achieved only through process off-gases enrichment with hydrogen and use of cutting-edge syntheses reactors coupled to advanced control systems. These aspects are addressed in the RFCS project i3 upgrade and the central role of hydrogen was evident from the first stages of the project. First stationary scenario analyses showed that the required hydrogen amount is significant and existing renewable hydrogen production technologies are not ready to satisfy the demand in an economic perspective. The poor availability of low-cost green hydrogen as one of the main barriers for producing methane and methanol from process off-gases is further highlighted in the application of an ad-hoc developed dispatch controller for managing hydrogen intensified syntheses in integrated steelworks. The dispatch controller considers both economic and environmental impacts in the cost function and although significant environmental benefits are obtainable by exploiting process off-gases in the syntheses the current hydrogen costs highly affect the dispatch controller decisions. This underlines the need for big scale green hydrogen production processes and dedicated green markets for hydrogen-intensive industries which would ensure easy access to this fundamental gas paving the way for a C-lean and more sustainable steel production.

Underground Hydrogen Storage (UHS) has received significant attention over the past few years as hydrogen seems well-suited for adjusting seasonal energy gaps. We present an integrated reservoir-well model for “Viking A00 the depleted gas field in the North Sea as a potential site for UHS. Our findings show that utilizing the integrated model results in more reasonable predictions as the gas composition changes over time. Sensitivity analyses show that the lighter the cushion gas the more production can be obtained. However the purity of the produced hydrogen will be affected to some extent which can be enhanced by increasing the fill-up period and the injection rate. The results also show that even though hydrogen diffuses into the reservoir and mixes up with the native fluids (mainly methane) the impact of hydrogen diffusion is marginal. All these factors will potentially influence the project's economics.

A substantial CO2-emmissions abatement from the steel sector seems to be a challenging task without support of so-called “breakthrough technologies” such as the hydrogen-based direct reduction process. The scope of this work is to evaluate both the potential for the implementation of green hydrogen generated via electrolysis in the direct reduction process as well as the constraints. The results for this process route are compared with both the well-established blast furnace route as well as the natural gas-based direct reduction which is considered as a bridge technology towards decarbonization as it already operates with H2 and CO as main reducing agents. The outcomes obtained from the operation of a 6-MW PEM electrolysis system installed as part of the H2FUTURE project provide a basis for this analysis. The CO2 reduction potential for the various routes together with an economic study are the main results of this analysis. Additionally the corresponding hydrogen- and electricity demands for large-scale adoption across Europe are presented in order to rate possible scenarios for the future of steelmaking towards a carbon-lean industry.

Hydrogen is a key enabler of a sustainable society. Refurbishment of the existing natural gas infrastructure for up to 100% H2 is considered one of the most energy- and resource-efficient energy transportation methods. The question remains whether the transportation of 100% H2 with reasonable adaptions of the infrastructure and comparable energy amounts to natural gas is possible. The well-known critical components for refurbishment such as increased compressor power reduced linepack as well as pipeline transport efficiencies and their influencing factors were considered based on thermodynamic calculations with a step-by-step overview. A H2 content of 20–30% results in comparable operation parameters to pure natural gas. In addition to transport in pipelines decentralized H2 production will also play an important role in addressing future demands.

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

The world is undergoing a substantial energy transition with an increasing share of intermittent sources of energy on the grid which is increasing the challenges to operate the power grid reliably. An option that has been receiving much focus after the COVID pandemic is the development of a hydrogen economy. Challenges for a hydrogen economy are the high investment costs involved in compression storage and long-distance transportation. This paper analyses an innovative proposal for the creation of hydrogen ocean links. It intends to fill existing gaps in the creation of a hydrogen economy with the increase in flexibility and viability for hydrogen production consumption compression storage and transportation. The main concept behind the proposals presented in this paper consists of using the fact that the pressure in the deep sea is very high which allows a thin and cheap HDPE tank to store and transport large amounts of pressurized hydrogen in the deep sea. This is performed by replacing seawater with pressurized hydrogen and maintaining the pressure in the pipes similar to the outside pressure. Hydrogen Deep Ocean Link has the potential of increasing the interconnectivity of different regional energy grids into a global sustainable interconnected energy system.

The rising demand for energy and the aim of moving away from fossil fuels and to low-carbon power have led many countries to move to alternative sources including solar energy wind geothermal energy biomass and hydrogen. Hydrogen is often considered a “missing link” in guaranteeing the energy transition providing storage and covering the volatility and intermittency of renewable energy generation. However due to potential injustice with regard to the distribution of risks benefits and costs (i.e. in regard to competing for land use) the large-scale deployment of hydrogen is a contested policy issue. This paper draws from a historical analysis of past energy projects to contribute to a more informed policy-making process toward a more just transition to the hydrogen economy. We perform a systematic literature review to identify relevant conflict factors that can influence the outcome of hydrogen energy transition projects in selected Economic Community of West African States countries namely Nigeria and Mali. To better address potential challenges policymakers must not only facilitate technology development access and market structures for hydrogen energy policies but also focus on energy access to affected communities. Further research should monitor hydrogen implementation with a special focus on societal impacts in producing countries.

The rapid expansion of renewable energies has the potential to decarbonize the electricity supply. This is more challenging in difficult-to-electrify sectors. The use of hydrogen provides a massive potential for this issue. However expanding hydrogen production increases electricity demand while providing additional flexibility to the electricity market. This paper mainly aims to analyze the economic effects of this sector coupling between the European electricity and national hydrogen markets. The developed energy market model jointly considers both markets to reach an overall welfare optimum. A novel modeling approach allows the interaction of these markets without the need for several iterative optimization runs. This allows for a detailed analysis of various market participants’ changes in consumer and producer surpluses. The optimization is conducted in 13 connected Central European countries to account for various power plant fleets generation mixes and electricity prices. Results show an overall welfare increase of EUR 4 to 28 billion in 2030 and an EUR 5 to 158 billion increase in 2040. However there is a surplus shift from consumers to producers. The consumer surplus is reduced by up to EUR 44 billion in 2030 and EUR 60 billion while producers benefit to achieve the overall welfare benefits. The reduction of consumer surplus changes if significant price peaks occur. Fuel cell applications can avoid these price peaks resulting in a surplus shift from thermal power plants to consumers. Hence consumer surplus can increase by up to EUR 146 billion in the respective 2040 scenarios. Pink hydrogen accounts for a sizable portion of total hydrogen production up to 58 percent in 2030 and up to 30 percent in 2040. As a result nuclear power plants that are nearly entirely allocated in France stand to benefit greatly from this sector coupling. Additional efforts could be made to address the link between hydrogen and natural gas prices. Furthermore the potential for cross-border hydrogen trade and the implementation of national legal and regulatory frameworks could be assessed.

A simulation tool called HYDRA to optimize individual hydrogen infrastructure layouts is presented. The different electrolyzer technologies namely proton exchange membrane electrolysis anion exchange membrane electrolysis alkaline electrolysis and solid oxide electrolysis as well as hydrogen storage possibilities are described in more detail and evaluated. To illustrate the application opportunities of HYDRA three project examples are discussed. The examples include central and decentral applications while taking the usage of hydrogen into account.

Ever more stringent emission regulations for vehicles encourage increasing numbers of battery electric vehicles on the roads. A drawback of storing electric energy in a battery is the comparable low energy density low driving range and the higher propensity to deplete the energy storage before reaching the destination especially at low ambient temperatures. When the battery is depleted stranded vehicles can either be towed or recharged with a mobile recharging station. Several technologies of mobile recharging stations already exist however most of them use fossil fuels to recharge battery electric vehicles. The proposed novel zero emission solution for mobile charging is a combined high voltage battery and hydrogen fuel cell charging station. Due to the thermal characteristics of the fuel cell and high voltage battery (which allow only comparable low coolant temperatures) the thermal design for this specific application (available heat exchanger area zero vehicle speed air flow direction) becomes challenging and is addressed in this work. Experimental methods were used to obtain reliable thermal and electric power measurement data of a 30 kW fuel cell system which is used in the Mobile Hydrogen Powersupply. Subsequently simulation methods were applied for the thermal design and optimisation of the coolant circuits and heat exchangers. It is shown that an battery electric vehicle charging power of 22 kW requires a heat exchanger area of 1 m2 of which 60 % is used by the fuel cell heat exchanger and the remainder by the battery heat exchanger to achieve steady state operation at the highest possible ambient temperature of 436 °C. Furthermore the simulation showed that when the charging power of 22 kW is solely provided by the high voltage battery the highest possible ambient temperature is 42 °C. When the charging power is decreased operation up to the maximum ambient temperatures of 45 °C can be achieved. The results of maximum charging power and limiting ambient temperature give insights for further system improvements which are: sizing of fuel cell or battery trailer design and heat exchanger area operation strategy of the system (power split between high voltage battery and fuel cell) as well as possible dynamic operation scenarios.

This paper analyses different levels and means of the electrification of space and hot water heating using an explorative modelling approach. The analysis provides guidance to the ongoing discussion on favourable pathways for heating buildings and the role of secondary energy carriers such as hydrogen or synthetic fuels. In total 12 different scenarios were modelled with decarbonisation pathways until 2050 which cover all 27 member states of the European Union. Two highly detailed optimisation models were combined to cover the building stock and the upstream energy supply sector. The analysis shows that decarbonisation pathways for space and water heating based on large shares of heat pumps have at least 11% lower system costs in 2050 than pathways with large shares of hydrogen or synthetic fuels. This translates into system cost savings of around €70 bn. Heat pumps are cost-efficient in decentralised systems and in centralised district heating systems. Hence heat pumps should be the favoured option to achieve a cost-optimal solution for heating buildings. Accordingly the paper makes a novel and significant contribution to understanding suitable and cost-efficient decarbonisation pathways for space and hot water heating via electrification. The results of the paper can provide robust guidance for policymakers.

The chances of a global hydrogen economy becoming a reality have increased significantly since the COVID pandemic and the war in Ukraine and for net zero carbon emissions. However intercontinental hydrogen transport is still a major issue. This study suggests transporting hydrogen as a gas at atmospheric pressure in balloons using the natural flow of wind to carry the balloon to its destination. We investigate the average wind speeds atmospheric pressure and temperature at different altitudes for this purpose. The ideal altitudes to transport hydrogen with balloons are 10 km or lower and hydrogen pressures in the balloon vary from 0.25 to 1 bar. Transporting hydrogen from North America to Europe at a maximum 4 km altitude would take around 4.8 days on average. Hydrogen balloon transportation cost is estimated at 0.08 USD/kg of hydrogen which is around 12 times smaller than the cost of transporting liquified hydrogen from the USA to Europe. Due to its reduced energy consumption and capital cost in some locations hydrogen balloon transportation might be a viable option for shipping hydrogen compared to liquefied hydrogen and other transport technologies.

The depletion of fossil fuel reserves has resulted from their application in the industrial and energy sectors. As a result substantial efforts have been dedicated to fostering the shift from fossil fuels to renewable energy sources via technological advancements in industrial processes. Microalgae can be used to produce biofuels such as biodiesel hydrogen and bioethanol. Microalgae are particularly suitable for hydrogen production due to their rapid growth rate ability to thrive in diverse habitats ability to resolve conflicts between fuel and food pro duction and capacity to capture and utilize atmospheric carbon dioxide. Therefore microalgae-based bio hydrogen production has attracted significant attention as a clean and sustainable fuel to achieve carbon neutrality and sustainability in nature. To this end the review paper emphasizes recent information related to microalgae-based biohydrogen production mechanisms of sustainable hydrogen production factors affecting biohydrogen production by microalgae bioreactor design and hydrogen production advanced strategies to improve efficiency of biohydrogen production by microalgae along with bottlenecks and perspectives to over come the challenges. This review aims to collate advances and new knowledge emerged in recent years for microalgae-based biohydrogen production and promote the adoption of biohydrogen as an alternative to con ventional hydrocarbon biofuels thereby expediting the carbon neutrality target that is most advantageous to the environment.

Climate change is projected to have substantial economic social and environmental impacts worldwide. Currently the leading solutions for hydrogen storage are in salt caverns and depleted natural gas reservoirs. However the required geological formations are limited to certain regions. To increase alternatives for hydrogen storage this paper proposes storing hydrogen in pipes filled with gravel in lakes hydropower and pumped hydro storage reservoirs. Hydrogen is insoluble in water non-toxic and does not threaten aquatic life. Results show the levelized cost of hydrogen storage to be 0.17 USD kg−1 at 200 m depth which is competitive with other large scale hydrogen storage options. Storing hydrogen in lakes hydropower and pumped hydro storage reservoirs increases the alternatives for storing hydrogen and might support the development of a hydrogen economy in the future. The global potential for hydrogen storage in reservoirs and lakes is 3 and 12 PWh respectively. Hydrogen storage in lakes and reservoirs can support the development of a hydrogen economy in the future by providing abundant and cheap hydrogen storage.

Integrated steelworks off-gases are generally exploited to produce heat and electricity. However further valorization can be achieved by using them as feedstock for the synthesis of valuable products such as methane and methanol with the addition of renewable hydrogen. This was the aim of the recently concluded project entitled “Intelligent and integrated upgrade of carbon sources in steel industries through hydrogen intensified synthesis processes (i3 upgrade)”. Within this project several activities were carried out: from laboratory analyses to simulation investigations from design development and tests of innovative reactor concepts and of advanced process control to detailed economic analyses business models and investigation of implementation cases. The final developed methane production reactors arerespectively an additively manufactured structured fixedbed reactor and a reactor setup using wash-coated honeycomb monoliths as catalyst; both reactors reached almost full COx conversion under slightly over-stoichiometric conditions. A new multi-stage concept of methanol reactor was designed commissioned and extensively tested at pilot-scale; it shows very effective conversion rates near to 100% for CO and slightly lower for CO2 at one-through operation for the methanol synthesis. Online tests proved that developed dispatch controller implements a smooth control strategy in real time with a temporal resolution of 1 min and a forecasting horizon of 2 h. Furthermore both offline simulations and cost analyses highlighted the fundamental role of hydrogen availability and costs for the feasibility of i 3 upgrade solutions and showed that the industrial implementation of the i 3 upgrade solutions can lead to significant environmental and economic benefits for steelworks especially in case green electricity is available at an affordable price.