United Kingdom

It is now well established that electrochemical systems can optimally perform only within a narrow range of temperature. Exposure to temperatures outside this range adversely affects the performance and lifetime of these systems. As a result thermal management is an essential consideration during the design and operation of electrochemical equipment and can heavily influence the success of electrochemical energy technologies. Recently significant attempts have been placed on the maturity of cooling technologies for electrochemical devices. Nonetheless the existing reviews on the subject have been primarily focused on battery cooling. Conversely heat transfer in other electrochemical systems commonly used for energy conversion and storage has not been subjected to critical reviews. To address this issue the current study gives an overview of the progress and challenges on the thermal management of different electrochemical energy devices including fuel cells electrolysers and supercapacitors. The physicochemical mechanisms of heat generation in these electrochemical devices are discussed in-depth. Physics of the heat transfer techniques currently employed for temperature control are then exposed and some directions for future studies are provided.

An  inter-comparison  among  partners’  CFD  simulations  has  been  carried  out  within  the  EU-funded project PRESLHY to investigate the dispersion of the mixture cloud formed from large scale liquid hydrogen release. Rainout experiments performed by Health and Safety Executive (HSE) have been chosen for the work. From the HSE experimental series trial-11 was selected forsimulation due to its conditions where  only  liquid  flow  at  the  nozzle  was  achieved.   During  trial-11  liquid  hydrogen  is spilled horizontally 0.5 m above a concrete pad from a 5 barg tank pressure through a 12 mm (1/2 inch) nozzle. The dispersion takes place outdoors and thus it is imposed to variant wind conditions. Comparison  of  the  CFD  results  with  the   measurements  at  several  sensors  is  presented  and  useful conclusions are drawn.

More effective energy production requires a greater penetration of storage technologies. This paper takes a looks at and compares the landscape of energy storage devices. Solutions across four categories of storage namely: mechanical chemical electromagnetic and thermal storage are compared on the basis of energy/power density specific energy/power efficiency lifespan cycle life self-discharge rates capital energy/power costs scale application technical maturity as well as environmental impact. It’s noted that virtually every storage technology is seeing improvements. This paper provides an overview of some of the problems with existing storage systems and identifies some key technologies that hold promise.

The advocacy narrative of the European Union gas community which focused on coal to gas switching and backing up renewables has failed to convince governments NGOs and media commentators that it can achieve post-2030 decarbonisation targets. The gas community therefore needs to develop decarbonisation narratives showing how it will develop commercial scale projects for biogas biomethane and hydrogen from power to gas (electrolysis) and reformed methane. COP21 carbon targets require an accelerating decline in EU methane demand starting around 2030. In 2050 the maximum projected availability of renewable gas is equivalent to 25 per cent of current EU gas demand. Maintaining current demand levels will therefore require very substantial volumes of hydrogen from reformed methane with carbon capture and storage (CCS). Pipeline gas and LNG suppliers will need to progressively decarbonise their product if it is to remain saleable in Europe. However networks face an existential threat unless they can maintain existing throughput while simultaneously adapting to a decarbonised product. Significant threats and challenges to these narratives include: short term geopolitical concerns stemming from dependence on Russian gas ‘hydrocarbon rejectionism’ and an inability of companies to invest for a post-2030 decarbonised future. Governments will need to shift current policy and regulatory frameworks from competition to decarbonisation which will require a ‘regulatory revolution’. In addition to government funding and regulatory support there will need to be very substantial corporate investment in projects for which there is currently no business case. Failure of the gas community to create and deliver credible decarbonisation narratives is likely to result in the adoption of electrification rather than gas decarbonisation options.

In the last couple of years there has been increasing recognition by key players in the European gas industry that to mitigate the risk of terminal decline in the context of a decarbonising energy system there will need to be rapid scale up of decarbonised gas. This has led to several projections of the scale of decarbonised gas which could potentially be supplied by 2030 2040 or 2050. This paper joint with the Sustainable Gas Institute at Imperial College London considers the very significant rate of scale up and the significant cost reductions contemplated by such projections.  Based on a database of actual announced projects (both committed and in earlier stages of development) for production of decarbonised gas it then considers the extent to which project activity is consistent with meeting the ambitious projections. It identifies a significant gap in current levels of activity largely because there is not yet sufficient economic incentive for investors to develop the required projects. It is intended that this paper will form the basis of continued tracking of the level of activity over the coming years to help inform industry players of further actions which may be required.

Hydrogen is receiving increasing attention as a versatile energy vector to help accelerate the transition to a decarbonised energy future. Gas turbines will continue to play a critical role in providing grid stability and resilience in future low-carbon power systems; however it is recognised that this role is contingent upon achieving increased thermal efficiencies and the ability to operate on carbon-neutral fuels such as hydrogen. An important consideration in the development of gas turbine combustors capable of operating with pure hydrogen or hydrogen-enriched natural gas are the significant changes in thermoacoustic instability characteristics associated with burning these fuels. This article provides a review of the effects of burning hydrogen on combustion dynamics with focus on swirl-stabilised lean-premixed combustors. Experimental and numerical evidence suggests hydrogen can have either a stabilising or destabilising impact on the dynamic state of a combustor through its influence particularly on flame structure and flame position. Other operational considerations such as the effect of elevated pressure and piloting on combustion dynamics as well as recent developments in micromix burner technology for 100% hydrogen combustion have also been discussed. The insights provided in this review will aid the development of instability mitigation strategies for high hydrogen combustion.

Proposed sustainable transition pathways for moving away from natural gas in domestic heating focus on two main energy vectors: electricity and hydrogen. Electrification would be implemented by using vapourcompression heat pumps which are currently experiencing market growth in many countries. On the other hand hydrogen could substitute natural gas in boilers or be used in thermally–driven absorption heat pumps. In this paper a consistent thermodynamic and economic methodology is developed to assess the competitiveness of these options. The three technologies along with the option of district heating are for the first time compared for different weather/ambient conditions and fuel-price scenarios first from a homeowner’s and then from a wholeenergy system perspective. For the former two-dimensional decision maps are generated to identify the most cost-effective technologies for different combinations of fuel prices. It is shown that in the UK hydrogen technologies are economically favourable if hydrogen is supplied to domestic end-users at a price below half of the electricity price. Otherwise electrification and the use of conventional electric heat pumps will be preferred. From a whole-energy system perspective the total system cost per household (which accounts for upstream generation and storage as well as technology investment installation and maintenance) associated with electric heat pumps varies between 790 and 880 £/year for different scenarios making it the least-cost decarbonisation pathway. If hydrogen is produced by electrolysis the total system cost associated with hydrogen technologies is notably higher varying between 1410 and 1880 £/year. However this total system cost drops to 1150 £/year with hydrogen produced cost-effectively by methane reforming and carbon capture and storage thus reducing the gap between electricity- and hydrogen-driven technologies.

These two joint reports required under the Environment (Wales) Act 2016 provide ministers with advice on Wales’ climate targets between now and 2050 and assess progress on reducing emissions to date. Our advice to the Welsh Government is set out in two parts:

Advice Report: The path to a Net Zero Wales provides recommendations on the actions that are needed in Wales including the legislation of a Net Zero target and package of policies to deliver it.

Progress Report: Reducing emissions in Wales looks back at the progress made in Wales since the 2016 Environment (Wales) Act was passed and assesses whether Wales is on track to meet its currently legislated emissions reductions targets.

This work is based on an extensive programme of analysis consultation and consideration by the Committee and its staff building on the evidence published last year for our Net Zero report. It is compatible with our advice on the UK’s Sixth Carbon Budget. In support of the advice in this report we have also published:

• All the charts and data behind the report as well as a separate dataset for the scenarios which sets out more details and data on the pathways than can be included in this report.
• A public Call for Evidence several new research projects three expert advisory groups and deep dives into the roles of local authorities and businesses.

Power to hydrogen (P2H) provides a promising solution to the geographic mismatch between sources of renewable energy and the market due to its technological maturity flexibility and the availability of technical and economic data from a range of active demonstration projects. In this review we aim to provide an overview of the status of P2H analyze its technical barriers and solutions and propose potential opportunities for future research and industrial demonstrations. We specifically focus on the transport of hydrogen via natural gas pipeline networks and end-user purification. Strong evidence shows that an addition of about 10% hydrogen into natural gas pipelines has negligible effects on the pipelines and utilization appliances and may therefore extend the asset value of the pipelines after natural gas is depleted. To obtain pure hydrogen from hydrogen-enriched natural gas (HENG) mixtures end-user separation is inevitable and can be achieved through membranes adsorption and other promising separation technologies. However novel materials with high selectivity and capacity will be the key to the development of industrial processes and an integrated membrane-adsorption process may be considered in order to produce high-purity hydrogen from HENG. It is also worth investigating the feasibility of electrochemical separation (hydrogen pumping) at a large scale and its energy analysis. Cryogenics may only be feasible when liquefied natural gas (LNG) is one of the major products. A range of other technological and operational barriers and opportunities such as water availability byproduct (oxygen) utilization and environmental impacts are also discussed. This review will advance readers’ understanding of P2H and foster the development of the hydrogen economy.

The building system is one of key energy consumption sector in the market and low-carbon building will make a significant contribution for the worldwide carbon emission reduction. The multiple energy systems including renewable generations hydrogen energy and energy storage is the perspective answer to the net-zero building system. However the research gap lies in the synergy power management among the renewable flexible loads batteries and hydrogen energy systems and at the same time taking the unique characteristic of different energy sectors into account by power managing. This paper proposed the power management approach based on the game theory by which the different characteristics of the energy players are described via creating the competing relationship against net-zero emission objective so that to achieve the power synergy. Under the proposed power management method the hydrogen and battery hybrid system including the fuel cell electrolyzer and battery is designed and investigated as to unlock the power management regions and control constraints within the building system. Particularly for the hydrogen system within the hybrid system the safe and long-lifetime operation is considered respectively by high-efficiency and pressure constraints within the power management. Simulation results show that providing the same energy storage services for the building system the fuel cell with the proposed power management method sustains for 9.9 years much longer than that of equivalent consumption minimization (4.98) model predictive control (4.61) and rule-based method (7.69). Moreover the maximum tank temperature of the hydrogen tank is reduced by 3.4 K and 2.9 K compared with consumption minimization strategy and model predictive control. Also the real-time of the proposed power management is verified by a scaled-down experiment platform.

The Hy4Heat Safety Assessment has focused on assessing the safe use of hydrogen gas in certain types of domestic properties and buildings. The summary reports (the Precis and the Safety Assessment Conclusions Report) bring together all the findings of the work and should be looked to for context by all readers. The technical reports should be read in conjunction with the summary reports. While the summary reports are made as accessible as possible for general readers the technical reports may be most accessible for readers with a degree of technical subject matter understanding. All of the safety assessment reports have now been reviewed by the HSE.<br/><br/>This document is an overview of the Safety Assessment work undertaken as part of the Hy4Heat programme

To ensure the UK’s net zero targets are met the transition from conventionally fueled transport to low emission alternatives is necessary. The impact from increased decarbonised electricity generation on ecosystem services (ES) and natural capital (NC) are not currently quantified with decarbonisation required to minimise impacts from climate change. This study aims to project the future electric and hydrogen energy demand between 2020 and 2050 for car bus and train to better understand the land/sea area that would be required to support energy generation. In this work predictions of the geospatial impact of renewable energy (onshore/offshore wind and solar) nuclear and fossil fuels on ES and NC were made considering generation mix number of generation installations and energy density. Results show that electric transport will require ~136599 GWh for all vehicle types analysed in 2050 much less than hydrogen transport at ~425532 GWh. We estimate that to power electric transport at least 1515 km2 will be required for solar 1672 km2 for wind and 5 km2 for nuclear. Hydrogen approximately doubles this requirement. Results provide an approximation of the future demands from the transport sector on land and sea area use indicating that a combined electric and hydrogen network will be needed to accommodate a range of socio-economic requirements. While robust assessments of ES and NC impacts are critical in future policies and planning significant reductions in energy demands through a modal shift to (low emission) public transport will be most effective in ensuring a sustainable transport future.

An update on the proposed commercial frameworks for transport and storage power and industrial carbon capture business models.

E4tech’s 6th annual review of the global fuel cell industry is now available here. Using primary data straight from the main players and free to download it quantifies shipments by fuel cell type by application and by region of deployment and summarises industry developments over the year.



2019 saw shipments globally grow significantly to 1.1 GW. Numbers grew slightly to around 70000 units. The growth in capacity came mainly from cars Hyundai with its NEXO and Toyota with its Mirai together accounting for around two-thirds of shipments by capacity. Unit numbers are still dominated by Japan’s ene-Farm cogeneration appliances at around 45000 shipments. Large numbers of trucks and buses are now manufactured and shipped in China though numbers deployed are limited by the availability of refuelling infrastructure. But growth in China is uncertain as policy changes are under discussion.



2020 looks like it will be an even bigger year again dominated by Hyundai and Toyota. The Japanese fuel cell market is expected also to grow partly on the back of the Tokyo ‘Hydrogen Olympics’. Korea is another growth story buoyed by its latest roadmap which aims to shift large swathes of its economy to hydrogen energy by 2040. Elsewhere much of the supply chain development is in heavy duty vehicles and big supply chain players like Cummins Weichai and Michelin are making significant investments.

This is a Network Innovation Allowance funded project overseen by a steering group comprising the UK and Ireland gas network operators (Cadent Gas Networks Ireland National Grid Northern Gas Networks SGN Wales and West). The project follows on from previous studies that modelled the role of green gases in decarbonising the GB economy. The role of this study is to understand the transition from the GB economy today to a decarbonised economy in 2050 focusing on how the transition is achieved and the competing and complementary nature of different low and zero emission fuels and technologies over time.

While the project covers the whole economy it focuses on  transport especially trucks as an early adopter of green gases and as a key enabler of the transition. The study and resulting report are aimed at the gas industry and government and tries to build a green gas decarbonisation narrative supported by a wide range of stakeholders in order clarify the path ahead and thereby focus future efforts on delivering decarbonisation through green gases as quickly as possible.

The objectives of the study are:

• Analyse the complete supply chain production distribution and use of electricity biomethane bio-SNG and hydrogen to understand the role of each fuel and the timeline for scaling up of their use.
• Develop a narrative based on these findings to show how the use of these fuels scales up over time and how they compete and complement one another.

Once a clear narrative to 2050 was developed put togethera series of policy asks and stakeholder actions to show what is required to achieve the narrative. The study included analysis of two scenarios a High Green Gas scenario and a Low Green Gas scenario. The narrative presented here focuses on the High Green Gas scenario with commentary on the Low Green Gas scenario covered in Chapter 6.

Green gases

This report discusses the future role of ‘green gases’ which are biomethane and hydrogen produced from low- and zero-carbon sources each produced via two main methods:

Biomethane from Anaerobic Digestion (AD): A mature technology for turning biological material into a non-fossil form of natural gas (methane). AD plants produce biogas which must then be upgraded to biomethane.

Biomethane from Bio-Substitute Natural Gas (Bio-SNG): This technology is at an earlier stage of development than AD but has the potential to unlock other feedstocks for biomethane production such as waste wood and residual household waste.

Blue Hydrogen: Hydrogen from reformation of natural gas which produces hydrogen and carbon monoxide. 90-95% of the carbon is captured and stored making this a low-carbon form of hydrogen.

Green Hydrogen: Water is split into hydrogen and oxygen via electrolysis using electricity generated by renewables. No carbon emissions are produced so this is zero-carbon hydrogen."

Outline

This independent report by Vivid Economics and University College London was commissioned to support the Climate Change Committee’s (CCC) 2020 report The Sixth Carbon Budget -The path to Net Zero. This research provided supporting information for Chapter 7 of the CCC’s report which considered the UK’s contribution to the global goals of the Paris Agreement.

Key recommendations

The report models ‘leadership-driven’ global scenarios that could reduce global emissions rapidly to Net Zero and analyses the levers available to developed countries such as the UK to help accelerate various key aspects of the required global transition.

It highlights a set of opportunities for the UK alongside other developed countries to help assist global decarbonisation efforts alongside achieving it’s domestic emissions reduction targets

Webinar to accompany the launch of the Cadent Future Role of Gas in Transport report which can be found here

The iron and steel industry is one of the world’s largest industrial emitters of greenhouse gases. One promising option for decarbonising the industry is hydrogen direct reduction of iron (H-DR) with electric arc furnace (EAF) steelmaking powered by zero carbon electricity. However to date little attention has been given to the energy system requirements of adopting such a highly energy-intensive process. This study integrates a newly developed long-term energy system planning tool with a thermodynamic process model of H-DR/EAF steelmaking developed by Vogl et al. (2018) to assess the optimal combination of generation and storage technologies needed to provide a reliable supply of electricity and hydrogen. The modelling tools can be applied to any country or region and their use is demonstrated here by application to the UK iron and steel industry as a case study. It is found that the optimal energy system comprises 1.3 GW of electrolysers 3 GW of wind power 2.5 GW of solar 60 MW of combined cycle gas with carbon capture 600 GWh/600 MW of hydrogen storage and 30 GWh/130 MW of compressed air energy storage. The hydrogen storage requirements of the industry can be significantly reduced by maintaining some dispatchable generation for example from 600 GWh with no restriction on dispatchable generation to 140 GWh if 20% of electricity demand is met using dispatchable generation. The marginal abatement costs of a switch to hydrogen-based steelmaking are projected to be less than carbon price forecasts within 5–10 years.

Hydrogen has the potential as an energy solution to contribute to decarbonisation targets as it has the capability to deliver low-carbon energy at the scale required. For this to be realised the suitability of the existing natural gas pipeline networks for transporting hydrogen must be established. The current paper describes a feasibility study that was undertaken to assess the potential for repurposing the UK’s Local Transmission System (LTS) natural gas pipelines for hydrogen service. The analysis focused on SGN’s network which includes 3000 km of LTS pipelines in Scotland and the south of England. The characteristics of the LTS pipelines in terms of materials of construction and operation were first evaluated. This analysis showed that a significant percentage of SGN’s LTS network consists of lower strength grades of steel pipeline that operate at low stresses which are factors conducive to a pipeline’s suitability for hydrogen service. An assessment was also made of where existing approaches in pipeline operation may require modifications for hydrogen. The effects of changes in mechanical properties of steel pipelines on integrity and lifetime as a result of potential hydrogen degradation were demonstrated using fitness-for-purpose analysis. A review of pipeline risk assessment and Land-Use Planning (LUP) zone calculations for hydrogen was undertaken to identify any required changes. Case studies on selected sections of the LTS pipeline were then carried out to illustrate the potential changes to LUP zones. The work concluded with a summary of identified gaps that require addressing to ensure safe pipeline repurposing for hydrogen which cover materials performance inspection risk assessment land use planning and procedures.

The Innovate UK KTN Hydrogen Innovation Network is bringing you this second episode with Steffan Eldred and Simon Buckley from Innovate UK KTN who continue their ‘back to basics' approach and delve deeper to understand where hydrogen should be used with their special guest Joanna Richart Head of Hydrogen Business at Ricardo. As with any technology or fuel discussions can get carried away implying they are the solution to all things but at Innovate UK KTN we strongly believe that we should ensure hydrogen is used where it can be most effective for decarbonising energy industrial and chemical industries.



The podcast can be found on their website

Throughout the history of the mining petroleum process and nuclear industries continuous efforts have been made to develop and improve measures to prevent and mitigate accidental explosions. Over the coming decades energy systems are expected to undergo a transition towards sustainable use of conventional hydrocarbons and an increasing share of renewable energy sources in the global energy mix. The variable and intermittent supply of energy from solar and wind points to energy systems based on hydrogen or hydrogen-based fuels as the primary energy carriers. However the safety-related properties of hydrogen imply that it is not straightforward to achieve and document the same level of safety for hydrogen systems compared to similar systems based on established fuels such as petrol diesel and natural gas. Compared to the conventional fuels hydrogen-air mixtures have lower ignition energy higher combustion reactivity and a propensity to undergo deflagration-to-detonation-transition (DDT) under certain conditions. To achieve an acceptable level of safety it is essential to develop effective measures for mitigating the consequences of hydrogen explosions in systems with certain degree of congestion and confinement. Extensive research over the last decade have demonstrated that chemical inhibition or partial suppression can be used for mitigating the consequences of vapour cloud explosions (VCEs) in congested process plants. Total and cooperation partners have demonstrated that solid flame inhibitors injected into flammable hydrocarbon-air clouds represent an effective means of mitigating the consequences of VCEs involving hydrocarbons. For hydrogen-air explosions these same chemicals inhibitors have not proved effective. It is however well-known that hydrocarbons can affect the burning velocity of hydrogen-air mixtures greatly. This paper gives an overview over previous work on chemical inhibitors. In addition experiments in a 20-litre vessel have been performed to investigate the effect of combinations of hydrocarbons and alkali salts on hydrogen/air mixtures.

Of all the sectors in the UK decarbonising heat remains one of the most challenging. Heat used for industrial domestic and commercial purposes generates around a third of all UK carbon emissions 70% of which is due to burning natural gas. In order to meet our legally binding national climate change targets unabated natural gas use for heat must be phased out. Low carbon gas - including hydrogen and biogases - is one option to replace it. The Future Gas Series examines the opportunities and challenges associated with using low carbon gas to help decarbonise the UK economy.<br/><br/>This is the second report in the three-part Future Gas Series. Part 1: Next Steps for the Gas Grid explored the potential to decarbonise the existing gas grid. The report Part 2: the Production of Low Carbon Gas focuses on the issues related to the production of low carbon gas. It considers the different production technologies the potential scale of deployment of each method and the potential feedstocks. It also discusses issues related to bulk transport and storage of gas. Put together from expert evidence from across industry and academia it provides a balanced guide for policy makers in this area. It was a co-chaired by James Heappey MP (Conservative) Alan Whitehead MP (Labour) and Alistair Carmichael MP (SNP).<br/><br/>Carbon Connect suggests that biogases- such as biomethane and bioSNG- provide low regrets opportunities in the near term to provide low carbon heat and could also potentially make use of waste that would otherwise go to landfill.  However they require further support to allow them to continue contributing to decarbonising the UK economy. Hydrogen could provide huge decarbonisation opportunities and has applications across the energy system from putting hydrogen in the gas grid to be burnt for heat in homes to hydrogen buses and trains. However to realise this potential a market for hydrogen must be built up. This should incentivise business to invest in hydrogen technologies reward those who use hydrogen and build up hydrogen infrastructure.<br/><br/>

Global climate targets have highlighted the need for a whole-systems approach to decarbonisation one that includes targeted national policy and industry specific change. Situated within this context this research examines policy and pricing barriers to decarbonisation of the UK steel industry. Here the techno-economic modelling of UK green steelmaking provides a technical contribution to analysis of pricing barriers and policy solutions to these barriers in the UK specifically but also to the broader industrial decarbonisation literature. Estimated costs and associated emissions projections reveal relevant opportunities for UK steel in contributing to national climate and emissions targets. Modelling demonstrates that green steelmaking options have been put at price disadvantages compared to emissions-intensive incumbents and that fossil-free hydrogen-based steel-making has lower emissions and lower levelised costs than carbon capture and storage options including top gas recycling blast furnace (TGR-BF) with CCS and HIsarna smelter with CCS. Two primary policy recommendations are made: the removal of carbon pricing discrepancies and reductions in industrial electricity prices that would level the playing field for green steel producers in the UK. The research also provides relevant policy considerations for the international community in other industrial decarbonisation efforts and the policies that must accompany these decarbonisation choices.

In this fourth episode Simon Buckley and Matthew Moss from Innovate UK KTN are exploring the use of hydrogen in the global maritime industry alongside their special guest Chester Lewis Business Development Manager at Ryze Hydrogen.

This podcast can be found on their website

The HyDeploy project [1] has undertaken an extensive research programme to assess safety and performance of the existing UK gas appliances population fueled with natural gas / hydrogen admixtures (hydrogen blended gas). The first stage of this work [2] focused on well maintained and normally functioning appliances. This work demonstrated that unmodified gas appliances can operate safely with hydrogen blended gas (up to 20 vol% hydrogen) and the key hazard areas of carbon monoxide (CO) production light back and flame out and the operation of flame failure devices are unaffected. It is widely recognized that due to aging and variable degrees of maintenance that the combustion performance of a gas appliance will depreciate over time. In extreme cases this can lead to situations where high levels of CO may be released back into the dwelling resulting in CO poisoning to the occupants. To obtain a universal appreciation of the effect of hydrogen addition on the safety and performance of all gas appliances operation under sub optimal conditions is required and therefore it is important that the operation of malfunctioning appliances fuelled with hydrogen blended gas is assessed. A review of failure modes identified six key scenarios where the composition of the fuel gas may lead to changes in safety performance - these primarily related to the resulting composition of the flue gas but also included delayed ignition. Gas appliance faults that will increase the CO production were tested through a series of experiments to simulate fault conditions and assess the effect of hydrogen blended gas. The fault modes examined included linting flame chilling incorrect appliance set up and modification of gas valve operation. The programme utilized six different appliances tested with three methane-hydrogen fuel blends (containing 0 20 and 28.4 vol% hydrogen). In all cases the switch to hydrogen blended gas reduced CO production. The change in CO production when using hydrogen blended gas is a consequence of a decrease in the theoretical air requirement to achieve complete combustion. In some cases the amount of CO produced was identical to the nonfault baseline performance on methane thereby fully mitigating the consequence of the malfunction. In the case of very high CO production a 90% reduction was recorded when using 20 vol% hydrogen blended gas. In situations such as non-optimal boiler set up the addition of hydrogen to the gas supply would prevent the production of high levels of CO. The findings here together with the results from HyDeploy 1 [2] indicate that the safety and performance of unmodified existing UK gas appliances are not detrimentally affected when using hydrogen blended gas. Furthermore the addition of hydrogen to the fuel gas has been shown to reduce CO production under fault conditions therefore the introduction of hydrogen into the gas network may serve to mitigate the hazard posed by existing faulty appliances that are producing elevated levels of CO.