Research explores wildfire smoke’s effect on solar power generation across US

New research from Colorado State University shows that while wildfire smoke increasingly covers large parts of the U.S. it does not have much of an impact on overall, long-term solar power generation activity.

The paper – published today in Nature Communications – shows that losses of average, or background, photovoltaic solar resources due to wildfire smoke remain modest outside of the areas immediately surrounding active fires, where plumes are dense. The researchers also found that power generated from photovoltaics remained relatively stable across the U.S. even in extreme fire seasons.

For the project, the CSU-led research team used both modeled and historic data from multiple seasons to better understand changes in baseline solar resource availability related to wildfire smoke.
 
CSU Postdoctoral Fellow Kimberley Corwin is the first author on the paper. She said that as the U.S. looks to increase the amount of solar it uses from 3% to 45% of its total energy portfolio, these findings could be used to make informed decisions around where to build collection sites.

“There has been similar research into specific events – particularly around the larger fires in California. Our work, however, goes further and quantifies the effects over large timescales and geographies,” she said. “We show there are significant impacts to solar power resources near these fires, but that when smoke is transported farther away, as we have seen in the Midwest and along the East Coast recently, it presents much less of a concern in terms of prolonged solar losses. That has implications for where upcoming facilities should be placed for long-term efficiency as well as stability with the grid.”

Solar power generation can be hindered by a variety of factors beyond smoke, such as cloud cover and air pollution. The research team was interested in specifically understanding wildfire smoke’s impact on irradiance – the amount of solar light making its way to the surface of a panel to be collected. They specifically focused on Global Horizontal Irradiance (GHI) which includes both direct sunlight and diffuse sunlight scattered by the atmosphere. GHI is most relevant for the flat-plate photovoltaic systems that account for most of the solar production in the U.S. 

Corwin said they leveraged daily case studies from both the particularly active 2020 wildfire season in California and the much quieter 2019 season to offer short- and long-term context for upcoming wildfire seasons. They also looked at monthly and yearly aggregations on impacts at the state, regional and national levels, and used satellite-based tools like the NOAA Hazard Mapping System Smoke product to understand impacts at different scales.

In 2020, smoke from wildfires burning in California, Colorado and Oregon eventually arrived on the East Coast. Corwin said those plumes can still result in large losses over short time scales, however longer-term impacts remain modest since the smoke is not as persistent.

“While you do see large reductions close to active fires, that drops off quickly with distance. Substantial losses are specific to the area directly around the fire where the smoke column is denser and therefore blocks more of the light,” she said. “Meanwhile, the impact of the large, transported plumes that can linger for days but are dilute, is relatively modest compared to the average solar resource change you may see under other conditions. The decreases from transported smoke are only about 5% and – in some places – even less than 2% versus the average in low smoke years.”

Corwin added that improved battery storage should help further limit short-term impacts to power collection near wildfires. By switching to reserves from batteries, operators could avoid having to use natural gas to make up for power losses from local fires.

Corwin began working on the project as a graduate student in the Department of Atmospheric Sciences with Professor Emily Fischer. She started the work as part of her now finished Ph.D. with funding and support through a CSU Food-Energy-Water Systems graduate program, a NASA grant, and a CSU SoGES GCRT grant. Other CSU-affiliated researchers involved in the paper include faculty members Jesse Burkhardt, Amit Munshi and Fischer.

Fischer said Kimberley’s work is a “critical step in understanding the full implications of climate-driven increases in wildfire smoke.” 

“This paper, and the other chapters of Kimberley’s dissertation, have radically expanded our understanding of how smoke impacts the light at the ground needed for photosynthesis, solar power generation, and also the impacts on other aspects of air quality,” said Fischer, who is part of the Walter Scott, Jr. College of Engineering at CSU.