Biofuel crops on photovoltaic farms

Scientists from Stanford University have created a model for solar farms that co-locates crops and solar panels, resulting in a harvest of biofuel plants along with solar energy. Their idea has been published in the journal Environment Science & Technology.

“Deserts, with a combination of high solar radiation and availability of large areas unusable for crop production, are ideal locations for large solar installations,” the researchers noted. “However, for efficient power generation, solar infrastructures use large amounts of water for construction and operation.”

A co-located solar farm could help solve this problem, proving especially useful in sunny, arid regions such as the southwestern United States where water is scarce, according to lead author Sujith Ravi from the Stanford Department of Environmental Earth System Science.

“Co-located solar-biofuel systems could be a novel strategy for generating two forms of energy from uncultivable lands: electricity from solar infrastructure and easily transportable liquid fuel from biofuel cultivation,” Ravi said.

Water is required to remove dust and dirt from photovoltaic panels to ensure they operate at maximum efficiency, as well as dampening the ground to prevent the build-up of dust. The researchers propose that any runoff could go on to nourish biofuel crops such as agave - a plant that thrives at high temperatures and in poor soil, and can be used to produce liquid ethanol. The plant’s roots would help anchor the soil and its foliage would provide ground cover, reducing the ability of wind to kick up dust.

Ravi and his colleagues created computer simulations of a hypothetical co-location solar farm in Southern California’s San Bernardino County, where they found “water inputs for cleaning solar panels and dust suppression are similar to amounts required for annual agave growth, suggesting the possibility of integrating the two systems to maximise the efficiency of land and water use”.  

“Sujith’s work is a great example of how thinking beyond a single challenge like water or food or energy sometimes leads to creative solutions,” said co-author Professor David Lobel. “Of course, creative solutions don’t always work in the real world, but this one at least seems worthy of much more exploration.”

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