Publications

In this study hydrogen-storage glass microballoons were introduced into emulsion explosives to improve the detonation performance of the explosives. The effect of hydrogen-storage pressure on the detonation characteristics of emulsion explosives was systematically investigated. Detonation velocity experiments shows that the change of sensitizing gas and the increase of hydrogen pressure have different effects on the detonation velocity. The experimental parameters of underwater explosion increase first and then decreases with the increase of hydrogen pressure. The decrease of these parameters indicates that the strength of glass microballoons is the limiting factor to improve the detonation performance of hydrogen-storage emulsion explosives. Compared with the traditional emulsion explosives the maximum peak pressure of shock wave of hydrogen-storage emulsion explosives increases by 10.6% at 1.0 m and 10.2% at 1.2 m the maximum values of shock impulse increase by 5.7% at 1.0 m and 19.4% at 1.2 m. The stored hydrogen has dual effects of sensitizers and energetic additives which can improve the energy output of emulsion explosives.

The direct hydrogenation of CO₂ to dimethyl ether (DME) is a promising technology for CO₂ valorisation. In this work a 1D phenomenological reactor model is developed to evaluate and optimize the performance of a membrane reactor for this conversion otherwise limited by thermodynamic equilibrium and temperature gradients. The co-current circulation of a sweep gas stream through the permeation zone promotes both water and heat removal from the reaction zone thus increasing overall DME yield (from 44% to 64%). The membrane properties in terms of water permeability (i.e. 4·10⁻⁷ mol·Pa⁻¹m−2s⁻¹) and selectivity (i.e. 50 towards H₂ 30 towards CO₂ and CO 10 towards methanol) for optimal reactor performance have been determined considering for the first time non-ideal separation and non-isothermal operation. Thus this work sheds light into suitable membrane materials for this applications. Then the non-isothermal performance of the membrane reactor was analysed as a function of the process parameters (i.e. the sweep gas to feed flow ratio the gradient of total pressure across the membrane the inlet temperature to the reaction and permeation zone and the feed composition). Owing to its ability to remove 96% of the water produced in this reaction the proposed membrane reactor outperforms a conventional packed bed for the same application (i.e. with 36% and 46% improvement in CO₂ conversion and DME yield respectively). The results of this work demonstrate the potential of the membrane reactor to make the CO₂ conversion to DME a feasible process.

Hydrogen Embrittlement (HE) is a topical issue for pipelines transporting sour products. Engineers need a simple and effective approach in materials selection at design stage. In other words they must know if a material is susceptible to cracking to be able of:

• selecting the right material 
• and apply correct operational measures during the service life.

Following ASTM F2078 HE is “a permanent loss of ductility in a metal or alloy caused by hydrogen in combination with stress either externally applied or internal residual stress”. In many cases hydrogen can play a role in crack propagation as for instance in Stress Corrosion Cracking (SCC) and Corrosion Fatigue (CF). Three parameters are required to cause failure: presence of hydrogen tensile stress and material susceptibility. The two previous ones are triggering the failure while the root cause is usually material susceptibility. This is why material selection is the important step to safely manage engineering structural materials.

As an example material selection for sour service pipeline is the object of well-known standards e.g. by Nace International and EFC: they pose some limits in the sour service of steels with reference to surface hardness. These standards have shown some weak points namely:

• In the definition of sour service;
• In defining the role of crack initiation and propagation considering that in Hydrogen embrittlement stress state and stress variations are very important.

As for the second point in hydrogen generation anodic processes shall be taken into account too. For instance there is a relationship between corrosion resistance and crack susceptibility. In carbon and low alloy steels cracking will not normally occur when there is a significant corrosion rate. If a brittle layer (or a brittle spot) is present on the metal surface this one can initiate a crack.

In Norway where nearly 100% of the power is hydroelectric it is natural to consider water electrolysis as the main production method of hydrogen for zero-emission transport. In a start-up market with low demand for hydrogen one may find that small-scale WE-based hydrogen production is more cost-efficient than large-scale production because of the potential to reach a high number of operating hours at rated capacity and high overall system utilization rate. Two case studies addressing the levelized costs of hydrogen in local supply systems have been evaluated in the present work: (1) Hydrogen production at a small-scale hydroelectric power plant (with and without on-site refuelling) and (2) Small hydrogen refuelling station for trucks (with and without on-site hydrogen production). The techno-economic calculations of the two case studies show that the levelized hydrogen refuelling cost at the small-scale hydroelectric power plant (with a local station) will be 141 NOK/kg while a fleet of 5 fuel cell trucks will be able to refuel hydrogen at a cost of 58 NOK/kg at a station with on-site production or 71 NOK/kg at a station based on delivered hydrogen. The study shows that there is a relatively good business case for local water electrolysis and supply of hydrogen to captive fleets of trucks in Norway particularly if the size of the fleet is sufficiently large to justify the installation of a relatively large water electrolyzer system (economies of scale). The ideal concept would be a large fleet of heavy-duty vehicles (with a high total hydrogen demand) and a refuelling station with nearly 100% utilization of the installed hydrogen production capacity.

The assessment of appropriate operational procedures to govern the injection of a hydrogen/natural gas blend into the Keele University G3 gas distribution network was a requirement as part of the HyDeploy project. To perform this assessment a group of gas industry experts (from Cadent Northern Gas Networks and Keele University Estates Team) along with scientists and engineers from the Health & Safety Laboratory came together to form an Operational Procedures Forum. This forum came together periodically in various workshops to explore and assess the impact of hydrogen blended gas on all the relevant and current operational procedures that govern the safe transportation and utilisation of natural gas within the Keele University G3 gas distribution network.

The operational procedures assessment has led to a determination as to whether a change is or is not required for relevant operational procedures where a basis of concern existed with respect to the injection of hydrogen blended gas. The report essentially summarises the key points of the basis of concern for different operational procedures by highlighting the key points of the existing procedure and whether this procedure requires modification for the hydrogen blended gas injection trial. Any requirements to modify an existing procedure have been given in this report referencing the source as to where the detailed analysis for the change/no change recommendation has been given.

The forum took into account the associated experimental and research carried out as part of the HyDeploy project such as the assessment of gas characteristics materials impact asset survey of assets on the Keele G3 GDN and impact of hydrogen blended gas on gas detection equipment references to these studies have been given accordingly to associated impacted operational procedures.

The conclusion of the assessment is that there are some operational procedures that are unchanged some that require an increase in the frequency as to how often they are performed and some procedures which require a fundamental modification. Therefore it is necessary that an appropriate training package is built off the back of the results presented in this report and disseminated accordingly to all relevant Operatives that will be responsible for the safety operation and maintenance of the Keele G3 GDN during the hydrogen blend injection period.

Click on Supplements to see the other documents from this report

In recent years the development of energy prices in Germany has been frequently accompanied by criticism and warnings of socio-economic disruptions. Especially with respect to the electricity sector the debate on increasing energy bills was strongly correlated with the energy system transition. However whereas fossil fuels have rapidly increased in price recently renewable substitutes such as green hydrogen and synthetic fuels also enter the markets at comparatively high prices. On the other hand the present fossil fuel supply is still considered too low-priced by experts because societal greenhouse gas-induced environmental impact costs are not yet compensated. In this study we investigate the development of the price gap between conventional energy carriers and their renewable substitutes until 2050 as well as a suitable benchmark price incorporating the societal costs of specific energy carriers. The calculated benchmark prices for natural gas (6.3 ct kWh−1 ) petrol (9.9 ct kWh−1 ) and grey hydrogen from steam methane reformation (12 ct kWh−1 ) are nearly 300% above the actual prices for industry customers in 2020 but below the price peaks of early 2022. In addition the price gap between conventional fuels and green hydrogen will be completely closed before 2050 for all investigated energy carriers. Furthermore prognosed future price developments can be considered rather moderate compared to historic and especially to the recent price dynamics in real terms. A gradual implementation of green hydrogen and synthetic fuels next to increasing CO2 prices however may temporarily lead to further increasing expenses for energy but can achieve lower price levels comparable to those of 2020 in the long term.

Using hydrogen as an energy carrier requires new technological solutions for its onboard storage. The exploration of two-dimensional (2D) materials for hydrogen storage technologies has been motivated by their open structures which facilitates fast hydrogen kinetics. Herein the hydrogen storage properties of lightweight metal functionalized r57 haeckelite sheets are studied using density functional theory (DFT) calculations. H₂ molecules are adsorbed on pristine r₅₇ via physisorption. The hydrogen storage capacity of r₅₇ is improved by decorating it with alkali and alkaline-earth metals. In addition the in-plane substitution of r57 carbons with boron atoms (B@r57) both prevents the clustering of metals on the surface of 2D material and increases the hydrogen storage capacity by improving the adsorption thermodynamics of hydrogen molecules. Among the studied compounds B@r57-Li4 with its 10.0 wt% H₂ content and 0.16 eV/H₂ hydrogen binding energy is a promising candidate for hydrogen storage applications. A further investigation as based on the calculated electron localization functions atomic charges and electronic density of states confirm the electrostatic nature of interactions between the H₂ molecules and the protruding metal atoms on 2D haeckelite sheets. All in all this work contributes to a better understanding of pure carbon and B-doped haeckelites for hydrogen storage.

Electric vehicles are becoming more and more popular. One of the most promising possible solutions is one where a hybrid powertrain made up of a FC (Fuel Cell) and a battery is used. This type of vehicle offers great autonomy and high recharging speed which makes them ideal for many industrial applications. In this work three ways to build a hybrid power-train are presented and compared. To illustrate this the case of an industrial robot designed to move loads within a fully automated factory is used. The analysis and comparison are carried out through different objective criteria that indicate the power-train performance in different battery charge levels. The hybrid configurations are tested using real power profiles of the industrial robot. Finally simulation results show the performance of each hybrid configuration in terms of hydrogen consumption battery and FC degradation and dc bus voltage and current regulation.

The aim of this project was to review the current purge standards for UK domestic installations in particular IGEM/UP/1B and carry out experiments to assess the validity of those standards for use in hydrogen in order to understand and recommend safe purge practices for hydrogen in a domestic environment.

This report provides the results and conclusions relating to the relative safety of purging domestic installations to hydrogen compared to Natural Gas and the implications of releasing any purged gas

into an enclosed volume representing a small room.

The two high-level findings from this work are:

• changeover to hydrogen will result in an increased risk of flammability inside the installation pipework
• changeover to hydrogen will result in a reduced risk of a build-up of flammable gas in any room where purging occurs.

This work recognises a number of important differences between hydrogen and methane. Hydrogen is more flammable than methane in air particularly at high concentrations. Hydrogen can maintain a flame at 4% but does not support general three dimensional deflagration until about 8.5%. Above about 18% given increased obstruction within the combustion zone or passage of the flame along a pipe the deflagration can transition to detonation. The flame speed suddenly increases to ~2000m/s. It is very important to avoid this situation although the inventory in a domestic pipe is low. This risk of detonation can occur at concentrations up to 59% and the risk of deflagration remains to 75 %.Methane behaves very differently to this with a range of deflagration of about 4.8 to 16% and a detonation range only marginally narrower. Initiating detonation is however much more difficult with methane.

The risks with hydrogen are associated with a wide range of flammability with methane the risks are smaller and mainly in lower concentrations of gas in air. Because of this it is particularly important to ensure hydrogen pipes are appropriately purged.

Japan’s energy consumption derives mostly from fossil fuels which are un-secure and release a much greenhouse gas emissions. To meet goals of reducing GHG hydrogen gas can be utilized in power generation in hydrogen fired and firing / co-combustion power plants. This paper analyses the impact of hydrogen in the power generation sector using the MARKAL-TIMES Japan optimization model framework. Two models are used: a base scenario without hydrogen and hydrogen scenario in which hydrogen is supplied from 2020 onwards. In the hydrogen scenario other processes which are normally supplied by natural gas are reduced because the gas is instead used to generate power. Adding hydrogen to the energy supply leads to a decrease in projected use of fossil fuels. The hydrogen scenario produces fewer emissions than the base scenario; by 2050 the hydrogen scenario’s estimated 388 metric tons of CO2 emissions is over 250 tons less than the base scenario’s emissions of 588 metric tons.

Green hydrogen i.e. the hydrogen generated from renewable energy sources (RES) will significantly contribute to a successful energy transition. Besides to facilitate the integration and storage of RES this promising energy carrier is well capable to efficiently link various energy sectors. By introduction of green hydrogen as a new flexibility source to power systems it is necessary to investigate its possible impacts on the generation scheduling and power system security. In this paper a security-constrained multi-period optimal power flow (SC-MPOPF) model is developed aiming to determine the optimal hourly dispatch of generators as well as power to hydrogen (P2H) units in the presence of large-scale renewable energy sources (RES). The proposed model characterizes the P2H demand flexibility in the proposed SC-MPOPF model taking into account the electrolyzer behavior reactive power support of P2H demands and hydrogen storage capability. The developed SC-MPOPF model is applied to IEEE 39-bus system and the obtained numerical results demonstrate the role of P2H flexibility on cost as well as RES's power curtailment reduction.

Three techniques for determining the hydrogen permeation properties of rubber samples were developed based on the volumetric and gravimetric measurements of released H2 gas after sample decompression. These methods include gas chromatography (GC) by thermal desorption analysis (TDA) volumetric collection (VC) measurement of hydrogen by graduated cylinder and gravimetric (GM) measurement by electronic balance. By measuring the released hydrogen against elapsed time after the decompression of pressure the charging amount (C0) and diffusivity (D) were obtained with the developed diffusion analysis program. From these values the solubility (S) and permeability (P) of polymers were evaluated through the relations of Henry's law and P=SD respectively. The developed techniques were applied to three kinds of spherically shaped sealing rubber materials. D S and P were analyzed as a function of pressure. The transport behaviors obtained in the three methods are discussed and compared with the characteristics of each measuring technique. The correlations between transport parameters and carbon black filler or density are discussed.

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.

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.

Hydrogen production by electrolysis is considered an essential means of consuming renewable energy in the future. However the current assessment of the potential of renewable energy electrolysis for hydrogen production is relatively simple and the perspective is not comprehensive. Here we established a Combined Wind and Solar Electrolytic Hydrogen system considering the influence of regional wind-solar-load characteristics and transmission costs to evaluate the hydrogen production potential of 31 provincial-level regions in China in 2050. The results show that in 2050 the levelized cost of hydrogen (LCOH) in China’s provincial regions will still be higher than 10 ¥/kg which is not cost-competitive compared to the current hydrogen production from fossil fuels. It is more cost-effective to deploy wind turbines than photovoltaic in areas with similar wind and solar resources or rich in wind resources. Wind-solar differences impact LCOH equipment capacity configuration and transmission cost composition while load fluctuation significantly impacts LCOH and electricity storage configuration. In addition the sensitivity analysis of 11 technical and economic parameters showed differences in the response performance of LCOH changes to different parameters and the electrolyzer conversion efficiency had the most severe impact. The analysis of subsidy policy shows that for most regions (except Chongqing and Xizang) subsidizing the unit investment cost of wind turbines can minimize LCOH. Nevertheless from the perspective of comprehensive subsidy effect subsidy cost and hydrogen energy development it is more cost-effective to take subsidies for electrolysis equipment with the popularization of hydrogen

In the current work the combustion behavior of hydrogen-carbon monoxide-air mixtures in semiconfined geometries is investigated in a large horizontal channel facility (dimensions 9 m x 3 m x 0.6 m (L x W x H)) as a part of a joint German nuclear safety project. In the channel with evenly distributed obstacles (blockage ratio 50%) and an open to air ground face homogeneous H2-CO-air mixtures are ignited at one end. The combustion behavior of the mixture is analyzed using the signals of pressure sensors modified thermocouples and ionization probes for flame front detection that are distributed along the channel ceiling. In the experiments various fuel concentrations (cH2 + cCO = 14 to 22 Vol%) with different H2:CO ratios (75:25 50:50 and 25:75) are used and the transition regions for a significant flame acceleration to sonic speed (FA) as well as to a detonation (DDT) are investigated. The conditions for the onset of these transitions are compared with earlier experiments performed in the same facility with H2-air mixtures. The results of this work will help to allow a more realistic estimation of the pressure loads generated by the combustion of H2-CO-air mixtures in obstructed semi-confined geometries.

UK homes are primarily heated by fossil fuels and contribute 13% of UK’s carbon footprint (equivalent to all the UK’s 38.4m cars). The report says this is incompatible with UK climate legislation targeting net-zero economy by 2050. New polling finds that consumers are open to cleaner greener ways to heat their homes into the future but that they are “still in the dark about smarter greener heating solutions and lack access to independent advice to help them make better decisions for their homes pockets and the planet”.<br/><br/>The report – Uncomfortable Home Truths: why Britain urgently needs a low carbon heat strategy – says a bold new national roadmap is needed by 2020 which puts consumers and households at the heart of a revolution in green heat innovation. It recommends the creation of an Olympic-style delivery body to catalyse and coordinate regional innovation and local leadership tailored to different parts of the UK and the nation’s diverse housing stock.<br/><br/>This report is the third in the Future Gas Series which has explored the opportunities and challenges associated with using low carbon gas in the energy system and is backed by cross-party parliamentary co-Chairs

We demonstrate a new approach for producing highly dispersed supported metal phosphide powders with small particle size improved stability and increased electrocatalytic activity towards some useful reactions. The approach involves a one-step conversion of metal supported on high surface area carbon to the metal phosphide utilising a very simple and scalable synthetic process. We use this approach to produce PdP₂ and Pd₅P₂ particles dispersed on carbon with a particle size of 4.5–5.5 nm by converting a commercially available Pd/C powder. The metal phosphide catalysts were tested for the oxygen reduction hydrogen oxidation and evolution and formic acid oxidation reactions. Compared to the unconverted Pd/C material we find that alloying the P at different levels shifts oxide formation on the Pd to higher potentials leading to greater stability during cycling studies (20% more ECSA retained 5k cycles) and in thermal treatment under air. Hydrogen absorption within the PdP₂ and Pd₅P₂ particles is enhanced. The phosphides compare favourably to the most active catalysts reported to date for formic acid oxidation especially PdP₂ and there is a significant decrease in poisoning of the surface compared to Pd alone. The mechanistic changes in the reactions studied are rationalised in terms of increased water activation on the surface phosphorus atoms of the catalyst. One of the catalysts PdP₂/C is tested in a fuel cell as anode and cathode catalyst and shows good performance.

This study analyzes future synergies between the Oil and Gas (O&G) and renewables sectors in a Danish context and explores how exploiting these synergies could lead to economic and environmental benefits. We review and highlight relevant technologies and related projects and synthesize the state of the art in offshore energy system integration. All of these preliminary results serve as input data for a holistic energy system analysis in the Balmorel modeling framework. With a timeframe out to 2050 and model scope including all North Sea neighbouring countries this analysis explores a total of nine future scenarios for the North Sea energy system. The main results include an immediate electrification of all operational Danish platforms by linking them to the shore and/or a planned Danish energy island. These measures result in cost and CO2 emissions savings compared to a BAU scenario of 72% and 85% respectively. When these platforms cease production this is followed by the repurposing of the platforms into hydrogen generators with up to 3.6 GW of electrolysers and the development of up to 5.8 GW of floating wind. The generated hydrogen is assumed to power the future transport sector and is delivered to shore in existing and/or new purpose-built pipelines. The contribution of the O&G sector to this hydrogen production amounts to around 19 TWh which represents about 2% of total European hydrogen demand for transport in 2050. The levelized costs (LCOE) of producing this hydrogen in 2050 are around 4 €2020/kg H2 which is around twice those expected in similar studies. But this does not account for energy policies that may incentivize green hydrogen production in the future which would serve to reduce this LCOE to a level that is more competitive with other sources.

The unbridled use of fossil fuels is a serious problem that has become increasingly evident over the years. As such fuels contribute considerably to environmental pollution there is a need to find new sustainable sources of energy with low emissions of greenhouse gases. Climate change poses a substantial challenge for the scientific community. Thus the use of renewable energy through technologies that offer maximum efficiency with minimal pollution and carbon emissions has become a major goal. Technology related to the use of hydrogen as a fuel is one of the most promising solutions for future systems of clean energy. The aim of the present review was to provide an overview of elements related to the potential use of hydrogen as an alternative energy source considering its specific chemical and physical characteristics as well as prospects for an increase in the participation of hydrogen fuel in the world energy matrix.

In this paper the composition function and structure of the catalyst layer (CL) of a proton exchange membrane fuel cell (PEMFC) are summarized. The hydrogen reduction reaction (HOR) and oxygen reduction reaction (ORR) processes and their mechanisms and the main interfaces of CL (PEM|CL and CL|MPL) are described briefly. The process of mass transfer (hydrogen oxygen and water) proton and electron transfer in MEA are described in detail including their influencing factors. The failure mechanism of CL (Pt particles CL crack CL flooding etc.) and the degradation mechanism of the main components in CL are studied. On the basis of the existing problems a structure optimization strategy for a high‐performance CL is proposed. The commonly used preparation processes of CL are introduced. Based on the classical drying theory the drying process of a wet CL is explained. Finally the research direction and future challenges of CL are pointed out hoping to provide a new perspective for the design and selection of CL materials and preparation equipment.

Non-energy use of natural gas is gaining importance. Gas used for 183 million tons annual ammonia production represents 4% of total global gas supply. 1.5-degree pathways estimate an ammonia demand growth of 3–4-fold until 2050 as new markets in hydrogen transport shipping and power generation emerge. Ammonia production from hydrogen produced via water electrolysis with renewable power (green ammonia) and from natural gas with CO2 storage (blue ammonia) is gaining attention due to the potential role of ammonia in decarbonizing energy value chains and aiding nations in achieving their net-zero targets. This study assesses the technical and economic viability of different routes of ammonia production with an emphasis on a systems level perspective and related process integration. Additional cost reductions may be driven by optimum sizing of renewable power capacity reducing losses in the value chain technology learning and scale-up reducing risk and a lower cost of capital. Developing certification and standards will be necessary to ascertain the extent of greenhouse gas emissions throughout the supply chain as well as improving the enabling conditions including innovative finance and de-risking for facilitating international trade market creation and large-scale project development.

Numerical experiments are performed to understand different regimes of hydrogen non-premixed combustion in an enclosure with passive ventilation through one horizontal or vertical vent located at the top of a wall. The Reynolds averaged Navier–Stokes (RANS) computational fluid dynamics (CFD) model with a reduced chemical reaction mechanism is described in detail. The model is based on the renormalization group (RNG) k-ε turbulence model the eddy dissipation concept (EDC) model for simulation of combustion coupled with the 18-step reduced chemical mechanism (8 species) and the in-situ adaptive tabulation (ISAT) algorithm that accelerates the reacting flow calculations by two to three orders of magnitude. The analysis of temperature and species (hydroxyl hydrogen oxygen water) concentrations in time as well as the velocity through the vent shed a light on regimes and dynamics of indoor hydrogen fires. A well-ventilated fire is simulated in the enclosure at a lower release flow rate and complete combustion of hydrogen within the enclosure. Fire becomes under-ventilated at higher release flow rates with two different modes observed. The first mode is the external flame stabilised at the enclosure vent at moderate release rates and the second mode is the self-extinction of combustion inside and outside the enclosure at higher hydrogen release rates. The simulations demonstrated a complex reacting flow dynamics in the enclosure that leads to formation of the external flame or the self-extinction. The air intake into the enclosure at later stages of the process through the whole vent area is a characteristic feature of the self-extinction regime. This air intake is due to faster cooling of hot combustion products by sustained colder hydrogen leak compared to the generation of hot products by the ceasing chemical reactions inside the enclosure and hydrogen supply. In general an increase of hydrogen sustained release flow rate will change fire regime from the well-ventilated combustion within the enclosure through the external flame stabilised at the vent and finally to the self-extinction of combustion throughout the domain.

Coke oven gas (COG) is one of the most important by-products in the steel industry and the conversion of COG to value-added products has attracted much attention from both economic and environmental views. In this work we apply the chemical looping reforming technology to produce pure H2 from COG. A series of La1-xSrxFeO3 (x = 0 0.2 0.3 0.4 0.5 0.6) perovskite oxides were prepared as oxygen carriers for this purpose. The reduction behaviours of La1-xSrxFeO3 perovskite by different reducing gases (H2 CO CH4 and the mixed gases) are investigated to discuss the competition effect of different components in COG for reacting with the oxygen carriers. The results show that reduction temperatures of H2 and CO are much lower than that of CH4 and high temperatures (>800 °C) are requested for selective oxidation of methane to syngas. The co-existence of CO and H2 shows weak effect on the equilibrium of methane conversion at high temperatures but the oxidation of methane to syngas can inhibit the consumption of CO and H2. The doping of suitable amounts of Sr in LaFeO3 perovskite (e.g. La0.5Sr0.5FeO3) significantly promotes the reactivity for selective oxidation of methane to syngas and inhibits the formation of carbon deposition obtaining both high methane conversion in the COG oxidation step and high hydrogen yield in the water splitting step. The La0.5Sr0.5FeO3 shows the highest methane conversion (67.82%) hydrogen yield (3.34 mmol·g-1) and hydrogen purity (99.85%). The hydrogen yield in water splitting step is treble as high as the hydrogen consumption in reduction step. These results reveal that chemical looping reforming of COG to produce pure H2 is feasible and an O2-assistant chemical looping reforming process can further improve the redox stability of oxygen carrier.

The combination of catalytic decomposition of ammonia and in situ separation of hydrogen holds great promise for the use of ammonia as a clean energy carrier. However finding the optimal catalyst – membrane pair and operation conditions have proved challenging. Here we demonstrate that cobalt-based catalysts for ammonia decomposition can be efficiently 2 used together with a Pd-Au based membrane to produce high purity hydrogen at elevated pressure. Compared to a conventional packed bed reactor the membrane reactor offers several operational advantages that result in energetic and economic benefits. The robustness and durability of the combined system has been demonstrated for more than 1000 h on stream yielding a very pure hydrogen stream (>99.97 % H2) and recovery (>90 %). When considering the required hydrogen compression for storage/utilization and environmental issues the combined system offers the additional advantage of production of hydrogen at moderate pressures along with full ammonia conversion. Altogether our results demonstrate the possibility of deploying high pressure (350 bar) hydrogen generators from ammonia with H2 efficiencies of circa 75% without any external energy input and/or derived CO2 emissions.

An important contribution to industry standards and to effective installation of hybrid renewable energy systems is evaluation of hydrogen (H2) monitoring techniques under pilot-scale and/or real-world conditions. We have designed a hybrid system to integrate solar power electrolysis and hydrogen fuel cell components in a DC micro-grid with capacity to evaluate novel nanomaterials for enhanced H2 gas sensing performance. In general enhanced hydrogen sensing performance is evaluated by high sensitivity selectivity and stability as well as low power consumption. Unique properties such as high surface area to volume ratio a large number of surface active sites high specific surface area and reactivity are key attributes of nanomaterials used for gas sensing. These attributes enable sensors to be embedded in Internet-of-Things applications or in mobile systems. With rapid development of hydrogen-based technologies for clean energy applications there remains a requirement for faster accurate and selective H2 sensors with low cost and low power consumption. Operating principles for these sensors include catalytic thermal conductivity electrochemical resistance based optical and acoustic methods. In this paper we review performance of H2 gas sensors based on conductometric devices operating at room temperature up to 200 °C. The focus of this work includes nanostructured metal oxides graphene materials and transition metal dichalcogenides employed as sensing materials.

Ethanol and palm oil biodiesel blended with diesel fuel have the potential to reduce greenhouse gas emissions such as carbon dioxide (CO2) and can gradually decrease dependence on fossil fuels. However the combustion products from these fuels such as oxides of nitrogen (NOx) total hydrocarbons (THC) and particulate matter (PM) require to be examined and any beneficial or detrimental effect to the environment needs to be assessed. This study investigates the hydrocarbon selective catalyst reduction (HC-SCR) activities by the effect of combustion using renewable fuels (biodiesel-ethanol-diesel) blends and the effect of hydrogen addition to the catalyst with the various diesel engine operating conditions. Lower values rate of heat released were recorded as the ethanol fraction increases resulting in trade-off where lower NOx was produced while greater concentration of carbon monoxide (CO) and THC was measured in the exhaust. Consequently increasing the THC/NOx promoting the NOx reduction activity (up to 43%). Additionally the HC-SCR performance was greatly heightened when hydrogen was added into the catalyst and able to improve the NOx reduction activity up to 73%. The experiment demonstrated plausible alternatives to improve the HC-SCR performance through the aids from fuel blends and hydrogen addition.

In recent years hydrogen is rapidly developing because it is environmentally friendly and sustainable. In this case hydrogen energy storage systems (HESSs) can be widely used in the distribution network. The application of hybrid electric-hydrogen energy storage systems can solve the adverse effects caused by renewable energy access to the distribution network. In order to ensure the rationality and effectiveness of energy storage systems (ESSs) configuration economic indicators of battery energy storage systems (BESSs) and hydrogen energy storage systems power loss and voltage fluctuation are chosen as the fitness function in this paper. Meanwhile multi-objective particle swarm optimization (MOPSO) is used to solve Pareto non-dominated set of energy storage systems’ optimal configuration scheme in which the technique for order preference by similarity to ideal solution (TOPSIS) based on information entropy weight (IEW) is used select the optimal solution in Pareto non-dominated solution set. Based on the extended IEEE-33 system and IEEE-69 system the rationality of energy storage systems configuration scheme under 20% and 35% renewable energy penetration rate is analyzed. The simulation results show that the power loss can be reduced by 7.9%–22.8% and the voltage fluctuation can be reduced by 40.0%–71% when the renewable energy penetration rate is 20% and 35% respectively in IEEE-33 and 69 nodes systems. Therefore it can be concluded that the locations and capacities of energy storage systems obtained by multi-objective particle swarm optimization can improve the distribution network stability and economy after accessing renewable generation.

From an evaluation of the GB housing stock it is clear that a mosaic of low carbon heating technologies will be needed to reach net zero. While heat pumps are an important component of this mix our analysis shows that it is likely to be impractical to heat many GB homes with heat pumps only. A combination of lack of exterior space and/or the thermal properties of the building fabric mean that a heat pump is not capable of meeting the space heating requirement of 8 to 12m homes (or 37% to 54% of the 22.7m homes assessed in this report) or can do so only through the installation of highly disruptive and intrusive measures such as solid wall insulation. Hybrid heat pumps that are designed to optimise efficiency of the system do not have the same requirements of a heat pump and may be a suitable solution for some of these homes. This is likely to mean that decarbonised gas networks are therefore critical to delivery of net zero. 3 to 4m homes1 (or 14% to 18% of homes assessed in our analysis) could be made suitable for heat pump retrofit through energy efficiency measures such as cavity wall insulation. For 7 to 10m homes there are no limiting factors and they require minimal/no upgrade requirements to be made heat pump-ready. Nevertheless given firstly the levels of disruption to the floors and interiors of homes caused by the installation of heat pumps and secondly the cost and disruption associated with the requirement to significantly upgrade the electricity distribution networks to cope with large numbers of heat pumps operating at peak demand times - combined with the availability of a decarbonised gas network which requires a simple like-for-like boiler replacement - is likely to mean that many of these ‘swing’ properties will be better served through a gas based technology such as hydrogen (particularly when consumer choice is factored in) or a hybrid system. A recent trial run in winter 2018-19 by the Energy System Catapult revealed that all participants were reluctant to make expensive investments to improve the energy efficiency of their homes just to enhance the performance of their heat pump. They were more interested in less costly upgrades and tangible benefits such as lower bills or greater comfort. This means that renewable gases including hydrogen as heating fuels are a crucial component of the journey to net zero and the UK’s hydrogen ambitions should be reflective of this. The analysis presented in this paper focuses on the external fabric of the buildings further analysis should be undertaken to consider the internal system changes that would be required for heat pumps and hydrogen boilers for example BEIS Domestic Heat Distribution Systems: Gathering Report from February 2021 which considers the suitability of radiators for the low carbon transition.

This review study attempts to summarize available energy storage systems in order to accelerate the adoption of renewable energy. Inefficient energy storage systems have been shown to function as a deterrent to the implementation of sustainable development. It is therefore critical to conduct a thorough examination of existing and soon-to-be-developed energy storage technologies. Various scholarly publications in the fields of energy storage systems and renewable energy have been reviewed and summarized. Data and themes have been further highlighted with the use of appropriate figures and tables. Case studies and examples of major projects have also been researched to gain a better understanding of the energy storage technologies evaluated. An insightful analysis of present energy storage technologies and other possible innovations have been discovered with the use of suitable literature review and illustrations. This report also emphasizes the critical necessity for an efficient storage system if renewable energy is to be widely adopted.

The application of newly available technologies in the green maritime sector is difficult due to conflicting requirements and the inter-relation of different ecological technological and economical parameters. The governments incentivize radical reductions in harmful emissions as an overall priority. If the politics do not change the continuous implementation of stricter government regulations for reducing emissions will eventually result in the mandatory use of what we currently consider alternative fuels. Immediate application of radically different strategies would significantly increase the economic costs of maritime transport thus jeopardizing its greatest benefit: the transport of massive quantities of freight at the lowest cost. Increased maritime transport costs would immediately disrupt the global economy as seen recently during the COVID-19 pandemic. For this reason the industry has shifted towards a gradual decrease in emissions through the implementation of “better” transitional solutions until alternative fuels eventually become low-cost fuels. Since this topic is very broad and interdisciplinary our systematic overview gives insight into the state-of-the-art available technologies in green maritime transport with a focus on the following subjects: (i) alternative fuels; (ii) hybrid propulsion systems and hydrogen technologies; (iii) the benefits of digitalization in the maritime sector aimed at increasing vessel efficiency; (iv) hull drag reduction technologies; and (v) carbon capture technologies. This paper outlines the challenges advantages and disadvantages of their implementation. The results of this analysis elucidate the current technologies’ readiness levels and their expected development over the coming years.

The manuscript presents the conceptual design phase of an unmanned aerial vehicle with the objective of a systems approach towards the integration of a hydrogen fuel-cell system and Li-ion batteries into an aerodynamically efficient platform representative of future aircraft configurations. Using a classical approach to aircraft design and a combination of low- and high-resolution computational simulations a final blended wing body UAV was designed with a maximum take-off weight of 25 kg and 4 m wingspan. Preliminary aerodynamic and propulsion sizing demonstrated that the aircraft is capable of completing a 2 h long mission powered by a 650 W fuel cell hybridized with a 100 Wh battery pack and with a fuel quantity of 80 g of compressed hydrogen.

This paper presents a real-time simulation with a hardware-in-the-loop (HIL)-based approach for verifying the performance of electrolyzer systems in providing grid support. Hydrogen refueling stations may use electrolyzer systems to generate hydrogen and are proposed to have the potential of becoming smarter loads that can proactively provide grid services. On the basis of experimental findings electrolyzer systems with balance of plant are observed to have a high level of controllability and hence can add flexibility to the grid from the demand side. A generic front end controller (FEC) is proposed which enables an optimal operation of the load on the basis of market and grid conditions. This controller has been simulated and tested in a real-time environment with electrolyzer hardware for a performance assessment. It can optimize the operation of electrolyzer systems on the basis of the information collected by a communication module. Real-time simulation tests are performed to verify the performance of the FEC-driven electrolyzers to provide grid support that enables flexibility greater economic revenue and grid support for hydrogen producers under dynamic conditions. The FEC proposed in this paper is tested with electrolyzers however it is proposed as a generic control topology that is applicable to any load.

This report outlines the key modalities and procedures for the Innovation Fund and focuses on the potential funding implications for CCUS projects. The assessment of the suitability of the Innovation Fund for CCS projects has been completed based on discussion during a workshop hosted by the EU CCUS Projects Network in October 2019. This session was part of the Network’s Thematic Group on Policy Regulation and Public Perception. The session was held according to Chatham House rules to allow the projects present to exchange viewpoints and ideas freely.<br/>Broadly speaking it is hoped that the Innovation Fund Call for Proposal documents expected in mid-2020 will provide more information on how applicants should approach some of the key evaluation criteria namely calculating emissions avoidance for part-chain CCS and CCU projects demonstrating project maturity as well as project innovativeness. Furthermore there remains a concern that the costs for developing sufficient contingent storage sites could be overlooked by the Innovation Fund and EU policies directed towards CCS in general. Finally whereas there does not seem to be any regulatory barriers to blending Innovation Fund financing with Member State subsidies the asynchronous timing between the planned final investment decisions (FIDs) of some of the more advanced projects and the outcomes of the Innovation Fund (expected in 2022) means that certain projects may not be able to benefit from this.

Austenitic stainless steels are used for hydrogen containment of high-pressure hydrogen gas due to their ability to retain high fracture properties despite the degradation due to hydrogen. Forging and other strain-hardening processes are desirable for austenitic stainless steels to increase the material strength and thus accommodate higher stresses and reduce material costs. Welding is often necessary for assembling components but it represents an area of concern in pressure containment structures due to the potential for defects more environmentally susceptible microstructure and reduced strength. Electron beam (EB) welding represent an advanced joining process which has advantages over traditional arc welding techniques through reduced input heat and reduced heat-affected zone (HAZ) microstructure and thus present a means to maintain high strength and improve weld performance in hydrogen gas containment. In this study fracture coupons were extracted from EB welds in forged 304L and subjected to thermal gaseous hydrogen precharging at select pressures to introduce different levels of internal hydrogen content. Fracture tests were then performed on hydrogen precharged coupons at temperatures of both 293 K and 223 K. It was observed that fracture resistance (JH) was dependent on internal hydrogen concentration; higher hydrogen concentrations resulted in lower fracture resistance in both the forged 304L base material and the 304L EB welds. This trend was also apparent at both temperatures: 293 K and 223 K. EB weld samples however maintain high fracture resistance comparable to the forged 304L base material. The role of weld microstructure solidification on fracture is discussed.

Energy production by methanization or gasification of biomass is dependant on the chemical composition of the gas generated. The resistive sensors based on semiconductor metal oxides like the MQ series sensors are inexpensive and frequently used in gas detection. These sensors initially dedicated to detecting gas leaks in safety systems have relatively small measurement ranges (i.e. limited to concentrations below 10000 ppm). It is therefore necessary to find solutions to adapt these categories of sensors for gas measurements in the energy sector where the gas concentration is much more significant. In this article we propose a protocol using an adaptable capsule for MQ-4 and MQ-8 sensors to measure high concentrations of CH4 and H2 respectively. The technique consists of diluting the gas to be studied in a known volume of air. Three methods are proposed and compared regarding the linearity and the repeatability of the measurements. The first method was done in an airtight enclosed chamber the second method consists of directly injecting the gas on the sensor placed in an open environment and the final method was accomplished by direct injection of the gas on the sensor placed in a partially closed capsule. Comparisons show that the first technique provides the best repeatability with a maximum standard deviation of 13.88% for CH4 measurement and 5.1% for H2. However its linearity is weak (i.e. R2 ¼ 0.8637 for CH4 and R2 ¼ 0.5756 for H2). The second technique has better linearity but bad repeatability. The third technique presents the best results with R2 values of 0.9973 for the CH4 measurement and 0.9472 for H2. The use of the partially closed capsule resulted in an acceptable linear response of the sensors by up to 20% concentration of CH4 and until 13.33% concentration of H2 in the studied gas. The use of this simple and low-cost technique facilitates the characterization of combustible gases in isolated areas. It allows local operators of biomass valorization systems to control and improve their installations while avoiding the high costs of conventional measurement devices. This study hence contributes to the development of rural electrification projects in remote areas.

Hydrogen presents an opportunity for Africa to not only decarbonise its own energy use and enable clean energy access for all but also to export renewable energy. This paper developed a framework for assessing renewable resources for hydrogen production and provides a new critical analysis as to how and what role hydrogen can play in the complex African energy landscape. The regional solar wind CSP and bio hydrogen potential ranges from 366 to 1311 Gt/year 162 to 1782 Gt/year 463 to 2738 Gt/year and 0.03 to 0.06 Gt/year respectively. The water availability and sensitivity results showed that the water shortages in some countries can be abated by importing water from regions with high renewable water resources. A techno-economic comparative analysis indicated that a high voltage direct current (HVDC) system presents the most cost-effective transportation system with overall costs per kg hydrogen of 0.038 $/kg followed by water pipeline with 0.084 $/kg seawater desalination 0.1 $/kg liquified hydrogen tank truck 0.12 $/kg compressed hydrogen pipeline 0.16 $/kg liquefied ammonia pipeline 0.38 $/kg liquefied ammonia tank truck 0.60 $/kg and compressed hydrogen tank truck with 0.77 $/kg. The results quantified the significance of economies of scale due to cost effectiveness of systems such as compressed hydrogen pipeline and liquefied hydrogen tank truck systems when hydrogen production is scaled up. Decentralization is favorable under some constraints e.g. compressed hydrogen and liquefied ammonia tank truck systems will be more cost effective below 800 km and 1400 km due to lower investment and operation costs.

The energy security landscape that we envisage in 2050 will be different from that of today. Meeting the future energy needs of the armed forces will be a key challenge not least for military security. The World Energy Council’s World Energy Scenarios forecast that the world’s population will rise to 10 billion by 2050 which will also necessitate an increase in the size of the armed forces. In this context energy extraction distribution and storage become essential to stabilizing the imbalance between production and demand. Among the available solutions Power to Hydrogen (P2H) is one of the most appealing options. However despite the potential many obstacles currently hinder the development of the P2H market. This article aims to identify and analyse existing barriers to the introduction of P2H technologies that use hydrogen. The holistic approach used which was based on a literature survey identified obstacles and possible strategies for overcoming them. The research conducted presents an original research contribution at the level of hydrogen strategies considered in leading countries around the world. The research findings identified unresolved regulatory issues and sources of uncertainty in the armed forces. There is a lack of knowledge in the armed forces of some countries about the process of producing hydrogen energy and its benefits which raises concerns about the consistency of its exploitation. Negative attitudes towards hydrogen fuel energy can be a significant barrier to its deployment in the armed forces. Possible approaches and solutions have also been proposed to eliminate obstacles and to support decision makers in defining and implementing a strategy for hydrogen as a clean energy carrier. There are decisive and unresolved obstacles to its deployment not only in the armed forces

This work presents a detailed breakdown of the energy conversion chains from intermittent electricity to a vehicle considering battery electric vehicles (BEVs) and fuel cell electric vehicles (FCEVs). The traditional well-to-wheel analysis is adapted to a grid to mobility approach by introducing the intermediate steps of useful electricity energy carrier and on-board storage. Specific attention is given to an effective coupling with renewable electricity sources and associated storage needs. Actual market data show that compared to FCEVs BEVs and their infrastructure are twice as efficient in the conversion of renewable electricity to a mobility service. A much larger difference between BEVs and FCEVs is usually reported in the literature. Focusing on recharging events this work additionally shows that the infrastructure efficiencies of both electric vehicle (EV) types are very close with 57% from grid to on-board storage for hydrogen refilling stations and 66% for fast chargers coupled with battery storage. The transfer from the energy carrier at the station to on-board storage in the vehicle accounts for 9% and 12% of the total energy losses of these two modes respectively. Slow charging modes can achieve a charging infrastructure efficiency of 78% with residential energy storage systems coupled with AC chargers.

The aim of this study was to determine how the efficiency of a proton exchange membrane (PEM) electrolyser is affected by an electric ripple current and the different characteristics of the ripple current (frequency amplitude and waveform). This paper presents the experimental method and measured results used to analyse the effect of ripple currents at various frequencies ripple factors and waveforms on the hydrogen production power consumption and efficiency of a PEM electrolyser. An active laboratory-size PEM electrolysis system was used to investigate the impact of various ripple currents on the efficiency of the system. The results revealed that the average power consumption increases as the ripple factor increases and decreases as the frequency of the ripple increases while the waveform of the applied current has no effect. Furthermore the average hydrogen flow rate is unaffected by the ripple factor frequency or waveform of the applied ripple current.

Chris Jackson is the Founder and CEO of Protium Green Solutions based in London. Protium is a hydrogen energy services company that designs develops finances owns and operates clean hydrogen solutions for clients to achieve net zero energy emissions at their industrial/manufacturing sites. Chris will talk to us about the Protium story and also give us some insight into a major project that Protium recently announced in conjunction Budweiser Brewing Group UK&Ireland to explore the deployment of zero emission green hydrogen at Magor brewery in South Wales one of the largest breweries in the UK. To that end in order to get the full story about this project we are delighted to say that we have yet another great guest on this episode. Tom Brewer who leads Global Environmental Sustainability efforts at AB InBev the parent company of Budweiser Brewing Group will join us for the final segment of the show to talk about how hydrogen fits into AB InBev’s vision of a sustainable future for the company.

The podcast can be found on their website

Renewable energy is a key solution in maintaining global warming below 2 °C. However its intermittency necessitates the need for energy conversion technologies to meet demand when there are insufficient renewable energy resources. This study aims to tackle these challenges by thermo-electrochemical modelling and simulation of a reversible solid oxide fuel cell (RSOFC) and integration with the Haber Bosch process. The novelty of the proposed system is usage of nitrogen-rich fuel electrode exhaust gas for ammonia synthesis during fuel cell mode which is usually combusted to prevent release of highly flammable hydrogen into the environment. RSOFC round-trip efficiencies of 41–53% have been attained when producing excess ammonia (144 kg NH3/hr) for the market and in-house consumption respectively. The designed system has the lowest reported ammonia electricity consumption of 6.4–8.21 kWh/kg NH₃ power-to-hydrogen power-to-ammonia and power-generation efficiencies of 80% 55–71% and 64–66%.

Adding hydrogen to mains natural gas has been identified as one of the main strategies to reduce CO2 emissions in the United Kingdom. This work aims to characterise the explosion severity of 80:20 v./v. methane/hydrogen blends (‘a blend’) and methane vented deflagrations. The explosion severity of homogenous mixtures was measured in a 15 m3 cubic steel chamber in which the relief area was provided by four windows and a door covered with polypropylene sheet. The pressure increase over time was characterised using piezo-resistive pressure transducers and the flame speed was estimated using ionisation probes installed in the walls of the enclosure. The explosion severity of both mixtures was determined for different equivalence ratios from lean to rich mixtures. The pressure over time presented very similar behaviour for both mixtures comprising multiple peaks divided into three main stages: a first stage related to a spherical confined explosion until the opening of the vent a second stage generated by increased combustion during venting and an oscillatory peak generated by acoustic disturbances with the enclosure. A slight increase in the first stage overpressure was observed for the blend in comparison with methane regardless of the equivalence ratio but no general trend in pressure was observed for other stages of the propagation. The effect of the blockage ratio on explosion severity was studied by adding metallic elements representing furniture in a room.

Hydrogen when is blended with natural gas over time degrades the materials used for pipe transport. Degradation is dependent on the proportion of hydrogen added to the natural gas. The assessment is made according to hydrogen permeation risk to the integrity of structures adaptation of surveillance and maintenance of equipment. The paper gives a survey of HE and its consequence on the design and maintenance. It is presented in a logical sequence: the design before use; the hydrogen embrittlement (HE) effects on Maximum Allowable Operating Pressure (MAOP); maintenance and surveillance during use of smooth and damaged pipes; and particularly for crack-like defects corrosion defects and dents.

Low vehicle occupancy rates combined with record conventional vehicle sales justify the requirement to optimize vehicle type based on passengers and a powertrain with zero-emissions. This study compares the performance of different vehicle types based on the number of passengers/payloads powertrain configuration (battery and fuel cell electric configurations) and drive cycles to assess range and energy consumption. An adequate choice of vehicle segment according to the real passenger occupancy enables the least energy consumption. Vehicle performance in terms of range points to remarkable results for the FCEV (fuel cell electric vehicle) compared to BEV (battery electric vehicle) where the former reached an average range of 600 km or more in all different drive cycles while the latter was only cruising nearly 350 km. Decisively the cost analysis indicated that FCEV remains the most expensive option with base cost three-fold that of BEV. The FCEV showed notable results with an average operating cost of less than 7 cents/km where BEV cost more than 10 €/km in addition to the base cost for light-duty vehicles. The cost analysis for a bus and semi-truck showed that with a full payload FCPT (fuel cell powertrain) would be more economical with an average energy cost of ~1.2 €/km while with BPT the energy cost is more than 300 €/km

Hydrogen is a promising commodity a renewable secondary energy source and feedstock alike to meet greenhouse gas emissions targets and promote economic decarbonization. A common goal pursued by many countries the hydrogen economy receives a blending of public and private capital. After European Green Deal state members created national policies focused on green hydrogen. This paper presents a study of energy transition considering green hydrogen production to identify Portugal’s current state and prospects. The analysis uses energy generation data hydrogen production aspects CO2 emissions indicators and based costs. A comprehensive simulation estimates the total production of green hydrogen related to the ratio of renewable generation in two different scenarios. Then a comparison between EGP goals and Portugal’s transport and energy generation prospects is made. Portugal has an essential renewable energy matrix that supports green hydrogen production and allows for meeting European green hydrogen 2030–2050 goals. Results suggest that promoting the conversion of buses and trucks into H2-based fuel is better for CO2 reduction. On the other hand given energy security thermoelectric plants fueled by H2 are the best option. The aggressive scenario implies at least 5% more costs than the moderate scenario considering economic aspects.

Blending hydrogen into ammonia can I mprove the burning intensity of ammonia and the safety of hydrogen and it is important to understand the flames of NH3/H2/air mixtures. In this work lamiar flame characteristics of 50-50 (vol%) ammonia-hydrogen mixtures in air were studied using the spherical flame propagation method in a constant-volume bom at initital temperature Tu = 298K and different pressures.

The present work aims to assess the influence of the composition of blends of hydrogen (H2 ) and Natural Gas (NG) on Dual Fuel (DF) combustion characteristics including gaseous emissions. The 3D-CFD study is carried out by means of a customized version of the KIVA-3V code. An automotive 2.8 L 4-cylinder turbocharged diesel engine was previously modified in order to operate in DF NG–diesel mode and tested at the dynamometer bench. After validation against experimental results the numerical model is applied to perform a set of combustion simulations at 3000 rpm–BMEP = 8 bar in DF H2/NG-diesel mode. Different H2–NG blends are considered: as the H2 mole fraction varies from 0 vol% to 50 vol% the fuel energy within the premixed charge is kept constant. The influence of the diesel Start Of Injection (SOI) is also investigated. Simulation results demonstrate that H2 enrichment accelerates the combustion process and promotes its completion strongly decreasing UHC and CO emissions. Evidently CO2 specific emissions are also reduced (up to about 20% at 50 vol% of H2 ). The main drawbacks of the faster combustion include an increase of in-cylinder peak pressure and pressure rate rise and of NOx emissions. However the study demonstrates that the optimization of diesel SOI can eliminate all aforementioned shortcomings.

The foreseen uptake of hydrogen mobility is a fundamental step towards the decarbonization of the transport sector. Under such premises both refuelling infrastructure and vehicles should be deployed together with improved refuelling protocols. Several studies focus on refuelling the light-duty vehicles with 10 kgH2 up to 700 bar however less known effort is reported for refuelling heavy-duty vehicles with 30–40 kgH₂ at 350 bar. The present study illustrates the application of a lumped model to a fuel cell bus tank-to-tank refuelling event tailored upon the real data acquired in the 3Emotion Project. The evolution of the main refuelling quantities such as pressure temperature and mass flow are predicted dynamically throughout the refuelling process as a function of the operating parameters within the safety limits imposed by SAE J2601/2 technical standard. The results show to refuel the vehicle tank from half to full capacity with an Average Pressure Ramp Rate (APRR) equal to 0.03 MPa/s are needed about 10 min. Furthermore it is found that the effect of varying the initial vehicle tank pressure is more significant than changing the ambient temperature on the refuelling performances. In conclusion the analysis of the effect of different APRR from 0.03 to 0.1 MPa/s indicate that is possible to safely reduce the duration of half-to-full refuelling by 62% increasing the APRR value from 0.03 to 0.08 MPa/s.

Biogas is a renewable gas with low heat energy which makes it extremely difficult to use as fuel in conventional natural gas equipment. Nonetheless the use of hydrogen as a biogas additive has proven to have a beneficial effect on flame stability and combustion behavior. This study evaluates the biogas–hydrogen combustion in a conventional natural gas burner able to work up to 100 kW. Tests were performed for three different compositions of biogas: BG70 (30% CO₂) BG60 (40% CO₂) and BG50 (50% CO₂). To achieve better flame stability each biogas was enriched with hydrogen from 5% to 25%. The difficulty of burning biogas in conventional systems was proven as the burner does not ignite when the biogas composition contains more than 40% of CO₂. The best improvements were obtained at 5% hydrogen composition since the exhaust gas temperature and thus the enthalpy rises by 80% for BG70 and 65% for BG60. The stability map reveals that pure biogas combustion is unstable in BG70 and BG60; when the CO₂ content is 50% ignition is inhibited. The properties change slightly when the hydrogen concentrations are more than 20% in the fuel gas and do not necessarily improve.