Publications

The dislocation and twinning evolution behaviors in high manganese steels Fe-22Mn-0.6C and Fe-17Mn-1.5Al-0.6C have been investigated under tensile deformation with and without diffusive hydrogen. The notched tensile tests were interrupted once primary cracks were detected using the applied direct current potential drop measurement. In parallel the strain distribution in the vicinity of the crack was characterized by digital image correlation using GOM optical system. The microstructure surrounding the crack was investigated by electron backscatter diffraction. Electron channeling contrast imaging was applied to reveal the evolution of dislocations stacking faults and deformation twins with respect to the developed strain gradient and amount of hydrogen. The results show that the diffusive hydrogen at the level of 26 ppm has a conspicuous effect on initiating stacking faults twin bundles and activating multiple deformation twinning systems in Fe-22Mn-0.6C. Eventually the interactions between deformation twins and grain boundaries lead to grain boundary decohesion in this material. In comparison hydrogen does not obviously affect the microstructure evolution namely the twinning thickness and the amount of activated twinning systems in Fe-17Mn-1.5Al-0.6C. The Al-alloyed grade reveals a postponed nucleation of deformation twins delayed onset of the secondary twinning system and develops finer twinning lamellae in comparison to the Al-free material. These observations explain the improved resistance to hydrogen-induced cracking in Al-alloyed TWIP steels.

The use of hydrogen as energy carrier is a promising option to decarbonize both energy and transport sectors. This paper presents an advanced techno-economic model for calculation of optimal dispatch of large-scale multi MW electrolysis plants in order to obtain a more accurate evaluation of the feasibility of business cases related to the supply of this fuel for different end uses combined with grid services' provision. The model is applied to the Spanish case using different scenarios to determine the minimum demand required from the FCEV market so that electrolysis facilities featuring several MW result in profitable business cases. The results show that grid services contribute to the profitability of hydrogen production for mobility given a minimum but considerable demand from FCEV fleets.

Solid oxide fuel cells (SOFCs) produce electricity with high electrical efficiency and fuel flexibility without pollution for example CO₂ NO_x SO_x and particles. Still numerous issues hindered the large‐scale commercialization of fuel cell at a large scale such as fuel storage mechanical failure catalytic degradation electrode poisoning from fuel and air for example lifetime in relation to cost. Computational fluid dynamics (CFD) couples various physical fields which is vital to reduce the redundant workload required for SOFC development. Modeling of SOFCs includes the coupling of charge transfer electrochemical reactions fluid flow energy transport and species transport. The Butler‐Volmer equation is frequently used to describe the coupling of electrochemical reactions with current density. The most frequently used is the activation‐ and diffusion‐controlled Butler‐Volmer equation. Three different electrode reaction models are examined in the study which is named case 1 case 2 and case 3 respectively. Case 1 is activation controlled while cases 2 and 3 are diffusion‐controlled which take the concentration of redox species into account. It is shown that case 1 gives the highest reaction rate followed by case 2 and case 3. Case 3 gives the lowest reaction rate and thus has a much lower current density and temperature. The change of activation overpotential does not follow the change of current density and temperature at the interface of the anode and electrolyte and interface of cathode and electrolyte which demonstrates the non‐linearity of the model. This study provides a reference to build electrochemical models of SOFCs and gives a deep understanding of the involved electrochemistry.

In the transition to a climate neutral future the transportation sector needs to be sustainably decarbonized. Producing advanced fuels (such as biomethane) and bio-based valorised products (such as pyrochar) may offer a solution to significantly reduce greenhouse gas (GHG) emissions associated with energy and agricultural circular economy systems. Biological and thermochemical bioenergy technologies together with power to gas (P2G) systems can generate green renewable gas which is essential to reduce the GHG footprint of industry. However each technology faces challenges with respect to sustainability and conversion efficiency. Here this study identifies an optimal pathway leading to a sustainable bioenergy system where the carbon released in the fuel is offset by the GHG savings of the circular bio-based system. It provides a state-of-the-art review of individual technologies and proposes a bespoke circular cascading bio-based system with anaerobic digestion as the key platform integrating electro-fuels via P2G systems and value-added pyrochar via pyrolysis of solid digestate. The mass and energy analysis suggests that a reduction of 11% in digestate mass flow with the production of pyrochar bio-oil and syngas and an increase of 70% in biomethane production with the utilization of curtailed or constrained electricity can be achieved in the proposed bio-based system enabling a 70% increase in net energy output as compared with a conventional biomethane system. However the carbon footprint of the electricity from which the hydrogen is sourced is shown to be a critical parameter in assessing the GHG balance of the bespoke system.

Frontier Economics has been engaged by the Commonwealth Department of the Environment and Energy (now Industry Science Energy and Resources) (the Department) to undertake an indicative analysis of the economics of blending hydrogen in Australian natural gas distribution networks. Our analysis is limited to a specific gas distribution network servicing urban areas of Melbourne.

We have investigated the economics of blending hydrogen in a natural gas distribution network by examining a number of energy supply options including options that involve blending hydrogen. While we consider that these cases we have examined are useful for understanding the economics of hydrogen blending at low rates in Victoria and for understanding the factors that are likely to drive the economics of blending at higher rates or in other regions it cannot be assumed that the results we find for the cases we investigate will necessarily apply in other regions or for blending at other rates. This report should be read as an assessment of the specific cases we have investigated and our findings cannot necessarily be extended to other cases (such as other locations or other rates of blending)"

The full report can be found via the website of the Australian government at this link

Heat is one of the UK’s largest energy-consuming and carbon-emitting sectors and potentially the most difficult to decarbonise. The UK’s Clean Growth Strategy identifies that heat decarbonisation in buildings and industry will likely involve shifting away from natural gas to alternative energy vectors like electricity and hydrogen. This will mean transition of existing cooking appliances away from natural gas resulting in social implications that require detailed analysis for optimal transition.

This report investigates the social dimensions of heat decarbonisation in cooking appliances specifically moving away from gas cookers and hobs. It presents a first step in tackling the following questions.

• How are current carbon-intensive cooking technologies part of existing cooking practices and broader social and material structures?
• What are the challenges and opportunities for cooking heat decarbonisation in terms of consumer acceptance carbon and energy reductions and business/market opportunities?
• What interventions are needed to realise policy objectives of heat de-carbonisation?
• The report builds on interviews with BEIS’s long-term heat strategy experts and key external stakeholders together with a review of secondary data on trends in cooking and appliance use in the UK. Further it presents an annotated bibliography of literature on the social implications of heat decarbonisation and sustainable food transitions more broadly. The multidisciplinary review of the literature is structured around Southerton et al.’s (2011) ISM (Individual- Social- and Material-context) framework for a systemic review of the various change-agents required for transition. Finally a comparative review of the social challenges and opportunities identified in the ISM contexts is presented along with the potential policy interventions in each. The report concludes with a list of recommendations in terms of evidence and data gathering; research; policy; and a set of general recommendations for heat decarbonisation policy.

There is a need for alternative marine fuels in order to reduce the environmental and climate impacts of shipping in the short and long term. This study assesses the prospects for seven alternative fuels for the shipping sector in 2030 including biofuels by applying a multi-criteria decision analysis approach that is based on the estimated fuel performance and on input from a panel of maritime stakeholders and by considering explicitly the influence of stakeholder preferences. Seven alternative marine fuels—liquefied natural gas (LNG) liquefied biogas (LBG) methanol from natural gas renewable methanol hydrogen for fuel cells produced from (i) natural gas or (ii) electrolysis based on renewable electricity and hydrotreated vegetable oil (HVO)—and heavy fuel oil (HFO) as benchmark are included and ranked by ten performance criteria and their relative importance. The criteria cover economic environmental technical and social aspects. Stakeholder group preferences (i.e. the relative importance groups assign to the criteria) influence the ranking of these options. For ship-owners fuel producers and engine manufacturers economic criteria in particular the fuel price are the most important. These groups rank LNG and HFO the highest followed by fossil methanol and then various biofuels (LBG renewable methanol and HVO). Meanwhile representatives from Swedish government authorities prioritize environmental criteria specifically GHG emissions and social criteria specifically the potential to meet regulations ranking renewable hydrogen the highest followed by renewable methanol and then HVO. Policy initiatives are needed to promote the introduction of renewable marine fuels.

The Swedish steel industry stands before a potential transition to drastically lower its CO₂ emissions using direct hydrogen reduction instead of continuing with coke-based blast furnaces. Previous studies have identified hydrogen direct reduction as a promising option. We build upon earlier efforts by performing a technological innovation system study to systematically examine the barriers to a transition to hydrogen direct reduction and by providing deepened quantitative empirics to support the analysis. We also add extended paper and patent analysis methodology which is particularly useful for identifying actors and their interactions in a technological system. We conclude that while the innovation system is currently focused on such a transition notable barriers remain particularly in coordination of the surrounding technical infrastructure and the issue of maintaining legitimacy for such a transition in the likely event that policies to address cost pressures will be required to support this development.

Recently hot stamping technology has been increasingly used in automotive structural parts with ultrahigh strength to meet the standards of both high fuel efficiency and crashworthiness. However one issue of concern regarding these martensitic steels which are fabricated using a hot stamping procedure is that the steel is highly vulnerable to hydrogen delayed cracking caused by the diffusible hydrogen flow through the surface reaction of the coating in a furnace atmosphere. One way to make progress in understanding hydrogen delayed fractures is to elucidate an interaction for desorption with diffusible hydrogen behavior. The role of diffusible hydrogen on delayed fractures was studied for different baking times and temperatures in a range of automotive processes for hot-stamped martensitic steel with aluminum- and silicon-coated surfaces. It was clear that the release of diffusible hydrogen is effective at higher temperatures and longer times making the steel less susceptible to hydrogen delayed fractures. Using thermal desorption spectroscopy the phenomenon of the hydrogen delayed fracture was attributed to reversible hydrogen in microstructure sites with low trapping energy.

The objective of this project is to take into account the mechanical constraints formed by diffusion of hydrogen or tritium in watertight palladium alloy cathode. To know the origin of these it was necessary to discriminating the damaging effects encountered. Effectively hydrogen and isotope induce deformation embrittlement stress corrosion cracking and cathodic corrosion in different regions of cathode. Palladium can be alloyed with silver or yttrium to favourably increase diffusion and reduce these constraints. Effects of electrochemical factors temperature cathode structure adsorbed transient complex of palladium and porous material support are given to estimate and to limit possible damage.

In a future fossil-free circular economy the petroleum-based plastics industry must be converted to non-fossil feedstock. A known alternative is bio-based plastics but a relatively unexplored option is deriving the key plastic building blocks hydrogen and carbon from electricity through electrolytic processes combined with carbon capture and utilization technology. In this paper the future demand for electricity and carbon dioxide is calculated under the assumption that all plastic production is electricity-based in the EU by 2050. The two most important input chemicals are ethylene and propylene and the key finding of this paper is that the electricity demand to produce these are estimated to 20 MWh/ton ethylene and 38 MWh/ton propylene and that they both could require about 3 tons of carbon dioxide/ton product. With constant production levels this implies an annual demand of about 800 TWh of electricity and 90 Mton of carbon dioxide by 2050 in the EU. If scaled to the total production of plastics including all input hydrocarbons in the EU the annual demand is estimated to 1600 TWh of electricity and 180 Mton of carbon dioxide. This suggests that a complete shift to electricity-based plastics is possible from a resource and technology point of view but production costs may be 2 to 3 times higher than today. However the long time frame of this paper creates uncertainties regarding the results and how technical economic and social development may influence them. The conclusion of this paper is that electricity-based plastics integrated with bio-based production can be an important option in 2050 since biomass resources are scarce but electricity from renewable sources is abundant.

Synthetic natural gas (SNG) is one of the promising energy carriers for the excessive electricity generated from variable renewable energy sources. SNG production from renewable H₂ and CO₂  via catalytic CO₂ methanation has gained much attention since CO₂ emissions could be simultaneously reduced. In this study Ni–Fe/(MgAl)O_x alloy catalysts for CO₂ methanation were prepared via hydrotalcite precursors using a rapid coprecipitation method. The effect of total metal concentration on the physicochemical properties and catalytic behavior was investigated. Upon calcination the catalysts showed high specific surface area of above 230 m² g⁻¹. Small particle sizes of about 5 nm were obtained for all catalysts even though the produced catalyst amount was increased by 10 times. The catalysts exhibited excellent space-time yield under very high gas space velocity (34000 h⁻¹) irrespective of the metal concentration. The CO₂ conversions reached 73–79% at 300 °C and CH₄ selectivities were at 93–95%. Therefore we demonstrated the potential of large-scale production of earth-abundant Ni–Fe based catalysts for CO₂ methanation and the Power-to-Gas technology.

Plastic pre-strains were applied to the metastable 304L austenitic stainless steel at both room temperature (20 °C) and higher temperatures (i.e. 50 80 and 100 °C) and then the hydrogen embrittlement (HE) susceptibility of the steel was evaluated by cathodically hydrogen-charging and tensile testing. The 20 °C pre-strain greatly strengthened the steel but simultaneously significantly increased the HE susceptibility of the steel since α′ martensite was induced by the pre-strain causing the pre-existence of α′ martensite which provided “highways” for hydrogen to transport deep into the steel during the hydrogen-charging. Although the warm pre-strains did not strengthen the steel as significantly as the 20 °C pre-strain they retained the HE resistance of the steel. This is because the higher temperatures particularly 80 and 100 °C suppressed the α′ martensite transformation during the pre-straining. Pre-strain at a temperature slightly higher than room temperature has a potential to strengthen the metastable 304L austenitic stainless steel without compromising its initial HE resistance.

Interest in hydrogen as a carbon-neutral energy carrier is on the rise around the globe including in Europe. In particular power-to-gas as a technology to transform electricity to hydrogen is receiving ample attention. This article scrutinises current updates in the energy law framework of the EU to explain the legal pre-conditions for the various possible applications of power-to-gas technology. It highlights the influence of both electricity and gas legislation on conversion storage and transmission of hydrogen and demonstrates why ‘green’ hydrogen might come with certain legal privileges under the Renewable Energy Directive attached to it as opposed to the European Commission’s so-called ‘clean’ hydrogen. The article concludes by advocating for legal system integration in EU energy law namely merging the currently distinct EU electricity and gas law frameworks into one unified EU Energy Act.

Taiwan stands out globally in the manufacture of scooters. If fuel cell technology could be applied to the scooter Taiwan could gain an advantage in the trend for commercial applications for fct. In 2011 The Bureau of Standards Metrology and Inspection proposed this project “the Demonstration of Hydrogen Fuel Cell Scooters.” Thirty rental fuel cell scooters are to run a long distance. Evaluation during everyday use of the cells performance will be made and reported by the riders. All the evaluations will be put into consideration of future adjustments. The project is to map out a practice route in Taipei and set up a control center to follow progress. The data gathered from the practice project will help examine the performance of fuel cell scooters contributing to the creation of legal drafts and future standards. The Taiwan fuel cell industry chain is complete and the industry possesses the ability to produce key components. Thus it is a potential market in Taiwan. A review of fuel cell development conditions in Taiwan shows that the fuel cell scooters is a niche industry owing to the strength of this technology.

The presence of a conductive layers of hot-formed oxide on the surface of bars for pre or post-compressing structures can promote localized attacks as a function of pH. The aggressive local environment in the occluded cells inside localized attacks has as consequence the possibility of initiation of stress corrosion cracking. In this paper the stress corrosion cracking behavior of high strength steels proposed for tendons was studied by means of Constant Load (CL) tests and Slow Strain Rate (SSR) tests. Critical ranges of pH for cracking were verified. The promoting role of localized attack was confirmed. Further electrochemical tests were performed on bars in as received surface conditions in order to evaluate pitting initiation. The adverse effect of mill scale was recognized.

The report documents current knowledge of the social issues surrounding hydrogen projects. It reviews leading practice stakeholder engagement and communication strategies and findings from focus groups and research activities across Australia.

The full report can be found at this link.

Deployed at scale hydrogen could account for almost one-fifth of total final energy consumed by 2050. This would reduce annual CO2 emissions by roughly 6 gigatons compared to today’s levels and contribute roughly 20% of the abatement required to limit global warming to two degrees Celsius.

On the demand side the Hydrogen Council sees the potential for hydrogen to power about 10 to 15 million cars and 500000 trucks by 2030 with many uses in other sectors as well such as industry processes and feedstocks building heating and power power generation and storage. Overall the study predicts that the annual demand for hydrogen could increase tenfold by 2050 to almost 80 EJ in 2050 meeting 18% of total final energy demand in the 2050 two-degree scenario. At a time when global populations are expected to grow by two billion people by 2050 hydrogen technologies have the potential to create opportunities for sustainable economic growth.

“The world in the 21st century must transition to widespread low carbon energy use” said Takeshi Uchiyamada Chairman of Toyota Motor Corporation and co-chair of the Hydrogen Council. “Hydrogen is an indispensable resource to achieve this transition because it can be used to store and transport wind solar and other renewable electricity to power transportation and many other things. The Hydrogen Council has identified seven roles for hydrogen which is why we are encouraging governments and investors to give it a prominent role in their energy plans. The sooner we get the hydrogen economy going the better and we are all committed to making this a reality.”

Achieving such scale would require substantial investments; approximately US$20 to 25 billion annually for a total of about US$280 billion until 2030. Within the right regulatory framework – including long-term stable coordination and incentive policies – the report considers that attracting these investments to scale the technology is feasible. The world already invests more than US$1.7 trillion in energy each year including US$650 billion in oil and gas US$300 billion in renewable electricity and more than US$300 billion in the automotive industry.

“This study confirms the place of hydrogen as a central pillar in the energy transition and encourages us in our support of its large-scale deployment. Hydrogen will be an unavoidable enabler for the energy transition in certain sectors and geographies. The sooner we make this happen the sooner we will be able to enjoy the needed benefits of Hydrogen at the service of our economies and our societies” said Benoît Potier Chairman and CEO Air Liquide. “Solutions are technologically mature and industry players are committed. We need concerted stakeholder efforts to make this happen; leading this effort is the role of the Hydrogen Council.”

The launch of the new roadmap came during the Sustainability Innovation Forum in the presence of 18 senior members of the Hydrogen led by co-chairs Takeshi Uchiyamada Chairman of Toyota and Benoît Potier Chairman and CEO Air Liquide and accompanied by Prof. Aldo Belloni CEO of The Linde Group Woong-chul Yang Vice Chairman of Hyundai Motor Company and Anne Stevens Board Member of Anglo American. During the launch the Hydrogen Council called upon investors policymakers and businesses to join them in accelerating deployment of hydrogen solutions for the energy transition. It was also announced that Woong-chul Yang of Hyundai Motor Company will succeed Takeshi Uchiyamada of Toyota in the rotating role of the Council’s co-chair and preside the group together with Benoit Potier CEO Air Liquide in 2018. Mr Uchiyamada is planning to return as Co-chairman in 2020 coinciding with the Tokyo Olympic and Paalympic Games an important milestone for showcasing hydrogen society and mobility.

You can download the full report from the Hydrogen Council website here

There is significant interest in Australia both federally and at the state level to develop a hydrogen production industry. Australia’s Chief Scientist Alan Finkel recently prepared a briefing paper for the COAG Energy Council outlining a road map for hydrogen. It identifies hydrogen has the potential to be a significant source of export revenue for Australia in future years assist with decarbonising Australia’s economy and could establish Australia as a leader in low emission fuel production.

As part of the ongoing investigations into the hydrogen production potential of Australia Geoscience Australia has been commissioned by the Department of Industry Innovation and Science to develop heat maps that show areas with high potential for future hydrogen production. The study is technology agnostic in that it considers hydrogen production via electrolysis using renewable energy sources and also fossil fuel hydrogen coupled with carbon capture and storage (CCS). The heat maps presented in this work are synthesized from the key individual national-scale datasets that are relevant for hydrogen production. In the case of hydrogen from electrolysis renewable energy potential and the availability of water are the most important factors with various infrastructural considerations playing a secondary role. In the case of fossil fuel hydrogen proximity to gas and coal resources water and availability of carbon storage sites are the important parameters that control the heat maps. In this report we present 5 different heat map scenarios reflecting different assumptions in the geospatial analysis and also reflecting to some degree the different projected timeframes for hydrogen production. The first three scenarios pertain to renewable energy and hydrogen There is significant interest in Australia both federally and at the state level to develop a hydrogen production industry. In August 2018 Australia’s Chief Scientist Dr Alan Finkel prepared a briefing paper for the COAG Energy Council outlining a road map for hydrogen. It identifies hydrogen has the potential to be a significant source of export revenue for Australia in future years assist with decarbonising Australia’s economy and could establish Australia as a leader in low emission fuel production.

As part of ongoing investigations into the hydrogen production potential of Australia Geoscience Australia has been engaged by the Department of Industry Innovation and Science to develop maps that show areas with high potential for future hydrogen production. The study is technology agnostic but considers only low carbon production processes. It includes hydrogen production via electrolysis using renewable energy sources (referred to as renewable hydrogen) as well as fossil fuel-derived hydrogen coupled with carbon capture and storage (CCS) (referred to as CCS hydrogen). The maps presented in this work are synthesized from the key individual national-scale datasets that are relevant for hydrogen production. In the case of hydrogen from electrolysis renewable energy potential (from wind solar and hydro resources) and the availability of water are the most important factors while various infrastructure considerations also play a role. In the case of CCS hydrogen proximity to gas and coal resources water and availability of carbon storage sites are the important parameters that control the spatial distribution of potential hydrogen production. In this report we present five different scenarios that reflect key differences in technologies for hydrogen production and the requirements of those technologies. Using geospatial analysis each scenario is translated into a heat map that shows regional trends in potential for hydrogen production based on access to underpinning resources and existing infrastructure.

Three scenarios explore the future potential for renewable hydrogen produced by electrolysis. These demonstrate a high potential for hydrogen production in the future near many Australian coastal areas which is even larger if infrastructure is available to transport renewable power generated from inland areas to the coast. Results also show significant future potential for hydrogen production in inland areas where water is available. The final two scenarios focus on the future potential for CCS hydrogen: a 2030 scenario and a 2050 scenario. A key factor in future CCS hydrogen potential is related to the timeframes for the availability of geological storage resources for CO_2.

This policy statement provides:

An overview of our key priorities for the short to medium-term and then moves on to look at how we have continued to abide by the three key principles set out in Scotland's Energy Strategy published in 2017 in our policy design and delivery. Those principles are:

• a whole-system view;
• an inclusive energy transition; and
• a smarter local energy model.

An overview of how we have committed to ensuring a green economic recovery in respect of energy while remaining aligned to our net zero ambitions. We have set these out under the following themes to align with our wider green recovery narrative in the Programme for Government

• Skills and Jobs;
• Supporting Local Communities:
• Investment; and
• Innovation

along with some specific policy examples.



Separate sections have been included on Maximising Scotland's International Potential in the lead up to the UN Framework Convention on Climate Change Conference of the Parties (COP26) and on Consumers to reflect the challenging economic climate we currently face and to highlight the action being taken by the Scottish Government to ensure the cost of our energy transition does not fall unequally.



This statement provides an overview of our approach to supporting the energy sector in the lead up to COP26 and as we embark on a green economic recovery from the COVID-19 pandemic. It summarises how our recent policy publications such as our Hydrogen Policy Statement Local Energy Policy Statement and Offshore Wind Policy Statement collectively support the delivery of the Climate Change Plan update along with the future findings from our currently live consultations including our draft Heat in Buildings Strategy our Call for Evidence on the future development of the Low Carbon Infrastructure Transition Programme (LCITP) and our consultation on Scottish skills requirements for energy efficiency.



While this statement sets out our comprehensive programme of work across the energy sector the current Energy Strategy (2017) remains in place until any further Energy Strategy refresh is adopted by Ministers. It is at the stage of refreshing Scotland's Energy Strategy where we will embark on a series of stakeholder engagements and carry out the relevant impact assessments to inform our thinking on future policy development.

Structural integrity of reactor pressure vessel (RPV) in light water reactors (LWR) is of highest importance regarding operation safety and lifetime. The fracture behaviour of low-alloy RPV steels with different dynamic strain aging (DSA) & environmental assisted cracking (EAC) susceptibilities in simulated LWR environments was evaluated by elastic plastic fracture mechanics tests (EPFM) and by metallo- and fractographic post-test analysis. Exposure to high temperature water (HTW) environments at LWR temperatures revealed only moderated reductions in the fracture initiation and tearing resistance of low alloy RPV steels with high DSA or EAC susceptibility accompanied with a moderate but clear change in fracture morphology which indicates the potential synergies of hydrogen/HTW embrittlement with DSA and EAC under suitable conditions. The most pronounced degradation effects occurred in a) RPV steels with high DSA susceptibility where the fracture initiation and tearing resistance reduction increased with decreasing loading rate and were most pronounced in hydrogenated HTW and b) high sulphur steels with high EAC susceptibility in aggressive occluded crevice environment and with preceding fast EAC crack growth in oxygenated HTW. The moderate effects are due to the low hydrogen availability in HTW together with high density of fine-dispersed hydrogen traps in RPV steels. Stable ductile transgranular tearing by microvoid coalescence was the dominant failure mechanism in all environments with additional varying few % of secondary cracks macrovoids and quasi-cleavage in HTW. The observed behavior suggests a combination of plastic strain localisation by the Hydrogen-enhanced Local Plasticity (HELP) mechanism in synergy with DSA and Hydrogen-enhanced Strain-induced Vacancies (HESIV) mechanism with additional minor contributions of Hydrogen-enhanced Decohesion Embrittlement (HEDE) mechanism.

Fuel cells are the most clean and efficient power source for vehicles. In particular proton exchange membrane fuel cells (PEMFCs) are the most promising candidate for automobile applications due to their rapid start-up and low-temperature operation. Through extensive global research efforts in the latest decade the performance of PEMFCs including energy efficiency volumetric and mass power density and low temperature startup ability have achieved significant breakthroughs. In 2014 fuel cell powered vehicles were introduced into the market by several prominent vehicle companies. However the low durability and high cost of PEMFC systems are still the main obstacles for large-scale industrialization of this technology. The key materials and components used in PEMFCs greatly affect their durability and cost. In this review the technical progress of key materials and components for PEMFCs has been summarized and critically discussed including topics such as the membrane catalyst layer gas diffusion layer and bipolar plate. The development of high-durability processing technologies is also introduced. Finally this review is concluded with personal perspectives on the future research directions of this area.

Alloying and structural modification are two effective ways to enhance the hydrogen storage kinetics and decrease the thermal stability of Mg and Mg-based alloys. In order to enhance the characteristics of Mg₂Ni-type alloys Cu and La were added to an Mg₂Ni-type alloy and the sample alloys (Mg₂₄Ni₁₀Cu₂)_100−xLa_x (x = 0 5 10 15 20) were prepared by melt spinning. The influences of La content and spinning rate on the gaseous and electrochemical hydrogen storage properties of the sample alloys were explored in detail. The structural identification carried out by XRD and TEM indicates that the main phase of the alloys is Mg₂Ni and the addition of La results in the formation of the secondary phases LaMg₃ and La₂Mg₁₇. The as-spun alloys have amorphous and nanocrystalline structures and the addition of La promotes glass formation. The electrochemical properties examined by an automatic galvanostatic system show that the samples possess a good activation capability and achieve their maximal discharge capacities within three cycles. The discharge potential characteristics were vastly ameliorated by melt spinning and La addition. The discharge capacities of the samples achieve their maximal values as the La content changes and the discharge capacities always increase with increasing spinning rate. The addition of La leads to a decline in hydrogen absorption capacity but it can effectively enhance the rate of hydrogen absorption. The addition of La and melt spinning significantly increase the hydrogen desorption rate due to the reduced activation energy.

Recent advances on synthesis characterization and hydrogen absorption properties of ultrasmall metal nanoparticles (defined here as objects with average size ≤3 nm) are briefly reviewed in the first part of this work. The experimental challenges encountered in performing accurate measurements of hydrogen absorption in Mg- and noble metal-based ultrasmall nanoparticles are addressed. The second part of this work reports original results obtained for ultrasmall bulk-immiscible Pd–Rh nanoparticles. Carbon-supported Pd–Rh nanoalloys in the whole binary chemical composition range have been successfully prepared by liquid impregnation method followed by reduction at 300°C. EXAFS investigations suggested that the local structure of these nanoalloys is partially segregated into Rh-rich core and Pd-rich surface coexisting within the same nanoparticles. Downsizing to ultrasmall dimensions completely suppresses the hydride formation in Pd-rich nanoalloys at ambient conditions contrary to bulk and larger nanosized (5–6 nm) counterparts. The ultrasmall Pd90Rh10 nanoalloy can absorb hydrogen-forming solid solutions under these conditions as suggested by in situ X-ray diffraction (XRD). Apart from this composition common laboratory techniques such as in situ XRD DSC and PCI failed to clarify the hydrogen interaction mechanism: either adsorption on developed surfaces or both adsorption and absorption with formation of solid solutions. Concluding insights were brought by in situ EXAFS experiments at synchrotron: ultrasmall Pd₇₅Rh₂₅ and Pd₅₀Rh₅₀ nanoalloys absorb hydrogen-forming solid solutions at ambient conditions. Moreover the hydrogen solubility in these solid solutions is higher with increasing Pd content and this trend can be understood in terms of hydrogen preferential occupation in the Pd-rich regions as suggested by in situ EXAFS. The Rh-rich nanoalloys (Pd₂₅Rh₇₅ and Pd₁₀Rh₉₀) only adsorb hydrogen on the developed surface of ultrasmall nanoparticles. In summary in situ characterization techniques carried out at large-scale facilities are unique and powerful tools for in-depth investigation of hydrogen interaction with ultrasmall nanoparticles at local level.

Chemical looping water splitting or chemical looping hydrogen is a very promising technology for the production of hydrogen. In recent years extensive research has enabled remarkable leaps towards a successful integration of the chemical looping technology into a future hydrogen infrastructure. Progress has been reported with iron based oxygen carriers for stable hydrogen production capacity over consecutive cycles without significant signs of degradation. The high stability improvements were achieved by adding alien metal oxides or by integrating the active component into a mineral structure which offers excellent resistance towards thermal stress. Prototype systems from small μ-systems up to 50 kW have been operated with promising results. The chemical looping water splitting process was broadened in terms of its application area and utilization of feedstocks using a variety of renewable and fossil resources. The three-reactor system was clearly advantageous due to its flexibility heat integration capabilities and possibility to produce separate pure streams of hydrogen CO₂ and N₂. However two-reactor and single fixed-bed reactor systems were successfully operated as well. This review aims to survey the recently presented literature in detail and systematically summarize the gathered data.