Phasing out the United States' entire nuclear power supply by 2030 would increase the country's carbon dioxide emissions by at least 5% and as much as 13%, depending on what mix of power plants replace the aging nuclear units. If the United States phased out the twenty-three nuclear power plants with the same design as Japan's troubled Fukushima Daiichi nuclear complex by 2030, carbon dioxide emissions in the United States would increase overall by at least 1 percent.

As the crisis at the Japanese Fukushima Daiichi nuclear complex continues to captivate global media attention, President Obama's domestic energy plans, which have long-included a push for the construction of new nuclear reactors, are beginning to be called into question. Two days ago, Senate Democrats demanded a broad review of the safety of the country's nuclear plants, with nine Democrats even seeking to delay legislation to allow the construction of a new plant in Iowa.

The Energy Information Administration (EIA) predicts that, by 2030, nuclear power will supply about 18% of the nation's electricity, as compared to roughly 20% in 2011.

Below, we illustrate the consequences for overall United States carbon dioxide emissions if the United States phases out its entire nuclear fleet. Three scenarios project the effect of replacing lost generation either entirely by coal generation, entirely by natural gas generation, or by an equal split of both.

If nuclear power were to be completely taken out of the United States' power supply by 2030, United States carbon emissions would rise by at least 300 million tons over baseline scenarios. Carbon emissions would increase by at least 5% and as much as 13% across the entire economy, while power-sector emissions would soar by 12% to 33%, depending on the mix of replacement power.

The lowest value corresponds to a scenario in which the nuclear plants are replaced by new natural gas-fired units, perhaps the most likely scenario given recent discovery of plentiful new natural gas supplies in North America.

*For exact numbers, see Chart 1 at the end of this post.

Replacing the generation lost from a complete phase-out of nuclear power entirely with non-hydropower renewable energy would require the United States to more than double expected generation of renewable energy, from current 2030 BAU projections of 404 million mWh to about 1.2 billion mWh. This means increasing conventional renewable energy's share of electricity generation from 4.1% today to 26% in 2030, as compared to the EIA's business-as-usual projection of 8.2% by 2030.

Now, concerns are rising about the relicensing of American nuclear power plants with a similar design as the Fukushima reactors.

Of the 104 operating commercial nuclear reactors in the United States, twenty-three are of the same design as the Fukushima reactors-- General Electric's Boiling Water Reactor Mark I. Plants of this design are among the oldest Generation-1 nuclear power plants in the US, most of which were built in the mid-1970's with original 40-year NRC licenses set to expire shortly. Many have renewed their licenses for another 20-year period, but without further extensions, would be phased out of operation by the late 2030's.

These twenty-three reactors would account for about 20% of total estimated nuclear power generation in 2030, if still operational at the time.

Below, we've projected the effect on US carbon dioxide emissions of the long-term closure of the twenty-three GE Mark I reactors by 2030. We find that the long-term closure of these plants would increase US carbon dioxide emissions by at least 64 million tons, an increase of 1% in total US CO2 emissions over the EIA's projected 2030 Business As Usual scenario. In the power sector alone, emissions would increase anywhere from 2.6% to 6.1%.

Emissions could increase by as much as 2.4% if the nuclear reactors are replaced by coal-fired power plants, however.

*For exact numbers, see Chart 2 at the end of this post.

To avoid these emissions increases, the US could replace lost generation from these plants entirely with power from non-hydro renewables. This would require a scale-up of conventional renewable power from supplying 4.1% of electricity today, to almost 11.5% of electricity in 2030.

The EIA itself projects a scenario wherein the United States allows its nuclear power plants to be retired after 60 years of operation, with no possibilities of life extension. In this case, the EIA finds that almost all of this lost zero-carbon power generation would be replaced largely through new natural gas and coal capacity, rather than construction of new nuclear plants:

"If all the existing nuclear power plants in the United States were retired after 60 years of operation, the impacts on electricity markets, fuel use, and GHG emissions would be substantial. Of the additional capacity built in the Nuclear 60-Year Life case, only about 2 gigawatts is nuclear. Instead, the retired nuclear capacity is replaced almost exclusively with coal and natural gas capacity, which in the absence of policies regulating GHG emissions remains more economical than either nuclear or renewable plants."

While the nuclear crisis in Japan is still unfolding, and the full implications of the potential meltdown at Fukushima Daiichi for the operation of nuclear power stations in the United States remain to be seen, it is clear that the decline of nuclear power as an energy source in the United States may significantly increase the country's carbon emissions.

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Decline in US Nuclear Power Would Increase Carbon Emissions

Mar 18, 2011

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