Solar on 1% of farmland could power all electricity – study

Source: By David Iaconangelo, E&E News reporter • Posted: Tuesday, August 20, 2019

Opening less than 1% of the world’s croplands to solar panels could generate the equivalent of global electricity demand, according to new research from Oregon State University.

But in order to tap into that potential, the agricultural and solar industries would need to learn how to coexist.

In a study published in Scientific Reports this month, OSU researchers explored ideal sites for “agrivoltaics” — systems designed so that agricultural activity can proceed around and under photovoltaic panels. The two industries haven’t always been the best bedfellows, as Chad Higgins, lead author of the study and an agricultural engineer at Oregon State, pointed out.

“There’s definite land competition between renewable energy and farming activities,” he said. “This is a possible avenue for those two camps to work together.”

Federal scientists at the National Renewable Energy Laboratory are among those working on demonstration projects where sheep graze around panels and flowers grow in their shade.

The idea remains a tough sell for solar power developers, which suspect that sharing space with a second industry would raise costs and cause delays. Nor is there any guarantee that agrivoltaic projects will win allies among farming groups focused on preserving agriculture’s claim to the most productive lands.

Proponents of the concept see a need to harmonize the two industries, claiming that shared-use strategies would give solar developers access to land while offering a second revenue stream to farmers.

“Modern agriculture manages water, soil and fertilizer, but it generally takes the sun as the given,” said Higgins. “There’s a lot of places on Earth where you can productively harvest excess sunlight and sell it, as a crop of electricity.”

Backed by funding from the National Science Foundation and the Department of Agriculture, Higgins and his team set out to identify which types of land were most productive for solar generation.

They began with the premise that a panel’s efficiency isn’t determined by sunlight intensity alone, but also hinges on a location’s air temperature, wind speed and humidity, and the degree to which solar radiation actually reaches the panel’s surface.

They found that solar is best suited to croplands, grasslands and wetlands. Deserts, despite their sunny reputation, ranked fifth, behind mixed forests.

Sean Gallagher, vice president for state affairs at the Solar Energy Industries Association, said he is “seeing a lot of solar development on agricultural lands now,” with members of the trade group taking part in sheep-grazing and bee-pollination pilots. But co-location of panels and crops is rarer, he said.

Scientists have managed to cultivate tomatoes and lettuce in the shade of panels, without any apparent decline in yield. Modifying panel arrays to accommodate those crops would almost certainly require additional expenses, said Gallagher.

“If this is ever going to become widespread, then we’re going to have to see continued reduction of costs in the construction of solar, or some policy support, or both,” he added.

Local pushback

Farm bureaus and rural conservation groups have protested cases in which large-scale solar developers bought out land considered rich for tilling, then converted it to expanses of PV panels.

Some state and local officials have responded by making prime land off-limits to renewable energy firms. In 2017, Currituck County in North Carolina — the nation’s No. 2 state for solar generation — banned big solar projects regarded as an industrial blemish. Commissioners overturned the moratorium earlier this year.

In Maryland, where a recent clean energy law aims to raise solar power’s share of the electricity mix to nearly 15% by 2030, conservation groups in one rural county say its proliferation threatens their area’s livelihood and cultural identity.

Utility-scale solar projects in Kent County — the state’s least populous, with an economy centered on farming — have forced several hundred acres of farmland out of production, said Janet Lewis, chair of the county’s Conservation and Preservation Alliance.

“They’ve put up panels across the entirety of it,” said Lewis. “There’s no co-location with that. That is what we’ve fought against.”

Lewis and her allies are trying to secure protections from a task force for renewable siting convened by the governor.

“We’re trying to make sure we get solar located in the right places” — like landfills, former industrial sites and rooftops — “and keep it off of places that are prime for production,” said Lewis.

Researchers at Oregon State predict that competition between solar and agriculture will increase across the United States, though they’ve also highlighted what they see as growing opportunities for collaboration.

“If agricultural lands diminish, then the communities around those services diminish. I want to see those communities thrive by having an extra revenue source,” Higgins said. “This could be seen as an invitation for farmers to be the energy barons of the future.”