Publications

Renewable power-to-hydrogen (P2H) technology is one of the most promising solutions for fulfilling the increasing global demand for hydrogen and to buffer large-scale fluctuating renewable energies. The high-power high-current ac/dc converter plays a crucial role in P2H facilities transforming medium-voltage (MV) ac power to a large dc current to supply hydrogen electrolyzers. This work introduces the general requirements and overviews several power converter topologies for P2H systems. The performances of different topologies are evaluated and compared from multiple perspectives. Moreover the future trend of eliminating the line frequency transformer (LFT) is discussed. This work can provide guidance for future designing and implementing of power-electronics-based P2H systems.

A better understanding of chemical kinetics under volumetric expansion is important for a number of situations relevant to industrial safety including detonation diffraction and direct initiation reflected shock-ignition at obstacles ignition behind a decaying shock among others. The ignition of stoichiometric hydrogen-air mixtures was studied using 0D numerical simulations with time-dependent specific volume variations. The competition between chemical energy release and expansion-induced cooling was characterized for different cooling rates and mathematical forms describing the shock decay rate. The critical conditions for reaction quenching were systematically determined and the thermo-chemistry dynamics were analyzed near the critical conditions.

In the present work methane carbon monoxide hydrogen and the binary mixtures 20 % CH4–80 % H2 80 % CH4–20 % H2 25 % CO–75 % H2 (by volume) were considered as fuels of a naturally aspirated port-fuel injection four-cylinder Volkswagen 1.4 L spark-ignition (SI) engine. The interest in these fuels lies in the fact that they can be obtained from renewable resources such as the fermentation or gasification of residual biomasses as well as the electrolysis of water with electricity of renewable origin in the case of hydrogen. In addition they can be used upon relatively easy modifications of the engines including the retrofitting of existing internal combustion engines. It has been found that the engine gives similar performance regardless the gaseous fuel nature if the air–fuel equivalence ratio (λ) is the same. Maximum brake torque and mean effective pressure values within 45–89 N⋅m and 4.0–8.0 bar respectively have been obtained at values of λ between 1 and 2 at full load engine speed of 2000 rpm and optimum spark-advance. In contrast the nature of the gaseous fuel had great influence upon the range of λ values at which a fuel (either pure or blend) could be used. Methane and methane-rich mixtures with hydrogen or carbon monoxide allowed operating the engine at close to stoichiometric conditions (i.e. 1 < λ < 1.5) yielding the highest brake torque and mean effective pressure values. On the contrary hydrogen and hydrogen-rich mixtures with methane or carbon monoxide could be employed only in the very fuel-lean region (i.e. 1.5 < λ < 2). The behavior of carbon monoxide was intermediate between that of methane and hydrogen. The present study extends and complements previous works in which the aforementioned fuels were compared only under stoichiometric conditions in air (λ = 1). In addition a simple zero-dimensional thermodynamic combustion model has been developed that allows describing qualitatively the trends set by the several fuels. Although the model is useful to understand the influence of the fuels properties on the engine performance its predictive capability is limited by the simplifications made.

Magnesium hydride (MgH₂) is a potential material for solid-state hydrogen storage. However the thermodynamic and kinetic properties are far from practical application in the current stage. In this work two-dimensional vanadium carbide (V₂C) MXene with layer thickness of 50−100 nm was fist synthesized by selectively HF-etching the Al layers from V₂AlC MAX phase and then introduced into MgH2 to improve the hydrogen sorption performances of MgH2. The onset hydrogen desorption temperature of MgH₂ with V2C addition is significantly reduced from 318 °C for pure MgH2 to 190 °C with a 128 °C reduction of the onset temperature. The MgH₂+ 10 wt% V₂C composite can release 6.4 wt% of H₂ within 10 min at 300 °C and does not loss any capacity for up to 10 cycles. The activation energy for the hydrogen desorption reaction of MgH₂ with V₂C addition was calculated to be 112 kJ mol−1 H₂ by Arrhenius's equation and 87.6 kJ mol−1 H₂ by Kissinger's equation. The hydrogen desorption reaction enthalpy of MgH₂ + 10 wt% V₂C was estimated by van't Hoff equation to be 73.6 kJ mol−1 H₂ which is slightly lower than that of the pure MgH₂ (77.9 kJ mol−1 H₂). Microstructure studies by XPS TEM and SEM showed that V₂C acts as an efficient catalyst for the hydrogen desorption reaction of MgH₂. The first-principles density functional theory (DFT) calculations demonstrated that the bond length of Mg−H can be reduced from 1.71 Å for pure MgH₂ to 2.14 Å for MgH₂ with V₂C addition which contributes to the destabilization of MgH₂. This work provides a method to significantly and simultaneously tailor the hydrogen sorption thermodynamics and kinetics of MgH₂ by two-dimensional MXene materials.

In response to the global climate emergency governments across the world are aiming to lower greenhouse gas emissions to slow the damaging effects of climate change.<br/>The Scottish Government has set a target of net zero emissions by 2045. Already a global leader in renewable energy and low-carbon technology deployment Scotland’s energy landscape is set to undergo more change as it moves toward becoming carbon-neutral. Key to that change will be the transition from natural gas to zero-carbon gases like hydrogen and biomethane.<br/>Scotland’s north-east and central belt are home to some of its largest industrial carbon emitters. The sector’s reliance on natural gas means that it emits 11.9Mt of CO2 emissions per year says NECCUS: the equivalent of 2.6 million cars or roughly all the cars in Scotland. Most homes and businesses across Scotland also use natural gas for heating.<br/>Our North-East Network and Industrial Cluster project is laying the foundations for the rapid decarbonisation of this high-emitting sector. We’ve published a report outlining the practical steps needed to rapidly decarbonise a significant part of Scotland’s homes and industry. It demonstrates how hydrogen can play a leading role in delivering the Scottish Government’s target of one million homes with low carbon heat by 2030.<br/>The research published with global consulting and engineering advisor Wood sets out a transformational and accelerated pathway to 100% hydrogen for Scotland’s gas networks which you can see on the map below. It also details the feasibility of a CO2 collection network to securely capture transport and store carbon dioxide emissions deep underground.

Hydrogen consumption and mileage are important economic indicators of fuel cell vehicles. Hydrogen consumption is the fundamental reason that restricts mileage. Since there are few quantitative studies on hydrogen consumption during actual vehicle operation the high cost of hydrogen consumption in outdoor testing makes it impossible to guarantee the accuracy of the test. Therefore this study puts forward a test method based on the hydrogen consumption of fuel cell vehicles under CLTC-P operating conditions to test the hydrogen consumption of fuel cell vehicles per 100 km. Finally the experiment shows that the mileage calculated by hydrogen consumption has a higher consistency with the actual mileage. Based on this hydrogen consumption test method the hydrogen consumption can be accurately measured and the test time and cost can be effectively reduced.

The electric power industry sector has become increasingly aware of how counterproductive voltage sag affects distribution network systems (DNS). The voltage sag backfires disastrously at the demand load side and affects equipment in DNS. To settle the voltage sag issue this paper achieved its primary purpose to mitigate the voltage sag based on integrating a hydrogen fuel cell (HFC) with the DNS using a distribution static synchronous compensator (D-STATCOM) system. Besides this paper discusses the challenges and opportunities of D-STATCOM in DNS. In this paper using HFC is well-designed modeled and simulated to mitigate the voltage sag in DNS with a positive impact on the environment and an immediate response to the issue of the injection of voltage. Furthermore this modeling and controller are particularly suitable in terms of cost-effectiveness as well as reliability based on the adaptive network fuzzy inference system (ANFIS) fuzzy logic system (FLC) and proportional–integral (P-I). The effectiveness of the MATLAB simulation is confirmed by implementing the system and carrying out a DNS connection obtaining efficiencies over 94.5% at three-phase fault for values of injection voltage in HFC D-STATCOM using a P-I controller. Moreover the HFC D-STATCOM using FLC proved capable of supporting the network by 97.00%. The HFC D-STATCOM based ANFIS proved capable of supporting the network by 98.00% in the DNS.

In order to study the effect of halogen bond on tautomerism in β-diketones in the solid-state we have prepared a series of cocrystals derived from an asymmetric β-diketone benzoyl-4-pyridoylmethane (b4pm) as halogen bond acceptor and perfluorinated iodobenzenes: iodopentaflourobenzene (ipfb) 12- 13- and 14-diiodotetraflorobenzene (12tfib 13tfib and 14tfib) and 135-triiodo-246-trifluorobenzene (135titfb). All five cocrystals are assembled by I···N halogen bonds involving pyridyl nitrogen and iodoperfluorobenzene iodine resulting in 1:1 (four compounds) or 1:2 (one compound) cocrystal stoichiometry. Tautomer of b4pm in which hydrogen atom is adjacent to the pyridyl fragment was found to be more stable in vacuo than tautomer with a benzoyl hydroxyl group. This tautomer is also found to be dominant in the majority of crystal structures somewhat more abundantly in crystal structures of cocrystals in which additional I···O halogen bond with the benzoyl oxygen has been established. Attempts have also been made to prepare an equivalent series of cocrystals using a closely related asymmetric β-diketone benzoyl-3-pyridoylmethane (b3pm); however all attempts were unsuccessful which is attributed to more effective crystal packing of b3pm isomer compared to b4pm which reduced the probability of cocrystal formation.

Global climate change concerns have pushed international governmental actions to reduce greenhouse gas emissions by adopting cleaner technologies hoping to transition to a more sustainable society. The hydrogen economy is one potential long-term option for enabling deep decarbonization for the future energy landscape. Progress towards an operating hydrogen economy is discouragingly slow despite global efforts to accelerate it. There are major mismatches between the present situation surrounding the hydrogen economy and previous proposed milestones that are far from being reached. The overall aim of this study is to understand whether there has been significant real progress in the achievement of a hydrogen economy or whether the current interest is overly exaggerated (hype). This study uses bibliometric analysis and content analysis to historically map the hydrogen economy’s development from 1972 to 2020 by quantifying and analyzing three sets of interconnected data. Findings indicate that interest in the hydrogen economy has significantly progressed over the past five decades based on the growing numbers of academic publications media coverage and projects. However various endogenous and exogenous factors have influenced the development of the hydrogen economy and created hype at different points in time. The consolidated results explore the changing trends and how specific events or actors have influenced the development of the hydrogen economy with their agendas the emergence of hype cycles and the expectations of a future hydrogen economy.

The commercialization of eco-friendly hydrogen vehicles has elicited attempts to expand hydrogen refueling stations in urban areas; however safety measures to reduce the risk of jet fires have not been established. The RISKCURVES software was used to evaluate the individual and societal risks of hydrogen refueling stations in urban areas and the F–N (Frequency–Number of fatalities) curve was used to compare whether the safety measures satisfied international standards. From the results of the analysis it was found that there is a risk of explosion in the expansion of hydrogen refueling stations in urban areas and safety measures should be considered. To lower the risk of hydrogen refueling stations this study applied the passive and active independent protection layers (IPLs) of LOPA (Layer of Protection Analysis) and confirmed that these measures significantly reduced societal risk as well as individual risk and met international standards. In particular such measures could effectively reduce the impact of jet fire in dispensers and tube trailers that had a high risk. Measures employing both IPL types were efficient in meeting international standard criteria; however passive IPLs were found to have a greater risk reduction effect than active IPLs. The combination of RISKCURVES and LOPA is an appropriate risk assessment method that can reduce work time and mitigate risks through protective measures compared to existing risk assessment methods. This method can be applied to risk assessment and risk mitigation not only for hydrogen facilities but also for hazardous materials with high fire or explosion risk.