Publications

The European Commission have just stated that hydrogen would play a major role in the economic recovery of post-COVID-19 EU countries. Hydrogen is recognised as one of the key players in a fossil fuel-free world in decades to come. However commercially practiced pathways to hydrogen production todays are associated with a considerable amount of carbon emissions. The Paris Climate Change Agreement has set out plans for an international commitment to reduce carbon emissions within the forthcoming decades. A sustainable hydrogen future would only be achievable if hydrogen production is “designed” to capture such emissions. Today nearly 98% of global hydrogen production relies on the utilisation of fossil fuels. Among these steam methane reforming (SMR) boasts the biggest share of nearly 3 50% of the global generation. SMR processes correspond to a significant amount of carbon emissions at various points throughout the process. Despite the dark side of the SMR processes they are projected to play a major role in hydrogen production by the first half of this century. This that a sustainable yet clean short/medium-term hydrogen production is only possible by devising a plan to efficiently capture this co-produced carbon as stated in the latest International Energy Agency (IEA) reports. Here we have carried out an in-depth technical review of the processes employed in sorption-enhanced steam methane reforming (SE-SMR) an emerging technology in low-carbon SMR for combined carbon capture and hydrogen production. This paper aims to provide an in-depth review on two key challenging elements of SE-SMR i.e. the advancements in catalysts/adsorbents preparation and current approaches in process synthesis and optimisation including the employment of artificial intelligence in SE-SMR processes. To the best of the authors‟ knowledge there is a clear gap in the literature where the above areas have been scrutinised in a systematic and coherent fashion. The gap is even more pronounced in the application of AI in SE-SMR technologies. As a result this work aims to fill this gap within the scientific literature.

The use of hydrogen as an alternative to fossil fuels for vehicle propulsion is already a reality. However due to its physical characteristics storage is still a challenge. There is an innovative way presented in this study to store hydrogen in conventional vehicles propelled by spark-ignition reciprocating engines and fuel cells using hydrogen as fuel; the storage of hydrogen will be at high pressure within small spheres randomly packed in a tank like the conventional tank of fuel used nowadays in current vehicles. Therefore the main purpose of the present study is to assess the performance of this storage system and compare it to others already applied by car manufacturers in their cars. In order to evaluate the performance of this storage system some parameters were taken into account: The energy stored by volume and stored by weight hydrogen leakage and compliance with current standards. This system is safer than conventional storage systems since hydrogen is stored inside small spheres containing small amounts of hydrogen. Besides its gravimetric energy density (GED) is threefold and the volumetric energy density (VED) is about half when compared with homologous values for conventional systems and both exceed the targets set by the U.S. Department of Energy. Regarding the leakage of hydrogen it complies with the European Standards provided a suitable choice of materials and dimensions is made.

Standalone renewable energy is widely used to power irrigation systems. However in agricultural facilities electricity from the grid and diesel are also consumed. The design and sizing of renewable generation involves difficulties derived from the different seasonal profiles of production and demand. If the generation is 100% renewable a considerable energy surplus is usually included. This paper is focused on a renewable energy system which has been installed in a vineyard located in the northeast of Spain. With energy from the photovoltaic fields the wastewater treatment plant of the winery a drip irrigation system and other ancillary consumptions are fed. The favourable effect of combining consumptions with different seasonal profiles is shown. The existence of some deferrable loads and the energy management strategy result in an aggregate consumption curve that is well suited to production. Besides the required energy storage is relatively small. The surplus energy is used for the on-site production of hydrogen by the electrolysis of water. The hydrogen refuels a hybrid fuel cell electric vehicle used for the mobility of workers in the vineyard. In summary electricity and hydrogen are produced on-site (to meet the energy needs) from 100% renewable sources and without operating emissions.

Automotive proton-exchange membrane fuel cells (PEMFCs) have finally reached a state of technological readiness where several major automotive companies are commercially leasing and selling fuel cell electric vehicles including Toyota Honda and Hyundai. These now claim vehicle speed and acceleration refueling time driving range and durability that rival conventional internal combustion engines and in most cases outperform battery electric vehicles. The residual challenges and areas of improvement which remain for PEMFCs are performance at high current density durability and cost. These are expected to be resolved over the coming decade while hydrogen infrastructure needs to become widely available. Here we briefly discuss the status of automotive PEMFCs misconceptions about the barriers that platinum usage creates and the remaining hurdles for the technology to become broadly accepted and implemented.

Since the UK’s Net Zero greenhouse gas emissions target was set in 2019 organisations across the energy systems community have released pathways on how we might get there – which end-use technologies are deployed across each sector of demand how our fossil fuel-based energy supply would be transferred to low carbon vectors and to what extent society must change the way it demands energy services. This paper presents a comparative analysis between seven published Net Zero pathways for the UK energy system collected from Energy Systems Catapult National Grid ESO Centre for Alternative Technology and the Climate Change Committee. The key findings reported are that (i) pathways that rely on less stringent behavioural changes require more ambitious technology development (and vice versa); (ii) electricity generation will increase by 51-160% to facilitate large-scale fuel-switching in heating and transport the vast majority of which is likely to be generated from variable renewable sources; (iii) hydrogen is an important energy vector in meeting Net Zero for all pathways providing 100-591 TWh annually by 2050 though the growth in demand is heavily dependent on the extent to which it is used in supplying heating and transport demand. This paper also presents a re-visited analysis of the potential renewable electricity generation resource in the UK. It was found that the resource for renewable electricity generation outstrips the UK’s projected 2050 electricity demand by a factor 12-20 depending on the pathway. As made clear in all seven pathways large-scale deployment of flexibility and storage is required to match this abundant resource to our energy demand.

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.

The depletion of fossil fuels and rising global warming challenges encourage to find safe and viable energy storage and delivery technologies. Hydrogen is a clean efficient energy carrier in various mobile fuel-cell applications and owned no adverse effects on the environment and human health. However hydrogen storage is considered a bottleneck problem for the progress of the hydrogen economy. Liquid-organic hydrogen carriers (LOHCs) are organic substances in liquid or semi-solid states that store hydrogen by catalytic hydrogenation and dehydrogenation processes over multiple cycles and may support a future hydrogen economy. Remarkably hydrogen storage in LOHC systems has attracted dramatically more attention than conventional storage systems such as high-pressure compression liquefaction and absorption/adsorption techniques. Potential LOHC media must provide fully reversible hydrogen storage via catalytic processes thermal stability low melting points favorable hydrogenation thermodynamics and kinetics large-scale availability and compatibility with current fuel energy infrastructure to practically employ these molecules in various applications. In this review we present various considerable aspects for the development of ideal LOHC systems. We highlight the recent progress of LOHC candidates and their catalytic approach as well as briefly discuss the theoretical insights for understanding the reaction mechanism.

Magnesium hydride and selected magnesium-based ternary hydride (Mg2FeH6 Mg2NiH4 and Mg2CoH5) syntheses and modification methods as well as the properties of the obtained materials which are modified mostly by mechanical synthesis or milling are reviewed in this work. The roles of selected additives (oxides halides and intermetallics) nanostructurization polymorphic transformations and cyclic stability are described. Despite the many years of investigations related to these hydrides and the significant number of different additives used there are still many unknown factors that affect their hydrogen storage properties reaction yield and stability. The described compounds seem to be extremely interesting from a theoretical point of view. However their practical application still remains debatable.

Using electricity for heating can contribute to decarbonization and provide flexibility to integrate variable renewable energy. We analyze the case of electric storage heaters in German 2030 scenarios with an open-source electricity sector model. We find that flexible electric heaters generally increase the use of generation technologies with low variable costs which are not necessarily renewables. Yet making customary night-time storage heaters temporally more flexible offers only moderate benefits because renewable availability during daytime is limited in the heating season. Respective investment costs accordingly have to be very low in order to realize total system cost benefits. As storage heaters feature only short-term heat storage they also cannot reconcile the seasonal mismatch of heat demand in winter and high renewable availability in summer. Future research should evaluate the benefits of longer-term heat storage.

Decarbonization of energy economy is nowadays a topical theme and several pathways are under discussion. Gaseous fuels have a fundamental role for this transition and the production of low carbon-impact fuels is necessary to deal with this challenge. The generation of renewable hydrogen is a trusted solution since this energy vector can be promptly produced from electricity and injected into the existing natural gas infrastructure granting storage capacity and easy transportation. This scenario will lead in the near future to hydrogen enrichment of natural gas whose impact on the infrastructures is being actively studied. The effect on end-user devices such as domestic gas boilers instead is still little analyzed and tested but is fundamental to be assessed. The aim of this research is to generate knowledge on the effect of hydrogen enrichment on the widely used premixed boilers: the investigations include pollutant emissions efficiency flashback and explosion hazard control system and materials selection. A model for calculating several parameters related to combustion of hydrogen enriched natural gas is presented. Guidelines for the design of new components are provided and an insight is given on the maximum hydrogen blending bearable by the current boilers.