What if the US followed Germany and shut down its nuclear plants?

Moving pollution

The baseline scenario comes from a few years back, when gas provided 32 percent of electricity generation and coal was responsible for 31 percent (coal was down below 20 percent as of last year). While natural gas rises slightly to 39 percent of the energy mix, coal use rises to 45 percent of the US's generation in this scenario. This boosts the emission of pollutants that lead to particulates: 42 percent more nitrogen oxides and 45 percent more sulfur dioxide are emitted. The heavy reliance on coal also boosts carbon dioxide emissions by over 40 percent. Ozone pollution rises as well.

Nuclear plants are heavily concentrated in the Eastern US, so most of the pollution increases end up there. The plants that compensate for the loss of nuclear generation, however, may not be in the same area (or even state) as the nuclear plant was, so there's some geographic shifting of pollution.

With both nuclear and coal shut down, natural gas dominates generation, providing three-quarters of all electricity in the US. In this scenario, we even end up relying on oil and diesel generation, which provide about 2 percent of the electricity. Natural gas is low in sulfur dioxide, so those emissions drop by roughly a quarter. Shutting down coal generation largely compensates for the loss of nuclear in terms of carbon emissions, which rise by just five percent. By contrast, natural gas still produces nitrogen oxides, so those go up by a staggering 194 percent.

The expected additions of renewables, by contrast, largely compensate for the loss of nuclear. Natural gas use barely moves, going from 32 percent to 33 percent of the generation, while coal goes from 31 to 34 percent. Emissions profiles remain similar overall, but there are regional changes, with pollution dropping in the west but rising in the east.

Counting the costs

The effects of particulates and ozone pollution have been extensively studied, and it's possible to estimate the health impacts these changes will trigger. For this study, the researchers convert this to additional deaths each year due to the increase in pollution. For climate change, the researchers estimated the cumulative deaths that would occur by the end of the century due to each year's additional carbon emissions.

For the no-nuclear scenario, particulates would cause an additional 3,600 deaths each year and ozone would cause an additional 1,600, for a total of just over 5,000. Again, these are mostly in the Eastern US. Based on the locations of the fossil fuel plants that would be activated, the impacts would hit Black Americans the hardest. Depending on the climate sensitivity, emissions of carbon dioxide would cause somewhere between 78,000 and 170,000 premature mortalities by the end of the century.

Obviously, that has a financial cost. Based on US government mortality estimates, the researchers place the annual costs from pollution at $40 billion. Using different estimates of the social cost of carbon tacks on anywhere from $11 billion to $180 billion. So quitting nuclear power without a low-emissions replacement is quite expensive—remember, these are the costs for just one year.

The one explored here is the no-nukes/high-renewables scenario. And it accomplishes about what you'd expect, producing a net change of only 260 additional deaths each year due to the slight changes in fossil fuel use. (Particulate deaths go up by about 1,000 per year, while ozone-driven deaths drop by 720 compared to the baseline scenario.)

Again, this is an unrealistically simple scenario. Even if the US were to transition off nuclear, it would do so gradually. And without storage and advanced grid management, renewables won't be able to provide a direct replacement for all the nuclear power we currently generate.

At the same time, the simplicity of the study allows the researchers to estimate all the savings provided by nuclear power that don't show up in the value of the electricity they generate, which can help offset the plants' higher operating costs. In addition, the analysis indicates that even a relatively rapid growth of renewables would only allow us to tread water on pollution and emissions if we don't find ways to extend the lifetime of existing nuclear plants. And that information can be very valuable for setting energy policy.

Nature Energy, 2023. DOI: 10.1038/s41560-023-01241-8  (About DOIs).