Californian carbon emissions higher due to nuclear closures

19 January 2017

Carbon emissions from California's electricity generation are two-and-a-half times higher today than they would have been if the state had kept open nuclear power plants forced to close prematurely and not abandoned plans for new units, according to a new analysis by the Environmental Progress (EP) research and policy organization.

Blueprints for Diablo Canyon show how the site was envisaged to accommodated six units (Image: Environmental Progress)

Based on data from the California Air Resources Board and the California Energy Commission, and assuming natural gas as a replacement for nuclear, EP calculates that the state's 2014 emissions were 30.5 million tonnes higher than they would have been had the Rancho Seco and San Onofre plants remained open and had five further units been built as planned.

"Had those plants been constructed and stayed open, 73% of power produced in California would be from clean (very low-carbon) energy sources as opposed to just 34%. Of that clean power, 48% would have been from nuclear rather than 9%," the organisation said.

The single-unit Rancho Seco plant, a 913 MWe pressurized water reactor (PWR), entered commercial operation in 1975 but closed in 1989 after 53.4% of voters in a local referendum, held shortly after the Chernobyl accident in Ukraine, called for its closure. Units 2 and 3 at Southern California Edison's San Onofre were shut down in June 2013, after 30 years of operation, due to regulatory delay and uncertainty following damage in the steam generators of one unit. San Onofre unit 1, a single PWR, operated from 1968 to 1992.

The early closure of San Onofre contributed to a 35% increase in greenhouse gas emissions from power plants in California in 2012, the California Air Resources Board reported in 2013.

Pacific Gas & Electric (PG&E) last year outlined plans to close California's only currently operating nuclear power plant, the two-unit Diablo Canyon, at the end of its current operating licences - in 2024 for unit 1 and 2025 for unit 2. The units would then have been in operation for 40 years. Unlike New York and Illinois, which have adopted state-level clean energy legislation recognising nuclear for its role in helping to cut carbon emissions, California's Renewable Portfolio Standard excludes nuclear.

EP's analysis includes plants that were "already built but closed" as well as plants that "were not yet under construction but were close to construction and had a utility operator intent on building it". Five unbuilt units - Diablo Canyon 3, 4, and 5, plus two units at the planned Sundesert nuclear power plant - were therefore included in the analysis. Nuclear plants "defeated in early planning stages" were not counted.

US emissions state-by-state

According to a newly released report from the US Energy Information Administration, energy-related carbon dioxide emissions vary significantly across states, with the overall size of a state, as well as the available fuels, types of businesses, climate, and population density, playing a role in determining the level of both total and per capita emissions. The EIA also notes that each state's energy system reflects specific circumstances.

Energy-Related Carbon Dioxide Emissions at the State Level, 2000-2014, released on 17 January, records California as having both the highest overall energy-related carbon emissions for 2014 - 358 million metric tonnes - and one of the lowest per capita carbon dioxide emissions at 9.2 tonnes.

Researched and written
by World Nuclear News