Power company Contact Energy is selling its gas storage facility in Taranaki to Gas Services New Zealand for $200 million.
Contact opened the Ahuroa facility in 2010 to store gas for use at the nearby Stratford Power Station.
Chief executive Dennis Barnes said as part of the deal, Contact would have the right to use the facility if needed.
He said the deal would let his company focus on the power generation and customer sides of the business.
The money would be used to repay debt.
The deal is subject to some conditions and regulatory approvals.