Researchers led by Georgia Tech have discovered that state-level clean energy policies in the United States create positive, far-reaching effects on renewable energy generation in neighboring states, paving the way for a more collaborative, nationwide approach to renewable energy.
In an inspiring climate breakthrough, researchers have uncovered the substantial impact of state-level renewable energy policies on neighboring states, spotlighting the interconnected nature of energy markets and underscoring the potential for broader, nationwide clean energy progress.
The study, led by Marilyn Brown, Regents’ and Brook Byers Professor of Sustainable Systems at Georgia Tech’s School of Public Policy, alongside Shan Zhou of Purdue University and Barry Solomon from Michigan Technological University, was recently published in the Proceedings of the National Academy of Sciences. The trio’s findings shed light on the far-reaching influence of Renewable Portfolio Standards (RPS) beyond the borders of the states that enact them.
“Analysts are asking if the United States should have a federal renewable mandate to put the whole country on the same page, or if individual state policies are sufficient,” Brown said in a news release. “To answer that question, it is useful to know if states with renewable energy policies are influencing those without them.”
RPSs, adopted by over half of the U.S. states, require utility providers to generate a specific portion of their electricity from renewable resources like wind or solar. These standards often come with stringent targets, and utilities face penalties if they fail to comply. The research team aimed to determine whether these policies have ripple effects across state lines.
By compiling 31 years of data (1991-2021) on renewable electricity generation from 48 U.S. states and the District of Columbia, the researchers conducted comparative analyses between states. They paired states with their geographical neighbors or electricity trading partners, yielding 1,519 comparisons. The results were illuminating.
“By only looking at the pairs, we can see if an RPS in one state directly affects renewable electricity generation in another state, and, if that’s the case, whether it is because they are geographic neighbors or if it’s because they are participating in the same wholesale electricity market,” Zhou, who is an assistant professor at Purdue University and Georgia Tech alumna, said in the news release.
Interestingly, the study revealed that geographical proximity had a greater impact on renewable energy generation than electricity trading partners. This finding highlights the complex interplay between state policies and the broader energy landscape. The researchers discovered that neighboring states with robust RPS policies tend to increase their renewable energy output, showcasing a “spillover effect.”
“We also learned that the stronger a neighboring state’s RPS policy is, the more likely a given state is to generate more renewable electricity,” Brown added. “It’s all a very interactive web with many co-benefits.”
A critical aspect of their study was the introduction of a refined “policy stringency” metric, which considers not only the targets set by the RPS but also the interim goals and current renewable energy production levels of each state.
“Our stringency variable includes interim targets as well as the existing share of renewable energy generation,” added Solomon, a professor emeritus of environmental policy at Michigan Technological University.
Though the study’s findings are groundbreaking, the researchers are keen to delve deeper into the factors that drive these spillover effects. They aim to explore the nuances influencing states without RPSs, which appear to be heavily swayed by their neighbors’ policies.
“The spillover effect is very significant and should not be overlooked by future research, especially for states without RPSs,” Zhou added. “For states without policies, their renewable electricity generation is very heavily influenced by their neighbors.”
This pioneering research not only reveals the hidden benefits of state-level renewable energy policies but also champions a collaborative approach as a potential pathway to a greener, more sustainable future for the United States and beyond.