New approach models potential and trade-offs of floating solar

Floating solar, the practice of placing solar panels on bodies of water, can generate even more electricity per square foot than terrestrial solar. But researchers are just starting to understand the impacts of floating solar on biodiversity and climate—so how should the new technology be implemented? At what pace, extent and at what costs?

In a new study, published June 13 in Cell Reports Sustainability, researchers found significant potential energy gains from using floating solar in the Northeastern U.S. and also model what might be sacrificed in terms of biodiversity, climate resilience and recreation. Importantly, the study provides a framework for incorporating social and environmental considerations into data analysis and decision-making about renewable energy technologies.

“With this study, we wanted to think more holistically about the social and environmental attributes of waterbodies, instead of just thinking about which ones provided the lowest-cost solar and the greatest energy generation potential,” said first author and postdoctoral researcher Adam Gallaher.

“The framework could be applied to other technologies—it’s really about understanding how these systems interact with the landscape and what trade-offs we might have to make in the future.”

In addition to quantifying those trade-offs, the new models provide data to help communities, policymakers and industry make more informed decisions about where to site the new technology.

The researchers first assessed waterbodies’ proximity to energy infrastructure and accessibility and found that 3.5% of existing waterbodies in the Northeast are eligible and realistic sites for floating solar. They then modeled energy gains in four scenarios, in which:

• all eligible waterbodies were used;
• waterbodies essential to climate-change resilience and biodiversity were avoided;
• recreational use of waterbodies remained undisturbed; and
• biodiversity and recreational areas were avoided—a precautionary model.

If all eligible waterbodies were utilized, 25% of the region’s solar energy needs could be generated by 2050, while offsetting all the land required for terrestrial solar. When avoiding waterways significant to biodiversity and social use, floating solar could still contribute 5% of the region’s solar energy needs, an increase of 194% over current contributions from terrestrial solar.

“Five percent doesn’t sound like a lot, but it is,” said senior author Steven Grodsky, assistant professor of natural resources and the environment in the College of Agriculture and Life Sciences (CALS). “That’s 5% less that you would need to generate with terrestrial solar, which equates to thousands of acres and a major boost to solar energy generation with low potential for conflict.”

In New York state, the researchers found that floating solar could contribute 55% of the needed energy by 2030, dropping to 24% when biodiversity areas are preserved.

The study dovetails with Grodsky’s field-based research into the environmental impacts of floating solar; in a recent study, he and his team found that floating solar, while still having lower overall emissions than terrestrial solar, increased greenhouse gas emissions on small ponds by nearly 27%. The data underscores the need to evaluate trade-offs, the potential energy gains versus the impact on biodiversity and climate resilience, that Grodsky and his team model in the current study.

“Freshwater is far rarer than land, and we may wish to consider socioecological impacts of floating photovoltaics concurrent with potential co-benefits like land sparing,” said Grodsky, who is also assistant unit leader of the U.S. Geological Survey New York Cooperative Fish and Wildlife Research Unit housed in CALS and faculty fellow in the Cornell Atkinson Center for Sustainability.

Taking those impacts into account could also increase communities’ adoption of floating solar, Grodsky said, as those considerations are often what hinder projects from getting approved.

“People are worried about their sense of place, their viewshed, what it’s going to do to fish and drinking-water reservoirs,” Grodsky said.

“If you ignore that in the modeling and only look at what’s technically viable, you’re shooting in the dark with regards to social response. Incorporating these other data is more complex, but it gives you information you can actually base decisions off of.”

Gallaher agreed. “This gives policymakers and stakeholders a playbook to take a data-driven, fact-based approach to tackling multiple crises,” he said.