Citing searing summer temperatures and expected energy shortages, California lawmakers approved legislation aimed at extending the life of the state's last-operating nuclear power plant.

The Diablo Canyon plant - the state's largest single source of electricity - had been slated to shutter by 2025. The last-minute proposal passed by the state legislature early Thursday could keep it open five years longer, in part by giving the plant's owner, Pacific Gas and Electric (PG&E), a $1.4 billion forgivable loan.

California, like other U.S. states and countries, has been struggling to reduce its climate-warming emissions while adapting to a rapidly warming world. Record-breaking heat waves have stressed the state's increasingly carbon-free electrical grid in recent years, triggering rolling blackouts as recently as 2020. Grid operators, fearing a similar crash, issued a statewide alert to conserve energy last month.

The state has set the goal of getting 100 percent of its electricity from clean and renewable sources by 2045. Advocates for Diablo Canyon claim that target will be difficult to achieve without the 2,250 megawatt nuclear power plant. Diablo Canyon generated nearly 9 percent of the state's electricity last year and roughly 15 percent of the state's clean energy production.

"Maintaining operations at Diablo Canyon will keep our power on while preventing millions of tons of carbon from being released into the atmosphere," said Isabelle Boemeke of the group Save Clean Energy. "This is a true win-win for the people of California and our planet."

Nuclear power has seen a resurgence in recent years as the climate crisis has worsened and governments increase efforts to cut climate-warming emissions. The Biden administration launched a $6 billion effort earlier this year aimed at keeping the country's aging nuclear plants running.

"Have no doubt, President Biden is serious about doing everything possible to get the U.S. to be powered by clean energy,"Assistant Secretary for Nuclear Energy Kathryn Huff told attendees at a nuclear energy assembly in Washington, D.C., earlier this summer. "Nuclear energy is really essential to this," she said.

Roughly one-fifth of the country's electricity comes from nuclear power plants. That's as much as all other clean energy sources combined. But nuclear power isn't without its warts.

Despite decades of debate and billions of dollars spent, the U.S. still does not have a permanent storage site for its growing amount of nuclear waste. Diablo Canyon, located on California's Central Coast, sits near several seismic fault lines, inspiring long-held fears of a nuclear disaster similar to the kind experienced in Fukushima, Japan in 2011.

PG&E has long maintained that Diablo Canyon is safe from tsunamis, earthquakes and flooding. But concerns remain.

Juliet Christian-Smith, a regional director at the Union of Concerned Scientists estimates an earthquake-induced accident could cause more than $100 billion in damages and 10,000 cancer deaths.

"The bill ignores the plant's environmental impacts and vulnerability to earthquakes," she said. "Safety cannot take a back seat in our quest to keep the lights on and reduce global warming emissions."

The bill now heads to Governor Newsom's desk where he's expected to sign it.