The sale of the defunct Vermont Yankee nuclear power plant was completed Friday.

Northstar Group Services has purchased the shuttered plant from Entergy Corp.

The completed business deal follows federal approval last October and state approval last month. Northstar has agreed to begin decommissioning the plant by 2021 and promises to complete the process by 2030. That's decades faster than Entergy had planned.

Jim Porter, the director of the public advocacy division for the Vermont Department of Public Safety, says the state believes the Northstar has the resources to fulfill its promises.

"I think everyone thought Northstar had the technical capability of doing this, we were just concerned about whether they had the financial wherewithal. And so we negotiated, the state agencies and others with Northstar, an additional $250 million in financial assurances. And once we were able to get those assurances in place then the state agencies and others supposed the transaction," Porter said.

Vermont Yankee was shut down at the end of 2014 after 42 years of operation.