Publications
Safety and Other Considerations in the Development of a Hydrogen Fueling Protocol for Heavy-duty Vehicles
Sep 2021
Publication
Several manufacturers are developing heavy duty (HD) hydrogen stations and vehicles as zeroemissions alternatives to diesel and gasoline. In order to meet customer demands the new technology must be comparable to conventional approaches including safety reliability fueling times and final fill levels. For a large HD vehicle with a storage rated to 70 MPa nominal working pressure the goal to meet liquid fuel parity means providing 100 kg of hydrogen in 10 minutes. This paper summarizes the results to date of the PRHYDE project efforts to define the concepts of HD fueling which thereby lays the groundwork for the development of the safe and effective approach to filling these large vehicles. The project starts by evaluating the impact of several different assumptions such as the availability of static vehicle data (e.g. vehicle tank type and volume) and station data (e.g. expected station precooling capability) but also considers using real time dynamic data (e.g. vehicle tank gas temperature and pressure station gas temperature etc.) for optimisation to achieve safety and efficiency improvements. With this information the vehicle or station can develop multiple maps of fill time versus the hydrogen delivery temperature which are used to determine the speed of fueling. This will also allow the station or vehicle to adjust the rate of fueling as the station pre-cooling levels and other conditions change. The project also examines different steps for future protocol development such as communication of data between the vehicle and station and if the vehicle or station is controlling the fueling.
Preparation, Performance and Challenges of Catalyst Layer for Proton Exchange Membrane Fuel Cell
Nov 2021
Publication
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.
Hydrogen Blowdown Release Experiments at Different Temperatures in the Discha-facility
Sep 2021
Publication
In this work experiments on horizontal hydrogen jet releases from a 2.815 dm³ volume tank to the ambience are described. For the main experimental series tank valve and release line were cooled down to a temperature of approx. 80 K in a bath of liquid nitrogen. As a reference similar experiments were also performed with the uncooled tank at ambient temperature. The releases were carried out through four nozzles with different circular orifice diameters from 0.5 to 4 mm and started from initial tank pressures from 0.5 to 20 MPa (rel.). During the releases pressures and temperatures inside the vessel as well as inside the release line were measured. Outside the nozzle further temperature and hydrogen concentration measurements were performed along and besides the jet axis. The electrostatic field builtup in the jet was monitored using two field meters in different distances from the release nozzle and optical observation via photo and video-cameras was performed for the visualization of the H2-jet via the BOS-method. The experiments were performed in the frame of the EU-funded project PRESHLY in which several tests of this program were selected for a comparative computational study the results of which will also be presented at this conference. So on the one hand the paper gives a comprehensive description of the facility on the other hands it also describes the experimental procedure and the main findings.
Ammonia Production from Clean Hydrogen and the Implications for Global Natural Gas Demand
Jan 2023
Publication
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.
Hydrogen Fuel for Future Mobility: Challenges and Future Aspects
Jul 2022
Publication
Nowadays the combustion of fossil fuels for transportation has a major negative impact on the environment. All nations are concerned with environmental safety and the regulation of pollution motivating researchers across the world to find an alternate transportation fuel. The transition of the transportation sector towards sustainability for environmental safety can be achieved by the manifestation and commercialization of clean hydrogen fuel. Hydrogen fuel for sustainable mobility has its own effectiveness in terms of its generation and refueling processes. As the fuel requirement of vehicles cannot be anticipated because it depends on its utilization choosing hydrogen refueling and onboard generation can be a point of major concern. This review article describes the present status of hydrogen fuel utilization with a particular focus on the transportation industry. The advantages of onboard hydrogen generation and refueling hydrogen for internal combustion are discussed. In terms of performance affordability and lifetime onboard hydrogen-generating subsystems must compete with what automobile manufacturers and consumers have seen in modern vehicles to date. In internal combustion engines hydrogen has various benefits in terms of combustive properties but it needs a careful engine design to avoid anomalous combustion which is a major difficulty with hydrogen engines. Automobile makers and buyers will not invest in fuel cell technology until the technologies that make up the various components of a fuel cell automobile have advanced to acceptable levels of cost performance reliability durability and safety. Above all a substantial advancement in the fuel cell stack is required.
Hydrogen Non-premixed Combustion in Enclosure with One Vent and Sustained Release: Numerical Experiments
Sep 2013
Publication
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.
Optimization of Operating Hydrogen Storage System for Coal–Wind–Solar Power Generation
Jul 2022
Publication
To address the severity of the wind and light abandonment problem and the economics of hydrogen energy production and operation this paper explores the problem of multi-cycle resource allocation optimization of hydrogen storage systems for coal–wind–solar power generation. In view of the seriousness of the problem of abandoning wind and photovoltaic power and the economy of hydrogen production and operation the node selection and scale setting issues for hydrogen production and storage as well as decision-making problems such as the capacity of new transmission lines and new pipelines and route planning are studied. This research takes the satisfaction of energy supply as the basic constraint and constructs a multi-cycle resource allocation optimization model for an integrated energy system aiming to achieve the maximum benefit of the whole system. Using data from Inner Mongolia where wind abandonment and power limitation are severe and Beijing and Shanxi provinces where hydrogen demand is high this paper analyzes the benefits of the hydrogen storage system for coal–wind–solar power generation and explores the impact of national subsidy policies and technological advances on system economics.
Hydrogenation Production via Chemical Looping Reforming of Coke Oven Gas
Jun 2020
Publication
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.
Relevance of Optimized Low-Scale Green H2 Systems in a French Context: Two Case Studies
May 2022
Publication
Hydrogen has been identified as a very promising vector for energy storage especially for heavy mobility applications. For this reason France is making significant investments in this field and use cases need to be evaluated as they are sprouting. In this paper the relevance of H2 in two storage applications is studied: a domestic renewable electricity production system connected to the grid and a collective hydrogen production for the daily bus refill. The investigation consists of the sizing of the system and then the evaluation of its performance according to several criteria depending on case. Optimizations are made using Bayesian and gradient-based methods. Several variations around a central case are explored for both cases to give insights on the impact of the different parameters (location pricing objective etc.) on the performance of the system.Our results show that domestic power-to-power applications (case 1) do not seem to be competitive with electrochemical storage. Meanwhile without any subsidies or incentives such configuration does not allow prosumers to save money (+16% spendings compared to non-equipped dwelling). It remains interesting when self-sufficiency is the main objective (up to 68% of energy is not exchanged). The power-to-gas application (case 2 central case) with a direct use of hydrogen for mobility seems to be more relevant according to our case study we could reach a production cost of green H2 around 5 €/kg similar to the 3–10 $/kg found in literature for 182 houses involved. In both cases H2 follows a yearly cycle charging in summer and discharging in winter (long term storage) due to low conversion efficiency.
High Purity, Self-sustained, Pressurized Hydrogen Production from Ammonia in a Catalytic Membrane Reactor
Dec 2021
Publication
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.
Life Cycle Assessment of Natural Gas-based Chemical Looping for Hydrogen Production
Dec 2014
Publication
Hydrogen production from natural gas combined with advanced CO2 capture technologies such as iron-based chemical looping (CL) is considered in the present work. The processes are compared to the conventional base case i.e. hydrogen production via natural gas steam reforming (SR) without CO2 capture. The processes are simulated using commercial software (ChemCAD) and evaluated from a technical point of view considering important key performance indicators such as hydrogen thermal output net electric power carbon capture rate and specific CO2 emissions. The environmental evaluation is performed using Life Cycle Analysis (LCA) with the following system boundaries considered: i) hydrogen production from natural gas coupled to CO2 capture technologies based on CL ii) upstream processes such as: extraction and processing of natural gas ilmenite and catalyst production and iii) downstream processes such as: H2 and CO2 compression transport and storage. The LCA assessment was carried out using the GaBi6 software. Different environmental impact categories following here the CML 2001 impact assessment method were calculated and used to determine the most suitable technology. Sensitivity analyses of the CO2 compression transport and storage stages were performed in order to examine their effect on the environmental impact categories.
Nanotechnology Enabled Hydrogen Gas Sensing
Sep 2019
Publication
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.
Lowest Cost Decarbonisation for the UK: The Critical Role of CCS
Sep 2016
Publication
A new report to the Secretary of State for Business Energy and Industrial Strategy from the Parliamentary Advisory Group on Carbon Capture and Storage (CCS) advises that that the UK should kickstart CCS in order to save consumers billions a year from the cost of meeting climate change targets.
Promotion Effect of Hydrogen Addition in Selective Catalytic Reduction of Nitrogen Oxide Emissions from Diesel Engines Fuelled with Diesel-biodiesel-ethanol Blends
Nov 2021
Publication
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.
Aqueous Phase Reforming of the Residual Waters Derived from Lignin-rich Hydrothermal Liquefaction: Investigation of Representative Organic Compounds and Actual Biorefinery Streams
Sep 2019
Publication
Secondary streams in biorefineries need to be valorized to improve the economic and environmental sustainability of the plants. Representative model compounds of the water fraction from the hydrothermal liquefaction (HTL) of biomass were subjected to aqueous phase reforming (APR) to produce hydrogen. Carboxylic and bicarboxylic acids hydroxyacids alcohols cycloketones and aromatics were identified as model compounds and tested for APR. The tests were performed with a Pt/C catalyst and the influence of the carbon concentration (0.3–1.8 wt. C%) was investigated. Typically the increase of the concentration negatively affected the conversion of the feed toward gaseous products without influencing the selectivity toward hydrogen production. A synthetic ternary mixture (glycolic acid acetic acid lactic acid) was subjected to APR to evaluate any differences in performance compared to the tests with single compounds. Indeed glycolic acid reacted faster in the mixture than in the corresponding single compound test while acetic acid remained almost unconverted. The influence of the reaction time temperature and carbon concentration was also evaluated. Finally residual water resulting from the HTL of a lignin-rich stream originating from an industrial-scale lignocellulosic ethanol process was tested for the first time after a thorough characterization. In this framework the stability of the catalyst was studied and found to be correlated to the presence of aromatics in the aqueous feedstock. For this reason the influence of an extraction procedure for the selective removal of these compounds was explored leading to an improvement in the APR performance.
Optimal Planning of Hybrid Electric-hydrogen Energy Storage Systems via Multi-objective Particle Swarm Optimization
Jan 2023
Publication
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.
Modeling of Thermal Performance of a Commercial Alkaline Electrolyzer Supplied with Various Electrical Currents
Nov 2021
Publication
Hydrogen produced by solar and other clean energy sources is an essential alternative to fossil fuels. In this study a commercial alkaline electrolyzer with different cell numbers and electrode areas are simulated for different pressure temperature thermal resistance and electrical current. This alkaline electrolyzer is considered unsteady in simulations and different parameters such as temperature are obtained in terms of time. The obtained results are compared with similar results in the literature and good agreement is observed. Various characteristics of this alkaline electrolyzer as thermoneutral voltage faraday efficiency and cell voltage are calculated and displayed. The outlet heat rate and generated heat rate are obtained as well. The pressure and the temperature in the simulations are between 1 and 100 bar and between 300 and 360 Kelvin respectively. The results show that the equilibrium temperature is reached 2-3 hours after the time when the Alkaline electrolyzer starts to work.
Decarbonising Heat in Buildings: Putting Consumers First
Apr 2021
Publication
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.
China Progress on Renewable Energy Vehicles: Fuel Cells, Hydrogen and Battery Hybrid Vehicles
Dec 2018
Publication
Clean renewable energy for Chinese cities is a priority in air quality improvement. This paper describes the recent Chinese advances in Polymer Electrolyte Membrane (PEM) hydrogen-fuel-cell-battery vehicles including buses and trucks. Following the 2016 Chinese government plan for new energy vehicles bus production in Foshan has now overtaken that in the EU USA and Japan combined. Hydrogen infrastructure requires much advance to catch up but numbers of filling stations are now increasing rapidly in the large cities. A particular benefit in China is the large number of battery manufacturing companies which fit well into the energy storage plan for hybrid fuel cell buses. The first city to manufacture thousands of PEM-battery hybrid buses is Foshan where the Feichi (Allenbus) company has built a new factory next to a novel fuel cell production line capable of producing 500 MW of fuel cell units per year. Hundreds of these buses are running on local Foshan routes this year while production of city delivery trucks has also been substantial. Results for energy consumption of these vehicles are presented and fitted to the Coulomb theory previously delineated.
Development and Future Scope of Renewable Energy and Energy Storage Systems
May 2022
Publication
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.
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