Project Summary

The GeoGrid project explores the use of Geothermal Long Duration Energy Storage (LDES) to store renewable electricity as heat with Leeds University as a trial site. LDES offers a cost-effective, scalable solution that will reduce constraint on the electricity networks. By storing off-peak electricity and discharging it during peak demand periods, LDES can lower curtailment costs, reduce network congestion, and enhance grid resilience. GeoGrid will assess the commercial potential of geothermal energy storage for both the trial site and nationally across GB to provide insights regarding its wider deployment, benefiting consumers with low-cost heat while supporting decarbonization and energy security.

Innovation Justification

The GeoGrid project will deliver a novel analysis for optimisation of an in-place geothermal energy heat and energy storage that supports cross-sector decarbonisation by facilitating, managing, and integrating heat and flexibility services.

Innovations

GeoGrid will provide evidence to enable the electricity and heat sectors to implement geothermal energy storage as a heat decarbonization solution with significant flexibility benefits. It will evaluate how flexible heat generation and storage using geothermal wells can accelerate heat decarbonisation whilst minimising the impact on electricity distribution networks and providing a long duration energy storage solution to optimise the electricity system. Geothermal energy is an established heating supply option and has already delivered environmental, economic and technical benefits in some European countries with similar geology to the UK, such as the Netherlands, Germany, and Belgium. However, only a small fraction of geothermal heat resources are used in the UK, covering approximately 0.3% of the heat demand. The existing operational sites include load balancing between heating and cooling, but geothermal energy has not been considered as an energy system asset.

This project will assess the potential for geothermal solutions to become an important tool in managing network constraints alongside providing long duration energy storage for inter-seasonal balancing. This will include stacking of a wide range of system services and associated revenue streams to ensure viable business case. Analysis by LCP Delta for DESNZ shows that deploying 20 GW of LDES could save the UK £24 billion by 2050, reducing reliance on costly natural gas. NESO estimates that 11.5 to 15.3 GW of LDES will be needed by 2050 to meet net-zero targets. Thermal long duration storage provided by geothermal could be a very cost-effective method of achieving some of this demand.

Our novel developments are:

For the first time, advanced simulation modelling and predictive control will permit geothermal production sites and local heat demands to be coordinated to manage excess renewable generation on the electricity system through recharging. This will facilitate alleviation of network constraints through diversity from geothermal storage and improved heat pump efficiency with higher ground temperatures.
Through development of a novel optimisation model, the flexible demand of the campus, partly derived from the ground source heat pump operation and the recharge of geothermal reservoir will be aggregated to provide flexibility to the power grid, by participating in system services market and local flexibility markets.
Learning from preceding projects

This project builds on extensive knowledge gained from the University of Leeds' Geothermal Living Lab. Extensive analysis has been conducted on the thermal design and planning including committed development activities for a geothermal energy system to provide heating and cooling on campus. This presents a low-risk trial opportunity with senior stakeholder buy-in. Existing work has also included extensive engagement with other stakeholders including Leeds City Council and DESNZ.

Among the published projects registered on the Smarter Networks Portal, GeoGrid stands out as a timely and crucial initiative for heat decarbonisation. Existing SIF funded projects (Heat Balance and Watt Heat) and schemes such as the Gateshead District Energy Scheme have explored system flexibility and stacking revenue streams, but not considering the duration and capacity of a geothermal storage system and its societal benefits.

Changes in TRL, IRL, CRL Currently, the Technology Readiness Level (TRL) of geothermal production is high (TRL 7-8), with lower Integration Readiness Level (IRL3) and Commercial Readiness Level (CRL 3). By the end of the alpha phase, it is expected that both the IRL and CRL will increase to 5.

Impacts and Benefits

Geothermal heat provision and LDES presents a promising solution for delivering substantial benefits to electricity consumers, while offering incidental advantages to vulnerable groups and the broader energy system. This project will demonstrate how geothermal LDES can alleviate network congestion, reduce consumer costs, and improve the UK's energy system resilience and flexibility, thereby supporting the UK's decarbonisation. The associated CBA spreadsheet submitted demonstrates the cost benefit of the core scheme.

Current Position (Baseline)

The UK's electricity network faces challenges of increasing heat electrification and the integration of intermittent renewable energy sources. These lead to higher peak demand, especially during winter, and contribute to network congestion. National Grid has forecasted that by 2026, constraint payments to curtail renewable energy could reach £2 billion annually.[1] Additionally, network reinforcement to manage peak demand such as new transmission links is costly and disruptive. Consumers currently bear the financial burden of these inefficiencies through higher energy bills. Vulnerable groups, particularly those in fuel poverty, are disproportionately impacted.

Metrics to measure the current baseline including annual curtailment costs, peak electricity demand during winter, and total costs of network reinforcement will be tracked throughout the project to assess the impact of the LDES solution.

Benefit to consumers

This project directly benefits consumers by reducing the curtailment of renewable energy, a cost ultimately placed on bills. LDES enables storage of excess renewable electricity as heat during off-peak periods, which can then be discharged (via efficient heat pumps) during periods of high demand. This reduces the need for costly network upgrades and mitigates curtailment, thereby driving down costs for consumers.

Benefits will be realised through identification of cost-effective ways to store renewable energy and avoid curtailment. The integration of LDES into business-as-usual will further reduce the need for peaking generation, leading to long-term savings for consumers. The system therefore benefits directly connected customers (the University and heat network consumers), alongside broader UK consumers via a better optimised system.

Wider System Benefits

Geothermal heat provision and LDES offers broader benefits to the entire energy system, including both electricity and gas sectors. By reducing peak electricity demand, it lowers the reliance on gas-fired generation during winter, thereby contributing reduced carbon emissions and enhancing the UK's energy security. The ability to store renewable energy for use during peak periods reduces the need for expensive peaking generation and imports of fossil fuels, further benefiting consumers. For heat network providers, integrating LDES improves the economic viability of heat networks by enabling the use of curtailed renewable energy and opening up a source of income generation through participation in system services market and local flexibility markets.

Supporting Decarbonisation and Energy Security

This project supports the UK's decarbonisation goals by exploiting geothermal as a high efficiency source of heat, whilst maximising the use of renewable energy and minimising curtailment. Currently, mismatches between renewable energy generation and demand often result in curtailment leading to higher system costs. LDES allows excess renewable energy to be stored as heat for later use, offering inter-seasonal storage that ensures peak winter demand is met without relying on costly fossil fuel generation.

By reducing the need for electricity network reinforcements, LDES also provides long-term financial savings and enhances the UK's energy security. It minimises reliance on global fossil fuel markets, protecting consumers from price volatility and supply disruptions. Carbon benefits are further realised through reductions in CO2 emissions associated with curtailed renewable energy and reduced fossil fuel generation.

There is a significant gap in technologies which can affordably provide long duration (weeks -- months) energy storage, and geothermal could be an important solution to fill the gap.