An experiment in co-locating renewable energy with agriculture is being carried out in the Sonoran Desert, just outside of Biosphere 2. Called "agrivoltaics," the project is headed by Greg Barron-Gafford, an assistant professor specializing in biogeography and ecosystem science in the University of Arizona's School of Geography and Development. Barron-Gafford describes the study as a new way of "doing agriculture in the dry lands of the world."
A year and a half ago, Barron-Gafford and his colleagues set out to measure the environmental impact of renewable energy, specifically solar panels. Using a series of instruments to measure and compare air temperature over the canopy of the desert ecosystem to the temperature under a solar array, they discovered that the solar array created a locally warmer environment than normal. Barron-Gafford calls this a "solar heat-island effect," which is similar to the urban heat-island effect seen in metropolitan areas. In the urban landscape, Barron-Gafford points out, "you've transformed the landscape to a built environment and it changes how sun energy moves through the system. It creates a net warming effect, especially at night."
In the case of the temperature shift under the solar array, Barron-Gafford suspected that the effect was being fueled by the absence of plants. In a normal environment, a mix of plants and soil allows for air to circulate unencumbered. Plants also take up carbon for photosynthesis by opening up their pores, while letting water escape from their leaves—Barron-Gafford refers to the plants as "little evaporative coolers on the landscape."
"We're co-locating the two and taking the benefits of each, hoping that there's an additive effect," Barron-Gafford says.
Soon to come: Barron-Gafford and his team plan to take the system to rural Arizona and northern Mexico, where there is a lack of reliable water and power.
"This is the ultimate goal of this work," he says. "Reaching into those rural landscape where a simple idea like growing your plants under solar panels can solve some important problems. This work truly is at the nexus of food, energy and water science."