California energy regulators voted Thursday to allow the Diablo Canyon nuclear plant to operate for an additional five years, despite calls from environmental groups to shut it down.
The California Public Utilities Commission agreed to extend the shutdown date for the state's last functioning nuclear power facility through 2030 instead of closing it in 2025 as previously agreed.
Separately, the Federal Nuclear Regulatory Commission will consider whether to extend the plant's operating licenses.
The twin reactors, located midway between Los Angeles and San Francisco, began operating in the mid-1980s. They supply up to 9% of the state's electricity on any given day.
The Public Utilities Commission's decision marks the latest development in a long fight over the operation and safety of the plant, which sits on a bluff above the Pacific Ocean.
In August, a state judge rejected a lawsuit filed by Friends of the Earth that sought to block Pacific Gas & Electric, which operates the plant, from seeking to extend its operating life.
And in October, the Nuclear Regulatory Commission rejected a request from environmental groups to immediately shut down one of two reactors.
PG&E agreed in 2016 to shutter the plant by 2025, but at the direction of the state changed course and now intends to seek a longer operating run for the plant, which doesn't produce greenhouse gases that can contribute to climate change.
Democratic Gov. Gavin Newsom, who once was a leading voice to close the plant, said last year that Diablo Canyon's power is needed beyond 2025 to ward off possible blackouts as California transitions to solar and other renewable energy sources.
Activists condemned the extension and noted that the projected costs of continuing to run the aging plant are expected to top $6 billion.
"This ill-conceived decision will further escalate financial strain on California ratepayers and extend the threat of a catastrophe at Diablo Canyon," said Ken Cook, president of the nonprofit Environmental Working Group.
"With California's annual renewable energy additions exceeding Diablo Canyon's output, there is zero reason to keep it running," he added in a statement.
