United Kingdom
Characterising the Performance of Hydrogen Sensitive Coatings for Nuclear Safety Applications
Sep 2017
Publication
The detection of hydrogen gas is essential in ensuring the safety of nuclear plants. However events at Fukushima Daiichi NPP highlighted the vulnerability of conventional detection systems to extreme events where power may be lost. Herein chemochromic hydrogen sensors have been fabricated using transition metal oxide thin films sensitised with a palladium catalyst to provide passive hydrogen detection systems that would be resilient to any plant power failures. To assess their viability for nuclear safety applications these sensors have been gamma-irradiated to four total doses (0 5 20 50 kGy) using a Co-60 gamma radioisotope. Optical properties of both un-irradiated and irradiated samples were investigated to compare the effect of increased radiation dose on the sensors resultant colour change. The results suggest that gamma irradiation at the levels examined (>5 kGy) has a significant effect on the initial colour of the thin films and has a negative effect on the hydrogen sensing abilities.
Communicating Leakage Risk in the Hydrogen Economy: Lessons Already Learned from Geoenergy Industries
Sep 2019
Publication
Hydrogen may play a crucial part in delivering a net zero emissions future. Currently hydrogen production storage transport and utilisation are being explored to scope opportunities and to reduce barriers to market activation. One such barrier could be negative public response to hydrogen technologies. Previous research around socio-technical risks finds that public acceptance issues are particularly challenging for emerging remote technical sensitive uncertain or unfamiliar technologies - such as hydrogen. Thus while the hydrogen value chain could offer a range of potential environmental economic and social benefits each will have perceived risks that could challenge the introduction and subsequent roll-out of hydrogen. These potential issues must be identified and managed so that the hydrogen sector can develop adapt or respond appropriately. Geological storage of hydrogen could present challenges in terms of perceived safety. Valuable lessons can be learned from international research and practice of CO2 and natural gas storage in geological formations (for carbon capture and storage CCS and for power respectively). Here we explore these learnings. We consider the similarities and differences between these technologies and how these may affect perceived risks. We also reflect on lessons for effective communication and community engagement. We draw on this to present potential risks to the perceived safety of - and public acceptability of – the geological storage of hydrogen. One of the key lessons learned from CCS and natural gas storage is that progress is most effective when risk communication and public acceptability is considered from the early stages of technology development.
Best Practice in Numerical Simulation and CFD Benchmarking. Results from the SUSANA Project
Sep 2017
Publication
Correct use of Computational Fluid Dynamics (CFD) tools is essential in order to have confidence in the results. A comprehensive set of Best Practice Guidelines (BPG) in numerical simulations for Fuel Cells and Hydrogen applications has been one of the main outputs of the SUSANA project. These BPG focus on the practical needs of engineers in consultancies and industry undertaking CFD simulations or evaluating CFD simulation results in support of hazard/risk assessments of hydrogen facilities as well as on the needs of regulatory authorities. This contribution presents a summary of the BPG document. All crucial aspects of numerical simulations are addressed such as selection of the physical models domain design meshing boundary conditions and selection of numerical parameters. BPG cover all hydrogen safety relative phenomena i.e. release and dispersion ignition jet fire deflagration and detonation. A series of CFD benchmarking exercises are also presented serving as examples of appropriate modelling strategies.
Promotion Effect of Proton-conducting Oxide BaZr0.1Ce0.7Y0.2O3−δ on the Catalytic Activity of Ni Towards Ammonia Synthesis from Hydrogen and Nitrogen
Aug 2018
Publication
In this report for the first time it has been observed that proton-conducting oxide BaZr0.1Ce0.7Y0.2O3−δ (BZCY) has significant promotion effect on the catalytic activity of Ni towards ammonia synthesis from hydrogen and nitrogen. Renewable hydrogen can be used for ammonia synthesis to save CO2 emission. By investigating the operating parameters of the reaction the optimal conditions for this catalyst were identified. It was found that at 620 °C with a total flow rate of 200 mL min−1 and a H2/N2 mol ratio of 3 an activity of approximately 250 μmol g−1 h−1 can be achieved. This is ten times larger than that for the unpromoted Ni catalyst under the same conditions although the stability of both catalysts in the presence of steam was not good. The specific activity of Ni supported on proton-conducting oxide BZCY is approximately 72 times higher than that of Ni supported on non-proton conductor MgO-CeO2. These promotion effects were suspected to be due to the proton conducting nature of the support. Therefore it is proposed that the use of proton conducting support materials with highly active ammonia synthesis catalysts such as Ru and Fe will provide improved activity of at lower temperatures.
Properties of the Hydrogen Oxidation Reaction on Pt/C catalysts at Optimised High Mass Transport Conditions and its Relevance to the Anode Reaction in PEFCs and Cathode Reactions in Electrolysers
Jul 2015
Publication
Using a high mass transport floating electrode technique with an ultra-low catalyst loading (0.84–3.5 μgPt cm−2) of commonly used Pt/C catalyst (HiSPEC 9100 Johnson Matthey) features in the hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) were resolved and defined which have rarely been previously observed. These features include fine structure in the hydrogen adsorption region between 0.18 < V vs. RHE < 0.36 V vs. RHE consisting of two peaks an asymptotic decrease at potentials greater than 0.36 V vs. RHE and a hysteresis above 0.1 V vs. RHE which corresponded to a decrease in the cathodic scan current by up to 50% of the anodic scan. These features are examined as a function of hydrogen and proton concentration anion type and concentration potential scan limit and temperature. We provide an analytical solution to the Heyrovsky–Volmer equation and use it to analyse our results. Using this model we are able to extract catalytic properties (without mass transport corrections; a possible source of error) by simultaneously fitting the model to HOR curves in a variety of conditions including temperature hydrogen partial pressure and anion/H+ concentration. Using our model we are able to rationalise the pH and hydrogen concentration dependence of the hydrogen reaction. This model may be useful in application to fuel cell and electrolyser simulation studies.
Modelling the UK Energy System: Practical Insights for Technology Development and Policy Making
Jun 2014
Publication
The Energy Technologies Institute (ETI) has developed an internationally peer-reviewed model of the UK’s national energy system extending across power heat transport and infrastructure. The Energy System Modelling Environment (ESME) is a policy neutral system-wide optimisation model. It models the key technology and engineering choices taking account of cost engineering spatial and temporal factors.
Key points:
Key points:
- A system-wide perspective informed by modelling is highly relevant because complex energy systems are made more inter-dependent by emissions reduction objectives
- Efforts to cut emissions are substitutable across a national energy system encompassing power heat transport and infrastructure.
- Energy systems are subject to key decision points and it is important to make the right choices in major long lived investments
- Policy makers should place policy in a system-wide context.
- Decarbonisation can be achieved affordably (at around 0.6% of GDP) provided that the most cost effective technologies and strategies to reduce emissions are deployed
- A broad portfolio of technologies is needed to deliver emissions reductions with bio-energy and carbon capture and storage of particular system-wide importance
Future Cost and Performance of Water Electrolysis: An Expert Elicitation Study
Nov 2017
Publication
The need for energy storage to balance intermittent and inflexible electricity supply with demand is driving interest in conversion of renewable electricity via electrolysis into a storable gas. But high capital cost and uncertainty regarding future cost and performance improvements are barriers to investment in water electrolysis. Expert elicitations can support decision-making when data are sparse and their future development uncertain. Therefore this study presents expert views on future capital cost lifetime and efficiency for three electrolysis technologies: alkaline (AEC) proton exchange membrane (PEMEC) and solid oxide electrolysis cell (SOEC). Experts estimate that increased R&D funding can reduce capital costs by 0–24% while production scale-up alone has an impact of 17–30%. System lifetimes may converge at around 60000–90000 h and efficiency improvements will be negligible. In addition to innovations on the cell-level experts highlight improved production methods to automate manufacturing and produce higher quality components. Research into SOECs with lower electrode polarisation resistance or zero-gap AECs could undermine the projected dominance of PEMEC systems. This study thereby reduces barriers to investment in water electrolysis and shows how expert elicitations can help guide near-term investment policy and research efforts to support the development of electrolysis for low-carbon energy systems.
Effect of Microstructural and Environmental Variables on Ductility of Austenitic Stainless Steels
Sep 2019
Publication
Austenitic stainless steels are used extensively in harsh environments including for high-pressure gaseous hydrogen service. However the tensile ductility of this class of materials is very sensitive to materials and environmental variables. While tensile ductility is generally insufficient to qualify a material for hydrogen service ductility is an effective tool to explore microstructural and environmental variables and their effects on hydrogen susceptibility to inform understanding of the mechanisms of hydrogen effects in metals and to provide insight to microstructural variables that may improve relative performance. In this study hydrogen precharging was used to simulate high-pressure hydrogen environments to evaluate hydrogen effects on tensile properties. Several austenitic stainless steels were considered including both metastable and stable alloys. Room temperature and subambient temperature tensile properties were evaluated with three different internal hydrogen contents for type 304L and 316L austenitic stainless steels and one hydrogen content for XM-11. Significant ductility loss was observed for both metastable and stable alloys suggesting the stability of the austenitic phase is not sufficient to characterize the effects of hydrogen. Internal hydrogen does influence the character of deformation which drives local damage accumulation and ultimately fracture for both metastable and stable alloys. While a quantitative description of hydrogen-assisted fracture in austenitic stainless steels remains elusive these observations underscore the importance of the hydrogen-defect interactions and the accumulation of damage at deformation length scales.
Ignited Releases of Liquid Hydrogen
Jan 2014
Publication
If the hydrogen economy is to progress more hydrogen fuelling stations are required. In the short term in the absence of a hydrogen distribution network these fuelling stations will have to be supplied by liquid hydrogen (LH2) road tanker. Such a development will increase the number of tanker offloading operations significantly and these may need to be performed in close proximity to the general public.<br/>Several research projects have been undertaken already at HSL with the aim of identifying and addressing hazards relating to the storage and transport of bulk LH2 that are associated with hydrogen refuelling stations located in urban environments.<br/>The first phase of the research was to produce a position paper on the hazards of LH2 (Pritchard and Rattigan 2009). This was published as an HSE research report RR769 in 2010. <br/>The second phase developed an experimental and modelling strategy for issues associated with LH2 spills and was published as an internal report HSL XS/10/06. The subsequent experimental work is a direct implementation of that strategy. LH2 was first investigated experimentally (Royle and Willoughby 2012 HSL XS/11/70) as large-scale spills of LH2 at a rate of 60 litres per minute. Measurements were made on unignited releases which included the concentration of hydrogen in air thermal gradients in the concrete substrate liquid pool formation and temperatures within the pool. Computational modelling on the un-ignited spills was also performed (Batt and Webber 2012 HSL MSU/12/01).<br/>The experimental work on ignited releases of LH2 detailed in this report is a direct continuation of the work performed by Royle and Willoughby.<br/>The aim of this work was to determine the hazards and severity of a realistic ignited spill of LH2 focussing on; flammability limits of an LH2 vapour cloud flame speeds through an LH2 vapour cloud and subsequent radiative heat and overpressures after ignition. The results of the experimentation will inform the wider hydrogen community and contribute to the development of more robust modelling tools. The results will also help to update and develop guidance for codes and standards.
Optimal Design and Operation of Integrated Wind-hydrogen-electricity Networks for Decarbonising the Domestic Transport Sector in Great Britain
Nov 2015
Publication
This paper presents the optimal design and operation of integrated wind-hydrogen-electricity networks using the general mixed integer linear programming energy network model STeMES (Samsatli and Samsatli 2015). The network comprises: wind turbines; electrolysers fuel cells compressors and expanders; pressurised vessels and underground storage for hydrogen storage; hydrogen pipelines and electricity overhead/underground transmission lines; and fuelling stations and distribution pipelines.<br/>The spatial distribution and temporal variability of energy demands and wind availability were considered in detail in the model. The suitable sites for wind turbines were identified using GIS by applying a total of 10 technical and environmental constraints (buffer distances from urban areas rivers roads airports woodland and so on) and used to determine the maximum number of new wind turbines that can be installed in each zone.<br/>The objective is the minimisation of the total cost of the network subject to satisfying all of the demands of the domestic transport sector in Great Britain. The model simultaneously determines the optimal number size and location of each technology whether to transmit the energy as electricity or hydrogen the structure of the transmission network the hourly operation of each technology and so on. The cost of distribution was estimated from the number of fuelling stations and length of the distribution pipelines which were determined from the demand density at the 1 km level.<br/>Results indicate that all of Britain's domestic transport demand can be met by on-shore wind through appropriately designed and operated hydrogen-electricity networks. Within the set of technologies considered the optimal solution is: to build a hydrogen pipeline network in the south of England and Wales; to supply the Midlands and Greater London with hydrogen from the pipeline network alone; to use Humbly Grove underground storage for seasonal storage and pressurised vessels at different locations for hourly balancing as well as seasonal storage; for Northern Wales Northern England and Scotland to be self-sufficient generating and storing all of the hydrogen locally. These results may change with the inclusion of more technologies such as electricity storage and electric vehicles.
Physics of Spontaneous Ignition of High-Pressure Hydrogen Release and Transition to Jet Fire
Sep 2009
Publication
The main objective of this study is an insight into physical phenomena underlying spontaneous ignition of hydrogen at sudden release from high pressure storage and its transition into the sustained jet fire. This paper describes modelling and large eddy simulation (LES) of spontaneous ignition dynamics in a tube with a rupture disk separating high pressure hydrogen storage and the atmosphere. Numerical experiments carried out by a LES model have provided an insight into the physics of the spontaneous ignition phenomenon. It is demonstrated that a chemical reaction commences in a boundary layer within the tube and propagates throughout the tube cross-section after that. Simulated by the LES model dynamics of flame formation outside the tube has reproduced experimental observation of combustion by high-speed photography including vortex induced “flame separation". It is concluded that the model developed can be applied for hydrogen safety engineering in particular for development of innovative pressure relief devices.
Hy4Heat Understanding Commercial Appliances - Work Package 5
Nov 2020
Publication
The 'Hydrogen for Heat' (Hy4Heat) programme aims to support the UK Government in its ambitions to decarbonise the UK energy sector in line with the targets of the Climate Change Act 2008 by attempting to evaluate and de-risk the natural gas to hydrogen network conversion option. The impact on the commercial sector is an important factor in understanding the feasibility of utilising hydrogen to decarbonise heat in the UK. The overall objective of the market research study Work Package 5 (WP5) was to determine if it is theoretically possible to successfully convert the commercial sector to hydrogen. This work will contribute to the understanding of the scale type and capacity of gas heating appliances within the sector providing a characterisation of the market and determining the requirements and feasibility for successfully transitioning them to hydrogen in the future.
This report and any attachment is freely available on the Hy4Heat website here. The report can also be downloaded directly by clicking on the pdf icon above
This report and any attachment is freely available on the Hy4Heat website here. The report can also be downloaded directly by clicking on the pdf icon above
Flow Loop Test for Hydrogen
Jul 2020
Publication
National Grid (NG) needs to understand the implications that a hydrogen rich gas mix may have on the existing pipeline network. The primary network consists extensively of X52 steel pipe sections welded together using girth welds. Different welding specifications that have been used in the past 40 years and girth welds with different specifications may behave differently when coming into contact with hydrogen gas.
The aim of the flow loop test programme is to begin to evaluate the durability of pipeline materials in the context of future proofing of gas grid service where the gas mix may include a significant proportion of hydrogen. One specific objective is to investigate the resistance to hydrogen embrittlement of a conventional steel (X52) with commonly used girth welds. The primary concern is that the phenomenon of hydrogen embrittlement may cause unexpected or early failure mechanisms especially in older pipe sections with less stringent girth weld specifications.
This report and any attachment is freely available on the ENA Smarter Networks Portal here. IGEM Members can download the report and any attachment directly by clicking on the pdf icon above.
The aim of the flow loop test programme is to begin to evaluate the durability of pipeline materials in the context of future proofing of gas grid service where the gas mix may include a significant proportion of hydrogen. One specific objective is to investigate the resistance to hydrogen embrittlement of a conventional steel (X52) with commonly used girth welds. The primary concern is that the phenomenon of hydrogen embrittlement may cause unexpected or early failure mechanisms especially in older pipe sections with less stringent girth weld specifications.
This report and any attachment is freely available on the ENA Smarter Networks Portal here. IGEM Members can download the report and any attachment directly by clicking on the pdf icon above.
Vapour Cloud Explosions from the Ignition of Methane, Hydrogen, Air Mixtures in a Congested Region
Sep 2007
Publication
To facilitate the transition to the hydrogen economy the EU project NATURALHY is studying the potential for the existing natural gas pipeline networks to transport hydrogen together with natural gas to end-users. Hydrogen may then be extracted for hydrogen fuel-cell applications or the mixture used directly by consumers in existing gas-fired equipment with the benefit of lower carbon emissions. The existing gas pipeline networks are designed constructed and operated to safely transport natural gas mostly methane. However hydrogen has significantly different properties that may adversely affect both the integrity of the network and thereby increase the likelihood of an accidental leak and the consequences if the leak finds a source of ignition. Consequently a major part of the NATURALHY project is focused on assessing how much hydrogen could be introduced into the network without adversely impacting on the safety of the network and the risk to the public. Hydrogen is more reactive than natural gas so the severity of an explosion following an accidental leak may be increased. This paper describes field-scale experiments conducted to measure the overpressures generated by ignition of methane/hydrogen/air mixtures in a congested but unconfined region. Such regions may be found in the gas handling and metering stations of the pipeline networks. The 3 m x 3 m x 2 m high congested region studied contained layers of pipes. The composition of the methane/hydrogen mixture used was varied from 0% hydrogen to 100% hydrogen. On the basis of the experiments performed the maximum overpressures generated by methane/hydrogen mixtures with 25% (by volume) or less hydrogen content are not likely to be much more than those generated by methane alone. Greater percentages of hydrogen did significantly increase the explosion overpressure.
Hydrogen and Fuel Cell Stationary Applications: Key Findings of Modelling and Experimental Work in the Hyper Project
Sep 2009
Publication
Síle Brennan,
A. Bengaouer,
Marco Carcassi,
Gennaro M. Cerchiara,
Andreas Friedrich,
O. Gentilhomme,
William G. Houf,
N. Kotchourko,
Alexei Kotchourko,
Sergey Kudriakov,
Dmitry Makarov,
Vladimir V. Molkov,
Efthymia A. Papanikolaou,
C. Pitre,
Mark Royle,
R. W. Schefer,
G. Stern,
Alexandros G. Venetsanos,
Anke Veser,
Deborah Willoughby,
Jorge Yanez and
Greg H. Evans
"This paper summarises the modelling and experimental programme in the EC FP6 project HYPER. A number of key results are presented and the relevance of these findings to installation permitting guidelines (IPG) for small stationary hydrogen and fuel cell systems is discussed. A key aim of the activities was to generate new scientific data and knowledge in the field of hydrogen safety and where possible use this data as a basis to support the recommendations in the IPG. The structure of the paper mirrors that of the work programme within HYPER in that the work is described in terms of a number of relevant scenarios as follows: 1. high pressure releases 2. small foreseeable releases 3. catastrophic releases and 4. the effects of walls and barriers. Within each scenario the key objectives activities and results are discussed.<br/>The work on high pressure releases sought to provide information for informing safety distances for high-pressure components and associated fuel storage activities on both ignited and unignited jets are reported. A study on small foreseeable releases which could potentially be controlled through forced or natural ventilation is described. The aim of the study was to determine the ventilation requirements in enclosures containing fuel cells such that in the event of a foreseeable leak the concentration of hydrogen in air for zone 2 ATEX is not exceeded. The hazard potential of a possibly catastrophic hydrogen leakage inside a fuel cell cabinet was investigated using a generic fuel cell enclosure model. The rupture of the hydrogen feed line inside the enclosure was considered and both dispersion and combustion of the resulting hydrogen air mixture were examined for a range of leak rates and blockage ratios. Key findings of this study are presented. Finally the scenario on walls and barriers is discussed; a mitigation strategy to potentially reduce the exposure to jet flames is to incorporate barriers around hydrogen storage equipment. Conclusions of experimental and modelling work which aim to provide guidance on configuration and placement of these walls to minimise overall hazards is presented. "
Hydrogen Releases Ignited in a Simulated Vehicle Refuelling Environment
Sep 2007
Publication
If the general public is to use hydrogen as a vehicle fuel customers must be able to handle hydrogen with the same degree of confidence and with comparable risk as conventional liquid and gaseous fuels. The hazards associated with jet releases from leaks in a vehicle-refuelling environment must be considered if hydrogen is stored and used as a high-pressure gas since a jet release in a confined or congested area could result in an explosion. As there was insufficient knowledge of the explosion hazards a study was initiated to gain a better understanding of the potential explosion hazard consequences associated with high-pressure leaks from refuelling systems. This paper describes two experiments with a dummy vehicle and dispenser units to represent refuelling station congestion. The first represents a ‘worst-case’ scenario where the vehicle and dispensers are enveloped by a 5.4 m x 6.0 m x 2.5 m high pre-mixed hydrogen-air cloud. The second is an actual high-pressure leak from storage at 40 MPa (400 bar) representing an uncontrolled full-bore failure of a vehicle refuelling hose. In both cases an electric spark ignited the flammable cloud. Measurements were made of the explosion overpressure generated its evolution with time and its decay with distance. The results reported provide a direct demonstration of the explosion hazard from an uncontrolled leak; they will also be valuable for validating explosion models that will be needed to assess configurations and conditions beyond those studied experimentally.
Numerical Simulation of Detonation Failure and Re-initiation in Bifurcated Tubes
Oct 2015
Publication
A numerical approach is developed to simulate detonation propagation attenuation failure and re-initiation in hydrogen–air mixture. The aim is to study the condition under which detonations may fail or re-initiate in bifurcated tubes which is important for risk assessment in industrial accidents. A code is developed to solve compressible multidimensional transient reactive Navier–Stokes equations. An Implicit Large Eddy Simulation approach is used to model the turbulence. The code is developed and tested to ensure both deflagrations (when detonation fails) and detonations are simulated correctly. The code can correctly predict the flame properties as well as detonation dynamic parameters. The detonation propagation predictions in bifurcated tubes are validated against the experimental work of Wang et al. [12] and found to be in good agreement with experimental observations.
Smart Systems and Heat: Decarbonising Heat for UK homes
Nov 2015
Publication
Around 20% of the nation’s carbon emissions are generated by domestic heating. Analysis of the many ways the energy system might be adapted to meet carbon targets shows that the elimination of emissions from buildings is more cost effective than deeper cuts in other energy sectors such as transport. This effectively means that alternatives need to be found for domestic natural gas heating systems. Enhanced construction standards are ensuring that new buildings are increasingly energy efficient but the legacy building stock of around 26 million homes has relatively poor thermal performance and over 90% are expected to still be in use in 2050. Even if building replacement was seen as desirable the cost is unaffordable and the carbon emissions associated with the construction would be considerable.
YouTube link to accompanying video
YouTube link to accompanying video
FutureGrid: Project Progress Report
Dec 2021
Publication
The facility will be built from a range of decommissioned transmission assets to create a representative whole-network which will be used to trial hydrogen and will allow for accurate results to be analysed. Blends of hydrogen up to 100% will then be tested at transmission pressures to assess how the assets perform.<br/>The hydrogen research facility will remain separate from the main National Transmission System allowing for testing to be undertaken in a controlled environment with no risk to the safety and reliability of the existing gas transmission network.<br/>Ofgem’s Network Innovation Competition will provide £9.07m of funding with the remaining amount coming from the project partners.<br/>The aim is to start construction in 2021 with testing beginning in 2022.
The Importance of Economies of Scale, Transport Costs and Demand Patterns in Optimising Hydrogen Fuelling Infrastructure: An Exploration with SHIPMod (Spatial Hydrogen Infrastructure Planning Model)
Jul 2013
Publication
Hydrogen is widely recognised as an important option for future road transportation but a widespread infrastructure must be developed if the potential for hydrogen is to be achieved. This paper and related appendices which can be downloaded as Supplementary material present a mixed-integer linear programming model (called SHIPMod) that optimises a hydrogen supply chains for scenarios of hydrogen fuel demand in the UK including the spatial arrangement of carbon capture and storage infrastructure. In addition to presenting a number of improvements on past practice in the literature the paper focuses attention on the importance of assumptions regarding hydrogen demand. The paper draws on socio-economic data to develop a spatially detailed scenario of possible hydrogen demand. The paper then shows that assumptions about the level and spatial dispersion of hydrogen demand have a significant impact on costs and on the choice of hydrogen production technologies and distribution mechanisms.
Numerical Modelling of Hazards of Hydrogen Storage
Sep 2017
Publication
For the general public to use hydrogen as a vehicle fuel they must be able to handle hydrogen with the same degree of confidence as conventional liquid and gaseous fuels. The hazards associated with jet releases from accidental leaks in a vehicle-refuelling environment must be considered if hydrogen is stored and used as a high-pressure gas since a jet release can result in a fire or explosion. This paper describes the work done by us in modelling some of the consequences of accidental releases of hydrogen implemented in our Fire Explosion Release Dispersion (FRED) software. The new dispersion model is validated against experimental data available in the open literature. The model predictions of hydrogen gas concentration as a function of distance are in good agreement with experiments. In addition FRED has been used to model the consequence of the bursting of a vessel containing compressed hydrogen. The results obtained from FRED i.e. overpressure as a function of distance match well in comparison to experiments. Overall it is concluded that FRED can model the consequences of an accidental release of hydrogen and the blast waves generated from bursting of vessel containing compressed hydrogen
Modelling of Hydrogen Jet Fires Using CFD
Sep 2011
Publication
The computational fluid dynamics (CFD) software FLACS has primarily been developed to model dispersion and explosion phenomena; however models for the simulation of jet fires are under development. The aim is to be able to predict industrial fires efficiently and with good precision. Newly developed models include e.g. flame models for non-premixed flames discrete transfer radiation model as well as soot models. Since the time scales for fire simulations are longer than for explosions the computational speed is important. The recent development of non-compressible and parallel solvers in FLACS may therefore be important to ensure efficiency. Hydrogen flames may be invisible will generate no soot and tend to radiate less than hydrocarbon fuels. Due to high pressure storage the flame lengths can be significant. Simpler jet flame relations can not predict the jet flame interaction with objects and barriers and thus the heat loads on impacted objects. The development of efficient and precise CFD-tools for hydrogen fires is therefore important. In this paper the new models for the simulation of fire are described. These models are currently under development and this manuscript describes the current status of the work. Jet fire experiments performed by Health and Safety Laboratories (HSL) both free jets and impinging jets will also be simulated to evaluate the applicability and validity of the new fire models.
Development of a Hydrogen and Fuel Cell Vehicle Emergency Response National Template
Sep 2013
Publication
The California Fuel Cell Partnership (CaFCP) is currently working with key stakeholders like the US Department of Energy (DOE) and National Fire Protection Association (NFPA) to develop a national template for educating and training first responders about hydrogen fuel cell-powered vehicles (FCV) and hydrogen fuelling infrastructure. Currently there are several existing programs that either have some related FCV/hydrogen material or have plans to incorporate this in the future. To create a robust national emergency responder (ER) program the strongest elements from these existing programs are considered for incorporation into the template. Working with the key stakeholders the national template will be evaluated on a regular basis to ensure accurate and up to date information and resources and effective teaching techniques for the emergency response community. This paper describes the evaluation process discusses elements of the template and reports on the steps and progress to implementation; all in the effort to effectively support the emergency response community as hydrogen infrastructure develops and FCVs are leased or sold.
Ia-HySafe Standard Benchmark Exercise Sbep-V21- Hydrogen Release and Accumulation within a Non-Ventilated Ambient Pressure Garage at Low Release Rates
Sep 2011
Publication
The successful Computational Fluid Dynamics (CFD) benchmarking activity originally started within the EC-funded Network of Excellence HySafe (2004-2009) continues within the research topics of the recently established “International Association of Hydrogen Safety” (IA-HySafe). The present contribution reports the results of the standard benchmark problem SBEP-V21. Focus is given to hydrogen dispersion and accumulation within a non-ventilated ambient pressure garage both during the release and post-release periods but for very low release rates as compared to earlier work (SBEP-V3). The current experiments were performed by CEA at the GARAGE facility under highly controlled conditions. Helium was vertically released from the centre of the 5.76 m (length) x 2.96 m (width) x 2.42 m (height) facility 22 cm from the floor from a 29.7 mm diameter opening at a volumetric rate of 18 L/min (0.027 g/s equivalent hydrogen release rate compared to 1 g/s for SBEP-V3) and for a period of 3740 seconds. Helium concentrations were measured with 57 catharometric sensors at various locations for a period up to 1.1 days. The simulations were performed using a variety of CFD codes and turbulence models. The paper compares the results predicted by the participating partners and attempts to identify the reasons for any observed disagreements.
Numerical Simulation of Diverging Detonation in Hydrogen Air Mixtures
Oct 2015
Publication
Propagation and stability of diverging cylindrical detonation in hydrogen air mixture is numerically simulated and the mechanism of the transverse waves is analysed. For the numerical modelling a new solver based on compressible transient reactive Navier–Stokes equations is developed which can the simulate detonation propagation and extinction in hydrogen-air mixture. A single step reaction mechanism is tuned to ensure the detonation and deflagration properties (in case of detonation failure) can be simulated accurately. The solver is used for modelling various detonation scenarios in particular cylindrical diverging-detonations because most of accidental industrial detonations start from a spark and then a diverging-detonation propagates outwards. The diverging detonation its cellular structure and adoption with the increased surface area at the detonation front as well as interactions with obstacles leading to detonation failure and re-initiation are studied.
Numerical Simulation of Deflagration-to-detonation Transition in Hydrogen-air Mixtures with Concentration Gradients
Oct 2015
Publication
Flame acceleration in inhomogeneous combustible gas mixture has largely been overlooked despite being relevant to many accidental scenarios. The present study aims to validate our newly developed density-based solver ExplosionFoam for flame acceleration and deflagration-to-detonation transition. The solver is based on the open source computational fluid dynamics (CFD) platform OpenFOAM®. For combustion it uses the hydrogen-air single-step chemistry and the corresponding transport coefficients developed by the authors. Numerical simulations have been conducted for the experimental set up of Ettner et al. [1] which involves flame acceleration and DDT in both homogeneous hydrogen-air mixture as well as an inhomogeneous mixture with concentration gradients in an obstucted channel. The predictions demonstrate good quantitative agreement with the experimental measurements in flame tip position speed and pressure profiles. Qualitatively the numerical simulations reproduce well the flame acceleration and DDT phenomena observed in the experiment. The results have shown that in the computed cases DDT is induced by the interaction of the precursor inert shock wave with the wall close to high hydrogen concentration rather than with the obstacle. Some vortex pairs appear ahead of the flame due to the interaction between the obstacles and the gas flow caused by combustion-induced expansion but they soon disappear after the flame passes through them. Hydrogen cannot be completely consumed especially in the fuel rich region. This is of additional safety concern as the unburned hydrogen can potentially re-ignite once more fresh air is available in an accidental scenario causing subsequent explosions. The results demonstrate the potential of the newly developed density based solver for modelling flame acceleration and DDT in both homogeneous/inhomogeneous hydrogen-air mixture. Further validation needs to be carried out for other mixtures and large-scale cases.
Modelling and Simulation of High-pressure Hydrogen Jets Using H2FC European Cyber-laboratory
Oct 2015
Publication
The Hydrogen and Fuel Cell (H2FC) European research infrastructure cyber-laboratory is a software suite containing ‘modelling’ and ‘engineering’ tools encompassing a wide range of H2FC processes and systems. One of the core aims of the H2FC Cyber-laboratory has been the creation of a state-of-the-art hydrogen CFD modelling toolbox. This paper describes the implementation and validation of this new CFD modelling toolbox in conjunction with a selection of the available ‘Safety’ engineering tools to analyse a high pressure hydrogen release and dispersion scenario. The experimental work used for this validation was undertaken by Shell and the Health and Safety Laboratory (UK). The overall goal of this work is to provide and make readily available a Cyber-laboratory that will be worth maintaining after the end of the H2FC project for the benefit of both the FCH scientific community and industry. This paper therefore highlights how the H2FC Cyber-laboratory which is offered as an open access platform can be used to replicate and analyse real-world scenarios using both numerical engineering tools and through the implementation of CFD modelling techniques.
Safe Operation of Combined Cycle Gas Turbine and Gas Engine Systems Using Hydrogen Rich Fuels
Oct 2015
Publication
This paper describes work performed by a consortium led by the UK Health and Safety Laboratory(HSL)to identify the safe operating conditions for combined cycle power generating systems running on high hydrogen fuels. The work focuses on hydrogen and high hydrogen syngas and biogas waste-stream fuel mixtures which may prove hazardous in the event of a turbine or engine flame out resulting in a flammable fuel mixture entering the hot exhaust system and igniting. The paper describes the project presenting some initial results from this work including the development of large scale experimental facilities on the550 acre HSL site near Buxton Derbyshire UK. It describes the large scale experimental facility which utilises the exhaust gas from a Rolls-Royce Viper jet-engine (converted to run on butane) feeding into a 12 m long 0.60 m diameter instrumented tube at a pre-combustion velocity of 22 m/s. A variable geometry simulated heat exchanger with a 40 %2blockage ratio is present in the tube. Flammable mixtures injected into the tube close to the Viper outlet together with make-up oxygen are then ignited. Extensive optical ionisation temperature and pressure sensors are employed along the length of the tube to measure the pressures and flame speeds resulting from the combustion event. Some preliminary results from the test programme are discussed including deflagration to detonation transitions at high equivalence ratios.
A Comparison Exercise on the CFD Detonation Simulation in Large Scale Confined Volumes
Sep 2009
Publication
The use of hydrogen as an energy carrier is going to widen exponentially in the next years. In order to ensure the public acceptance of the new fuel not only the environmental impact has to be excellent but also the risk management of its handling and storage must be improved. As a part of modern risk assessment procedure CFD modeling of the accident scenario development must provide reliable data on the possible pressure loads resulted from explosion processes. The expected combustion regimes can be ranged from slow flames to deflagration-to-detonation transition and even to detonation. In the last case the importance of the reliability of simulation results is particularly high since detonation is usually considered as a worst case state of affairs. A set of large-scale detonation experiments performed in Kurchatov Institute at RUT facility was selected as benchmark. RUT has typical industry-relevant characteristic dimensions. The CFD codes possibilities to correctly describe detonation in mixtures with different initial and boundary conditions were surveyed. For the modeling two detonation tests HYD05 and HYD09 were chosen; both tests were carried out in uniform hydrogen/air mixtures; first one with concentration of 20.0% vol. and the second one with 25.5% vol. In the present exercise three CFD codes using a number of different models were used to simulate these experiments. A thorough inter-comparison between the CFD results including codes models and obtained pressure predictions was carried out and reported. The results of this inter comparison should provide a solid basis for the further code development and detonation models’ validation thus improving CFD predictive capabilities.
Hydrogen Venting Under Variable Flow Conditions
Sep 2011
Publication
Safety distances for hydrogen plumes are currently derived using models developed for hydrocarbon releases. It is well known that hydrogen behaves in a significantly different manner to that of hydrocarbons when released to atmosphere. There are two main aspects involved with the development of safety distances for credible hydrogen releases; the intensity of the thermal radiation from such a plume should it be ignited and the distance downwind from the release point to the point where a flammable mixture with air no longer exists. A number of distinct areas of venting behaviour were investigated; Thermal radiation from ignited plumes from vertical open ended vent pipes Far field radiation measurements for direct comparison with models Thermal radiation from ignited plumes from vertical vent pipes terminating in a T-piece Thermal radiation measurements from ignited hydrogen with a 45 vent termination Hydrogen concentration measurements with a T-piece.
Analysis of Wind to Hydrogen Production and Carbon Capture Utilisation and Storage Systems for Novel Production of Chemical Energy Carriers
Apr 2022
Publication
As the offshore energy landscape transitions to renewable energy useful decommissioned or abandoned oil and gas infrastructure can be repurposed in the context of the circular economy. Oil and gas platforms for example offer opportunity for hydrogen (H2) production by desalination and electrolysis of sea water using offshore wind power. However as H2 storage and transport may prove challenging this study proposes to react this H2 with the carbon dioxide (CO2) stored in depleted reservoirs. Thus producing a more transportable energy carriers like methane or methanol in the reservoir. This paper presents a novel thermodynamic analysis of the Goldeneye reservoir in the North Sea in Aspen Plus. For Goldeneye which can store 30 Mt of CO2 at full capacity if connected to a 4.45 GW wind farm it has the potential to produce 2.10 Mt of methane annually and abate 4.51 Mt of CO2 from wind energy in the grid.
Self-ignition of Hydrogen-nitrogen Mixtures During High-pressure Release Into Air
Oct 2015
Publication
This paper demonstrates experimental and numerical study on spontaneous ignition of H2–N2 mixtures during high-pressure release into air through the tubes of various diameters and lengths. The mixtures included 5% and 10% (vol.) N2 addition to hydrogen being at initial pressure in range of 4.3–15.9 MPa. As a point of reference pure hydrogen release experiments were performed with use of the same experimental stand experimental procedure and extension tubes. The results showed that N2 addition may increase the initial pressure necessary to self-ignite the mixture as much as 2.12 or 2.85 – times for 5% and 10% N2 addition respectively. Additionally simulations were performed with use of Cantera code (0-D) based on the ideal shock tube assumption and with the modified KIVA3V code (2-D) to establish the main factors responsible for ignition and sustained combustion during the release.
Integration of Experimental Facilities: A Joint Effort for Establishing a Common Knowledge Base in Experimental Work on Hydrogen Safety
Sep 2009
Publication
With regard to the goals of the European HySafe Network research facilities are essential for the experimental investigation of relevant phenomena for testing devices and safety concepts as well as for the generation of validation data for the various numerical codes and models. The integrating activity ‘Integration of Experimental Facilities (IEF)’ has provided basic support for jointly performed experimental work within HySafe. Even beyond the funding period of the NoE HySafe in the 6th Framework Programme IEF represents a long lasting effort for reaching sustainable integration of the experimental research capacities and expertise of the partners from different research fields. In order to achieve a high standard in the quality of experimental data provided by the partners emphasis was put on the know-how transfer between the partners. The strategy for reaching the objectives consisted of two parts. On the one hand a documentation of the experimental capacities has been prepared and analysed. On the other hand a communication base has been established by means of biannual workshops on experimental issues. A total of 8 well received workshops has been organised covering topics from measurement technologies to safety issues. Based on the information presented by the partners a working document on best practice including the joint experimental knowledge of all partners with regard to experiments and instrumentation was created. Preserving the character of a working document it was implemented in the IEF wiki website which was set up in order to provide a central communication platform. The paper gives an overview of the IEF network activities over the last 5 years.
Pressure Effects of an Ignited Release from Onboard Storage in a Garage with a Single Vent
Sep 2017
Publication
This work is driven by the need to understand the hazards resulting from the rapid ignited release of hydrogen from onboard storage tanks through a thermally activated pressure relief device (TPRD) inside a garage-like enclosure with low natural ventilation i.e. the consequences of a jet fire which has been immediately ignited. The resultant overpressure is of particular interest. Previous work [1] focused on an unignited release in a garage with minimum ventilation. This initial work demonstrated that high flow rates of unignited hydrogen through a thermally activated pressure relief device (TPRD) in ventilated enclosures with low air change per hour can generate overpressures above the limit of 10- 15 kPa which a typical civil structure like a garage could withstand. This is due to the pressure peaking phenomenon. Both numerical and phenomenological models were developed for an unignited release and this has been recently validated experimentally [2]. However it could be expected that the majority of unexpected releases through a TPRD may be ignited; leading to even greater overpressures and to date whilst there has been some work on fires in enclosures the pressure peaking phenomenon for an ignited release has yet to be studied or compared with that for an equivalent unignited release. A numerical model for ignited releases in enclosures has been developed and computational fluid dynamics has then been used to examine the pressure dynamics of an ignited hydrogen release in a real scale garage. The scenario considered involves a high mass flow rate release from an onboard hydrogen storage tank at 700 bar through a 3.34 mm diameter orifice representing the TPRD in a small garage with a single vent equivalent in area to small window. It is shown that whilst this vent size garage volume and TPRD configuration may be considered “safe” from overpressures in the event of an unignited release the overpressure resulting from an ignited release is two orders of magnitude greater and would destroy the structure. Whilst further investigation is needed the results clearly indicate the presence of a highly dangerous situation which should be accounted for in regulations codes and standards. The hazard relates to the volume of hydrogen released in a given timeframe thus the application of this work extends beyond TPRDs and is relevant where there is a rapid ignited release of hydrogen in an enclosure with limited ventilation.
Guidelines and Recommendations for Indoor Use of Fuel Cells and Hydrogen Systems
Oct 2015
Publication
Deborah Houssin-Agbomson,
Simon Jallais,
Elena Vyazmina,
Guy Dang-Nhu,
Gilles Bernard-Michel,
Mike Kuznetsov,
Vladimir V. Molkov,
Boris Chernyavsky,
Volodymyr V. Shentsov,
Dmitry Makarov,
Randy Dey,
Philip Hooker,
Daniele Baraldi,
Evelyn Weidner,
Daniele Melideo,
Valerio Palmisano,
Alexandros G. Venetsanos,
Jan Der Kinderen and
Béatrice L’Hostis
Hydrogen energy applications often require that systems are used indoors (e.g. industrial trucks for materials handling in a warehouse facility fuel cells located in a room or hydrogen stored and distributed from a gas cabinet). It may also be necessary or desirable to locate some hydrogen system components/equipment inside indoor or outdoor enclosures for security or safety reasons to isolate them from the end-user and the public or from weather conditions.<br/>Using of hydrogen in confined environments requires detailed assessments of hazards and associated risks including potential risk prevention and mitigation features. The release of hydrogen can potentially lead to the accumulation of hydrogen and the formation of a flammable hydrogen-air mixture or can result in jet-fires. Within Hyindoor European Project carried out for the EU Fuel Cells and Hydrogen Joint Undertaking safety design guidelines and engineering tools have been developed to prevent and mitigate hazardous consequences of hydrogen release in confined environments. Three main areas are considered: Hydrogen release conditions and accumulation vented deflagrations jet fires and including under-ventilated flame regimes (e.g. extinguishment or oscillating flames and steady burns). Potential RCS recommendations are also identified.
Operation of UK Gas Appliances with Hydrogen Blended Natural Gas
Sep 2019
Publication
The HyDeploy project has undertaken a programme of work to assess the effect of hydrogen addition on the safety and performance of gas appliances and installations. A representative set of eight appliances have been assessed in laboratory experiments with a range of test gases that explored high and low Wobbe Number and hydrogen concentrations up to 28.4 % mol/mol. Tests have demonstrated that the addition of hydrogen does not affect the key hazard areas of CO production light back flame out or the operation of flame failure devices. It was identified that for some designs of gas fire appliances the operation of the oxygen depletion sensors may be affected by the addition of hydrogen and further studies in this area are planned. A laboratory based study was supported by an onsite testing programme where 133 installations were assessed for gas tightness appliance combustion safety and operation against normal line natural gas G20 reference gas and two hydrogen blended gases. Where installations were gas tight for natural gas analysis showed that no additional leakage occurred with hydrogen blended gases. There were also no issues identified with the combustion performance of appliances and onsite results were in line with those obtained in the laboratory testing programme.
Computational Analysis of Hydrogen Diffusion in Polycrystalline Nickel and Anisotropic Polygonal Micro, Nano Grain Size Effects
Sep 2013
Publication
The effect of irregular polygonal grain size and random grain boundary on hydrogen diffusion in polycrystalline nickel is investigated. Hydrogen diffusion behavior in micropolycrystalline nickel is compared with that in nanopolycrystalline nickel through numerical analysis. The two dimensional computational finite element microstructural and nanostructural analyses are based on Fick's law corresponding to heterogeneous polycrystalline model geometry. The heterogeneous polycrystalline model consists of random irregular polygonal grains. These grains are divided into internal grain and grain boundary regions the size of which is determined from the grain size. The computational analysis results show that hydrogen diffusion in nanostructural irregular polycrystalline nickel is higher in magnitude than the microstructural irregular polycrystalline nickel. However models of voids traps and micro and nano clustered grains are yet to be included.
Vented Hydrogen Deflagrations in an ISO Container
Sep 2017
Publication
The commercial deployment of hydrogen will often involve housing portable hydrogen fuel cell power units in 20-foot or 40-foot shipping containers. Due to the unique properties of hydrogen hazards identification and consequence analysis is essential to safe guard the installations and design measures to mitigate potential hazards. In the present study the explosion of a premixed hydrogen-air cloud enclosed in a 20-foot container of 20’ x 8’ x 8’.6” is investigated in detail numerically. Numerical simulations have been performed using HyFOAM a dedicated solver for vented hydrogen explosions developed in-house within the frame of the open source computational fluid dynamics (CFD) code OpenFOAM toolbox. The flame wrinkling combustion model is used for modelling turbulent deflagrations. Additional sub-models have been added to account for lean combustion properties of hydrogen-air mixtures. The predictions are validated against the recent experiments carried out by Gexcon as part of the HySEA project supported by the Fuel Cells and Hydrogen 2 Joint Undertaking (FCH 2 JU) under the Horizon 2020 Framework Programme for Research and Innovation. The effects of congestion within the containers on the generated overpressures are also investigated.
Socio-economic Analysis and Quantitative Risk Assessment Methodology for Safety Design of Onboard Storage Systems
Sep 2017
Publication
Catastrophic rupture of onboard hydrogen storage in a fire is a safety concern. Different passive e.g. fireproofing materials the thermally activated pressure relief device (TPRD) and active e.g. initiation of TPRD by fire sensors safety systems are being developed to reduce hazards from and associated risks of high-pressure hydrogen storage tank rupture in a fire. The probability of such low-frequency highconsequences event is a function of fire resistance rating (FRR) i.e. the time before tank without TPRD ruptures in a fire the probability of TPRD failure etc. This safety issue is “confirmed” by observed recently cases of CNG tanks rupture due to blocked or failed to operate TPRD etc. The increase of FRR by any means decreases the probability of tank rupture in a fire particularly because of fire extinction by first responders on arrival at an accident scene.<br/>This study of socio-economic effects of safety applies a quantitative risk assessment (QRA) methodology to an example of hydrogen vehicles with passive tank protection system on roads in London.<br/>The risk is defined here through the cost of human loss per fuel cell hydrogen vehicle (FCHV) fire accident and fatality rate per FCHV per year. The first step in the methodology is the consequence analysis based on validated deterministic engineering tools to estimate the main identified hazards: overpressure in the blast wave at different distances and the thermal hazards from a fireball in the case of catastrophic tank rupture in a fire. The population can be exposed to slight injury serious injury and fatality after an accident. These effects are determined based on criteria by Health and Safety Executive (UK) and a cost metrics is applied to the number of exposed people in these three harm categories to estimate the cost per an accident. The second step in the methodology is either the frequency or the probability analysis. Probabilities of a vehicle fire and failure of the thermally activated pressure relief device are taken from published sources. A vulnerability probit function is employed to calculate the probability of emergency operations’ failure to prevent tank rupture as a function of a storage tank FRR and time of fire brigade arrival. These later results are integrated to estimate the tank rupture frequency and fatality rate. The risk is presented as a function of fire resistance rating.<br/>The QRA methodology allows to calculate the cost of human loss associated with an FCHV fire accident and demonstrates how the increase of FRR of onboard storage as a safety engineering measure would improve socio-economics of FCHV deployment and public acceptance of the technology.
Mn-based Borohydride Synthesized by Ball-milling KBH4 and MnCl2 for Hydrogen Storage
Dec 2013
Publication
In this work a mixed-cation borohydride (K2Mn(BH4)4) with P21/n structure was successfully synthesized by mechanochemical milling of the 2KBH4–MnCl2 sample under argon. The structural and thermal decomposition properties of the borohydride compounds were investigated using XRD Raman spectroscopy FTIR TGA-MS and DSC. Apart from K2Mn(BH4)4 the KMnCl3 and unreacted KBH4 compounds were present in the milled 2KBH4–MnCl2. The two mass loss regions were observed for the milled sample: one was from 100 to 160 °C with a 1.6 ± 0.1 wt% loss (a release of majority hydrogen and trace diborane) which was associated with the decomposition of K2Mn(BH4)4 to form KBH4 boron and finely dispersed manganese; the other was from 165 to 260 °C with a 1.9 ± 0.1 wt% loss (only hydrogen release) which was due to the reaction of KBH4 with KMnCl3 to give KCl boron finely dispersed manganese. Simultaneously the formed KCl could dissolve in KBH4 to yield a K(BH4)xCl1−x solid solution and also react with KMnCl3 to form a new compound K4MnCl6.
Numerical Modelling of Flame Acceleration and Transition to Detonation in Hydrogen & Air Mixtures with Concentration Gradient
Sep 2017
Publication
Hydrogen gas explosions in homogeneous reactive mixtures have been widely studied both experimentally and numerically. However in practice combustible mixtures are usually inhomogeneous and subject to both vertical and horizontal concentration gradients. There is still very limited understanding of the hydrogen explosion characteristics in such situations. The present numerical investigation aims to study the effect of mixture concentration gradient on the process of Deflagration to Detonation Transition and the effect of different hydrogen concentration gradient in the obstructed channel of hydrogen/air mixtures. An obstructed channel with 30% blockage ratio (BR=30) and three different average hydrogen concentrations of 20 % 30% and 35% have been considered using a specially developed density-based solver within the OpenFOAM toolbox. A high-resolution grid was built with the using adaptive mesh refinement technique providing 10 grid points in half reaction length. The numerical results are in reasonably good agreement with the experimental observations [1]. These studies show that the concentration gradient has a considerable effect on the accelerated flame tip speed and the location of transition to detonation in the obstructed channel. In all the three cases the first localised explosion occurred near the bottom wall where the shock and flame interacted and the mixture was most lean; and the second localised explosion occurred at the top wall due to the reflection of shock and flame front and later develops to form the leading detonation wave. The increase in the fuel concentration was found to increase the flame acceleration (FA) and having a faster transition to detonation.
Safety Issues of the Liquefaction, Storage and Transportation of Liquid Hydrogen
Sep 2013
Publication
The objectives of the IDEALHY project which receives funding from the European Union’s 7th Framework Programme (FP7/2007-2013) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement No. 278177 are to design a novel process that will significantly increase the efficiency of hydrogen liquefaction and be capable of delivering liquid hydrogen at a rate that is an order of magnitude greater than current plants. The liquid hydrogen could then be delivered to refueling stations in road tankers. As part of the project the safety management of the new large scale process and the transportation of liquid hydrogen by road tanker into urban areas are being considered. Effective safety management requires that the hazards are identified and well understood. This paper describes the scope of the safety work within IDEALHY and presents the output of the work completed so far. Initially a review of available experimental data on the hazards posed by releases of liquid hydrogen was undertaken which identified that generally there is a dearth of data relevant to liquid hydrogen releases. Subsequently HAZIDs have been completed for the new liquefaction process storage of liquid hydrogen and its transportation by road. This included a review of incidents relevant to these activities. The principal causes of the incidents have been analysed. Finally the remaining safety work for the IDEALHY project is outlined.
Calibration of Hydrogen Coriolis Flow Meters Using Nitrogen and Air and Investigation of the Influence of Temperature on Measurement Accuracy
Feb 2021
Publication
The performance of four Coriolis flow meters designed for use in hydrogen refuelling stations was evaluated with air and nitrogen by three members of the MetroHyVe JRP consortium; NEL METAS and CESAME EXADEBIT.<br/>A wide range of conditions were tested overall with gas flow rates ranging from (0.05–2) kg/min and pressures ranging from (20–86) bar. The majority of tests were conducted at nominal pressures of either 20 bar or 40 bar in order to match the density of hydrogen at 350 bar and 20 °C or 700 bar and −40 °C. For the conditions tested pressure did not have a noticeable influence on meter performance.<br/>When the flow meters were operated at ambient temperatures and within the manufacturer's recommended flow rate ranges errors were generally within ±1%. Errors within ±0.5% were achievable for the medium to high flow rates.<br/>The influence of temperature on meter performance was also studied with testing under both stable and transient conditions and temperatures as low as −40 °C.<br/>When the tested flow meters were allowed sufficient time to reach thermal equilibrium with the incoming gas temperature effects were limited. The magnitude and spread of errors increased but errors within ±2% were achievable at moderate to high flow rates. Conversely errors as high as 15% were observed in tests where logging began before temperatures stabilised and there was a large difference in temperature between the flow meter and the incoming gas.<br/>One of the flow meters tested with nitrogen was later installed in a hydrogen refuelling station and tested against the METAS Hydrogen Field Test Standard (HFTS). Under these conditions errors ranged from 0.47% to 0.91%. Testing with nitrogen at the same flow rates yielded errors of −0.61% to −0.82%.
Hydrogen and Decarbonisation of Gas- False Dawn or Silver Bullet?
Mar 2020
Publication
This Insight continues the OIES series considering the future of gas. The clear message from previous papers is that on the (increasingly certain) assumption that governments in major European gas markets remain committed to decarbonisation targets the existing natural gas industry is under threat. It is therefore important to develop a decarbonisation narrative leading to a low- or zero-carbon gas implementation plan.
Previous papers have considered potential pathways for gas to decarbonise specifically considering biogas and biomethane and power-to-gas (electrolysis) . This paper goes on to consider the potential for production transport and use of hydrogen in the decarbonising energy system. Previous papers predominately focused on Europe which has been leading the way in decarbonisation. Hydrogen is now being considered more widely in various countries around the world so this paper reflects that wider geographical coverage.
Since the term ‘hydrogen economy’ was first used in 1970 there have been a number of ‘false dawns’ with bold claims for the speed of transition to hydrogen. This Insight argues that this time for some applications at least there are grounds for optimism about a future role for decarbonised hydrogen but the lesson from history is that bold claims need to be examined carefully and treated with some caution. There are no easy or low-cost solutions to decarbonisation of the energy system and this is certainly the case for possible deployment of low-carbon hydrogen. A key challenge is to demonstrate the technical commercial economic and social acceptability of various possibilities at scale. Hydrogen will certainly play a role in decarbonisation of the energy system although the size of the role may be more limited than envisaged in some more optimistic projections.
Open document on OIES website
Previous papers have considered potential pathways for gas to decarbonise specifically considering biogas and biomethane and power-to-gas (electrolysis) . This paper goes on to consider the potential for production transport and use of hydrogen in the decarbonising energy system. Previous papers predominately focused on Europe which has been leading the way in decarbonisation. Hydrogen is now being considered more widely in various countries around the world so this paper reflects that wider geographical coverage.
Since the term ‘hydrogen economy’ was first used in 1970 there have been a number of ‘false dawns’ with bold claims for the speed of transition to hydrogen. This Insight argues that this time for some applications at least there are grounds for optimism about a future role for decarbonised hydrogen but the lesson from history is that bold claims need to be examined carefully and treated with some caution. There are no easy or low-cost solutions to decarbonisation of the energy system and this is certainly the case for possible deployment of low-carbon hydrogen. A key challenge is to demonstrate the technical commercial economic and social acceptability of various possibilities at scale. Hydrogen will certainly play a role in decarbonisation of the energy system although the size of the role may be more limited than envisaged in some more optimistic projections.
Open document on OIES website
HyDeploy Report: Gas Characteristics (Leakage, Dispersion and Flammability)
Sep 2018
Publication
The Health and Safety Laboratory (HSL) has carried out an investigation into the gas characteristics that may influence the leakage dispersion and flammability hazards associated with blended natural gas-hydrogen mixtures containing up to 20 % mol/mol hydrogen. The work was carried out under contract to Cadent & Northern Gas Networks as part of the HyDeploy project which was commissioned to investigate the feasibility of using blended hydrogen-natural gas mixtures in UK mains gas distribution networks.
Under the HyDeploy project a demonstration scheme is being carried out at Keele University in which it is planned to inject up to 20 % mol/mol hydrogen. Keele is Britain’s largest campus university and an ideal test site for a demonstration scheme as its gas distribution network is largely independent of the national gas network but still subject to UK gas industry procedural controls. It is anticipated that a successful demonstration scheme will facilitate the use of blended natural gas-hydrogen mixtures throughout the UK leading to significant reductions in carbon dioxide emissions. The project is being led by Cadent & Northern Gas Networks and also involves ITM Power Progressive Energy Keele University and HSL in consortium.
Click the supplements tab to view the other documents in this report
Under the HyDeploy project a demonstration scheme is being carried out at Keele University in which it is planned to inject up to 20 % mol/mol hydrogen. Keele is Britain’s largest campus university and an ideal test site for a demonstration scheme as its gas distribution network is largely independent of the national gas network but still subject to UK gas industry procedural controls. It is anticipated that a successful demonstration scheme will facilitate the use of blended natural gas-hydrogen mixtures throughout the UK leading to significant reductions in carbon dioxide emissions. The project is being led by Cadent & Northern Gas Networks and also involves ITM Power Progressive Energy Keele University and HSL in consortium.
Click the supplements tab to view the other documents in this report
HyDeploy Report: Quantitative Risk Assessment of the Field Trial of Hydrogen Injection into the Keele University Gas Distribution System
Oct 2018
Publication
A consortium comprising Cadent Northern Gas Networks Keele University Health and Safety Laboratory ITM Power and Progressive Energy is undertaking the research project HyDeploy. The project funded under the UK Network Innovation Competition scheme aims to demonstrate that natural gas containing levels of hydrogen beyond the upper limit set out in Schedule 3 of in the Gas Safety (Management) Regulations (GSMR) can be distributed and utilised safely and efficiently in a section of the UK distribution network. It will conclude with a field trial in which hydrogen will be injected into part of a private gas distribution system owned and operated by Keele University. Dave Lander Consulting Limited and Kiwa Ltd are providing technical support to the HyDeploy project and this report presents the results of Quantified Risk Assessment (QRA) for the proposed field trial. The QRA is intended to support an application by Keele University for exemption from the legal requirement to only convey gas that is compliant with the requirements of Schedule 3 of the GSMR. The QRA is aimed at demonstrating that the field trial will not result in a material increase in risk to persons within Keele University affected by the proposed field trial.<br/>Check the supplements tab for the other documents from this report
Zero-In on NI-Heat Exploring Pathways Towards Heat Decarbonisation in Northern Ireland
Jul 2020
Publication
Northern Ireland has achieved its 2020 targets in the electricity sector ahead of time with 46.8% of its electricity demand supplied by renewable generators. When it comes to heat the progress is less impressive – 68% of domestic heating is provided by oil and only around 2500 customers use low carbon heat generators in their homes. In addition 22% of consumers live in fuel poverty. Fuel poverty support programmes still propose the replacement of old oil boilers with new models or with gas boilers where a connection to the grid is possible.<br/>Failure of the commercial RHI scheme and the knock-on effect of the closure of the domestic RHI scheme caused significant damage to the industry and to the reputation of low carbon heat technologies leaving NI consumers without any explicit supporting mechanisms for low carbon heat supply. Decreases in carbon emissions from the heat sector are mainly achieved through switching from oil to gas heating. Gas infrastructure is under development in NI and promises to reach 60% of customers by 2022.
H21- Consumer and Gas Network Metering Phase 1: A Review of the Worldwide Hydrogen Meter Technologies and Applications
Feb 2018
Publication
There is no inherent property of hydrogen that makes it unsuitable for metering at distribution or transmission pressures. Towns gas containing large percentages of hydrogen was used for many years in the UK and continues to be in use in Hong Kong and Singapore. Many manufacturers sell their ordinary mechanical gas meters as suitable for hydrogen in a laboratory or industrial situation; unfortunately lack of demand has meant that none of these meters seem to have certified under appropriate metering regulations for gaseous hydrogen (e.g. the Measuring Instruments Directive)<br/>Some of the more sophisticated modern inferential meters (e.g. thermal or ultrasonic) currently designed specifically for natural gas (or LPG if suitably calibrated) are likely to unsuitable for repurposing directly to hydrogen but none of the problems appear fundamental or insuperable. The largest potential hurdle probably surrounds the physical size of current meters. A hydrogen appliance will consume about 3.3 more hydrogen than natural gas (on a volumetric basis) and using traditional designs this would have been measured through a meter probably too large to fit within an existing meter box. Unless unsolved such an increase in size would add materially to any hydrogen re-purposing programme.<br/>The meter trade thus need to be challenged to come up with a hydrogen meter that is the same physical size as a natural gas meter on a power rating basis (i.e. in kW). Ultrasonic and thermal mass meters should be included in the necessary Research and Development programme.<br/>A meter test programme is suggested that will provide evidence to meter manufacturers that the metering of hydrogen is not inherently difficult and thus convince them to make the necessary investments and/or approach the GDNO’s for assistance with such a programme.
HyDeploy Report: Keele Information
Jun 2018
Publication
Keele University was chosen as the site for the HyDeploy project as it was seen as the site offered a high degree of control regarding safety functions high availability of operational data and minimal supply chain interfaces given that Keele University is the supplier transporter and distributer of natural gas at the site. The site was offered to the project as a living laboratory in line with the university's ambition to be at the forefront of energy innovation through the Smart Energy Network Demonstrator (SEND). Evidenced within this report is the supporting data that confirms the rationale for selecting Keele University and the necessary data to profile the section of the gas network which hydrogen will be injected into. The gas network at Keele University is segregated via the governor stations which regulate pressure within the network. The section of network which has been chosen for the HyDeploy project is the G3 network which is regulated by the G3 governor.
Hydrogen Gas Quality for Gas Network Injection: State of the Art of Three Hydrogen Production Methods
Jun 2021
Publication
The widescale distribution of hydrogen through gas networks is promoted as a viable and cost-efficient option for optimising its application in heat industry and transport. It is a key step towards achieving decarbonisation targets in the UK. A key consideration before the injection of hydrogen into the UK gas networks is an assessment of the difference in hydrogen contaminants presence from different production methods. This information is essential for gas regulation and for further purification requirements. This study investigates the level of ISO 14687 Grade D contaminants in hydrogen from steam methane reforming proton exchange membrane water electrolysis and alkaline electrolysis. Sampling and analysis of hydrogen were carried out by the National Physical Laboratory following ISO 21087 guidance. The results of analysis indicated the presence of nitrogen in hydrogen from electrolysis and water carbon dioxide and particles in all samples analysed. The contaminants were at levels below or at the threshold limits set by ISO 14687 Grade D. This indicates that the investigated production methods are not a source of contaminants for the eventual utilisation of hydrogen in different applications including fuel cell electric vehicles (FCEV’s). The gas network infrastructure will require a similar analysis to determine the likelihood of contamination to hydrogen gas.
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