How to Make Solar Energy Better: Use Spinach
Spinach is one of my favorite superfoods. It’s a delicious, leafy dark green vegetable that’s chock full of vitamins, minerals, proteins and nutrients the human body needs to be well. Popeye told kids spinach would make them grow big and strong. Now, new research from Vanderbilt University suggests spinach can do the same thing for solar energy production.
Scientists have found a way to combine spinach’s photosynthetic protein, which naturally converts light into electrochemical energy, with silicon in a new “biohybrid” solar cell. The protein is called Photosystem 1 (PS1). Researchers say that this spinach-based material produces substantially more electrical current than has been reported by previous “biohybrid” solar cells, and could be key to increasing solar energy efficiency.
The study, which was published online in the journal Advanced Materials, was inspired by the fact that spinach plants are able to convert sunlight into electrical energy with nearly 100 percent efficiency. Most manmade solar cells can achieve only 40 percent efficiency or less. It’s taken several decades for scientists to figure out how to extract this PS1 from the spinach plant, and now, they’ve demonstrated that it can be made into cells that produce electrical current when exposed to sunlight. Vanderbilt’s David Salisbury explains more:
To make the device, the researchers extracted PS1 from spinach into an aqueous solution and poured the mixture on the surface of a p-doped silicon wafer. Then they put the wafer in a vacuum chamber in order to evaporate the water away leaving a film of protein. They found that the optimum thickness was about one micron, about 100 PS1 molecules thick.
The implications of this technological advancement are not to be ignored. A major criticism of photovoltaic solar cells is that they require rare earth materials, the extraction of which is expensive and bad for the planet. Biohybrid cells, however, could be made from renewable and relatively cheap sources, like spinach or even kudzu, which is an invasive species.
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