Project Summary

Hydrogen as an alternative to natural gas is key to ensuring that energy demands are met for heat, power, industry and transport in 2050. In order to transport & store hydrogen across the UK compression is required. This project evaluates the costs and opportunities to repurpose the existing National Transmission System (NTS) compression equipment minimising impact to gas consumers. Directly addressing the SIF challenge requirement of "evaluating the costs and opportunities of repurposing existing infrastructure or assets" and "co-ordinating approaches to sitting assets to deliver more efficient capital investment on the energy system".

The repurposing of NTS compressor systems for hydrogen has not been demonstrated, although desktop studies indicate its feasibility and cost effectiveness. The cost of a new compression system can be greater than £40m per unit and there are 70units on the NTS today. Discovery determined that Avon gas turbines could be enabled to be fuelled by 100% hydrogen and analysis of the compressor suggested that the compressor could operate with up to 50% hydrogen. However, for a blend of over 50% hydrogen, we will need to consider innovative solutions to modify or upgrade the compressor. The innovative solutions in development through this project to enable reuse of the compressors are vital to reducing the cost to the consumer of the energy transition.

Discovery found that future NTS scenarios are still in fluctuation and an important step to refine our strategy and business case is to undertake further network modelling utilising whole systems datasets. National Grid Electricity Transmission (NGET) will contribute work undertaken on electricity demand and capacity alongside their work on potential locations of electrolysers in the UK which will feed into the modelling work to determine not only the level of compression required but where compressor stations will be required in the future. ITM Power will support with this task as an electrolyser manufacturer and green hydrogen producer.

Beta will look to demonstrate the potential for compression to meet the requirements determined through the whole system modelling with a minimal impact to the consumer. The compression loop will compress and transport hydrogen gas, to demonstrate the compatibility of typical NTS components. Engagement with the HSE through Discovery determined that application testing was required to provide safety and operational evidence for the repurposing of this system.

We have added two additional partners into the Alpha phase of the project, NGET and Cullum. As discussed NGET will support the modelling activities and ITM Power are also ideally placed to provide support with electrolyser requirements for the modelling work. Cullum join as our experts on compressor ancillary equipment and cab units to support Siemens Energy whom continue to deploy their knowledge and experience of the compressor systems. NGN and SGN will continue to support the project by contributing to the demand modelling, meetings and evidence gathering, as compression will impact the supply to the distribution networks in the future. DNV support the demonstration of the compression system and have extensive experience of gas pipelines, large scale testing and of the current compression systems.

The users of the project output will be the gas networks both in the UK and globally, providing alternative options to replacement of systems with hydrogen ready solutions that come at a premium. As the gas industry moves towards the use of hydrogen, there will likely be a requirement for hydrogen production facilities throughout the UK. The variability in production of green hydrogen will mean that compression is crucial to ensuring hydrogen can be moved through the pipeline system, dependent on demand, and is likely to be required on local transmission systems, not just the NTS.

Innovation Justification

Use of hydrogen as an alternative to natural gas is essential for decarbonisation of the UKs energy network. The National Transmission System (NTS) will ensure hydrogen can be supplied to consumers reliably from producers. Compression is required to move gas from the producer to the consumer, build the linepack to store gas and direct flows within the network. The NTS currently pressurises gas up to 70-90 bar but it is thought this may need to increase with hydrogen due to the lower energy content. Hydrogen has different properties to natural gas and the same pressure ratio, which is currently achieved with methane, cannot be achieved with hydrogen without modification to the systems.

From the initial work undertaken it is thought that existing Avon gas turbines can be modified to be fuelled with 100% hydrogen, eliminating carbon dioxide and monoxide emissions. It is known that due to the high flame temperature of hydrogen, that nitrogen oxide emissions will increase and the potential to reduce, remove or capture these emissions will be considered in the Alpha phase of the project.

The initial analysis undertaken on the existing compressor unit suggests that the compressor may be able to compress blends of up to 50% hydrogen, if a drop in the pressure ratio achieved can be accepted. Beyond this 50% blend, modifications to the system in terms of more stages of compression would be required. This will increase the footprint of the compression system on site. The Alpha phase will have consider whether it would be more cost effective to modify the compressor, or replace with a hydrogen ready compressor for 100% hydrogen.

The next step was to consider the compression opportunity with various hydrogen blends. To achieve compression of varying hydrogen blends the compressor is required to rotate at varying speeds. An analysis was carried out on 60%, 80% and 100% hydrogen to determine the speed of rotation required. The Alpha phase will investigate the implications of a varying hydrogen blends in more detail and the potential systems which could be utilised to sense the gas composition upstream of the compressor and feedback to the compressor and control the speed of rotation.

In Europe, compression testing has been undertaken at a blend of 10% hydrogen, however this has not looked at the possibility of repurposing existing equipment. Our challenge looks at both existing equipment and blends \\>10%. The production of hydrogen and injection into the NTS is likely to be inconsistent due to weather fluctuations and varying demand, therefore we will need to understand how the system can manage variable blends of hydrogen and methane. To enable the compressor to react to the gas blend as required, automated systems at compressor stations will be required to sense the gas composition at the inlet of the compressor and feedback to control the compressor operation.

Each compressor on the network would cost at least £40m to replace. The project will consider the opportunity to repurpose the current compression assets for use with hydrogen and the system modifications which would be required. Determining the most cost effective and efficient route to compress hydrogen is vital to keep costs at a minimum for the NTS transition, and therefore energy customers, through to 2050.

Until the evidence has been provided that the gas network can accept hydrogen, natural gas will continue to be the transported fuel within the network and so any research into hydrogen requires funding outside of business-as-usual routes. SIF offers a unique opportunity to understand the technical feasibility of repurposing NTS compression assets and help to determine the most cost-effective solution for compression of hydrogen.

Benefits

The repurposing of the UK gas assets in the energy transition is a key step in ensuring value for our consumers, with residual value of the current system being £6.5b. Supporting the continued utilisation of this system, and maintaining the jobs associated, is clearly an approach worth reviewing.

Natural gas compressor stations currently installed on the National Transmission System (NTS) emit large volumes of greenhouse gases, through both combustion and venting of natural gas. From 2020 to 2021, compressor stations released approximately 165,000 kg of carbon dioxide and 2,240,000 kg of methane into the atmosphere. The development of hydrogen ready compression systems will eliminate carbon emissions whilst the deployment of NOx capture will eliminate emissions and provide a truly green system.

Direct project benefits:

Economic: Determining the most cost-effective method of hydrogen compression for the NTS, providing a reduction in consumer costs through the transition and into Net Zero.
Whole System: Providing a strategy for compression and developing whole system knowledge which will allow compression to be implemented across gas networks and hydrogen production facilities, where required in the UK.
Governmental: Developing UK capability, skills and competencies for net zero solutions, providing significant opportunity for export
Governmental: UK technology solutions development increasing the value of UK industry, encouraging inward investment into the UK hydrogen economy
Other hydrogen enabling benefits:

Consumer: Utilising existing gas assets with hydrogen for the National Transmission System prevents the installation of new significant investment systems and time delays for net zero
Safety: Prevents having to transport hydrogen above ground, eliminating the likelihood of transportation accidents
Resilience: Enabling hydrogen to be distributed through the gas pipeline network will allow the market for industrial and residential products that run off hydrogen to be both feasible and enter the market at a competitive price because the cost of transition to blended gases running in the network will be minimised.
Environmental: The C02 saving is substantial if the hydrogen is produced by renewable energy (green hydrogen), further reducing the countries reliance on fossil fuels and pulling demand for more renewables.
Consumer: Upgrades to existing gas boilers possible, maintaining the market for use of gas networks and existing central heating systems - reducing costs for consumers
The Discovery phase of the project has found that it is feasible to repurpose an existing Avon Gas Turbine to enable the turbine to be fuelled with 100% hydrogen. Implementing hydrogen as a fuel gas for gas turbines on the NTS would eliminate the 165,000 kg of carbon dioxide emissions which are released at compressor stations annually. The transportation of a hydrogen gas blend vs. natural gas will reduce the 2,240,000 kg of methane which is released into the atmosphere annually.

The cost to repurpose an existing compressor unit has not yet been assessed, but the costs will be developed in the Alpha phase of the project to develop a more accurate cost benefit analysis. A methane compression unit costs approximately £40m - £50m to replace, whereas a typical compressor upgrade costs £25m - £30m.

The attached business case demonstrates an approximated difference in costs for three future scenarios (method 1-3) this shows a potential for £2billion of savings. As we do not have all the costs for a hydrogen ready compression system, or a repurposed system; even utilising the costs of a methane unit upgrade (baseline 3) vs. new methane unit (baseline 2) would result in a potential saving of £1.165billion. Please see accompanying cost benefit analysis. This provides ample reasoning to further investigate this opportunity and deliver consumer savings through the transition.