PD Editorial: Diablo Canyon’s green power challenge

PG&E’s decision to close Diablo Canyon by 2025 is likely to mark the end of the nuclear power era in California.

For critics of atomic energy, Tuesday’s announcement was long overdue and the reactors at the state’s last operating nuclear power plant can’t be shut down soon enough.

Voluntarily decommissioning forestalls a political battle over relicensing the San Luis Obispo County power plant, and evidently it makes economic sense for PG&E.

But closing the 31-year-old power plant also could complicate efforts to reduce California’s carbon footprint.

Diablo Canyon produces enough power for 1.7 million homes. The plant accounts for about 9 percent of California’s in-state power generation, 6 percent of the state’s total energy mix and about 20 percent of the power supplied in PG&E’s service area - all without producing any greenhouse gases.

To its credit, PG&E is promising to replace Diablo Canyon’s output with a combination of stepped-up investments in renewable energy sources, increased efficiency and enhanced storage capabilities. In other words, without increasing its greenhouse gas emissions.

Yet with an investment that could run into billions of dollars, PG&E will replace an existing source of GHG-free energy when it may have been possible to increase its clean-energy portfolio if Diablo Canyon remained in the mix. There still could be a net increase as the shutdown agreement, negotiated with labor and environmental groups, includes a target of generating 55 percent of PG&E’s energy from renewable sources by 2031 - exceeding a state mandate of 50 percent by 2030.

At this point, however, it isn’t clear that enough renewable energy will be available, and turning to natural gas may save money, but it would come at the expense of greenhouse gas emissions.

Any new energy sources are subject to regulatory approval, as is the closure of the Diablo Canyon plant. It will fall upon the Nuclear Regulatory Commission and the California Public Utilities Commission to ensure that shut-down plans are complete, that they’re implemented safely and that closure won’t adversely affect the state’s clean-energy goals.

State regulators also will determine who foots the bill for closing Diablo Canyon, estimated at $3.8 billion. About $2.8 billion has been set aside already, and it’s likely that PG&E will ask to pass most of the remaining cost on to ratepayers, including those who have installed rooftop solar systems or signed up with Sonoma Clean Power and other community-based providers.

The regulatory review must be transparent, and state lawmakers should give careful scrutiny to actions by the PUC, which is revisiting the financial plan it approved in 2014 for closure of the San Onofre nuclear power plant after revelations about improper contacts between the commission’s staff and Southern California Edison officials.

Since the early 1960s, when protests forced PG&E to abandon plans for a reactor in Bodega Bay, Californians have been skeptical of nuclear power. Concern mounted after a tsunami caused a meltdown at the Fukushima nuclear plant in Japan. Those fears should ease with the closure of Diablo Canyon, but they could be quickly supplanted by concerns about producing enough clean energy to address the growing threat of global climate change.