Biologically inspired design: How sunflowers could reshape solar power

By Kirsten Korosec | January 11, 2012, 2:04 PM PST

The key to building an efficient concentrated solar power plant that uses less land may just lie within the face of a sunflower. Researchers at Massachusets Institute of Technology in collaboration with RWTH Aachen University in Germany found they could reduce the footprint of a CSP install by nearly 16 percent percent and increase the amount of sunlight collected by arranging the mirrors — otherwise known as heliostats — in a pattern similar to the spirals on the face of a sunflower. The researchers, who have recently filed for patent protection for their design, published the results in the journal Solar Energy.

Concentrated solar power (CSP) uses mirrors or lenses to harness and concentrate the sun’s heat onto a small area to produce steam, which is used to drive turbines and generate electricity. There are a number of different solar thermal technologies including power towers, which use mirrors to concentrate sunlight on to a small area atop a tower that contains fluid such as oil.  BrightSource Energy is one company that has developed solar thermal power systems in the United States.

Available land and shadows are the primary challenges with CSP. Typically, CSP plants have mirrors arranged around a central tower in concentric circles. The mirrors are staggered so every other row is aligned. But this pattern creates shading, which in turn, reduce efficiency.

Solar thermal developers have tinkered with their own designs to combat the problem. For example, BrightSource plans to use higher towers, which should allow it to pack more of its sun-tracking mirrors into a smaller area, for its Rio Mesa project in California.

The golden angle