United Kingdom

The formation of a flammable hydrogen-air mixture is a major safety concern especially for closed space. This hazardous situation can arise when considering permeation from a car equipped with a composite compressed hydrogen tank with a non-metallic liner in a closed garage. In the following paper a scenario is developed and analysed with a simplified approach and a numerical simulation in order to estimate the evolution of hydrogen concentration. The system is composed of typical size garage and hydrogen car’s tank. Some parameters increasing permeation rate (i.e. tank’s material thickness and pressure) have been chosen to have a conservative approach. A close look on the top of tank surface showed that the concentration grows as square root of time and does not exceed 8.2×10-3 % by volume. Also a simplified comparative analysis estimated that the buoyancy of hydrogen-air mixture prevails on the diffusion 35 seconds after permeation starts in good agreement with simulation where time is at about 80 seconds. Finally the numerical simulations demonstrated that across the garage height the hydrogen is nearly distributed linearly and the difference in hydrogen concentration at the ceiling and floor is negligible (i.e. 3×10-3 %).

The UK government has committed to reducing greenhouse gas emissions to net zero by 2050. All future energy modelling identifies a key role for hydrogen (linked to CCUS) in providing decarbonised energy for heat transport industry and power generation. Blending hydrogen into the existing natural gas pipeline network has already been proposed as a means of transporting low carbon energy. However the expectation is that a gas blend with maximum hydrogen content of 20 mol% can be used without impacting consumers’ end use applications. Therefore a transitional solution is needed to achieve a 100% hydrogen future network.

Deblending (i.e. separation of the blended gas stream) is a potential solution to allow the existing gas transmission and distribution network infrastructure to transport energy as a blended gas stream. Deblending can provide either hydrogen natural gas or blended gas for space heating transport industry and power generation applications. If proven technically and economically feasible utilising the existing gas transmission and distribution networks in this manner could avoid the need for investment in separate gas and hydrogen pipeline networks during the transition to a future fully decarbonised gas network.

The Energy Network Association (ENA) “Gas Goes Green” programme identifies deblending could play a critical role in the transition to a decarbonised gas network. Gas separation technologies are well-established and mature and have been used and proven in natural gas processing for decades. However these technologies have not been used for bulk gas transportation in a transmission and distribution network setting. Some emerging hydrogen separation technologies are currently under development. The main hydrogen recovery and purification technologies currently deployed globally are:

• Cryogenic separation
• Membrane separation
• Pressure Swing Adsorption (PSA)

The technologies noted above require an energy input to drive the separation of gas components in the form of compression to provide a pressure differential. The configuration of the GB gas transmission and distribution networks provides a possible source of available energy through the pressure let-down in the network pressure tiers which could be used to drive the gas component separation processes. This study evaluated the gas separation technologies noted above against a selection of case studies based on actual network operating conditions to assess the technical andeconomic feasibility of hydrogen deblending in the GB gas network context. This study constitutes the first stage (proof of concept) in a programme of works that should provide the critical evidence for hydrogen deblending as a necessary component to enable the use of GB gas networks to transport and distribute hydrogen.

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.

This work presents the results of the Standard Benchmark Exercise Problem (SBEP) V20 of Work Package 6 (WP6) of HySafe Network of Excellence (NoE) co-funded by the European Commission in the frame of evaluating the quality and suitability of codes models and user practices by comparative assessments of code results. The benchmark problem SBEP-V20 covers release scenarios that were experimentally investigated in the past using helium as a substitute to hydrogen. The aim of the experimental investigations was to determine the ventilation requirements for parking hydrogen fuelled vehicles in residential garages. Helium was released under the vehicle for 2 h with 7.200 l/h flow rate. The leak rate corresponded to a 20% drop of the peak power of a 50 kW fuel cell vehicle. Three double vent garage door geometries are considered in this numerical investigation. In each case the vents are located at the top and bottom of the garage door. The vents vary only in height. In the first case the height of the vents is 0.063 m in the second 0.241 m and in the third 0.495 m. Four HySafe partners participated in this benchmark. The following CFD packages with the respective models were applied to simulate the experiments: ADREA-HF using k–ɛ model by partner NCSRD FLACS using k–ɛ model by partner DNV FLUENT using k–ɛ model by partner UPM and CFX using laminar and the low-Re number SST model by partner JRC. This study compares the results predicted by the partners to the experimental measurements at four sensor locations inside the garage with an attempt to assess and validate the performance of the different numerical approaches.

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.

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

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.

For the UK to meet their national target of net zero emissions as part of the central Paris Agreement target further emphasis needs to be placed on decarbonizing public transport and moving away from personal transport (conventionally fuelled vehicles (CFVs) and electric vehicles (EVs)). Electric buses (EBs) and hydrogen buses (HBs) have the potential to fulfil requirements if powered from low carbon renewable energy sources.

A comparison of carbon dioxide (CO₂) emissions produced from conventionally fuelled buses (CFB) EBs and HBs between 2017 and 2050 under four National Grid electricity scenarios was conducted. In addition emissions per person at different vehicle capacity levels (100% 75% 50% and 25%) were projected for CFBs HBs EBs and personal transport assuming a maximum of 80 passengers per bus and four per personal vehicle.

Results indicated that CFVs produced 30 g CO₂km⁻¹ per person compared to 16.3 g CO₂ km⁻¹ per person by CFBs by 2050. At 100% capacity under the two-degree scenario CFB emissions were 36 times higher than EBs 9 times higher than HBs and 12 times higher than EVs in 2050. Cumulative emissions under all electricity scenarios remained lower for EBs and HBs.

Policy makers need to focus on encouraging a modal shift from personal transport towards sustainable public transport primarily EBs as the lowest level emitting vehicle type. Simple electrification of personal vehicles will not meet the required targets. Simultaneously CFBs need to be replaced with EBs and HBs if the UK is going to meet emission targets.

The Energy Systems Catapult (ESC) explored the role of households in a net-zero emissions society to accompany the CCC’s Net Zero report looking at opportunities and challenges for households to reduce emissions from today’s levels and to support the stretch from an 80% emissions reduction to a net-zero greenhouse gas target. As well as describing a net-zero emissions world for households of different types the ESC looked at average household emissions under different decarbonisation scenarios and the options households can take to contribute to the decarbonisation effort.

This supported the Net Zero Technical report.

In this paper CFD techniques were applied to the simulations of hydrogen release from a 400-bar tank to ambient through a Pressure Relieve Device (PRD) 6 mm (¼”) opening. The numerical simulations using the TOPAZ software developed by Sandia National Laboratory addressed the changes of pressure density and flow rate variations at the leak orifice during release while the PHOENICS software package predicted extents of various hydrogen concentration envelopes as well as the velocities of gas mixture for the dispersion in the domain. The Abel-Noble equation of state (AN-EOS) was incorporated into the CFD model implemented through the TOPAZ and PHOENICS software to accurately predict the real gas properties for hydrogen release and dispersion under high pressures. The numerical results were compared with those obtained from using the ideal gas law and it was found that the ideal gas law overestimates the hydrogen mass release rates by up to 35% during the first 25 seconds of release. Based on the findings the authors recommend that a real gas equation of state be used for CFD predictions of high-pressure PRD releases.

The manuscript firstly describes the data collection and validation process for the European Hydrogen Incidents and Accidents Database (HIAD 2.0) a public repository tool collecting systematic data on hydrogen-related incidents and near-misses. This is followed by an overview of HIAD 2.0 which currently contains 706 events. Subsequently the approaches and procedures followed by the authors to derive lessons learned and formulate recommendations from the events are described. The lessons learned have been divided into four categories including system design; system manufacturing installation and modification; human factors and emergency response. An overarching lesson learned is that minor events which occurred simultaneously could still result in serious consequences echoing James Reason's Swiss Cheese theory. Recommendations were formulated in relation to the established safety principles adapted for hydrogen by the European Hydrogen Safety Panel considering operational modes industrial sectors and human factors. This work provide an important contribution to the safety of systems involving hydrogen benefitting technical safety engineers emergency responders and emergency services. The lesson learned and the discussion derived from the statistics can also be used in training and risk assessment studies being of equal importance to promote and assist the development of sound safety culture in organisations.

The modelling of Rayleigh–Taylor instability during premixed combustion scenarios is presented. Experimental data obtained from experiments undertaken by FM Global using their large-scale vented deflagration chamber was used to develop the modelling approach. Rayleigh–Taylor instability is introduced as an additional time-dependent combustion enhancing mechanism. It is demonstrated that prior to the addition of this mechanism the LES deflagration model under-predicted the experimental pressure transients. It is confirmed that the instability plays a significant role throughout the coherent deflagration process. The addition of the mechanism led to the model more closely replicating the pressure peak associated with the external deflagration.

This technical report accompanies the ‘Net Zero’ advice report which is the Committee’s recommendation to the UK Government and Devolved Administrations on the date for a net-zero emissions target in the UK and revised long-term targets in Scotland and Wales.<br/>The conclusions in our advice report are supported by detailed analysis that has been carried out for each sector of the economy plus consideration of F-gas emissions and greenhouse gas removals. The purpose of this technical report is to lay out that analysis.

The Committee’s report ‘The compatibility of UK onshore petroleum with meeting the UK’s carbon budgets’ is the result of a new duty under the Infrastructure Act 2015. This duty requires the CCC to advise the Secretary of State for Energy and Climate Change about the implications of exploitation of onshore petroleum including shale gas for meeting UK carbon budgets.<br/>The CCC’s report finds that the implications of UK shale gas exploitation for greenhouse gas emissions are subject to considerable uncertainty – from the size of any future industry to the potential emissions footprint of shale gas production. It also finds that exploitation of shale gas on a significant scale is not compatible with UK carbon budgets or the 2050 commitment to reduce emissions by at least 80% unless three tests are satisfied.

This is the Committee’s 2020 report to Parliament assessing progress in reducing UK emissions over the past year. This year the report includes new advice to the UK Government on securing a green and resilient recovery following the COVID-19 pandemic. The Committee’s new analysis expands on its May 2020 advice to the UK Prime Minister in which it set out the principles for building a resilient recovery. In its new report the Committee has assessed a wide set of measures and gathered the latest evidence on the role of climate policies in the economic recovery. Its report highlights five clear investment priorities in the months ahead:

• Low-carbon retrofits and buildings that are fit for the future
• Tree planting peatland restoration and green infrastructure
• Energy networks must be strengthened
• Infrastructure to make it easy for people to walk cycle and work remotely
• Moving towards a circular economy.

There are also opportunities to support the transition and the recovery by investing in the UK’s workforce and in lower-carbon behaviours and innovation:

• Reskilling and retraining programmes
• Leading a move towards positive behaviours
• Targeted science and innovation funding

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.

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.

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.

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

Over the last century there have been reports of high pressure hydrogen leaks igniting for no apparent reason and several ignition mechanisms have been proposed. Although many leaks have ignited there are also reported leaks where no ignition has occurred. Investigations of ignitions where no apparent ignition source was present have often been superficial with a mechanism postulated which whilst appearing to satisfy the conditions prevailing at the time of the release simply does not stand up to rigorous scientific analysis. Some of these proposed mechanisms have been simulated in a laboratory under superficially identical conditions and appear to be rigorous and scientific but the simulated conditions often do not have the same large release rates or quantities mainly because of physical constraints of a laboratory. Also some of the release scenarios carried out or simulated in laboratories are totally divorced from the realistic situation of most actual leaks. Clearly there are gaps in the knowledge of the exact ignition mechanism for releases of hydrogen particularly at the high pressures likely to be involved in future storage and use. Mechanisms which have been proposed in the past are the reverse Joule-Thomson effect; electrostatic charge generation; diffusion ignition; sudden adiabatic compression; and hot surface ignition. Of these some have been characterized by means of computer simulation rather than by actual experiment and hence are not validated. Consequently there are discrepancies between the theories releases known to have ignited and releases which are known to have not ignited. From this postulated ignition mechanisms which are worthy of further study have been identified and the gaps in information have been highlighted. As a result the direction for future research into the potential for ignition of hydrogen escapes has been identified.

This report sets out our advice on the fifth carbon budget covering the period 2028-2032 as required under Section 4 of the Climate Change Act; the Government will propose draft legislation for the fifth budget in summer 2016.

As part of its statutory role the Committee provides annual reports to Parliament on the progress that Government is making in meeting carbon budgets and in reducing emissions of greenhouse gases.<br/>Meeting Carbon Budgets – ensuring a low-carbon recovery is the Committee’s 2nd progress report. Within this report we assess the latest emissions data and determine whether emissions reductions have occurred as a result of the recession or as a result of other external factors. We assess Government’s progress towards achieving emissions reductions in 4 key areas of: Power Buildings and Industry Transport and Agriculture.

This report for the CCC by Madano and Element Energy assesses the public acceptability of two alternative low-carbon technologies for heating the home: hydrogen heating and heat pumps.

These technologies could potentially replace natural gas in many UK households as part of the government’s efforts to decrease carbon emissions in the UK.

The report’s key findings are:

• carbon emissions reduction is viewed as an important issue but there is limited awareness of the need to decarbonise household heating or the implications of switching over to low-carbon heating technologies
• acceptability of both heating technologies is limited by a lack of perceived tangible consumer benefit which has the potential to drive scepticism towards the switch over more generally
• heating technology preferences are not fixed at this stage although heat pumps appear to be the favoured option in this research studythree overarching factors were identified as influencing preferences for heating technologies.

These factors manifested differently for different people meaning that the same factor could lead one person to prefer heat pumps and another to prefer hydrogen depending on their overall heating preferences and understanding of the two technologies. The factors are:

• perceptions of the negative installation burden
• familiarity with the lived experience of using the technologies for heating
• perceptions of how well the technologies would meet modern heating needs both hydrogen heating and heat pumps face significant challenges to secure public acceptability

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.

This paper presents a compilation of the results supplied by HySafe partners participating in the Standard Benchmark Exercise Problem (SBEP) V2 which is based on an experiment on hydrogen combustion that is first described. A list of the results requested from participants is also included. The main characteristics of the models used for the calculations are compared in a very succinct way by using tables. The comparison between results together with the experimental data when available is made through a series of graphs. The results show quite good agreement with the experimental data. The calculations have demonstrated to be sensitive to computational domain size and far field boundary condition.

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