Diablo Canyon nuclear power plantCalifornia lawmakers have voted to extend the operating life of the state's only nuclear power plant at Diablo Canyon. The proposal passed by the legislature could keep open the state's largest single source of electricity for five more years, in part by giving plant owner Pacific Gas and Electric (PG&E), a $1.4 billion forgivable loan. The loan is expected to be repaid with federal funding. PG&E in 2016 proposed closing Diablo Canyon when the two pressurised water reactor units reached the end of their current operating licences, in 2024 and 2025.

The California Assembly passed Senate Bill 846 (SB846) by 69 votes to three late on 31 August. The bill then returned to the Senate for the final vote where 31 senators voted in favour, with one against. On 1 September, California declared a State of Emergency with an intense heat wave resulting in temperatures in excess of 100°F (38°C) and putting severe strain on California's energy grid. The heat wave prompted the California Independent System Operator (ISO), the non-profit organisation tasked with maintaining reliable energy on behalf of customers, to issue two calls urging people to conserve energy to prevent blackouts.

The state has targeted 100% clean and renewable electricity by 2045. Advocates for Diablo Canyon believe that will be difficult to achieve without the 2,250MWe Diablo Canyon NPP, which generated nearly 9% of California's electricity in 2021 and some 15% of its clean energy production. The bill now heads to Governor Gavin Newsom, who had proposed keeping the plant open as part of a broad energy package pushed through in the final days of the legislative session. Newsom had previously supported closure of Diablo Canyon, but earlier this year asked the US Department of Energy (DOE) to change eligibility criteria under its $6 billion programme to support the continued operation of US nuclear reactors under threat of premature closure.

The bill faced opposition from some environmental groups, citing nuclear safety concerns, and Assembly Democrats circulated a counterproposal to spend the money on building more solar and wind instead. However, a supermajority of both chambers — the required threshold for a bill to go into effect immediately — ultimately agreed.

DOE Assistant Secretary for Nuclear Energy Kathryn Huff said she was "extremely pleased" to see the operation of Diablo Canyon extended. "These reactors critically underpin our nation's decarbonisation goals and their 24/7 power will support grid stability for consumers in the state during our transition to net zero," she said. Maria Korsnick, president and CEO of the Nuclear Energy Institute. Extending operation of Diablo Canyon will help California reach its climate goals and ensure a reliable clean energy workhorse continues to serve residents.

Image: The Diablo Canyon nuclear power plant (courtesy of CNBC)