National Gas Transmission (NGT) are committed to reducing emissions from the operation of the National Transmission System (NTS) and eliminating emissions by 2050. A key technology in this transition is hydrogen as an alternative for carbon fuels in heat, transport, and industrial uses.
Linepack currently provides flexibility in the NTS by strategically storing gas in pipelines and releasing the gas to meet demand for heat and electricity generation. The future energy system is likely to see increasing sources of renewable energy including wind and solar, however this supply can be intermittent. The project will investigate how the NTS of the future can support energy generation using linepack by assessing the value of linepack flexibility and investigating how the required market, policy and regulatory frameworks can be developed.
Benefits
- A detailed understanding of the developments of gas supply & demand mix and how the role of linepack has changed
- Summary of linepack swing nationally and potentially by zone and across the whole system
- Clarity on the current costs and value in managing linepack flexibility
- An understanding of alternative methods of energy system flexibility and a look at international systems
- Understanding of future linepack swing over next decade (based on FES scenarios)
- Understanding of linepack flexibility between 50bar vs 70bar
- Clearer understanding of linepack opportunities with hydrogen as key part of network
Learnings
Outcomes
Phase 1
Phase 1 produced a thorough report, including well documented and full primary data sources, of historic linepack swing volumes and trends (from 2010 to 2023) across the UK, and by UK-regions. This report investigated the drivers and causes of historic linepack swing, and considered how those drivers had changed the role of linepack management over the time period considered. The report detailed the service provided by linepack flexibility to different stakeholders in the energy system, and made comparisons to international counterpoints for further exploration later on in the project – particularly how different TSO’s manage swing by different methods.
Phase 2
Phase 2 made a more in-depth of current linepack data and trends, by considering whole system energy flexibility and the role of linepack swing within that. Study was made of how National Gas Transmission currently manages network balancing and linepack. It also focused on current sources of natural gas to the current system, and demand sources – and considered how both have changed in recent years. Commercial balancing actions for current linepack management were analysed, and key linepack swing days were analysed for both drivers and to see how those commercial balancing actions are used in today’s system. Phase 2 also valued current linepack swing: figures were calculated for provided energy flexibility by the system, as well as a hypothetical maximum. This was compared to alternative means of energy flex/storage. Linepack was valued by gathering costs (compressor fuel use, other opex costs, unit replacements,) and proportioning against total cost of managing total demand on the network. Further international comparison was made by studying the balancing mechanisms used by European TSO counterparts.
Phase 3
Phase 3 focused on future linepack swing modelling and conducted an in-depth analysis and comparison of different FES models (particularly ST and CT,) with regional and UK-wide linepack modelling, to examine how linepack may function on different energy days (changes in UK renewables production and weather.) A workshop was held with relevant colleagues from across the business, including network control managers, to consider how different hydrogen linepack swings could or should be managed by National Gas Transmission through market and balancing mechanisms.
Phase 4
Phase 4 produced a set of twelve potential future mechanisms which could be deployed to manage flexibility needs in a future hydrogen system. These represented a spectrum of approaches, ranging from asset-focused to market-focused. Some would accommodate flexibility. Others would dampen flexibility. The impact that each mechanism would have on managing flexibility depends on market liquidity and maturity. The twelve mechanisms were divided up between those most relevant to a nascent network (2028 – mid 2030s), growing market phase (mid 2030s to 2040) and an established market (2040 onwards). Current and potential future underlying positions for NGT, the regulator, shippers and network users were used to qualitatively define stakeholder views on each mechanism. These views were used to prioritise mechanisms from most to least promising for each hydrogen market stage.
The main outcome from this project has been to provide high-level information on network flexibility, for natural gas and hydrogen service, that had not previously been realised. The project has:
- Provided a monetary value for linepack flexibility which had not previously been described. Linepack swing is a key feature of the UK’s energy fix, providing gas storage to industry and homes. Placing a £/Mwh value to this storage capacity is a prerequisite for strategic decision making when comparing against other forms of energy storage and energy system flexibility – for instance against pumped hydro installations or large-scale Battery Energy Storage Systems (BESS.)
- Modelled, as best as is currently possible, likely linepack swings on a future hydrogen transmission network. This modelling had not been done before. Existing network data was combined with FES data, in lieu of known supply and demand, to predict future swing volume. This modelling has provided new data to the GSO and network modelling teams and has allowed for the creation of initial linepack management mechanisms, which prior to this project had not been considered.
- Provided an actionable list of mechanisms for dampening linepack swing on a future hydrogen network, which is being used by the GSO and Project Union when considering the operations of a future hydrogen transmission system. This includes mechanisms for dampening by ‘rules’ - market mechanisms – as well as assets – which has emphasised the need for strategic storage on a hydrogen network, which is being considered by Project Union ahead of future network design. This data is being considered for future system operability and planning decisions.
- Estimated remaining fatigue lifetimes of a small sample of representative feeders on the NTS, using real TD/1 data, should those pipelines be switched to hydrogen service. This was a crucial undertaking as hydrogen introduction reduces repurposed pipeline’s fatigue life, and combined with the innovative H2 linepack modelling, allowed NGT to better understand and model the feasibility of repurposing pipelines, and linepack, to hydrogen.
- Identified areas for further learning including 12 mechanisms that could be employed on a future hydrogen network to manage predicted increased linepack swings.
Value Tracking Data Point Definition
Maturity TRL2-3 This work remains in the early research stages, the opportunity to move up to demonstration or trials does not yet exist, and would be difficult at the scale required.
Opportunity 100% or multiple asset class The work of this project effects the entire
functioning of the NTS, both at an asset level but also in the operations of the GSO and market mechanisms behind system balancing.
Deployment Cost - No immediate deployment from this project.
Cost £466,667 Cost of project
Financial Savings - No immediate savings
Safety - No immediate safety benefits
Environmental Benefits - No immediate environmental benefits however this work is a prerequisite to safe and efficient operation of a bulk hydrogen transport system. This project is an enablement activity to projects which will offer huge environmental savings.
Compliance Ensures Compliance The project has provided an early indication of linepack requirements for hydrogen, which will affect NGT’s obligations to meet energy demand for customers across the UK.
Skills & Competencies Group The project outputs have fed into various teams across NGT including GNCC, network modelling and Project Union.
Future Proof Must have for business strategy Safe and efficient management of linepack swing is key to operating a resilient NTS, which only becomes more important in hydrogen due to the lower energy content by volume. The GSO/GNCC will have to design for, and react to, different linepack behaviour than is seen today on the natural gas system.
Lessons Learnt
National Gas Transmission took longer than predicted to produce accurate costs for compression operations, as data and expertise had to be drawn into the project that had not initially been accounted for. This delayed work package 2, however the project team decided to prioritise accuracy in linepack valuations over expediency – as compressor operations formed the largest cost component of linepack provision. In the future National Gas Transmission may want to more thoroughly consider SME and technical expertise that will be needed in a project and ensure that this provision is available and on-board from the beginning.
Besides this, no significant changes were made to scope, cost, or methodology during the run of this project.
