What’s better than a solar farm that produces electricity from the sun? Well, a solar farm that produces electricity and biofuels from the sun, of course!
A recent Stanford study shows that growing agave and other select plants amid photovoltaic panels could allow solar farms to not only produce crops for biofuels but can also conserve water and boost the productivity of the solar panels through reduced soiling.
Sujith Ravi, a Stanford post-doctoral researcher and lead author of a new study published in the scientific journal, Environmental Science & Technology, says, “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.”
Although novel, water-free panel-cleaning methods are increasingly becoming popular, a majority of solar farms around the world continue to use water as a way to clean PV panels. In fact, as the study shows, more water is used to clean panels over their lifetime than is used in the production of the panels (see graphic below).
Image Credit: Sujith Ravi et al via American Chemical Society
In such situations, crops planted underneath the solar panels could capture the runoff water and dampen the ground, preventing the build-up and spread of dust. Computer simulations of a hypothetical solar farm based in California also suggested that co-location could lead to a reduction in the overall amount of water needed for such solar farms to operate.
According to the study, the approach is particularly useful in areas where water is scarce. Co-locating PV panels and vegetation can also help optimize land use and prevent soil from becoming barren.
However, it is important to select the right kind of crops. Most food crops, for example, would find arid climates to be inhospitable. Plants like agave, on the other hand, can not only thrive at high temperatures and in poor soils, but can also produce biofuels in the form of liquid ethanol, which can be blended with petrol to power vehicles (as is done in Australia and many other countries).
“It could be a win-win situation,” says Ravi. “Water is already limited in many areas and could be a major constraint in the future. This approach could allow us to produce energy and agriculture with the same water”. And what makes agave a particularly good choice, according to Ravi, is that “unlike corn or other grains, most of the agave plant can be converted to ethanol”.
Says David Lobell, a co-author of the recently published work, “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”. Lobell adds, “Of course, creative solutions don’t always work in the real world, but this one at least seems worthy of much more exploration.”
Having already determined the water requirements for such a system, the next step for the Stanford researchers is to test the co-location approach to gather realistic estimates for crop yield and economic incentives while also determining the ideal plants to use.
Pursuing such creative (and potentially profitable) solutions could boost the case for solar farms in arid regions not only in the US, which is the primary focus of the study, but also in Australia, where we’re blessed with plenty of land and sunlight but are short on water resources.
Top Image Credit: Sujith Ravi et al / American Chemical Society
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