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Flame Characteristics of High-Pressure Hydrogen Gas Jet
Sep 2005
Publication
It is expected that hydrogen will serve as a nonpolluting carrier of energy for the next generation of vehicles and guidelines for its safe use are required. Hydrogen-gas service stations for supplying fuel cell vehicles will have to handle high-pressure hydrogen gas but safety regulations for such installations have not received much investigation. In this study we experimentally investigated the flame characteristics of a rapid leakage of high-pressure hydrogen gas. A hydrogen jet diffusion flame was injected horizontally from convergent nozzles of various diameters between 0.1 and 4 mm at reservoir over pressures of between 0.01 and 40 MPa. The sizes of the flame were measured and experimental equations were obtained for the length and the width of the flame. Flame sizes depend not only on the nozzle diameter but also on the spouting pressure. Blow-off limits exists and are determined by the nozzle diameter and the spouting pressure. Furthermore the radiation from a hydrogen flame can be predicted from the flow rate of the gas and the distance from the flame.
Digital Navigation of Energy–structure–function Maps for Hydrogen-bonded Porous Molecular Crystals
Feb 2021
Publication
Energy–structure–function (ESF) maps can aid the targeted discovery of porous molecular crystals by predicting the stable crystalline arrangements along with their functions of interest. Here we compute ESF maps for a series of rigid molecules that comprise either a triptycene or a spiro-biphenyl core functionalized with six different hydrogen-bonding moieties. We show that the positioning of the hydrogen-bonding sites as well as their number has a profound influence on the shape of the resulting ESF maps revealing promising structure–function spaces for future experiments. We also demonstrate a simple and general approach to representing and inspecting the high-dimensional data of an ESF map enabling an efficient navigation of the ESF data to identify ‘landmark’ structures that are energetically favourable or functionally interesting. This is a step toward the automated analysis of ESF maps an important goal for closed-loop autonomous searches for molecular crystals with useful functions.
Sectoral Scenarios for the Fifth Carbon Budget
Nov 2015
Publication
This report forms part of the Committee’s advice on the level of the fifth carbon budget.<br/>The report describes the scenarios used by the Committee to inform its judgements over the cost-effective path to meeting the UK’s greenhouse reduction targets in the period 2028-2032.
Role of Chemical Kinetics on the Detonation Properties of Hydrogen, Natural Gas & Air Mixtures
Sep 2005
Publication
The first part of the present work is to validate a detailed kinetic mechanism for the oxidation of hydrogen – methane – air mixtures in a detonation waves. A series of experiments on auto-ignition delay times have been performed by shock tube technique coupled with emission spectrometry for H2 / CH4 / O2 mixtures highly diluted in argon. The CH4/H2 ratio was varied from 0 to 4 and the equivalence ratio from 0.4 up to 1. The temperature range was from 1250 K to 2000 K and the pressure behind reflected shock waves was between 0.15 and 1.6 MPa. A correlation was proposed between temperature (K) concentration of chemical species (mol m-3) and ignition delay times. The experimental auto-ignition delay times were compared to the modelled ones using four different mechanisms from the literature: GRI [22] Marinov et al. [23] Hughes et al. [24] Konnov [25]. A large discrepancy was generally found between the different models. The Konnov’s model that predicted auto-ignition delay times close to the measured ones has been selected to calculate the ignition delay time in the detonation waves. The second part of the study concerned the experimental determination of the detonation properties namely the detonation velocity and the cell size. The effect of the initial composition hydrogen to methane ratio and the amount of oxygen in the mixture as well as the initial pressure on the detonation velocity and on the cell size were investigated. The ratio of methane / (methane + hydrogen) varied between 0 and 0.6 for 2 different equivalence ratio (0.75 and 1) while the initial pressure was fixed to 10 kPa. A correlation was established between the characteristic cell size and the ignition delay time behind the leading shock of the detonation. It was clearly showed that methane has an important inhibitor effect on the detonation of these combustible mixtures.
Hydrogen – Analysis
Jun 2020
Publication
Hydrogen technologies maintained strong momentum in 2019 awakening keen interest among policy makers. It was a record year for electrolysis capacity becoming operational and several significant announcements were made for upcoming years. The fuel cell electric vehicle market almost doubled owing to outstanding expansion in China Japan and Korea. However low-carbon production capacity remained relatively constant and is still off track with the SDS. More efforts are needed to: scale up to reduce costs; replace high-carbon with low-carbon hydrogen in current applications; and expand hydrogen use to new applications.
Link to Document on IEA Website
Link to Document on IEA Website
Scenarios for Deployment of Hydrogen in Meeting Carbon Budgets (E4tech)
Nov 2015
Publication
This research considers the potential role of hydrogen in meeting the UK’s carbon budgets. It was written by consultancy E4tech.<br/>The CCC develops scenarios for the UK’s future energy system to assess routes to decarbonisation and to advise UK Government on policy options. Uncertainty to 2050 is considerable and so different scenarios are needed to assess different trajectories targets and technology combinations. Some of these scenarios assess specific technologies or fuels which have the potential to make a significant contribution to future decarbonisation.<br/>Hydrogen is one such fuel. It has been included in limited quantities in some CCC scenarios but not extensively examined in part due to perceived or anticipated higher costs than some other options. But as hydrogen technology is developed and deployed the cost projections and other performance indicators have become more favourable.
Experimental Study of Hot Inert Gas Jet Ignition of Hydrogen-Oxygen Mixture
Sep 2005
Publication
Experiments were performed to investigate the diffusion ignition process that occurs when hot inert gas (argon or nitrogen) is injected into the stoichiometric hydrogen-oxygen mixture at the test section. Detonation wave initiated by spark plug in the driver section in stoichiometric acetylene-oxygen mixture At P=0.5 MPa and room temperature propagates as incident shockwave in the driven section through inert gas after bursting the diaphragm separating the sections. At the end wall of driver section the inert gas is heated behind the reflected shock wave and then injected in to the test section with the stoichiometric hydrogen-oxygen mixture through the hole 8mm in diameter. An increase of the initial pressure of the combustible mixture in the test section from 0.2 to 0.6MPa resulted in decrease of the minimum temperature of injected gas causing ignition from 1650K to 850K. At the same time the induction time for ignition process has increased from 190 to 320μs when hot argon was injected. For the injection of hot nitrogen an increase of the initial pressure of the combustible mixture from 0.2 to 0.4 MPa resulted in decrease of the minimum temperature of injected inert gas giving ignition from 1150K to 850Kand an increase of the induction time from 170 to 240μs.The results of experiments indicate that ignition occurs when the static enthalpy of injected mass of inert gas exceeds some critical value. The mechanism of ignition process was also studied by schlieren photography.
The Techno-economics Potential of Hydrogen Interconnectors for Electrical Energy Transmission and Storage
Dec 2021
Publication
This research introduces a ‘Hydrogen Interconnector System’ (HIS) as a novel method 7 for transporting electrical energy over long distances. The system takes electricity from 8 stranded renewable energy assets converts it to hydrogen in an electrolyser plant transports 9 hydrogen to the demand centre via pipeline where it is reconverted to electricity in either a 10 gas turbine or fuel cell plant. This paper evaluates the competitiveness of the technology with 11 High Voltage Direct Current (HVDC) systems calculating the following techno-economic 12 indicators; Levelised Cost Of Electricity (LCOE) and Levelised Cost Of Storage (LCOS). The 13 results suggest that the LCOE of the HIS is competitive with HVDC for construction in 2050 14 with distance beyond 350km in case of all scenarios for a 1GW system. The LCOS is lower 15 than an HVDC system using large scale hydrogen storage in 6 out of 12 scenarios analysed 16 including for construction from 2025. The HIS was also applied to three case studies with 17 the results showing that the system outperforms HVDC from LCOS perspectives in all cases 18 and has 15-20% lower investment costs in 2 studies analysed.
Energy Essentials: A Guide to Hydrogen
Jan 2020
Publication
Climate change and air quality concerns have pushed clean energy up the global agenda. As we switch over to new cleaner technologies and fuels our experience of using power heat and transport are going to change transforming the way we live work and get from A to B. Explore this guide to find out what hydrogen is how it is made transported and used what the experience would be like in the home for transport and for businesses and discover what the future of hydrogen might be.
Visit the Energy Institute website for more information
Visit the Energy Institute website for more information
Measuring and Modelling Unsteady Radiation of Hydrogen Combustion
Sep 2005
Publication
Burning hydrogen emits thermal radiation in UV NIR and IR spectral range. Especially in the case of large cloud explosion the risk of heat radiation is commonly underestimated due to the non-visible flame of hydrogen-air combustion. In the case of a real explosion accident organic substances or inert dust might be entrained from outer sources to produce soot or heated solids to substantially increase the heat release by continuum radiation. To investigate the corresponding combustion phenomena different hydrogen-air mixtures were ignited in a closed vessel and the combustion was observed with fast scanning spectrometers using a sampling rate up to 1000 spectra/s. In some experiments to take into account the influence of organic co-combustion a spray of a liquid glycol-ester and milk powder was added to the mixture. The spectra evaluation uses the BAM code of ICT to model bands of reaction products and thus to get the temperatures. The code calculates NIR/IR-spectra (1 - 10 μm) of non-homogenous gas mixtures of H2O CO2 CO NO and HCl taking into consideration also emission of soot particles. It is based on a single line group model and makes also use of tabulated data of H2O and CO2 and a Least Squares Fit of calculated spectra to experimental ones enables the estimation of flame temperatures. During hydrogen combustion OH emits an intense spectrum at 306 nm. This intermediary radical allows monitoring the reaction progress. Intense water band systems between 1.2 and 3 μm emit remarkable amounts of heat radiation according to a measured flame temperature of 2000 K. At this temperature broad optically-thick water bands between 4.5 μm and 10 μm contribute only scarcely to the total heat output. In case of co-combustion of organic materials additional emission bands of CO and CO2 as well as a continuum radiation of soot and other particles occur and particularly increase the total thermal output drastically.
Getting Net Zero Done- The Crucial Role of Decarbonised Gas and How to Support It
May 2020
Publication
The term ‘decarbonised gas’ refers to biogases hydrogen and carbon capture utilisation and storage (CCUS). This strategy paper sets out how decarbonised gas can help to get net zero done by tackling the hard-to-decarbonise sectors – industry heavy transport and domestic heating – which together account for around 40% of UK greenhouse gas emissions. It also illustrates the crucial importance of supportive public opinion and sets out in detail how decarbonised gas can help to ensure that net zero is achieved with public support. The report is based on extensive quantitative and qualitative opinion research on climate change in general net zero emissions in the UK and the specific decarbonised gas solutions in homes transport and industry. The full quantitative data is contained in the Supplements tab.<br/><a href="https://www.dgalliance.org/wp-content/uploads/2020/05/DGA-Getting-Net-Zero-Done-final-May-2020.pdf"/><a href="https://www.dgalliance.org/wp-content/uploads/2020/05/DGA-Getting-Net-Zero-Done-final-May-2020.pdf"/>
Gas Future Scenarios Project- Final Report: A Report on a Study for the Energy Networks Association Gas Futures Group
Nov 2010
Publication
When looking out to 2050 there is huge uncertainty surrounding how gas will be consumed transported and sourced in Great Britain (GB). The extent of the climate change challenge is now widely accepted and the UK Government has introduced a legislative requirement for aggressive reductions in carbon dioxide (CO2) emissions out to 2050. In addition at European Union (EU) level a package of measures has been implemented to reduce greenhouse gas emissions improve energy efficiency and significantly increase the share of energy produced from renewable sources by 2020. These policy developments naturally raise the question of what role gas has to play in the future energy mix.
To help inform this debate the Energy Networks Association Gas Futures Group (ENA GFG) commissioned Redpoint and Trilemma to undertake a long-range scenario-based modelling study of the future utilisation of gas out to 2050 and the consequential impacts of this for gas networks. Our modelling assumptions draw heavily on the Department of Energy and Climate Change (DECC) 2050 Pathways analysis and we consider that our conclusions are fully compatible with both DECC‟s work and current EU policy objectives.
Link to document
To help inform this debate the Energy Networks Association Gas Futures Group (ENA GFG) commissioned Redpoint and Trilemma to undertake a long-range scenario-based modelling study of the future utilisation of gas out to 2050 and the consequential impacts of this for gas networks. Our modelling assumptions draw heavily on the Department of Energy and Climate Change (DECC) 2050 Pathways analysis and we consider that our conclusions are fully compatible with both DECC‟s work and current EU policy objectives.
Link to document
National Training Facility for Hydrogen Safety. Five year plan for HAMMER
Sep 2005
Publication
A suitably trained emergency response force is an essential component for safe implementation of any type of fuel infrastructure. Because of the relative newness of hydrogen as a fuel however appropriate emergency response procedures are not yet well understood by responder workforces across the United States and around the world. A significant near-term training effort is needed to ensure that the future hydrogen infrastructure can be developed and operated with acceptable incident risk. Efforts are presently underway at the HAMMER site in Washington State to develop curricula related to hydrogen properties and behavior identification of problems (e.g. incorrect equipment installation) and appropriate response and other relevant information intended for classroom instruction. In addition a number of hands-on training props are planned for realistic simulation of hydrogen incidents in order to convey proper response procedures in high-pressure cryogenic high leakage or other high-risk accident situations. Surveys of emergency responders fire marshals regulatory authorities manufacturers and others are being undertaken to ensure that the capabilities developed and offered at HAMMER will meet the acknowledged need. This paper describes the training curricula and props anticipated at HAMMER and is intended to provide useful information to others planning similar training programs.
Effect of Hydrogen–diesel Dual-fuel Usage on Performance, Emissions and Diesel Combustion in Diesel Engines
Jul 2016
Publication
Diesel engines are inevitable parts of our daily life and will be in the future. Expensive after-treatment technologies to fulfil normative legislations about the harmful tail-pipe emissions and fuel price increase in recent years created expectations from researchers for alternative fuel applications on diesel engines. This study investigates hydrogen as additive fuel in diesel engines. Hydrogen was introduced into intake manifold using gas injectors as additive fuel in gaseous form and also diesel fuel was injected into cylinder by diesel injector and used as igniter. Energy content of introduced hydrogen was set to 0% 25% and 50% of total fuel energy where the 0% references neat diesel operation without hydrogen injection. Test conditions were set to full load at 750 900 1100 1400 1750 and finally 2100 r/min engine speed. Variation in engine performance emissions and combustion characteristics with hydrogen addition was investigated. Hydrogen introduction into the engine by 25% and 50% of total charge energy reveals significant decrease in smoke emissions while dramatic increase in nitrogen oxides. With increasing hydrogen content a slight rise is observed in total unburned hydrocarbons although CO2 and CO gaseous emissions reduced considerably. Maximum in-cylinder gas pressure and rate of heat release peak values raised with hydrogen fraction.
Experimental Study on Hydrogen Explosions in a Full-scale Hydrogen Filling Station Model
Sep 2005
Publication
In order for fuel cell vehicles to develop a widespread role in society it is essential that hydrogen refuelling stations become established. For this to happen there is a need to demonstrate the safety of the refuelling stations. The work described in this paper was carried out to provide experimental information on hydrogen outflow dispersion and explosion behaviour. In the first phase homogeneous hydrogen-air-mixtures of a known concentration were introduced into an explosion chamber and the resulting flame speed and overpressures were measured. Hydrogen concentration was the dominant factor influencing the flame speed and overpressure. Secondly high-pressure hydrogen releases were initiated in a storage room to study the accumulation of hydrogen. For a steady release with a constant driving pressure the hydrogen concentration varied as the inlet airflow changed depending on the ventilation area of the room the external wind conditions and also the buoyancy induced flows generated by the accumulating hydrogen. Having obtained this basic data the realistic dispersion and explosion experiments were executed at full-scale in the hydrogen station model. High-pressure hydrogen was released from 0.8-8.0mm nozzle at the dispenser position and inside the storage room in the full-scale model of the refuelling station. Also the hydrogen releases were ignited to study the overpressures that can be generated by such releases. The results showed that overpressures that were generated following releases at the dispenser location had a clear correlation with the time of ignition distance from ignition point.
A Hydrogen-Air Explosion in a Process Plant: A Case History
Sep 2005
Publication
In the summer of 1985 a severe hydrogen-air explosion occurred in an ammonia plant in Norway. The accident resulted in two fatalities and the destruction of the building where the explosion took place. This paper presents the main findings from an investigation in 1985 and 1986 of the gas explosion and its consequences. The event started when a gasket in a water pump was blown out. The water pump was situated inside a 100 m long 10 m wide and 7 m high building. The pump was feeding water to a vessel containing hydrogen gas at pressure of 30 bars. This pressure caused a back flow of water flow through the pump and out through the failed gasket. The hydrogen reached the leakage point after about 3 minutes. The discharge of gas lasted some 20 to 30 seconds before the explosion occurred. The total mass of the hydrogen discharge was estimated at 10 to 20 kg hydrogen. The main explosion was very violent and it is likely that the gas cloud detonated. The ignition source was almost certainly a hot bearing. Several damage indicators were used to estimate the amount of hydrogen that exploded. The indicators include deflection of pipes and panels distances traveled by fragments and the distribution of glass breakage. We found that 3.5 to 7 kg of hydrogen must have been burning violently in the explosion. Window glass was broken up to 700 m from the centre of the explosion. Concrete blocks originally part of the north wall of the building and weighing 1.2 metric tons were thrown up to 16 meters. The roof of the building was lifted by an estimated 1.5 meters before resettling. The displacement of the roof caused a guillotine break of a 350 mm diameter pipe connected to the vessel that was the source of the original gas discharge. The gas composition in the vessel was 65 - 95 % hydrogen. This resulted in a large horizontal jet fire lasting about 30 seconds. Minor explosions occurred in the plant culvert system.<br/><br/>To our knowledge this gas explosion is one of the largest industrial hydrogen explosions reported. We believe this case history is a valuable reference for those who are investigating the nature of accidental<br/>hydrogen explosions.
Gas Goes Green: Delivering the Pathway to Net Zero
May 2020
Publication
Gas Goes Green brings together the engineering expertise from the UK’s five gas network operators building on the foundations of our existing grid infrastructure innovation projects and the wider scientific community. This is a blueprint to meet the challenges and opportunities of climate change delivering net zero in the most cost effective and least disruptive way possible.<br/>Delivering our vision is not just an engineering challenge but will involve active participation from policy makers regulators the energy industry and consumers. Gas Goes Green will undertake extensive engagement to deliver our programme and collaborate with existing projects already being delivered across the country.<br/>Britain’s extensive gas network infrastructure provides businesses and the public with the energy they need at the times when they need it the most. The gas we deliver plays a critical role in our everyday lives generating electricity fuelling vehicles heating our homes and providing the significant amounts of energy UK heavy industry needs. The Gas Goes Green programme aims to ensure that consumers continue to realise these benefits by transitioning our infrastructure into a net zero energy system.
Pathways to Net-Zero: Decarbonising the Gas Networks in Great Britain
Oct 2019
Publication
Natural gas plays a central role in the UK energy system today but it is also a significant source of greenhouse gas (GHG) emissions. The UK committed in 2008 to reduce GHG emissions by at least 80% compared to 1990 levels by 2050. In June 2019 a more ambitious target was adopted into law and the UK became the first major economy to commit to “net-zero” emissions by 2050. In this context the Energy Networks Association (ENA) commissioned Navigant to explore the role that the gas sector can play in the decarbonisation of the Great Britain (GB) energy system. In this report we demonstrate that low carbon and renewable gases can make a fundamental contribution to the decarbonisation pathway between now and 2050.
Explosion Characteristics of Hydrogen-air and Hydrogen-Oxygen Mixtures at Elevated Pressures
Sep 2005
Publication
An essential problem for the operation of high pressure water electrolyzers and fuel cells is the permissible contamination of hydrogen and oxygen. This contamination can create malfunction and in the worst case explosions in the apparatus and gas cylinders. In order to avoid dangerous conditions the exact knowledge of the explosion characteristics of hydrogen/air and hydrogen/oxygen mixtures is necessary. The common databases e.g. the CHEMSAFE® database published by DECHEMA BAM and PTB contains even a large number of evaluated safety related properties among other things explosion limits which however are mainly measured according to standard procedures under atmospheric conditions.<br/>Within the framework of the European research project “SAFEKINEX” and other research projects the explosion limits explosion pressures and rates of pressure rise (KG values) of H2/air and H2/O2 mixtures were measured at elevated conditions of initial pressures and temperatures by the Federal Institute of Materials Research and Testing (BAM). Empirical equations of the temperature influence could be deduced from the experimental values. An anomaly was found at the pressure influence on the upper explosion limits of H2/O2 and H2/air mixtures in the range of 20 bars. In addition explosion pressures and also rates of pressure rises have been measured for different hydrogen concentrations inside the explosion range. Such data are important for constructive explosion protection measures. Furthermore the mainly used standards for the determination of explosion limits have been compared. Therefore it was interesting to have a look at the systematic differences between the new EN 1839 tube and bomb method ASTM E 681-01 and German DIN 51649-1.
Progressing the Gas Goes Green Roadmap to Net Zero Webinar
Dec 2021
Publication
The Gas Goes Green Programme developed by the gas networks and the Energy Networks Association (ENA) describes a viable pathway to the injection of hydrogen and biomethane as a practical step towards the decarbonisation of the UK gas sector and will play a key role in the UK’s Net Zero energy strategy. It therefore follows that technical and management teams in the supply chain and related industries will need a sound understanding of the issues surrounding this deployment. This video shares the industry’s progress towards implementing the Gas Goes Green programme. Presenters including Oliver Lancaster CEO IGEM Dr Thomas Koller Programme Lead Gas Goes Green at the Energy Network Association (ENA) and Ian McCluskey CEng FIMechE FIGEM Head of Technical and Policy IGEM share their views on what has already been achieved and explain what they feel still needs to be done to develop the decarbonised gas network of tomorrow.
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