Project Summary

SIF Innovation Challenge

The National Transmission System (NTS) provides flexibility in the UK's energy system, through its capability to store energy for long periods of time. Hydrogen as an alternative to natural gas ensures 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. Compression provides flow and builds linepack at times of increased demand in certain locations of the network. This demand is generated from heating (distribution networks), large industrial users or power generation. In the future, energy could be stored as hydrogen linepack in the NTS at times of excess renewable electricity generation and low gas demand.

Energy network innovation evolution

The re-purposing of NTS compressor systems for hydrogen has not been demonstrated, although desktop studies indicate its feasibility and cost effectiveness. There is a need to provide a demonstration to develop the technical and commercial evidence and enable the predicted benefits for repurposing compression assets. The cost of a new compression system can be approximately £60m per unit and there are 74 units on the NTS today, therefore, re-purposing existing assets would bring about large cost savings to the consumer. We have determined that gas turbines could be modified to be fuelled with up to 100% hydrogen and analysis of the compressor suggested that the compressor could operate with up to 50% hydrogen. Above 50% hydrogen, a compressor upgrade is required. This will be demonstrated in Beta bringing in Siemens for the required upgrades to the gas turbine and compressor unit. 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.

Project evolution: Alpha to Beta

The Alpha phase further developed our understanding of the feasibility of repurposing compressor assets. Beta will demonstrate this understanding and the potential for compression to meet the requirements determined through the whole system modelling with a minimal impact to the consumer. A gas turbine representative of the current fleet will be fuelled by different blends of hydrogen up to 25% hydrogen in natural gas and subsequently 100% hydrogen following modifications, providing technical and safety evidence for the repurposing of our current gas turbine fleet. Concurrently, the Cab and Ancillary equipment will undergo offline testing to determine the requirements for operation with hydrogen blends and 100% hydrogen. The system demonstration test loop will be constructed whilst the gas turbine tests and modifications take place, to enable evidence to be created throughout the project timeline and feed into Project Union in a timely manner. The test programme will be undertaken on the full compression system with hydrogen blends and 100% hydrogen, providing the evidence for the safety case, business case and technical feasibility.

Problem evolution: Alpha to Beta & Key User

Whilst the problem proposed at the start of Alpha remains consistent we have developed our understanding of the network requirements and feasibility for both the demonstration and implementation of the project outputs. Project Union our key user has now been approved for its PreFEED funding, with the first proposed compressor unit moving to hydrogen in 2028. Evidence for repurposing compressors for hydrogen is required prior to construction to feed into the Union business and project plan and allow sufficient time for procurement. The evidence for repurposing existing compressors for hydrogen is limited and would be required prior to including this in any business plan.

Project Partner Expertise

• DNV lead the demonstration of the compression system and have extensive experience of gas pipelines, large scale testing and of the current compression systems.
• Siemens Energy a rotating machinery OEM whom will provide testing, modification and technical insight into repurposing compression system
• Cullums experts on compressor ancillary equipment and cab units
• Network partners - provide insight into deployment through their networks
  For the Beta phase additional partners have been included in the consortium to help deliver the demonstration.
• Premtech have expertise in engineering design and 3D modelling and will produce a virtual model of the test facility at Spadeadam as part of the detailed design phase.
• Cardiff University have expertise in gas turbine research with the Gas Turbine Research Centre. They will peer review the evidence from the demonstration and provide input through project steering group meetings.
• HSE are the UK's Health and Safety Executive and will provide input to the demonstration programme through project steering group meetings and peer review safety evidence generated throughout the project.

Addressing the needs of the user

The users of the project output will be onshore and offshore gas networks both in the UK and globally alongside many industrial users of rotating machinery. This project provides alternative options to replacement of current systems at a reduced cost to support users in their transition to net zero.

Innovation Justification

Relevant State of the Art

Hydrogen compression systems are available to purchase as new units but this option will be costly for the energy transition. There has been some consideration for re-purposing units although most tests are on newer units than those seen on our network. Project HyFLEX has demonstrated 10% hydrogen on a Siemens SGT400 unit whilst several power stations are also considering re-purposing of their larger Gas Turbine (GT) units. We can not utilise this data directly for our assets but are utilising it to guide our activities. 

In Europe, compression testing has been undertaken at a blend of 10% hydrogen, however this has not looked at the possibility of re-purposing existing equipment. A Solar Titan 130 turbine has been tested at up to 25% hydrogen at the Waidhaus compressor station in Germany, however, this does not show the full compression system operating on hydrogen. Our challenge looks at both existing equipment and blends of hydrogen up to 100%.

Innovative Solution

Alpha showed that existing Avon GT's can be modified to be fuelled with 100% hydrogen, eliminating carbon dioxide and monoxide emissions. Due to the high flame temperature of hydrogen, nitrogen oxide emissions will increase and the potential to reduce, remove or capture these emissions will be considered in the Beta 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.

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. Analysis was carried out on 60% - 100% hydrogen to determine the speed of rotation required. The Alpha phase investigated the implications of a varying hydrogen blends in more detail and the potential systems which could be utilised to sense the gas composition and feedback to the compressor to control the speed of rotation.

Each compressor unit on the network costs approximately £60m to replace. The project will consider the opportunity to re-purpose the current compression assets for use with hydrogen and any system modifications required. Determining the most cost effective, safe 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.

Beyond incremental innovation

Alongside the re-purposing of the unit, we will also consider how to eliminate NOx emissions reviewing both Selective Catalytic Reduction (SCR) and Dry Low Emission (DLE) technological options. 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.

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.

Readiness level & Scale

At the end of the project we will have an implementation plan aligned to the compressor strategy, with a detailed model of the network aligned to the systems transformation and Future Energy Scenarios. With updates through the period that are due to reflect the supply and demand of hydrogen in more detail through to 2050. The Cost Benefit Analysis will also be updated to enable integration into Project Union re-openers and future business plan activities.

The options for full-scale offline testing of compression assets are very limited. Construction of a test loop at Spadeadam was determined to be the best approach during Discovery and Alpha.

Funding route

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 safety and technical feasibility of re-purposing NTS compression assets and help to determine the most cost-effective solution for compression of hydrogen with collaborative partners.

Competitive Markets

Whilst Siemens are working with us on the re-purposing project, the route to re-purposing will be shared with other OEMs to encourage them to consider this option. Our engagement has already shown a difference in approach by one other OEM. The activity of re-purposing the network will be undertaken through our standard investment procedures which requires competitive tender.

Counterfactual

We have considered several routes to enable compression on the network, through our work, the most cost effective option, is to utilise the assets already deployed on our network. We have compared options for compression solutions in the appendix.

Benefits

SIF benefits

• Cost reductions in operating the network​s and wider energy system (£m)
  The re-purposing 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, it is clearly an approach worth reviewing. A key element of the project is to ensure that in repurposing our assets we do not increase the cost of operating the compression equipment. Studies to date show that the rotating machinery maintenance costs do not vary for new vs old units. However, ancillary equipment and systems need further investigation.
• cost savings for users of network services & end consumers (£m)
  The cost to re-purpose an existing compressor unit has been assessed against the cost of replacement. A methane compression unit costs approximately £60m to replace. The early phase cost benefit analysis shows that savings of approximately £1.4b could be seen in repurposing our units instead of replacing. It is likely in the transition we will need to provide a selection of options for the various sites and systems. This includes extending the lifetime of the assets to manage blends and meet emissions targets to ensure assets are not replaced with systems that are not fit for purpose once the network reaches net zero. The costs to re-purpose are estimated as 100% H2 = ~£29m, 50% H2 = ~£17m & 25% H2 = ~£11m. These numbers will be refined with the compressor strategy team as we deliver the HyNTS Compression project.
• new to market products, processes and services (qualitative)
  Whilst compression is not a new product, in repurposing and modifying the equipment to accept hydrogen we will be creating solutions and management processes that could be utilised worldwide.
• carbon reductions -- direct or indirect (MTCO2e)
  Natural gas compressor stations currently installed on the National Transmission System (NTS) emit 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. A parallel project; Ch4rge; looks to prevent natural gas emissions from our compressor units and will be considered for deployment on our system demonstration.

The prior phases of the project have found that it is feasible to re-purpose an existing Avon Gas Turbine to enable the turbine to be fuelled with up to 100% hydrogen. Implementing hydrogen as a fuel gas for gas turbines on the NTS would eliminate 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 seek to reduce the 2,240,000 kg of methane which is released into the atmosphere annually.

Please refer to the business case and CBA in the project management work book for more information.

The Benefits Map can be found attached and demonstrates the key outcomes of the project.

• Whole System - Providing a strategy for compression and developing whole system knowledge will allow compression to be implemented across gas networks and hydrogen production facilities, where required in the UK. 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.
• Consumer impact - The utilisation of existing NTS assets with hydrogen prevents the need for installation of new significant investment systems and time delays for Net Zero. Consumers will benefit from the introduction of hydrogen either through energy storage for electrical applications or reduced impact of replacement domestic heating systems.
• Economic benefits - 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.
• Government priorities - Developing UK capability, skills and competencies for Net Zero solutions, providing significant opportunity for export. UK technology solutions development increasing the value of UK industry, encouraging inward investment into the UK hydrogen economy.
• Environmental impacts - The CO2 saving is substantial if the hydrogen is produced by renewable energy (green hydrogen), further reducing the country's reliance on fossil fuels and pulling demand for more renewables.
• Resilience benefits - the project will benefit resilience during the transition to hydrogen buy enabling compression of hydrogen blended and 100% hydrogen networks, building linepack and providing pressures and flows to meet demand for industry, power and distribution networks.
• Safety - Prevents having to transport hydrogen above ground, eliminating the likelihood of transportation accidents