Farming Energy & Food Simultaneously

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Crops grow under solar panels at the Biosphere 2 Agrivoltaics Learning Lab operated by the University of Arizona, north of Tucson. Patrick Murphy/University of Arizona

When we think of farming, we know sunlight is important, but too much sun is not normally a good thing. For solar, no such thing as too much sunlight–the more the better. But counterintuitive though it may be, here is a story about overlapping advantages of sunlight for farming and solar energy production:

The Best Place for Harvesting Solar Energy Is Not Where I Expected It to Be

And the same land can produce loads of food and electricity simultaneously.

Even after a boom in recent years, solar energy delivers less than 2 percent of power generation to the US electrical grid. But if we’re going to avoid the worst impacts of climate change, the sun’s contribution is going to have to ramp up dramatically. Where to put all the solar panels? You might envision vast solar farms stretching across the sun-scorched barren lands of the Southwest. But according to two recent papers—one from Oregon and Utah researchers, another from a team centered at the University of Arizona—a much different kind of landscape makes the most sense for harvesting solar power: the land currently occupied by food farms.

That’s because the technology that drives solar power—photovoltaic (PV) panels made of silicon that convert light photons directly into electricity—works most efficiently under a specific set of conditions. Most important for this power, of course, is abundant sunlight, which is why deserts make tempting sites for solar energy production. But air temperature is important, too. Above the threshold of 78°F, the hotter it gets outside, the less efficient PV panels are at converting sunlight to electricity. And that’s why blazing-hot deserts pose some problems for solar panels.

In addition to plenty of sun and moderate temperatures, solar works best in regions with light winds and low humidity. Bringing all of those factors together, the Oregon/Utah authors found that regions currently covered with crops and grass provided the most optimal conditions for solar all over the world. Barren terrain, the kind of parched desert landscape I associate with big solar installations, came in fifth.

It makes sense that plants and solar panels do well in similar microclimates, the authors note. “One could think of agriculture as a form of solar harvesting where the sun’s energy is stored in the chemical bonds of the plant matter,” they write. “And agricultural activities already occupy those places on earth most amenable to solar harvesting.”

When I first picked up the report, I thought the authors were suggesting that some farmers should switch from food production to solar production. Turns out that the two activities can co-exist. Raising the panels up off the ground leaves room for people and animals to move in under them. Their shading effect can actually help some crops by reducing heat stress; the cover also saves water in farming by cutting down evaporation.

Two of the paper’s authors, Oregon State University researchers Elnaz Adeh and Chad Higgins, co-authored a 2018 PLOS One study looking at grass production on a solar installation on a pasture near Corvallis, Oregon. Their finding: Areas covered by the panels generated 90 percent more grass than before, using a fraction of the water. Similar projects are showing promising results in Germany and Massachusetts…

Read the whole story here.

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