How shutting down nuclear reactors could lead to poor air quality

5 May 2023

Image: © Ulf/

Scientists based at MIT have claimed that if all nuclear reactors in the US were to stop working, pollution-related deaths could dramatically increase.

The role of nuclear power in the future of renewable energy is a controversial topic among environmentalists and climate activists, mainly because of the potential dangers and exuberant costs involved in the development and maintenance of nuclear power plants.

Arguments in its favour are compelling. Energy produced through nuclear fusion does not come with the same baggage af greenhouse gas emission as many other processes do, notably coal mining and oil and gas drilling. Moreover, the energy produced is immense.

In the US alone, home to the world’s largest fleet of nuclear reactors, 20pc of the nation’s electricity comes from nuclear power. Closer to home, nuclear plants generated around a fourth of total electricity generated in the EU as of 2021.

But with many of the 92 nuclear reactors in the US approaching the end of their expected lifecycles, policymakers are debating whether to retire the old structures or invest in their reinforcement so they continue to power one of the world’s most energy-consuming countries.

While they are no doubt a low-carbon alternative to the heavily polluting coal, oil and natural gas options, and potentially more productive than existing renewable technologies in terms of total output, some researchers have found another important factor to consider: air pollution.

In a study published in Nature Energy last month, researchers based at the Massachusetts Institute of Technology (MIT) have argued that phasing out nuclear energy without enough renewable sources to fill the production gap would drastically increase air pollution levels in the US.

“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,” said lead author Lyssa Freese, a graduate student at MIT’s department of earth, atmospheric and planetary sciences.

“Shutting down something that doesn’t have direct emissions itself can still lead to increases in emissions, because the grid system will respond.”

Environmental and social impacts

The team, comprising MIT-affiliated co-authors Sebastian Eastham, Guillaume Chossière and Noelle Selin as well as Alan Jenn of the University of California at Davis, imagine a scenario in which every nuclear reactor in the US has shut down and consider how oil, gas and renewables would fill the needs in one year.

Based on the assumption that more coal, gas and oil would step in to meet energy demands, air pollution levels would see a dramatic rise and severely affect public health – resulting in an additional 5,200 pollution-related deaths per year.

What’s more, the population most likely to be victims of this health crisis are black or African American communities, a disproportionate number of whom live near fossil-fuel plants.

“This adds one more layer to the environmental health and social impacts equation when you’re thinking about nuclear shutdowns, where the conversation often focuses on local risks due to accidents and mining or long-term climate impacts,” added Freese.

However, if more renewable energy sources were to become available – as is expected by 2030 – air pollution would be minimised, but not avoided. The team estimates that the resulting rise in air pollution would still cause around 260 pollution-related deaths over a one-year period.

“In the debate over keeping nuclear power plants open, air quality has not been a focus of that discussion,” said Selin, who is a professor at MIT’s institute for data, systems and society.

“What we found was that air pollution from fossil fuel plants is so damaging, that anything that increases it, such as a nuclear shutdown, is going to have substantial impacts, and for some people more than others.”

Last December, scientists based at the US National Ignition Facility made a major scientific breakthrough in nuclear fusion by producing more energy from a fusion reaction than was used to trigger it – a landmark step in the pursuit of clean energy.

However, there has been ongoing debate about how nuclear energy is viewed when it comes to its environmental impact. Last year, the EU faced backlash for its decision to label gas and nuclear power as sustainable energy sources.

Earlier this year, the EU Renewable Energy Directive labelled nuclear hydrogen as ‘low carbon’ rather than green after much debate between member states. At the time, French MEP Pascal Canfin tweeted that the directive now recognises “the specific role of nuclear power, which is neither green nor fossil”.

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Vish Gain is a journalist with Silicon Republic