Modest solar boost could cut US CO2 by 8.5 million tons

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Boosting US solar power by 15% could reduce annual carbon dioxide emissions from the nation’s electricity sector by more than 8.5 million metric tons, the equivalent of removing the emissions of nearly two million gas-powered cars annually, according to a new study.

The study, published Wednesday in the journal Science Advances, estimates that increasing solar power in California, Florida, Texas, and the Mid-Atlantic, Midwest and Southwest regions — even a small amount — would provide the most CO2 reductions. Adding solar in other regions, such as the central US and New England, showed smaller estimated CO2 reductions. 

“Our findings highlight the importance of implementing policies that encourage the adoption and investment of solar infrastructure to achieve the CO2 emission reduction goals of the US electricity sector,” the authors wrote. 

Last year was the warmest year since global records started, according to the National Oceanic and Atmospheric Administration (NOAA), and the 10 warmest years on record have occurred over the past decade. Scientific research shows that burning fossil fuels for electricity, transportation and to power manufacturing is the major cause of this global warming, with fossil fuels accounting for over 75% of global greenhouse gas emissions.

Despite these global warming trends, the study comes as the US Environmental Protection Agency seeks to weaken climate change regulations, and the Trump administration is removing credits and other incentives for solar and other clean energy sources.  

Solar growth 

The researchers looked at five years of data — starting July 1, 2018 —  on hourly electricity generation and demand from the US Energy Information Administration (EIA), and modeled how increasing the hourly solar power generation would affect CO2 emissions in certain regions. 

The US emitted an estimated 1.43 billion metric tons of CO2 generating electricity last year, according to the EIA. Energy consumption overall in the US produced 4.8 billion metric tons of CO2 in 2024. 

It is the first study to look at both immediate and delayed reductions in CO2 from increasing solar energy. 

“If you increase solar at noon, not only do you get immediate changes in terms of reduction of emissions, but you’ll also see like two or three or four hours later there is a reduction in carbon emissions,” said lead author Arpita Biswas, an assistant professor of computer science at Rutgers University. “This is due to the increase in solar generation at the earlier hours.”

“If you increase solar at noon, not only do you get immediate changes in terms of reduction of emissions, but you’ll also see like two or three or four hours later there is a reduction in carbon emissions.” – Arpita Biswas, Rutgers University

Solar energy accounted for 3.9% of US electricity (165 billion kilowatt-hours) generated by utilities in 2023, according to the EIA, compared to 60% coming from fossil fuels. The agency estimates an additional 73.62 billion kilowatt-hours came from small-scale solar systems. 

California, Texas, and Florida generated the most solar power in 2024, and a March analysis from Climate Central found that solar power grew in all 50 states over the past decade and is the fastest growing source of electricity in the country, increasing 7.8-fold over that time.

This clean energy growth is running into political headwinds, however. 

Reversing course

The study’s estimated CO2 reductions represent 13% of the EPA’s current annual target of CO2 emissions reductions. But the EPA announced this week it is aiming to rescind the 2009 endangerment finding, which required the agency to regulate greenhouse gases.

“The proposal would, if finalized, amount to the largest deregulatory action in the history of the United States,” EPA administrator Lee Zeldin said during the announcement at a truck dealership in Indianapolis on Tuesday. 

The move is the latest effort by the Trump administration to advance fossil fuels while hindering expansion of solar and other clean energy sources. The recently passed “One Big Beautiful Bill,” for example, ends the residential clean energy tax credit at the end of this year. The credit allowed homeowners to deduct 30% of an installed clean energy system — such as solar, wind, geothermal or battery storage. President Trump also signed an executive order this month that removes subsidies for wind and solar power. 

Abigail Ross Hopper, president and CEO of the Solar Energy Industries Association, called the bill “deeply disappointing” in a statement.  

“Solar and storage are America’s best bet to lower energy costs, build long-term energy resilience, and break free from the grip of foreign energy dependence,” she said. “Regardless of what happens in Washington in the coming months and years, markets will continue to drive outcomes. The solar and storage industry is resilient.” 

Biswas said, while “quite ambitious,” she hopes policymakers would use the new study to understand where to best invest in solar and “try to think about all the benefits that it could give,” which includes removing other harmful pollutants formed from burning fossil fuels, such as sulfur dioxide, nitrogen oxides, particulate matter and mercury.

“I would really want people to think about clean energy meaning clean air,” she said. 

(Featured image by Getty Images/Unsplash+)