UK Power Reserve (UKPR) has awarded a contract for the construction of the second phase of its battery-based energy storage portfolio to Fluence.

The deal between UKPR and Fluence, a joint venture between Siemens and AES, extends an existing contract to build UKPR’s first, 60 MW phase of energy storage projects.

Fluence says that it will deliver the entire UK-based 120 MW battery storage fleet by the end of summer 2019. The storage plants will use the company’s Advancion battery technology, which is based on lithium-ion technology.

UKPR secured the portfolio of ultra-fast energy storage projects in the UK’s 2016 capacity market auction and in June 2018 announced that it had signed Fluence to deliver the first phase.

“By splitting our portfolio into two 60 MW sets of projects, we’ve had the opportunity to fully assess the market and took a nimble approach to keep up with this rapidly evolving space,” said Sam Wither, head of UKPR. “Fluence and its Advancion technology again proved their worth throughout this highly competitive process.”

“We continue to make strong progress on the initial phase of battery projects with Fluence,” said Wither. “The first 60 MW of projects across England are on schedule and will be ready to deliver flexibility services to the UK grid by the end of this winter.”

The build-out of battery-based energy storage for the UK grid is happening alongside UKPR’s build-out of gas assets. The company is currently delivering 160 MW of rapid-response, flexible gas assets, which it won in the 2015 capacity market auction, and will be online by the end of winter 2019.