Solar power is growing the fastest in developing countries that don’t have access to electrical grids. Solar panels are still expensive although cheaper than purchasing fossil fuels for generators. MIT scientists have come up with a method of creating your own solar cells using grass clippings that will be extremely cheap to make.
According to MIT News research scientist in the MIT Center for Bits and Atoms, Andreas Mershin, has built upon previous work by Shuguang Zhang, a principal research scientist and associate director at MIT’s Center for Biomedical Engineering, to develop this new type of solar cell. Mershin’s work has been published in Nature.com’s Scientifi Reports.
Zhang’s earlier research was able to take “photosystem-I (PS-I), the tiny structures within plant cells that carry out photosynthesis”, stabilized it, and applied it to a glass substrate to create a very weak solar cell. It was so weak as to be useless.
Mershin claims that he has simplified the process so that even high school labs could create solar cells from PS-I molecules derived from plants. The resulting solar panels, while 10,000 more efficient than Zhang’s earlier ones would still be too weak to be useless. They would need to improve in efficiency by 10 times to make them useable. Which is why Mershin wants to get researchers around the world to help improve the process.
The simplified process required that rather a flat coating on glass, the PS-I molecules had to achieve a three dimensional structure similar to pine trees in a forest where the majority of a pine tree’s canopy is at the top with smaller limbs down the trunk to catch sunlight that leaked through.
Turning that insight into a practical device took years of work, but in the end Mershin was able to create a tiny forest of zinc oxide (ZnO) nanowires as well as a sponge-like titanium dioxide (TiO2) nanostructure coated with the light-collecting material derived from bacteria. The nanowires not only served as a supporting structure for the material, but also as wires to carry the flow of electrons generated by the molecules down to the supporting layer of material, from which it could be connected to a circuit. “It’s like an electric nanoforest,” he says.
The zinc oxide and titanium dioxide also absorb ultraviolet light that would damage the PS-I molecules. Both ZnO and TiO2 are found in sunscreen lotions so they are fairly cheap and plentiful.
The source of the PS-I is also cheap and plentiful. You can use simple grass or other plant clippings that are normally considered trash. While MIT does use a centrifuge to separate the PS-I from other element of the plant, using a filter would do the same thing eliminating the need for expensive equipment.
While improvements still need to be made to the system, Mershin sees the final process as simple enough that a single sheet of illustrations would be enough to teach anyone how to do it. The only ingredient that would need to be purchased would be a bag of chemicals to stabilize the PS-1 filtered from plants. It would be cheap and simple enough that anyone in the most remote parts of the world would be able to construct their own functional solar cells.
Meanwhile, Mershin and colleagues are continuing to work on improving the efficiency of the final solar cells and are hoping that the recently published paper will entice other researchers to help find improvements.
One day we may all be able to make our own solar cells out of whatever plant material we find and trash pieces of metal or glass as substrates. Not bad, not bad at all.
Above and below illustrations from Scientific Reports used under a creative commons license.Mershin, MIT, PS-1, Scientific Reports, Zhang