UK long-duration energy storage has taken another step forward after Frontier Power acquired the rights to two Scottish projects from Apatura Energy, supporting grid resilience and clean power ambitions.
Frontier Power Energy Holdings Ltd has acquired the rights to two long-duration energy storage (LDES) projects at Ayr and Busby from Apatura Energy.
The transaction, completed on 26 May 2026, gives Frontier rights to two projects in Scotland with a combined planned capacity of 350 MW and 2,800 MWh.
The Ayr project has a planned capacity of 200 MW, or 1,600 MWh. The Busby project is planned to deliver 150 MW, or 1,200 MWh.
Both projects are intended to use long-duration battery systems supplied by Eos Energy Enterprises, Inc., including its Z3 technology platform, under an existing framework agreement with Frontier.
UK long-duration energy storage portfolio grows
The acquisition supports Frontier’s plan to build one of the UK’s largest long-duration energy storage portfolios.
Frontier said it has assembled a 2.6 GW / 20 GWh UK pipeline designed to deploy long-duration battery storage at scale and support a wider investment programme in UK energy infrastructure.
Long-duration energy storage is expected to play an important role in balancing a power system with rising levels of renewable generation.
Ofgem describes long-duration electricity storage as storing electricity when renewable generation is high or prices are low, so that it can be used later when demand is high or prices rise.
Ayr and Busby projects advance under UK grid reform process
Frontier said both the Ayr and Busby projects have received Gate 2 notifications under the National Energy System Operator’s Grid Connections Reform process.
The company said this reflects their strategic importance to the UK electricity system and their role in supporting the Government’s Clean Power 2030 ambitions.
The UK Government’s Clean Power 2030 Action Plan sets out measures to support a cleaner electricity system, including action on networks, planning, renewable generation and long-duration flexibility.
Frontier intends to advance Ayr and Busby as part of its UK long-duration energy storage portfolio, with a view to participation in Ofgem’s Cap and Floor regime.
The Cap and Floor scheme, developed by the UK Government and Ofgem, is intended to help unlock investment in long-duration electricity storage projects.
Apatura to remain involved in project development
For Apatura, the transaction represents the next phase in the development of two assets it has originated and progressed.
Apatura will retain an active role in the ongoing development of the sites, working alongside Frontier to advance them towards delivery.
Apatura CEO Giles Hanglin commented: “This transaction reflects the progress at Ayr and Busby and marks the next step in their development, and we’re pleased to remain involved as the projects move forward with Frontier. Long-duration energy storage has an important role in strengthening energy security and supporting a more resilient, low-carbon energy system.”
Frontier Power targets UK energy storage growth
Humza Malik, CEO of Frontier Power, said: “Ayr and Busby are excellent additions to our portfolio, and we look forward to working with Apatura as they progress. We continue to see significant opportunities for long-duration energy storage in the UK and remain focused on bringing forward projects capable of delivering energy security, economic growth and long-term system resilience.”
Joe Mastrangelo, Chief Executive Officer of Eos, said: “We continue to build upon our relationship with Frontier as they advance long-duration energy storage opportunities across the UK. The selection of Eos Z3 technology for projects such as Ayr and Busby reflects the growing recognition of long-duration energy storage as a critical component of modern grid infrastructure. As customers seek solutions that enhance grid reliability and energy security, we believe Eos is uniquely positioned to address those needs with a safe, scalable and purpose-built technology.”
Subject to successful participation in Ofgem’s Cap and Floor regime, Frontier said its wider portfolio could unlock up to £5 billion of UK investment, create up to 1,900 skilled jobs and support thousands more across manufacturing, engineering and the wider supply chain.
Source: Frontier Power; Apatura Energy; Ofgem; UK Government
