Friday, 1 June 2018

Harnessing nature’s solar cells

Photovoltaic panels made from plant material could become a cheap, easy alternative to traditional solar cells. Within a few years, people in remote villages in the developing world may be able to make their own solar panels, at low cost, using otherwise worthless agricultural waste as their raw material.

In his original work, Zhang was able to enlist a complex of molecules known as photosystem-I (PS-I), the tiny structures within plant cells that carry out photosynthesis. Zhang and colleagues derived the PS-I from plants, stabilized it chemically and formed a layer on a glass substrate that could — like a conventional photovoltaic cell — produce an electric current when exposed to light.

Now Mershin says the process has been simplified to the point that virtually any lab could replicate it — including college or even high school science labs — allowing researchers around the world to start exploring the process and making further improvements. The new system’s efficiency is 10,000 times greater than in the previous version — although in converting just 0.1 percent of sunlight’s energy to electricity, it still needs to improve another tenfold or so to become useful, he says.

“You can use anything green, even grass clippings” as the raw material, he says — in some cases, waste that people would otherwise pay to have hauled away. While centrifuges were used to concentrate the PS-I molecules, the team has proposed a way to achieve this concentration by using inexpensive membranes for filtration. No special laboratory conditions are needed, Mershin says: “It can be very dirty and it still works, because of the way nature has designed it. Nature works in dirty environments — it’s the result of billions of experiments over billions of years.”

Article Link: http://web.mit.edu/newsoffice/2012/biosolar-0203.html

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