A new study led by researchers at the Harvard TH Chan School of Public Health has found that increasing solar power generation in the USA by just 15% could reduce annual carbon dioxide emissions by around 8.54 million metric tons.
The researchers studied five years of hourly data on electricity production, demand, and emissions across 13 US regions using records from the Energy Information Administration. By applying a sophisticated statistical model, they were able to estimate both immediate and delayed CO₂ reductions from solar power increases.
The analysis revealed that the climate benefits of solar power expansion vary widely depending on the region. States like California, Texas, Florida and those in the Mid-Atlantic, Midwest and Southwest showed the largest emissions reductions from increasing solar output.
In California, a 15% increase in solar generation at noon led to a drop of 147 metric tons of CO₂ in the first hour, with another 16 metric tons avoided eight hours later.
On the other hand, regions such as New England, Central and Tennessee saw comparatively limited emissions savings, even with larger increases in solar capacity. These differences are driven by regional electricity grid dynamics, the existing energy mix and the timing of peak demand and generation.
The study also uncovered a ripple effects, whereby emissions reductions were not confined to the region generating the solar power, neighboring areas also benefited. For example, solar growth in California was linked to substantial daily CO₂ declines in the Northwest and Southwest regions, suggesting that clean energy investments in one area can influence air quality and climate outcomes in others.
The findings underscore the importance of strategic, regionally coordinated investments in renewable energy. By identifying where solar adoption delivers the greatest carbon savings, policymakers can prioritize projects that maximize both environmental and public health benefits.
Corresponding author Francesca Dominici, director of the Harvard Data Science Initiative said: ‘This is an exciting study in that it harnesses the power of data science to offer insights to policymakers and stakeholders on how we can achieve CO2 reduction targets.’
Lead author Arpita Biswas, assistant professor in the Department of Computer Science at Rutgers University said: ‘Our study offers policymakers and investors a roadmap for targeting solar investments where emissions reductions are most impactful and where solar energy infrastructure can yield the highest returns. From a research perspective, our findings also demonstrate the power of harnessing large-scale, high-resolution energy data to generate actionable insights.’
The full research can be read here.
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