AIP Teams Up with BW ESS in Strategic 700MW UK Battery Storage Deal

AIP Management, an energy and decarbonisation infrastructure investor, has acquired a 49 percent equity stake in a UK-based battery energy storage system (BESS) portfolio with a total capacity of 700MW and 3.5-hour duration from BW ESS.

Opening AIP’s way into the battery segment, the transaction is the company’s first dedicated investment in standalone battery storage.

“This investment reflects our conviction in the UK energy storage market and builds on the knowledge we have developed through our existing investments in co-located BESS,” said Greg Falzon, Partner and Co-Head of Investments at AIP. “We are very pleased to form this partnership with BW ESS, which brings highly complementary industrial expertise and operational capabilities to our investment approach. Together we will deliver long-term value while enabling the deployment of critical flexibility in the UK power system.”

Portfolio

The portfolio of the acquisition comprises three assets, including the already operational Bramley (100MW / 331MWh), and the under-construction projects of Hams Hall and Berkswell, with capacities of 400MW/1,422MWh and 200MW/712MWh, respectively. 

On completion, the assets will be held in a newly formed AssetCo, with BW ESS retaining a 51 percent majority stake. As per the agreement, BW ESS is tasked to manage construction and operations across the portfolio. The ESS firm has a history of more than 500MWh of operational BESS, 3.3GWh under construction, and a development pipeline spanning six markets.

Catering to Rising Storage Demand

The investment is underpinned by strong market fundamentals in the UK, where the growing share of intermittent renewables, declining baseload generation, and rising grid constraints are creating an urgent need for flexible capacity. 

Large-scale battery storage has become critical to ensuring system stability, managing power price volatility, and supporting the security of supply, BW ESS said. 

The portfolio is located in the Midlands and the South-East of England. The ESS firm further added that it benefits from its proximity to major electricity load centres and National Grid substations, reducing congestion risks while maximising access to arbitrage and balancing services. 

Once operational, these batteries are expected to cater to the electricity needs of 2.3 million UK homes for 3.5 hours. Revenue stability is supported by long-term capacity market contracts and robust offtake arrangements.

“We are delighted to welcome AIP as our partner in this strategically important portfolio,” said Erik Strømsø, CEO of BW ESS. “We see strong alignment in our approaches and a shared ambition to deliver storage assets at scale. With AIP’s infrastructure expertise and long-term perspective alongside our operational capabilities, we are confident this partnership will support the UK’s energy transition and provide lasting benefits to both parties.”

The acquisition is subject to customary regulatory approvals. 

To date, AIP has invested over EUR 8 billion in infrastructure assets. This includes renewable energy assets with a capacity of approximately 7 GW. AIP is part of Storebrand, a Nordic financial group, which owns 60 percent of AIP. 

Part of BW Group, BW ESS is a global energy storage owner-operator with a presence across multiple countries. Typically working with local development partners, the business is active in the UK, Australia, Italy, Germany, Spain, and Sweden. It has more than 500MWh of operating BESS projects, with 3.3GWh under construction and a development pipeline of about 9.5GWh.