UK-based Frontier Power has acquired two long-term energy storage projects (LDES) currently under development in Scotland from Apatura Energy.
The projects are the 200 MW/1,600 MWh Ayr battery energy storage system (BESS) and the 150 MW/1,200 MWh Busby BESS, located in Ayrshire and East Renfrewshire respectively. The projects will use the Z3 technology platform developed by New Jersey-based Eos Energy Enterprises, which develops hybrid zinc cathode batteries.
While the company reported back-to-back quarters of losses in its most recent financial results, CEO Joe Mastrangelo described the 2025 financial results as a “structural turning point” ahead of his work going forward. Eos signed other agreements with Frontier Power for a 5GWh portfolio in the UKnext to a 2GWh portfolio with its US subsidiaryand Mastrangelo was optimistic about the company’s partnership with Frontier in Britain.
“The choice of Eos Z3 technology for projects such as Ayr and Busby reflects the growing recognition of long-term energy storage as a crucial part of modern grid infrastructure,” he said. “As customers seek solutions that improve grid reliability and energy security, we believe Eos is uniquely positioned to meet these needs with a secure, scalable and purpose-built technology.”
Apatura said it will “continue to play an active role” in the development of the projects alongside Frontier until they become commercially operational, although the companies did not provide a date for the start of commercial operations for either project.
However, they noted that both projects had received “Gate 2 notifications” under the National Energy System Operator’s (NESO) reformed grid connection process. Last week, NESO confirmed firm connection offers for 37 GW of new electricity generation capacitywhich will come online by the end of the decade.
Frontier also noted that it intends for the Ayr and Busby projects to participate in Ofgem’s LDES cap and floor scheme, and the company received awards for 16 vanadium flow batteries and zinc batteries in the program’s first award September 2025.
