A THIRD of North America was once an ocean of grass stretching from what is now central Canada to Mexico. Today, almost all of that original habitat, called prairie, is gone, ploughed for agriculture, paved over for cities and roads, or taken over by encroaching trees and shrubs. Most native prairie remnants are unmarked and hidden to the untrained eye 鈥� at least until the spring bloom reveals what grows there.
So, it was a surprise for Danish energy company to learn that the field in which it planned to build a giant solar facility was among the largest areas of intact prairie left in Texas. It was also a 鈥渨ake-up call鈥� for conservationists, says at the Native Prairies Association of Texas. 鈥淪uddenly there are thousands of acres going into these solar projects.鈥� Unlikely as it seems, this could be good for both clean energy and biodiversity.
Advertisement
Rapid development of renewable energy facilities, such as solar farms and wind turbines, is necessary to cut greenhouse gas emissions and fight climate change. But the industry鈥檚 demand for rural land 鈥� what , director of the Large-scale Solar Association, calls 鈥渢he biggest shift in land-use patterns in modern history鈥� 鈥� has . Amid this, researchers and some developers, including 脴谤蝉迟别诲, are looking for ways to make facilities that bring benefits not only to rural populations but landscapes too.
The one that has perhaps gained most traction is the idea that solar development can restore lost habitat if native flora is planted beneath panels, supporting birds and insects and improving the soil on potentially millions of hectares. This, the argument goes, could finally herald the return of the iconic prairie.
Acres of solar panels
The ongoing energy transition in the US requires vast amounts of land. A from The Nature Conservancy found that the current trajectory of energy development would need more than 650,000 square kilometres, about 7 per cent of the continental US or an area more than twice that of the UK.
This transformative enterprise has gained momentum as a result of huge investments from the federal government and the private sector as well as the falling costs of renewable energy. It has also provoked increasing opposition. 鈥淲e鈥檙e seeing growing resistance in local communities to the deployment of these clean energy projects,鈥� says at the University of California, Santa Barbara, and an author of the report. 鈥淲e need to do what we can to make sure this is generating benefits for everybody.鈥�
One approach would be to reduce the overall amount of land needed. Wu and her colleagues found that this could feasibly be almost halved through strategic choices about where and what to build. Carefully siting these remaining developments could avoid most impacts to valuable habitat and prime agricultural land, while increasing the cost of the transition by only about 6 per cent. For example, putting projects nearer cities would reduce land needed for transmissions lines. Wind and solar could be built together on the same land. More solar panels could also be put on rooftops and over car parks. However, this wouldn鈥檛 avoid the need for lots of ground-level solar panels, says Wu. 鈥淲e need all of it.鈥�
Another approach is to design renewable energy projects so the land they occupy can still be used for other things. Growing crops or grazing livestock underneath solar panels 鈥� known respectively as agrivoltaics and rangevoltaics 鈥� is proving promising. The added shade can help some plants . Sheep also appear to benefit from grazing under solar panels, thanks to the shade they provide and the more nutritious grass that can thrive there. This is a and there are across the political divide. However, such projects can be expensive and are likely to happen on only a few hundred square kilometres of land.
Another dual-use approach that could have much wider potential application is to use energy development to restore habitat. For instance, wind turbines off the north-east coast of the US, which have been falsely linked to the deaths of whales, could actually . If carefully constructed, solar facilities in deserts of the south-west US could rather than endanger them. And solar facilities atop lost prairies could help bring them back. 鈥淲e can use infrastructure in a way that provides ecosystem services,鈥� says Wu. However, many questions remain about how to make this work, she adds.
Some researchers and energy companies are already addressing them. At 脴谤蝉迟别诲鈥檚 Texas development, for example, the company plans to collect seeds from the site鈥檚 intact prairie and plant them across the rest of the facility. Developers have also planted prairie habitat in Minnesota, which, in 2016, became the first state to adopt a 鈥減ollinator friendly鈥� certification programme to rate the quality of the environment at solar facilities. It scores them based on a range of factors such as the diversity of native flowering plants and the area they cover. New York, Maryland, Vermont and Illinois have since begun similar efforts.
Meanwhile, at Iowa State University and his colleagues are beginning to . Hopes are high after his group found that strips of prairie planted between rows of crops had positive effects on honeybee health. 鈥淚 have some confidence we can do this under solar panels,鈥� he says. And in California鈥檚 agriculture-rich Central valley 鈥� much of which was once prairie 鈥� , Davis, is running a built on the site of a decommissioned nuclear power plant. Results there will determine the best mix of plants for restoring California prairie habitat and supporting animals that live there, such as the threatened California tiger salamander (Ambystoma californiense).
Restoring habitat under solar panels is far from the norm. The usual procedure is to level the ground, cover it with gravel and fence it off. Even in states with 鈥減ollinator friendly鈥� programmes, restoring prairie habitat is voluntary, says at Argonne National Laboratory in Illinois. But, he says, developers usually make some effort or else risk being blacklisted by environmental groups. 鈥淚t鈥檚 almost a requirement now,鈥� he says. In Minnesota, for instance, , roughly half of the area covered by solar in the state.
However, even where planting happens, efforts vary. What gets planted largely depends on how much a developer is willing to spend. Access to native seeds can be an issue, and even when they are available, they cost more than basic clover or turfgrass. Ecological surveys cost money. What can grow also depends on how high the panels are raised and how much shading of the panels from tall plants operators are willing to tolerate. Walston says raising panels by just 25 centimetres extra can enable a greater diversity of plants 鈥� although this requires additional steel, and extra cost.
Prairie rewilding
Then there are decisions about the maintenance needed to ensure seeds grow and outcompete invasive plants. Mowing is better than herbicides for pollinators. Some sites use goats or sheep to control vegetation through grazing. Prescribed burning would be ideal, says Walston: native prairie plants have deep roots adapted to withstand fire. Indeed, fire suppression by European settlers is a major reason for the loss of prairie to encroaching woody plants. However, burning hasn鈥檛 yet been tried at a solar facility to his knowledge. Beneath solar panels or not, 鈥減rairie restoration is not going to be easy鈥�, says Harms.
Restoring habitat isn鈥檛 all expense, though. Once established, a solar prairie might actually require less maintenance than close-cut turfgrass and it may be less prone to erosion than gravel, says Walston. Prairie locks up carbon in the soil, so restoration projects could be marketed as carbon credits. Research has also found that having by cooling them. The scale of these benefits is potentially vast. In California alone, Hernandez envisions solar developments that incorporate prairie restoration happening on the hundreds of thousands of hectares of farmland set to be taken out of production to prevent overuse of groundwater.
Nevertheless, there is no guarantee that any of this will stem opposition to new developments. 鈥淲e don鈥檛 have a grand model for a way to build out solar that will make everyone happy,鈥� says Hernandez.
In Texas, where solar energy projects are being developed faster than anywhere else in the US, some people feel rural land is being sacrificed for energy hungry cities and cite concerns about the impacts on soil and vegetation, as well as the changing character of rural places 鈥� and prairie in particular. 鈥淯nless we have guarantees that the land is protected, we don鈥檛 want anything to happen,鈥� says B. F. Hicks, an attorney and conservationist based in Mount Vernon. Other fears range from concerns about fires from battery storage facilities to the fact that the developments are largely being created by foreign companies.
There is some legal opposition too. It is likely to become more challenging for solar and wind projects to be built in Texas at all due to adopted by the state government, some of which is in response to environmental concerns. Though the new rules aren鈥檛 as restrictive as clean energy advocates had feared, the fact this is happening at all in famously unregulated Texas highlights the central role state and local planning will play in clean energy development across the US. 鈥淭he community licence part of deploying all of this clean energy is going to be increasingly important,鈥� says Wu. Developers and governments could avoid a lot of opposition, she adds, by engaging with local communities early on about what to build and how they might benefit.
Renewable energy
More prairie habitat is one possible upside. But it is early days. O鈥橬eal points out that even the most sophisticated restoration projects are still in an experimental phase and it remains to be seen what the quality of habitat that gets planted is and how well it is maintained. 鈥淲e need a lot more science to be able to deploy large-scale restorative energy projects,鈥� says Wu. However, she is optimistic. As is Hernandez. 鈥淲e have to build out renewable energy infrastructure, but we don鈥檛 have to sacrifice our ecosystem services to do that,鈥� she says. It depends on the developer whether a site ends up a 鈥渂arren wasteland鈥� or something more, she says. 鈥淧eople want to see beautiful things in their communities.鈥�
James Dinneen is an environment reporter for New Scientist, based in聽New York
Article amended on 12 September 2023
We corrected a quote that had been misattributed
