New research from MIT and RWTH Aachen University in Germany joins a growing list of biomimetic concepts—from whale-inspired wind turbines to artificial photosynthesis—that are helping renewable energy push forward. This time, the researchers copied a seemingly appropriate source to boost the efficiencies of concentrating solar power (CSP) technology: the sunflower.
The florets on the face of a sunflower are arranged in what is known as a Fermat's spiral, with each individual floret sitting at approximately a 137-degree angle to the one next to it. The researchers, led by Corey Noone of MIT, found that arranging mirrors—or heliostats—that sit around a central tower at such angles to each other yield big improvements in CSP output. An existing field, the PS10 plant in southern Spain (pictured above), would gain 0.36 percent in efficiency while also reducing its land footprint by 15.8 percent. They note in their paper, published in the journal Solar Energy, that "the improvement in area becomes more pronounced with an increased number of heliostats." The improvements come from an increase in the amount of sunlight that hits each mirror and decreases in shading and blocking from the heliostats around it.
“Concentrated solar thermal energy needs huge areas,” said senior author Alexander Mitsos in a press release. “If we’re talking about going to 100 percent or even 10 percent renewables, we will need huge areas, so we better use them efficiently.”
CSP has not taken hold in a big way yet, but some of the largest solar projects in the world are using such technology. Construction is under way in the Mojave Desert, for example, on Brightsource Energy's Ivanpah Solar Electric Generating System. The 392-megawatt facility will cover 3,600 acres of land, and with continuing objections regarding public land use and concerns over native flora and fauna, reducing land footprints for such projects is a noble goal.