Hourly Model of Air Pollution Can Reduce Health Costs

Photo: John Amis/AP Photo

Fossil-fuel-burning power plants can reduce the impact their pollution has on air quality and human health by controlling how active they are during certain hours, scientists at Georgia Institute of Technology say. These findings could help limit the drawbacks of generating electricity from fossil fuels without additional investment, they add.

Burning coal and other fossil fuels releases pollutants such as sulfur dioxide and nitrogen oxides. Prior research suggested that air pollution causes 200,000 early deaths each year in the United States alone.

The impact of each source of air pollution depends not just on how much pollution each produces and how close it is to population centers but also on environmental factors such as temperature, sunlight, and wind velocity, all of which can vary by hour, day, and season. Although researchers can use computer simulations to predict how and where air pollutants might disperse, until now the air quality models they used for these simulations were too complex and computationally demanding to accurately model hourly fluctuations in power plant emissions.

By developing a simplified version of a comprehensive model of air quality that is often used by the scientific community and government agencies, physicist Valerie Thomas at the Georgia Institute of Technology and her colleagues are now able to analyze pollution levels from power plants on an hourly basis. Instead of taking days to run, their new model "takes less than a second," Thomas says.

The scientists used their Air Pollutant Optimization Model to analyze data from the state of Georgia from 2004 to 2011. They then examined what strategies were best at minimizing both health impacts and the cost of generating electricity. By controlling the output of power plants during certain hours, their simulation suggests that for nearly US $84 million in increased electricity costs over the eight-year period, they could have reduced the health-related costs of power generation by more than $175 million. "The hour-by-hour consideration of air-quality impacts can really pay off," Thomas says.

This tradeoff between costs and benefits mostly centers around coal. Coal is the leading source of power in the United States, used to produce 39 percent of the nation's electricity in 2013, but it is also the country's biggest source of air pollution. By limiting coal plant emissions at certain times in favor of burning more expensive fuels such as natural gas, the researchers found they could reduce the impact of coal pollution while keeping up with power demands.

"Emissions from a specific hour of day can have a disproportionately large impact on the pollution that forms, owing to the synergy with emissions from other hours, combined with the effects of changing winds, atmospheric mixing, and sunlight," Thomas says. "We can now leverage this knowledge to improve electricity generating patterns."

This new model "can be used to reduce impacts of emissions from transportation, manufacturing, and other sectors," as well, Thomas adds. But she cautions that "this approach to reducing health costs does not replace the need for pollution control equipment. Both approaches can be used together."

In the future, the scientists plan to extend their research to a larger U.S. study. Moreover, they would like to include emissions from transportation, evaluate the impacts of their model on ecosystems—especially croplands and sensitive ecosystems—and apply this approach to regions or countries with severe air quality issues, Thomas says.

The scientists detailed their findings online 17 August in the journal Proceedings of the National Academy of Sciences.

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