Long duration electricity storage
Long Duration Electricity Storage (LDES) technologies contribute to decarbonising and making our energy system more resilient by storing electricity and releasing it when needed.
LDES technologies are an important part of the GB energy system as we move to more renewables and electrification. They store electricity when renewable generation is high or prices are low and release it when electricity demand or prices rise. This helps keep the system balanced and can lower costs for consumers by reducing bills and avoiding costly grid upgrades.
Our role and responsibilities
Ofgem is the regulator for Long Duration Electricity Storage and oversees implementation of a 'cap and floor' regime for LDES projects, proposed by the Department for Energy Security and Net Zero (DESNZ). The aim of this regime is to stimulate investment in Long Duration Electricity Storage projects.
Under the cap and floor model, when revenues fall below a set minimum (the floor), consumers top up the difference. If revenues go above a set maximum (the cap), the extra money goes back to consumers. This provides investors with revenue certainty and tackles the issues of high upfront costs and market uncertainty for LDES projects.
What we're working on
Ofgem has published a joint technical document with DESNZ. This document sets out the details of the Long Duration Electricity Storage (LDES) cap and floor regime, including the eligibility criteria, assessment process and timelines for approving projects.
Ofgem opened its first application window for new LDES projects under the cap and floor regime on 8th April 2025.
Following consultation Ofgem has published a set of decisions that underpin the LDES cap and floor regime. These includes the project assessment decision and framework and the financial framework decision, supported by the cap and floor model and handbook. Together, these documents set out how applications are assessed and how cap and floor levels will be set. The financial model and handbook will be made available on our website as part of the regime documentation.
Projects that met the eligibility criteria are now progressing to the project assessment stage, where Ofgem, working with the National Energy System Operator (NESO), will evaluate project costs, benefits and consumer value with final approvals expected in Summer 2026.
In parallel, we will also work with stakeholders to develop regime documents, including the licence (a modified form of the Electricity Generation Licence with Standard and Special Conditions).
The timelines align with National Energy System Operator (NESO)’s Clean Power 2030 advice to the government, which sees an important role for LDES in achieving clean power by 2030.
To learn more, listen to our webinar about Long Duration Electricity Storage.
Contact the LDES team
If you would like to speak to someone at Ofgem about our work on the Long Duration Electricity Storage cap and floor regime, please email LDES@ofgem.gov.uk.
Long duration electricity storage publications
Includes licensing guidance, policy, news and insights.