ArcLight Capital Partners is investing in Kleen Energy Systems, which owns a 620-megawatt natural gas-fired power plant in Middletown, Connecticut.

ArcLight said it had entered into a definitive purchase agreement with Sojitz Corporation of America to acquire Sojitz’s indirect ownership interests in Kleen Energy Systems, including all of the preferred equity and a minority common equity stake.

Financial terms of the private transaction were not disclosed.

The Kleen plant provides critical capacity, energy and ancillary services to the New England region.

ArcLight said Kleen benefits from stable cashflows under a capacity supply agreement with Connecticut Light & Power, alongside an advantaged market heat rate and dual fuel capability that allows reliable, dispatchable output into the New England market.

“Kleen builds upon ArcLight’s focus on the electrification mega-trend and on supporting the energy grid of the future, which we expect to include a complementary mix of renewable resources and reliable, low carbon power infrastructure,” said Dan Revers, managing partner and founder of ArcLight.

“The high-quality asset provides critical infrastructure and grid stability services as one of the core power suppliers in the New England market.”