Part 2 of 2 Parts (Please read Part 1 first)
The closure of U.S. commercial nuclear power plants in the past has caused an increased use of fossil fuels. The closure of reactors in Tennessee Valley in 1985 resulted in a surge in coal consumption. Shutdown of a nuclear power plant in California in 2012 caused an increase in natural gas usage. The phasing out of nuclear power in Germany led to a surge in power generation from coal plants. The MIT group noted these trends and wondered how the U.S. energy grid would respond if nuclear power were entirely phased out.
Freese says, “We wanted to think about what future changes were expected in the energy grid. We knew that coal use was declining, and there was a lot of work already looking at the impact of what that would have on air quality. But no one had looked at air quality and nuclear power, which we also noticed was on the decline.”
The MIT group utilized an energy grid dispatch model created by Jenn in the new MIT study. The model aimed to evaluated how the U.S. energy system would react to the shutdown of nuclear power. The model mimics the production of all power plants in the U.S. It operates continuously to estimate energy requirements per hour in sixty-four regions across the country. Reflecting the actual energy market in the U.S., the model considers costs when determining whether to raise or lower a plant’s production. Plants that produce energy at the cheapest price were prioritized over more expensive sources.
The MIT group performed various simulations using the model. They included a scenario with no nuclear power, a baseline grid that includes nuclear power, and a grid without nuclear power but with additional renewable sources that are expected to be integrated by 2030. The researchers then coupled each simulation with an atmospheric chemistry model to study the movement of emissions and laid them over population density maps. The MIT group also calculated the risk of premature deaths for populations exposed to air pollution.
The MIT researcher’s analysis uncovered a distinct trend. The absence of nuclear power resulted in an overall deterioration of air quality, predominantly affection regions on the East Coast that host most of the U.S. nuclear power plants. The group observed a rise in production from coal and gas plants in the absence of nuclear power which led to over five thousand pollution-induced deaths across the U.S. compared to the baseline scenario. The MIT study also estimated that more people are likely to experience premature death due to the effects of climate change resulting from the increased carbon dioxide emissions as the grid compensates for the lack of nuclear power. These additional carbon dioxide emissions could cause as many as one hundred and sixty thousand more deaths over the next century.
Freese says, “We need to be thoughtful about how we’re retiring nuclear power plants if we are trying to think about them as part of an energy system. Shutting down something that doesn’t have direct emissions itself can still lead to increases in emissions, because the grid system will respond.”
Selin adds, “This might mean that we need to deploy even more renewables, in order to fill the hole left by nuclear, which is essentially a zero-emissions energy source. Otherwise we will have a reduction in air quality that we weren’t necessarily counting on.”