Solar Panels From Grass Clippings: Researchers Make Progress on “Biophotovoltaics”

by Stephen Lacey Posted on February 5, 2012 at 9:01 am

It’s chore day. You’ve raked the leaves, taken out the recycling, and emptied out the old junk in your garage. But wait — don’t toss it all out! You have all the ingredients for your very own homemade solar system.

If new advances in “biophotovoltaics” research are any indication, you may someday be able to create your own solar “goo” from plant matter and apply it to metal or glass.

A group of researchers has found a way to break down plant matter, isolate photosynthetic molecules, and then spread those molecules on a metal or glass substrate. So theoretically, you could take a bag full of leaves and grass, pour in a mixture of chemicals to break them down, and then finish your chores by painting the liquid on your windows to produce electricity. Not bad for a day’s work.

Researchers have been working on biophotovoltaics for many years, only to be hindered by low efficiencies, rapid degradation, and difficulties in spreading the photovoltaic “goo” onto a substrate. But nine scientists have just published research on new advances that boost performance and may allow for inexpensive substrates like recycled glass and metal to be used:

To improve photovoltaic performance we increased the light absorption cross-section without changing the footprint by departing from the traditional flat electrode geometry in favor of mesoscopic, high-surface area semiconducting electrodes (TiO₂ nanocrystals and ZnO nanowires). Finally, we showed how high affinity peptide motifs¹⁰ bioengineered to promote selective adsorption to specific substrates can enhance photovoltaic performance. These materials, geometries and design resulted in simple, robust biophotovoltaic devices of unprecedented performance.

In short, the researchers have created a method to stabilize the photosynthetic molecules. And by coating a substrate with titanium dioxide and zinc oxide nanowires, they can now turn any sort of glass or metal material into a working solar cell with efficiencies better than ever before.

It’s a fascinating discovery. But don’t get too excited yet. Efficiencies are still extraordinarily low — only at .01%. They’d need to be about 10 times that in order to power a light or charge a cell phone. So for the foreseeable future, don’t expect to be painting your house with a bag of grass clippings.

However, as research advances and performance continues to improve, MIT physicist Andreas Mershin says it could be perfect for remote applications in developing countries. In the video below, Mershin explains the significance of the findings: