The Idea: Copy sunflowers

Have you ever visited the marketplace of ideas? Since it’s an abstract concept that helps our economy and democracy function, I’m going to guess your answer is no. I hadn’t either, until recently.

One of journalism’s perks is a free pass to visit the marketplace of ideas, if I can find it. I never get to see the whole thing at once,  but whenever I talk to a researcher or entrepreneur it draws back the marketplace’s invisibility cloak a tad. I’m intrigued by the ideas interviewees share with me and have decided to pass on the thrill of intellectual epiphany. This will be a sporadic (ideas and the people who have them can be elusive) but ongoing series for my blog titled “The Idea.” Commence.

The Idea: Solar panels copy sunflowers

In August, UW-Madison researcher Hongrui Jiang published his design for solar panels that act like sunflowers and track the sun’s movement throughout the day. Jiang, a professor in computer and electrical engineering, used nanotechnology to design a system that helps the panels move by reacting to the warmth of the sun’s rays, rather than using a motor and global positioning system (GPS) as many solar tracking panels do.

The usual motorized sun-tracking solar panels require energy inputs whereas Jiang’s “passive” design uses sunlight. When the sun’s rays hit a part of the panel containing a mixture of carbon nanotubes and other materials, the special medium contracts as it warms. His description reminded me of ice cubes. The carbon nanotubes are frozen into formation while they’re cool. Like water contracts when ice melts, the nanotubes take up less space when they’re warm. As the sun moves across the sky, the location of warm, contracted nanotubes follows that movement and keeps the solar panel leaning toward the sun, just like sunflowers.

“The idea is very simple but it is not easy to realize it with solar panels. It is complicated because you have to mimic complex biochemical processes,” Jiang said.

Jiang said his passive design may increase the efficiency of solar panels up to 10 percent. The efficiency results from eliminating energy use to power a motor as well as extending the panel’s arc. Jiang’s panels can follow the entire 180˚ arc of the sun which is difficult for current solar-tracking panels.

You can read more about Jiang’s idea in his research article published in Advanced Functional Materials in August 2012.


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