23rd June 2026 – London, UK

We challenged Ofgem’s design of a cap and floor regime for Long Duration Energy Storage (LDES) at the Competition Appeal Tribunal (CAT) due to concerns that the scheme could unintentionally disrupt markets on which storage has already established itself as cost effective and competitive. This would increase costs for consumers and whilst we are glad to see this process conclude, some questions remain unresolved.  

Zenobē remains supportive of the overall ambition of the Long Duration Energy Storage (LDES) scheme and the UK Government’s ambition to deliver affordable, clean and secure energy for households and businesses. With a need for between 4GW to 6GW of LDES capacity identified in the Clean Power 2030 Action Plan – an addition of 1.1GW to 3.1GW to current installed capacity – these assets must operate alongside unsubsidised short duration energy storage (SDES) where the government requires 23GW to 27GW by 2030. Together they increase system security and reduce costs.  

At a time when electricity bills remain exceptionally high, our concerns remain that the proposed LDES cap and floor scheme may place additional and unnecessary costs on consumers. It could unintentionally disrupt an existing, unsubsidised and highly competitive Short Duration Energy Storage (SDES) market which has taken £188m off consumer bills since December 2024 alone.  

If subsidised LDES is allowed to compete in SDES markets, investors and offtakers will be less likely to support the technology, and this places the 23-27GW target at risk. It will slow progress to reduce the costs of integrating renewables onto the grid, making the UK’s power supply less secure and risking alienating the public at a critical time in delivering the UK’s energy transition.  

We will continue to engage constructively with the Government and Ofgem to ensure that future support mechanisms deliver a balanced and competitive market which provides value for consumers and works towards Government’s Clean Power 2030 goals.