Heating with Hydrogen

Article by Tommy Isaac

HyDeploy is the UK’s first hydrogen demonstration project to inject hydrogen into a live gas network, up to 20 vol%, with the aim of providing a launch pad for the hydrogen blending market within the UK. A UK wide 20 vol% blend for domestic gas use would be the equivalent of removing 2.5m cars from the road.1

The HyDeploy project is a collaboration between Cadent, Northern Gas Networks (NGN), Progressive Energy, HSE Bespoke Research and Consultancy, ITM Power and Keele University. Key subcontractors are Otto Simon Ltd (OSL), Dave Lander Consulting, and Kiwa Gastec. The programme is funded by Ofgem through the Network Innovation Competition and is the largest gas innovation project ever funded by Ofgem.

HyDeploy is a 6-year programme which started in 2017 and is due for completion in 2023. The programme involves three separate trials of blending hydrogen at 20 vol% into the gas distribution network – one on Keele University’s private network, one on NGN’s network, and one on Cadent’s network.

The overarching aim of the project is to provide the safety case for hydrogen blending and facilitate the clearance of regulatory barriers necessary to kick start the hydrogen blending market. By the end of the programme, the objective is to enable a hydrogen producer to inject hydrogen into the gas network – just as a biomethane supplier can today.

Why 20 vol%?

Hydrogen and low carbon electricity, are likely to be the two key pillars for a decarbonised energy system. The no-regrets, low-risk, deployment of hydrogen is paramount to establish the lowest cost pathways for the UK to achieve its legally binding carbon reduction targets.

Previous work undertaken by the HSE2 indicated that a 20 vol% blend of hydrogen would be unlikely to require significant gas network interventions. Additionally, all domestic gas appliances post the 1996 Gas Appliance Directive (GAD) have been tested with 23 vol% hydrogen as part of EU certification.  The objective of HyDeploy is therefore to build the necessary evidence base to demonstrate that a 20 vol% hydrogen blend is as safe as natural gas.

By demonstrating that current appliances and gas networks are capable of adopting a 20 vol% hydrogen blend without modification, the commercial deployment of hydrogen becomes decoupled from the adoption of bespoke appliances, removing the need for mandated appliance change. This solves the ‘chicken and egg’ problem of supply waiting for demand and vice versa. It allows early hydrogen deployment to focus investment on the necessary supply infrastructure needed to deliver bulk production – most notably natural gas conditioning and CCUS infrastructure, whilst laying the groundwork for deeper carbon savings through transport fuel cells; low carbon flexible electricity generation; and potentially full gas grid hydrogen conversion.

Carbon savings

Heating demand in the UK accounts for just over half of total emissions3, therefore small changes make a large impact. Blending hydrogen at 20 vol% into the natural gas network would unlock 29 TWh/y of low carbon heating within domestic gas demand.1

To put this figure into perspective, in 2018 the Renewable Heat Incentive (RHI) delivered a total of 11 TWh of low carbon heat, and is forecast to deliver an additional 10 TWh/y by its end in 20214 (21 TWh/y in total).  The RHI is the UK Government’s support mechanism for low carbon heat and covers both non-domestic (biomethane, waste, etc) and domestic (biomass boilers, air source heat pumps, etc) low carbon heat. The comparison with a hydrogen blend is illustrated shown in Figure 1.

It is therefore clear that blending hydrogen at 20 vol% would create material carbon savings, whilst de-risking the early deployment pathway of hydrogen adoption.

Figure 1: Low carbon heat comparison

Building the safety case

All gas distribution networks are licensed by Ofgem to transport natural gas to consumers within the Gas Safety (Management) Regulations (GS(M)R). The current hydrogen limit within GS(M)R is 0.1 mol%5, therefore HSE approval is required to transport gas with a greater hydrogen content. HSE approval is granted via bespoke Exemptions based on the presentation of scientific evidence to demonstrate that any proposed change is ‘as safe as’ the current operation.

HyDeploy was granted the UK’s first ever hydrogen Exemption by the HSE in November 2018, for the first trial at Keele University.

A separate approval process will be required for each trial, therefore in total three Exemptions will be sought from the HSE to enable all three trials to be delivered.

Why three trials?

The three-trial structure of HyDeploy has been deliberately designed to appropriately manage the delivery risk of a 20 vol% hydrogen blend. Each trial is due to last for 10 months.

The first trial is due to commence in September  2019 and will blend hydrogen into the one of the live gas networks operated by Keele University. This first trial will deliver a hydrogen blend to 100 homes and 30 faculty buildings.

Figure 2: Overall programme timeline

As part of the evidence gathering to support the first Exemption application, the gas appliances on the network were:

  • Gas Safe checked;
  • leak tested with up to 28 vol% hydrogen; and,
  • safety tested with up to 28 vol% hydrogen.

All appliances that were safe and leak tight on natural gas were found to be safe and leak tight on blended natural gas – with no exceptions.

The ultimate rollout of a 20 vol% hydrogen blend cannot be contingent on visiting every home in the UK to Gas Safe and test all gas appliances. Therefore, a pathway exists between the appropriately-controlled trial at Keele, and ensuring the evidence base is sufficiently compelling to allow hydrogen to be blended without intervention.

By conducting two further trials, the necessary reduction in pre-trial intervention can be incrementally delivered as the evidence base allows. The two further trials will commence in 2020 and 2021, each supplying a 20 vol% blend to around 700 homes. The second trial will take place on NGN’s network in the North East and the third will take place in Cadent’s network in the North West.

Trial approval process

The successful approval process for each trial is dependent on identifying, understanding and mitigating the risk profile of the proposed undertaking. HSE Bespoke Research and Consultancy is leading the generation of the scientific evidence base. To support the first Exemption application, 18 months of laboratory, desk and field work was undertaken, with the key focus areas being:

  • appliances;
  • materials;
  • gas detection;
  • gas characteristics; and,
  • operational procedures.

A comprehensive evidence base was generated in each of these areas, with a quantitative risk assessment (QRA) developed to allow all of the evidence to be aggregated into a single comparative analysis. The QRA was focused on understanding the trial risk profile and concluded that a blended natural gas containing 20 vol% hydrogen was as safe as natural gas6

Process design

The operational equipment used to deliver each trial will be a 0.5 MWe electrolyser, supplied by ITM power, and a hydrogen grid entry unit (H2GEU), supplied by Thyson. The electrolyser will be supplied with renewable electricity to ensure the hydrogen generated is low-carbon. For each trial, a medium pressure natural gas supply line will be diverted into a secure compound. Within the compound, hydrogen will be generated by the electrolyser and blended with the natural gas within the H2GEU (see Figure 3).

Figure 3: HyDeploy process design

The blended gas will be returned to the medium pressure supply line, which will then be let down via the existing governor station into an isolated low-pressure network supplying homes. The control scheme will maximise the blend level, within process limits, whilst remaining within the Wobbe Index limits as specified by GS(M)R. The Wobbe Index is a measure of the energy delivery capacity of a gas, measured in MJ/m3.

A rigorous safety assessment has been undertaken throughout the design, including a Layers of Protection Analysis (LOPA) and HAZOP. The electrolyser and H2GEU have been designed to operate automatically, with manual intervention only required to restart operation following a shutdown.

Each trial will locate the electrolyser and H2GEU to minimise risk according to ALARP principles. Following the delivery of each trial, the electrolyser and H2GEU will be decommissioned and transported to the next trial location for installation and operation. 

Blending pathways

The purpose of HyDeploy is to provide a platform for hydrogen blending deployment. Following the successful delivery of the programme, a hydrogen supplier should be capable of applying for an Exemption without the need to generate any further evidence. This will kick start the hydrogen blending market to bring hydrogen blending on a par with biomethane as a low-carbon gas vector.

There are a number of deployment pathways that hydrogen blending could take, two examples are bulk supply, and power-to-gas projects.

Bulk supply of hydrogen blended gas, such as the HyNet project, enables widespread application of blended natural gas. HyNet is designed to deliver a hydrogen blend to over 2m consumers across the UK's North West, along with decarbonising the North West industrial cluster. The production approach will be natural gas conditioning via auto-thermal reforming (ATR) in combination with CCUS infrastructure to decarbonise the gas and sequester the carbon dioxide.

Figure 4: HyNet project

Another blending deployment pathway is to utilise low-carbon electricity, where available and economic to do so, and generate hydrogen via electrolysis. This pathway would be unlikely to provide bulk supply in the near term7 but could prove instrumental in early production, especially for distributed demand and high purity usage such as fuel cells.

Deeper carbon savings

By decoupling hydrogen supply investment from use, the investment requirements and deployment risk profile of hydrogen adoption is substantially reduced. This lays the foundations for hydrogen-based deeper carbon savings via fuel cells, low carbon dispatchable electricity generation – enabling use of more intermittent renewables – as well as  potentially full gas network conversion.

HyDeploy is delivering practical deployment today, providing a launch pad for hydrogen adoption within the UK and beyond.


1. HyDeploy NIC Bid Submission, Ofgem, 2016

2. Injecting hydrogen into the gas network (RR 1047), Health & Safety Executive, 2015

3. UK GHG emissions 1990–2017, BEIS, 2019

4. Renewable Heat Incentive Statistics, BEIS, 2019

5. Gas Safety (Management) Regulations, 1996

6. HyDeploy: The UK’s First Hydrogen Blending Deployment Project, Clean Energy Journal, 2019

7. Why Hydrogen?, The Chemical Engineer, 2019

This is the seventh article in a series discussing the challenges and opportunities of the hydrogen economy, developed in partnership with IChemE's Clean Energy Special Interest Group. For more entries visit the series hub.

Article by Tommy Isaac

Principal Engineer, Progressive Energy

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