The Nature Conservancy in 2023 released its “Power of Place” study, laying out recommendations for achieving net-zero carbon emissions by 2050 while avoiding negative impacts to ecologically sensitive lands. Contributor Grace Wu, assistant professor of environmental studies at the University of California, Santa Barbara, said that determining the sites of renewable-energy projects such as solar is an emerging concern, and that manufacturing may be outpacing demand for solar panels due to infrastructure constraints and land-acquisition hurdles.
In an Energy Week event, Wu and Jonathan Thompson, senior ecologist and research director at Harvard Forest, asked and addressed questions about energy siting. How can states meet carbon reduction goals without losing tens of thousands of acres of forest? How can solar arrays exist in harmony with—and even support—crop production?
They spoke during the solutions-oriented “From Forests to Farmlands: Navigating the Tradeoffs in Land Use for Renewable Energy,” sponsored by the Kleinman Center for Energy Policy. School of Veterinary Medicine Dean Andrew M. Hoffman moderated the discussion, an example of how Penn is fostering dialogue on the existential challenge of climate change, in line with the University’s strategic framework In Principle and Practice.
“I don’t think you need to pick clean energy or forests,” Thompson said. “These are the dichotomies that are created by people who want to divide us and who don’t want either, and I’m really interested in trying to find solutions that aren’t on either end of the spectrum but can look to the middle.”
Massachusetts aims to build 27 gigawatts of solar capacity to meet its goal of carbon neutrality by 2050, Thompson said, but new ground-mount solar construction has become the leading cause of forest loss in the state. Harvard Forest worked with Mass Audubon and Evolved Energy Research on the 2023 report “Growing Solar, Protecting Nature” to address this issue.
“For the state of Massachusetts, parcel by parcel, we analyzed multiple scenarios,” Thompson said. “We looked at every single rooftop and every parcel in the state, and we said, Can we get 27 gigawatts without losing 130,000 acres of forest? And the bottom line to that was yes.”
The report lays out strategies for what are called land-sparing and land-sharing technologies. Wu discussed several types of land-sparing technologies, such as crop-based agrivoltaics, meaning the use of land for both agriculture and solar generation. She is working on a study in Washington state about orchards, whose owners could benefit from having their apples and pears shaded by solar panels in the summer instead of costly shade cloth. Wu said there is also interest in thinking about how solar arrays provide lower air temperature under the panels for livestock.
Other land-sparing technologies she cited include co-locating wind and solar projects—an area where Wu said the U.S. is not a leader—and using a type of solar-racking system that takes up less space.
Thompson says a lot remains unknown, though, about the ecological consequences of these buildouts. He noted that solar panels “act as little urban heat islands that affect the microclimate in the adjacent forest” and that Harvard Forest is working on understanding the impacts of solar on soil carbon.
Another question he raised is how much land area is associated with one megawatt of solar. Thompson said in a perfect scenario it would be 4 acres per megawatt, but, because of hilly land and shade from trees, it’s more like 8.5 acres.
Hoffman asked Wu and Thompson about the potential in terms of scale and technology of siting clean-energy developments on parking lots, rooftops, landfills, and brownfields, former industrial or commercial sites that may be contaminated.
“I think the answer to that is ‘all hands on-deck.’ We need every possible technology,” Wu said. “I think we need to make use of everything as our disposal because the scale of the transition is just enormous.”
