Growing the Business of Ecovoltaics: New Opportunities on Federal Land

Researchers are assembling evidence that agriculture and solar arrays can be combined on the same land, in an emerging field called agrivoltaics. A new wrinkle is also appearing in the form of ecovoltaics, in which solar projects serve as hosts for habitat restoration. The restoration factor can open up a new pathway for solar developers to engage community support for their projects, including those on public lands as well as private property.

Solar development on federal land: An untapped resource

Policy in the United States has long supported economic activities on federal lands, such as livestock grazing and mining. The fossil energy industry, in particular, benefitted from low-cost federal leases for many years.

Roughly 12 percent of oil and gas production in the contiguous U.S. currently takes place on federal lands, according to the National Renewable Energy Laboratory (NREL). In contrast, only 4 percent of renewable energy capacity is currently located on federal lands. That figure includes wind farms, geothermal facilities and solar arrays.

Earlier this week, the lab issued a new technical report taking a close look at the potential for deploying more renewable energy on federal lands. The NREL research team drew on new imaging technology to assess features of the land suitable for renewable energy development. They also considered other key factors including the availability of transmission lines and other energy infrastructure, to describe seven realistic scenarios that maximize renewable energy development.

“Importantly, all seven scenarios achieve 100 percent carbon-free electricity by 2035 and assume high electrification through 2050,” according to the report.

The technical potential for utility-scale solar development on federal land totals 5,750 gigawatts. The number drops considerably when real-world siting constraints are applied, but a substantial amount still remains at 1,750 gigawatts.

To put that into perspective, California has been a hotbed of solar activity since the early 2000’s, yet the installed capacity of the state barely topped 49 gigawatts as of last year.

How ecovoltaics can make room for solar development on federal land

Tapping federal lands to meet the demand for renewable energy would only involve a small percentage of the total acreage under federal management, according to NREL. Most of the seven scenarios described in the new report involve less than 2 million acres for a combination of solar, wind, and geothermal to meet the 2035 goal for 100 percent renewable energy.

“That is less than 0.5 percent of all federal land area and less than 5 percent of the total land area available for developing these technologies," according to the report. "Of the 2 million acres that would be needed to meet 2035 demand, less than 815,000 acres or 0.2 percent of all federal lands would be permanently disturbed."

Even a statistically tiny disruption could still have an outsized impact on species preservation. With ecovoltaics, though, the converse can also be true. A solar project can help restore habitat that is already stressed or at risk.

In November, NREL published the results of the first long term study of ecovoltaics. It was undertaken in collaboration with Argonne National Laboratory and academic researchers, along with the ecological services company MNL (formerly Minnesota Native Landscapes). The research took place on three utility-scale arrays comprising the Aurora solar power plant in Minnesota, which is owned by the developer Enel Green Power.

“These solar–pollinator sites are the first U.S. commercial utility-scale photovoltaic (PV) solar projects that included comprehensive research on ecovoltaics,” according a statement from NREL.

NREL released the Aurora research in a series of three peer-reviewed papers. Together, the studies show that native prairies in Minnesota can be restored within the environs of a solar power plant, including underneath the solar panels as well as between them. The research affirms agrivoltaic studies that show solar panels help improve soil health by providing shelter from the sun, enabling some vegetation to thrive in the partial shade.

Once the prairie is reestablished, the researchers also found that pollinator populations were comparable to those in dedicated conservation lands, an important finding in terms of using federal property for solar development. In addition, nearby farmland showed an increase in pollinator activity.

Next steps for ecovoltaics

NREL cautions that its research only covers one type of ecosystem in one part of the country, and further investigation is needed to explore the interplay of solar arrays and habitat restoration in other regions.

The researchers also advise that the full effect of the solar has yet to unfold and the full impact of the soil restoration efforts will not be clear for years to come. Even after construction was completed at the Aurora arrays, prairie vegetation did not fully establish itself for three or four years. Some species took even longer to appear, ranging up to six years.

Research is ongoing at the site as new plant species continue to emerge. In the meantime, ecovoltaics is emerging as a specialty within the U.S. landscape industry, though not necessarily by the same name. The Minnesota firm Prairie Restorations, for example, has applied its experience with native vegetation to solar arrays for years.

The ecovoltaic field is also beginning to cross paths with restorative energy, another emerging field that supports the potential for solar development on public lands. One particularly interesting prairie restoration research project is underway as part of a restorative energy project under the Sacramento Municipal Utility District in California, where the site of a decommissioned nuclear power plant now hosts a utility-scale solar power plant.