Publications

Preventing humanity from serious impact of climate crisis requires carbon neutrality across all economic sectors including steel industry. Although fossil-free steelmaking routes receiving increasing attention fundamental process aspects especially approaches towards the improvement of efficiency and flexibility are so far not comprehensively studied. In this paper optimized process concepts allowing for a gradual transition towards fossil-free steelmaking based on the coupling of direct reduction process electric arc furnace and electrolysis are presented. Both a high-temperature and low-temperature electrolysis were modeled and possibilities for the integration into existing infrastructure are discussed. Various schemes for heat integration especially when using high-temperature electrolysis are highlighted and quantified. It is demonstrated that the considered direct reduction-based process concepts allow for a high degree of flexibility in terms of feed gas composition when partially using natural gas as a bridge technology. This allows for an implementation in the near future as well as the possibility of supplying power grid services in a renewable energy system. Furthermore it is shown that an emission reduction potential of up to 97.8% can be achieved with a hydrogen-based process route and 99% with a syngas-based process route respectively provided that renewable electricity is used.

Water electrolysis is a promising approach for the sustainable production of hydrogen however the unfavorable thermodynamics and sluggish kinetics of oxygen evolution reaction (OER) are associated with high anodic potentials. To lower the required potentials an effective strategy is proposed to substitute OER with partial oxidation of degradation products of carbohydrate origin from the waste stream of a chemical pulping industry. In this work two different catalytic materials e PdNi and NiO are investigated comparatively to understand their catalytic performance for the oxidation of carbohydrate alkaline degradation products (CHADs). PdNi can catalyze CHADs with low potential requirements (0.11 V vs. Hg/HgO at 150 mA cm2 ) but is limited to current densities opportunities to study earth-abundant electrocatalysts to efficiently oxidize biomass-derived substances.

The STOPIL-H2 project supported by the French Geodenergies research consortium aims to design a demonstrator for underground hydrogen storage in cavern EZ53 of the Etrez gas storage (France) operated by Storengy. Two types of tests are planned in this cavern: a tightness test with nitrogen and hydrogen then a cycling test during which the upper part of the cavern (approximately 200 m3) will be filled with hydrogen during 6 to 9 months. In this paper the PRA for the cycling test is presented comprising the identification of the major hazards and the proposed prevention and protection measures. The implemented methodology involves the following steps: data mining from the description of the project; analysis of lessons learned from accidents that occurred in underground gas storage and subface facilities; identification of the potential hazards pertaining to the storage process; analysis of external potential aggressors. Resulting as one of the outcomes of the PRA major accidental scenarios are presented and classified according to concerned storage operation phases as well as determined preventive or protective barriers able to prevent their occurrence of mitigate their consequences.

Fuel cell vehicles (FCVs) have clear societal and environmental benefits and can help mitigate the issues of climate change urban air pollution and oil dependence. In order for FCVs to have the biggest impact on these issues they need to be employed in large numbers. First though they need to be adopted by consumers. Their acceptance depends on positive consumer attitudes towards the vehicles. Currently there is a limited understanding within the literature on how consumers perceive FCVs and what the likelihood of adoption by consumers would be despite significant governmental and organisational investments into the technology. Therefore this study assesses consumer attitudes towards FCVs in the United Kingdom. 81 persons drove a Hyundai FCV at the Low Carbon Vehicle Event in September 2015 of which 30 took part in this study. The results show that at present FCVs are perceived mostly as being similar to incumbent internal combustion engine vehicles. This is an admirable technical achievement however in order for consumers to adopt FCVs they will need to be perceived as having distinctive benefits. Two significant barriers to the adoption of FCVs are observed in this sample: high costs and lack of refuelling infrastructure. This paper goes on to make suggestions on how and which beneficial attributes of the vehicles can be promoted to consumers and also makes suggestions on how the barriers can be overcame so that FCVs will be adopted by consumers.

Underground Hydrogen Storage (UHS) is an attractive technology for large-scale (TWh) renewable energy storage. To ensure the safety and efficiency of the UHS it is crucial to quantify the H2 interactions with the reservoir fluids and rocks across scales including the micro scale. This paper reports the experimental measurements of advancing and receding contact angles for different channel widths for a H2 /water system at P = 10 bar and T = 20 ◦C using a microfluidic chip. To analyse the characteristics of the H2 flow in straight pore throats the network is designed such that it holds several straight channels. More specifically the width of the microchannels range between 50 μm and 130 μm. For the drainage experiments H2 is injected into a fully water saturated system while for the imbibition tests water is injected into a fully H2 -saturated system. For both scenarios high-resolution images are captured starting the introduction of the new phase into the system allowing for fully-dynamic transport analyses. For better insights N2 /water and CO2 /water flows were also analysed and compared with H2 /water. Results indicate strong water-wet conditions with H2 /water advancing and receding contact angles of respectively 13◦–39◦ and 6◦–23◦ . It was found that the contact angles decrease with increasing channel widths. The receding contact angle measured in the 50 μm channel agrees well with the results presented in the literature by conducting a core-flood test for a sandstone rock. Furthermore the N2 /water and CO2 /water systems showed similar characteristics as the H2 /water system. In addition to the important characterization of the dynamic wettability the results are also crucially important for accurate construction of pore-scale simulators.

In recent years with the development of hydrogen energy economy there is an increasing demand for hydrogen in the market and hydrogen production through biomass will provide an important way to supply clean environmentally friendly and highly efficient hydrogen. In this study cow dung was selected as the biomass source and the efficiency of the biomass to hydrogen reaction was explored by coupling high temperature pyrolysis and water vapor gasification. The experimental conditions of gasification temperature water mass fraction heating rate and feed temperature were systematically studied and optimized to determine the optimal conditions for in situ hydrogen production by gasification of cow dung. The relationship of each factor to the yield of hydrogen production by gasification of cow dung semi-coke was investigated in order to elucidate the mechanism of the hydrogen production. The experiment determined the optimal operating parameters of in situ gasification: gasification temperature 1173 K water mass fraction 80% heating rate 10 K/min and feed temperature 673 K. The semi-coke treatment separated high temperature pyrolysis and water vapor gasification and reduced the influence on gasification of volatile substances such as tar extracted from pyrolysis. The increase of semi-coke preparation temperature increases the content of coke reduces the volatile matter and improves the yield of hydrogen; the small size of semi-coke particles and large specific surface area are beneficial to the gasification reaction.

Liquid hydrogen (LH2) has the potential to form part of the UK energy strategy in the future and therefore could see widespread use due to the relatively high energy density when compared to other renewable energy sources. To study the feasibility of this the European Fuel Cells and Hydrogen Joint Undertaking (FCH JU) funded project PRESLHY undertook pre-normative research for the safe use of cryogenic LH2 in non-industrial settings. Several key scenarios were identified as knowledge gaps and both theoretical and experimental studies were conducted to provide insight into these scenarios. This included experiments studying the effect of congestion on an ignited hydrogen plume that develops from a release of LH2; this paper describes the objectives experimental setup and a summary of the results from these activities. Characterisation of the LH2 release hydrogen concentration and temperatures measurements within the resulting gas cloud was undertaken along with pressure measurements both within the cloud and further afield. Various release conditions and congestion levels were studied. Results showed that at high levels of congestion increased overpressures occurred with the higher flow rates studied including one high order event. Data generated from these experiments is being taken forward to generate and validate theoretical models ultimately to contribute to the development of regulations codes and standards (RCS) for LH2."

This paper proposes a method for improving hydrogen generation using pulse current in a proton exchange membrane-type electrolyzer (PEMEL). Traditional methods of electrolysis using direct current are known as the simplest approach to produce hydrogen. However it is highly dependent on environmental variables such as the temperature and catalyst used to enhance the rate of electrolysis. Therefore we propose electrolysis using a pulse current that can apply several dependent variables rather than environmental variables. The proposed method overcomes the difficulties in selecting the frequency of the pulse current by deriving factors affecting hydrogen generation while changing the concentration generated by the cell interface during the pulsed water-electrolysis process. The correlation between the electrolyzer load and the frequency characteristics was analyzed and the limit value of the applicable frequency of the pulse current was derived through electrical modeling. In addition the operating characteristics of PEMEL could be predicted and the PEMEL using the proposed pulse current was verified through experiments.

Due to practical computational resource limits current simulations of premixed turbulent combustion experiments are often performed using simplified turbulence treatment. From all available RANS models k-ε and k-ω SST are the most widely used. k-ω SST model is generally expected to be more accurate in bounded geometries since it corresponds to k-ε model further from the walls but switches to more appropriate k-ω model near the walls. However k-ε is still widely used and in some instances is shown to provide better results. In this paper we perform RANS simulations of premixed hydrogen flame propagation in an acceleration tube using k-ε and k-ω SST models. Accuracy of the models is assessed by comparing obtained results with the experiment. In order to better understand differences between k-ε and k-ω-SST results parameters of main k-ω-SST model features are examined. The distribution of the blending functions values and corresponding zones of are analysed in relation to flame position and resulting observed propagation velocity. We show that in the simulated case biggest difference between k-ω-SST and k-ε model results can be attributed to turbulent eddy viscosity limiting by shear strain rate in the k-ω-SST model.

By considering the weight penalty of batteries on payload and total vehicle weight this paper shows that almost all forms of land-based transport may be served by battery electric vehicles (BEV) with acceptable cost and driving range. Only long-distance road freight is unsuitable for battery electrification. The paper models the future Indian electricity grid supplied entirely by low-carbon forms of generation to quantify the additional solar PV power required to supply energy for transport. Hydrogen produced by water electrolysis for use as a fuel for road freight provides an inter-seasonal energy store that accommodates variations in renewable energy supply. The advantages and disadvantages are considered of midday electric vehicle charging vs. overnight charging considering the temporal variations in supply of renewable energy and demand for transport services. There appears to be little to choose between these two options in terms of total system costs. The result is an energy scenario for decarbonized surface transport in India based on renewable energy that is possible realistically achievable and affordable in a time frame of year 2050.

To accelerate clean energy transition China has explored the potential of hydrogen as an energy carrier since 2001. Until 2020 49 national hydrogen policies were enacted. This paper explores the relevance of these policies to the development of the hydrogen industry and energy transition in China. We examine the reasons impacts and challenges of Chinese national hydrogen policies through the conceptual framework of Thomas Dye’s policy analysis method and the European Training Foundation’s policy analysis guide. This research provides an ex‐post analysis for previous policies and an ex‐ante analysis for future options. We argue that the energy supply revolution and energy technology revolution highlight the importance of hydrogen development in China. Particularly the pressure of the automobile industry transition leads to experimentation concerning the application of hydrogen in the transportation sector. This paper also reveals that hydro‐ gen policy development coincides with an increase in resource input and has positive spill over effects. Furthermore we note that two challenges have impeded progress: a lack of regulations for the industry threshold and holistic planning. To address these challenges the Chinese government can design a national hydrogen roadmap and work closely with other countries through the Belt and Road Initiative.

The IEA produced this dataset as part of efforts to track advances in low-carbon hydrogen technology. It covers all projects commissioned worldwide since 2000 to produce hydrogen for energy or climate-change-mitigation purposes. It includes projects which their objective is either to reduce emissions associated with producing hydrogen for existing applications or to use hydrogen as an energy carrier or industrial feedstock in new applications that have the potential to be a low-carbon technology. Projects in planning or construction are also covered.

Link to Download Database from IEA Website

Policymakers and global energy models are increasingly looking towards hydrogen as an enabling energy carrier to decarbonize hard-to-abate sectors (projecting growth in hydrogen consumption in the magnitude of hundreds of megatons). Combining scenarios from global energy models and life cycle impacts of different hydrogen production technologies the results of this work show that the life cycle emissions from proposed configurations of the hydrogen economy would lead to climate overshoot of at least 5.4–8.1x of the defined “safe” space for greenhouse gas emissions by 2050 and the cumulative consumption of 8–12% of the remaining carbon budget. This work suggests a need for a science-based definition of “clean” hydrogen agnostic of technology and compatible with a “safe” development of the hydrogen economy. Such a definition would deem blue hydrogen environmentally unviable by 2025–2035. The prolific use of green hydrogen is also problematic however due to the requirement of a significant amount of renewable energy and the associated embedded energy land and material impacts. These results suggest that demand-side solutions should be further considered as the large-scale transition to hydrogen which represents a “clean” energy shift may still not be sufficient to lead humanity into a “safe” space.

Currently a progressively different approach to the generation of power and the production of fuels for the automotive sector as well as for domestic applications is being taken. As a result research on the feasibility of applying renewable energy sources to the present energy scenario has been progressively growing aiming to reduce greenhouse gas emissions. Following more than one approach the integration of renewables mainly involves the utilization of biomass-derived raw material and the combination of power generated via clean sources with conventional power generation systems. The aim of this review article is to provide a satisfactory overview of the most recent progress in the catalysis of hydrogen production through sustainable reforming and CO2 utilization. In particular attention is focused on the route that starting from bioethanol reforming for H2 production leads to the use of the produced CO2 for different purposes and by means of different catalytic processes passing through the water–gas shift stage. The newest approaches reported in the literature are reviewed showing that it is possible to successfully produce “green” and sustainable hydrogen which can represent a power storage technology and its utilization is a strategy for the integration of renewables into the power generation scenario. Moreover this hydrogen may be used for CO2 catalytic conversion to hydrocarbons thus giving CO2 added value.

More than 90% of the world’s growing energy demand is satisfied by fossil fuels (BP Statistical Review … 2015)1. One consequence of the unrestrained use of this technology is the continuous increase of the CO₂ level of the atmosphere2. There are also the challenges associated with the limitations of the corresponding resources (Hubbert 1956; BP Statistical Review … 2015). Climate change as a consequence of the growing CO₂ level (see text footnote 2 ESRL Global Monitoring Division 2015) has been identified as one of the most critical challenges facing mankind and requires immediate action: “The Paris Agreement aims to strengthen the global response to the threat of climate change ( … ) by low greenhouse gas emissions development in a manner that does not threaten food production” (United Nations Framework … 2015). How to reach the corresponding significant reduction of CO₂ emission by 2050 is not defined in this document but it implies that mankind must transform its energy technology from a fossil to a renewable basis. Numerous studies and publications have indicated that the sun’s energy and its derivatives (wind water) are by far sufficient to supply world’s energy demand (see e.g. Smalley 2005; Züttel et al. 2010); but the large daily and seasonal power variation of renewable energy is an additional complication for a wide spread replacement of fossil energy by renewable energy.

With future regulations on the horizon port authorities and ship owners/operators are looking at alternative propulsion solutions to reduce emission. Fuel cell technology provides an attractive zeroemission solution to generate electric power on board using hydrogen as a fuel. Fuel cell systems are scalable from 200kW to multi-MW providing high efficiency dispatchable clean quiet power generation. Several innovative pilot projects are on the way to demonstrate the marine application of this proven technology. Electrification of propulsion systems is advancing and fuel cell technology provides the opportunity to produce on board large quantity of power with zero-emission using hydrogen as a fuel. We will present the value proposition of having a fuel cell power generator on board of an electric vessel while discussing the safety considerations with the fuel cell module and the onboard fuel storage. We will present some of our current fuel cell marine projects and review some of the product development considerations including system architecture and safety as well as hydrogen supply and on-board fuel storage.

The year 2014 marked hydrogen fuel cell electric vehicles (FCEVs) first becoming commercially available in California where significant investments are being made to promote the adoption of alternative transportation fuels. A refueling infrastructure network that guarantees adequate coverage and expands in line with vehicle sales is required for FCEVs to be successfully adopted by private customers. In this paper we provide an overview of modelling methodologies used to project hydrogen refueling infrastructure requirements to support FCEV adoption and we describe in detail the National Renewable Energy Laboratory’s scenario evaluation and regionalization analysis (SERA) model. As an example we use SERA to explore two alternative scenarios of FCEV adoption: one in which FCEV deployment is limited to California and several major cities in the United States; and one in which FCEVs reach widespread adoption becoming a major option as passenger vehicles across the entire country. Such scenarios can provide guidance and insights for efforts required to deploy the infrastructure supporting transition toward different levels of hydrogen use as a transportation fuel for passenger vehicles in the United States.

Poland    The present paper is aimed at determining the less investigated effects of hydrogen uptake on the microstructure and the mechanical behavior of the oxidized Zircaloy-2 alloy. The specimens were oxidized and charged with hydrogen. The different oxidation temperatures and cathodic current densities were applied. The scanning electron microscopy X-ray electron diffraction spectroscopy hydrogen absorption assessment tensile and nanoindentation tests were performed. At low oxidation temperatures an appearance of numerous hydrides and cracks and a slight change of mechanical properties were noticed. At high-temperature oxidation the oxide layer prevented the hydrogen deterioration of the alloy. For nonoxidized samples charged at different current density nanoindentation tests showed that both hardness and Young’s modulus revealed the minims at specific current value and the stepwise decrease in hardness during hydrogen desorption. The obtained results are explained by the barrier effect of the oxide layer against hydrogen uptake softening due to the interaction of hydrogen and dislocations nucleated by indentation test and hardening caused by the decomposition of hydrides. The last phenomena may appear together and result in hydrogen embrittlement in forms of simultaneous hydrogen-enhanced localized plasticity and delayed hydride cracking.

A group experts from European research organisations and industry have assessed the state of the art and future needs for materials' R&D for hydrogen and fuel cell technologies. The work was performed as input to the European Commission's roadmapping exercise on materials for the European Strategic Energy Technology Plan. The report summarises the results including key targets identified for medium term (2020/2030) and long term (2050) timescales.

A proton exchange membrane fuel cell (PEMFC) is known as one of the most promising energy sources for electric vehicles. A hydrogen system is required to provide hydrogen to the stack in time to meet the flow and pressure requirements according to the power requirements. In this study a 1-D model of a hydrogen system including the fuel cell stack was established. Two modes one with and one without a proportion integration differentiation (PID) control strategy were applied to analyze the pressure characteristics and performance of the PEMFC. The results showed that the established model could be well verified with experimental data. The anode pressure fluctuation with a PID control strategy was more stable which reduced the damage to the fuel cell stack caused by sudden changes of anode pressure. In addition the performance of the stack with the PID control mode was slightly improved. There was an inflection point for hydrogen utilization; the hydrogen utilization rate was higher under the mode without PID control when the current density was greater than 0.4 A/cm2 . What is more a hierarchical control strategy was proposed which made the pressure difference between the anode and cathode meet the stack working requirements and more importantly maintained the high hydrogen utilization of the hydrogen system.

Given that conversion efficiencies of incident solar radiation to liquid fuels e.g. H2 are of the order of a few percent or less as quantified by ‘solar to hydrogen’ (STH) economically inexpensive and operationally straightforward ways to boost photo-electrochemcial (PEC) H2 production from solar-driven water splitting are important. In this work externally-applied static electric fields have led to enhanced H2 production in an energy-efficient manner with up to ~30–40% increase in H2 (bearing in mind fieldinput energy) in a prototype open-type solar cell featuring rutile/titania and hematite/iron-oxide (Fe2O3) respectively in contact with an alkaline aqueous medium (corresponding to respective relative increases of STH by ~12 and 16%). We have also performed non-equilibrium ab-initio molecular dynamics in both static electric and electromagnetic (e/m) fields for water in contact with a hematite/iron-oxide (0 0 1) surface observing enhanced break-up of water molecules by up to ~70% in the linear-response régime. We discuss the microscopic origin of such enhanced water-splitting based on experimental and simulation-based insights. In particular we external-field direction at the hematite surfaces and scrutinise properties of the adsorbed water molecules and OH– and H3O+ species e.g. hydrogen bonds between water-protons and the hematite surfaces’ bridging oxygen atoms as well as interactions between oxygen atoms in adsorbed water molecules and underlying iron atoms.

The authors have proposed a new combustion process called the Plume Ignition Combustion Concept (PCC) in which with an optimal combination of hydrogen injection timing and controlled jet geometry the plume of the hydrogen jet is spark-ignited to accomplish combustion of a rich mixture. This combustion process markedly improves thermal efficiency by reducing cooling loss which is essential for increasing thermal efficiency in a hydrogen engine while maintaining high power. In order to improve thermal efficiency and reduce NOx formation further PCC was applied to a lean-burn regime to burn a leaner mixture globally. In this study the effect of supercharging which was applied to recover the reduced output power due to the leaner mixture on improving thermal efficiency was confirmed along with clarifying the cause.

The aim of this study is to assess numerically the influence of terrain landscape on the distribution of probable harmful consequences to personnel of hydrogen fueling station caused by an accidentally released and exploded hydrogen. In order to extract damaging factors of the hydrogen explosion wave (maximum overpressure and impulse of pressure phase) a three-dimensional mathematical model of gas mixture dynamics with chemical interaction is used. It allows controlling current pressure in every local point of actual space taking into account complex terrain. This information is used locally in every computational cell to evaluate the conditional probability of such consequences on human beings as ear-drum rupture and lethal ones on the basis of probit analysis. In order to use this technique automatically during the computational process the tabular dependence ""probit-functionimpact probability"" is replaced by a piecewise cubic spline. To evaluate the influence of the landscape profile on the non-stationary three-dimensional overpressure distribution above the earth surface near an epicenter of accidental hydrogen explosion a series of computational experiments with different variants of the terrain is carried out. Each variant differs in the level of mutual arrangement of the explosion epicenter and the places of possible location of personnel. Two control points with different distances from the explosion epicenter are considered. Diagrams of lethal and ear-drum rupture conditional probabilities are build to compare different variants of landscape profile. It is found that the increase or decrease in the level of the location of the control points relative to the level of the epicenter of the explosion significantly changes the scale of the consequences in the actual zone around the working places and should be taken into account by the risk managing experts at the stage of deciding on the level of safety at hydrogen fueling stations.

Decarbonization in several countries is now linked to the prospect of implementing a national hydrogen economy. In countries with extensive natural gas infrastructure hydrogen may provide a real opportunity to decarbonize space heating. While this approach may prove technically and economically feasible in the longterm it is unclear whether consumers will be willing to adopt hydrogen-fueled appliances for heating and cooking should techno-economic feasibility be achieved. In response this paper develops an analytical framework for examining hydrogen acceptance which links together socio-technical barriers and social acceptance factors. Applying this framework the study synthesizes the existing knowledge on public perceptions of hydrogen and identifies critical knowledge gaps which should be addressed to support domestic hydrogen acceptance. The paper demonstrates that a future research agenda should account for the interactions between acceptance factors at the attitudinal socio-political market community and behavioral level. The analysis concludes that hydrogen is yet to permeate the public consciousness due to a lack of knowledge and awareness owing to an absence of information dissemination. In response consumer engagement in energy markets and stronger public trust in key stakeholders will help support social acceptance as the hydrogen transition unfolds. Affordability may prove the most critical barrier to the large-scale adoption of hydrogen homes while the disruptive impacts of the switchover and distributional injustice represent key concerns. As a starting point the promise of economic environmental and community benefits must be communicated and fulfilled to endorse the value of hydrogen homes.

Supercritical water gasification is a promising technology for wet biomass utilization. In this paper Ni and other metal catalysts were synthesized by wet impregnation. The stability and catalytic activities of Ni catalysts were evaluated. Firstly catalytic activities of Ni Fe Cu catalysts supported on MgO were tested using wheat straw as raw material in a batch reactor at 723 K and water density of 0.07 cm³/g. Experimental results showed that the order of metal catalyst activity for hydrogen generation was Ni/MgO > Fe/MgO > Cu/MgO. Secondly the influence of different supports on Ni catalysts performance was investigated. The results showed that the order of the Ni catalysts’ activity with different supports was Ni/MgO > Ni/ZnO > Ni/Al2O3 > Ni/ZrO2. Finally the effects of Ni loading and the amount of Ni catalyst addition on hydrogen production and the stability of Ni/MgO catalyst were studied. It was found that serious deactivation of Ni catalyst in the process of supercritical water gasification took place. Even if carbon deposited on the catalyst surface was removed by high temperature calcination and the catalyst was reduced with hydrogen the activity of used catalyst was only partially restored.