Institution of Gas Engineers & Managers

The combustion emissions of the hydrogen-fueled engines are very clean but the problems of abnormal combustion and high NOx emissions limit their applications. Nowadays hydrogen engines use exhaust gas recirculation (EGR) technology to control the intensity of premixed combustion and reduce the NOx emissions. This study aims at improving the abnormal combustion and decreasing the NOx emissions of the hydrogen engine by applying a three-dimensional (3D) computational fluid dynamics (CFD) model of a single-cylinder hydrogen-fueled engine equipped with an EGR system. The results indicated that peak in-cylinder pressure continuously increased with the increase of the ignition advance angle and was closer to the top dead center (TDC). In addition the mixture was burned violently near the theoretical air–fuel ratio and the combustion duration was shortened. Moreover the NOx emissions the average pressure and the in-cylinder temperature decreased as the EGR ratio increased. Furthermore increasing the EGR ratio led to an increase in the combustion duration and a decrease in the peak heat release rate. EGR system could delay the spontaneous combustion reaction of the end-gas and reduce the probability of knocking. The pressure rise rate was controlled and the in-cylinder hot spots were reduced by the EGR system which could suppress the occurrence of the pre-ignition in the hydrogen engine.

Liquid hydrogen may have an important role in the storage and transportation of hydrogen energy. It may also provide the best option for some users of hydrogen energy notably the aviation sector. In the 1960’s liquid hydrogen spillages in open uncongested conditions sometimes produced violent condensed phase explosions as well as the familiar gas phase flash and sustained pool fire. Testing showed that burning mixtures of LH2 and solid oxygen/nitrogen readily transitioned to detonation for oxygen concentrations in the solid phase at or above 50%. Such explosive events have been observed in more recent research work on LH2 spillage and the pressure effects could be significant in some accident scenarios. There is a need to understand how solids are produced following spillage and what factors determine the level of oxygen enrichment. This paper describes the physical processes involved in the accumulation of solids during a horizontal discharge at ground level based on observations made in a recent HSE test that led to a condensed phase explosion. Areas where solids accumulated but remained in intimate contact with LH2 are identified. The paper also includes a thermodynamic and fluid mechanical analysis of the condensation process that includes the calculation of densities of mixtures of LH2 and air in different proportions. When the difference in flow speed between air and underlying LH2 is low a stable condensation layer can develop above the liquid where the temperature is just under the initial condensation point of air allowing sustained oxygen enrichment of condensate.

Hydrogen is the ultimate vector for a carbon-free sustainable green-energy. While being the most promising candidate to serve this purpose hydrogen inherits a series of characteristics making it particularly difficult to handle store transport and use in a safe manner. The researchers’ attention has thus shifted to storing hydrogen in its more manageable forms: the light metal hydrides and related derivatives (ammonia-borane tetrahydridoborates/borohydrides tetrahydridoaluminates/alanates or reactive hydride composites). Even then the thermodynamic and kinetic behavior faces either too high energy barriers or sluggish kinetics (or both) and an efficient tool to overcome these issues is through nanoconfinement. Nanoconfined energy storage materials are the current state-of-the-art approach regarding hydrogen storage field and the current review aims to summarize the most recent progress in this intriguing field. The latest reviews concerning H2 production and storage are discussed and the shift from bulk to nanomaterials is described in the context of physical and chemical aspects of nanoconfinement effects in the obtained nanocomposites. The types of hosts used for hydrogen materials are divided in classes of substances the mean of hydride inclusion in said hosts and the classes of hydrogen storage materials are presented with their most recent trends and future prospects.

On this episode of Everything About Hydrogen Jan Klawitter Head of International Policy for Anglo American speaks with Andrew Chris and Patrick about Anglo American's strategy for decarbonizing its mining operations and how they plan to use hydrogen and fuel cell technologies as a key part of their approach.

The podcast can be found on their website

In this work a model of an energy system based on photovoltaics as the main energy source and a hybrid energy storage consisting of a short‐term lithium‐ion battery and hydrogen as the long‐term storage facility is presented. The electrical and the heat energy circuits and resulting flows have been modelled. Therefore the waste heat produced by the electrolyser and the fuel cell have been considered and a heat pump was considered to cover the residual heat demand. The model is designed for the analysis of a whole year energy flow by using a time series of loads weather and heat profile as input. This paper provides the main set of equations to derive the component properties and describes the implementation into MATLAB/Simulink. The novel model was created for an energy flow simulation over one year. The results of the simulation have been verified by comparing them with well‐established simulation results from HOMER Energy. It turns out that the novel model is well suited for the analysis of the dynamic system behaviour. Moreover different characteristics to achieve an energy balance an ideal dimensioning for the particular use case and further research possibilities of hydrogen use in the residential sector are covered by the novel model.

The effect of carbon monoxide (CO) on the performance of polymer electrolyte fuel cells (PEFCs) with either a hydrogen circulation system or a hydrogen one-way pass system is investigated and compared. The voltage drop induced by adding 0.2 ppm of CO to the PEFC with the hydrogen circulation system was less than one-tenth of that observed in the PEFC with the hydrogen one-way pass system at 1000 mA cm–2 and a cell temperature of 60 °C. Gas analysis results showed that CO concentration in the hydrogen circulation system was lower than the initially supplied CO concentration. In the hydrogen circulation system permeated oxygen from the cathode should enhance CO oxidation. This should lead to decrease the CO concentration and mitigate the voltage drop in the hydrogen circulation system.

Among numerous techniques for the hydrogen production without harmful emissions especially avoiding the carbon dioxide emissions hydrogen technologies driven by geothermal energy represent an attractive solution. This paper is interested in the process by which the electricity generated from geothermal power plant that is operated using CO2 as heat transmission fluid is exploited for hydrogen production through water electrolysis. A numerical simulation is used to evaluate the potential for hydrogen production and to estimate the levelized cost of electrolytic hydrogen. We also present brief analysis of environmental issues including the carbon tax. The results show that the process has a good potential for geothermal hydrogen production is capable of producing about 22 kg/h of electrolytic hydrogen for the geothermal source of carbon dioxide mass flow rate of 40 kg/s and a temperature of 296 K. In economic regard the electric energy system costs are the major component of the total hydrogen production cost (more than 90%). The estimated cost of hydrogen is 8.24 $/kg H2. By including the carbon tax the cost of hydrogen production becomes far more competitive.

HyPoint led by its CEO and co-founder Alex Ivanenko is at the cutting edge of the industry's efforts to find zero-emissions aircraft propulsion systems that do not sacrifice speed and power in the name of sustainability. HyPoint is a leading producer of high-temperature PEM fuel cells for aviation applications including for logistic drones air taxis electric vertical takeoff and landing vehicles (eVTOLs) and fixed-wing airplanes. On this episode of the EAH podcast the team speaks with Alex about the incredible pace of development and rapid innovation that he and his colleagues are driving in the hydrogen aviation space and how his company is leading the way in a highly complex and competitive race to decarbonize modern air travel.

The podcast can be found on their website

The thermochemical conversion of methane (CH4) and water (H2O) to syngas and hydrogen via chemical looping using concentrated sunlight as a sustainable source of process heat attracts considerable attention. It is likewise a means of storing intermittent solar energy into chemical fuels. In this study solar chemical looping reforming of CH4 and H2O splitting over non-stoichiometric ceria (CeO2/CeO2−δ) redox cycle were experimentally investigated in a volumetric solar reactor prototype. The cycle consists of (i) the endothermic partial oxidation of CH4 and the simultaneous reduction of ceria and (ii) the subsequent exothermic splitting of H2O and the simultaneous oxidation of the reduced ceria under isothermal operation at ~1000°C enabling the elimination of sensible heat losses as compared to non-isothermal thermochemical cycles. Ceria-based reticulated porous ceramics with different sintering temperatures (1000 and 1400°C) were employed as oxygen carriers and tested with different methane flow rates (0.1–0.4 NL/min) and methane concentrations (50 and 100%). The impacts of operating conditions on the foam-averaged oxygen non-stoichiometry (reduction extent δ) syngas yield methane conversion solar-to-fuel energy conversion efficiency as well as the effects of transient solar conditions were demonstrated and emphasized. As a result clean syngas was successfully produced with H2/CO ratios approaching 2 during the first reduction step while high-purity H2 was subsequently generated during the oxidation step. Increasing methane flow rate and CH4 concentration promoted syngas yields up to 8.51 mmol/gCeO2 and δ up to 0.38 at the expense of enhanced methane cracking reaction and reduced CH4 conversion. Solar-to-fuel energy conversion efficiency namely the ratio of the calorific value of produced syngas to the total energy input (solar power and calorific value of converted methane) and CH4 conversion were achieved in the range of 2.9–5.6% and 40.1–68.5% respectively.

High performing proton exchange membrane fuel cells (PEMFCs) that can operate at low relative humidity is a continuing technical challenge for PEMFC developers. In this work micro-patterned membranes are demonstrated at the cathode side by solution casting techniques using stainless steel moulds with laser-imposed periodic surface structures (LIPSS). Three types of patterns lotus lines and sharklet are investigated for their influence on the PEMFC power performance at varying humidity conditions. The experimental results show that the cathode electrolyte pattern in all cases enhances the fuel cell power performance at 100% relative humidity (RH). However only the sharklet pattern exhibits a significant improvement at 25% RH where a peak power density of 450 mW cm⁻² is recorded compared with 150 mW cm⁻² of the conventional flat membrane. The improvements are explored based on high-frequency resistance electrochemically active surface area (ECSA) and hydrogen crossover by in situ membrane electrode assembly (MEA) testing.