The Science of Sustainability

Plant Proteins Power Solar Panel

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This new solar panel really is green. Instead of using semiconducting silicon, proteins from plants transform light into electricity.

Physicist Andreas Mershin, at Massachusetts Institute for Technology, and his colleagues say they’ve simplified the production of plant-based solar cells so that any lab can make them. Mershin hopes these biological solar panels could provide power in places that currently have no electricity.

“People have been growing their own food for millennia,” he says. “I think it’s time to start growing our own solar power.”

Plants make sugars using energy from the sun in a process called photosynthesis. Protein complexes convert the light energy into electrons, which drive the plant’s sugar-producing factories.

These plant proteins are tuned to maximize the sun’s energy. Practically all of the sunlight that hits them gets converted to electrons. Commercial solar panels struggle to match this efficiency because they can’t absorb all wavelengths of visible light.

Mershin wanted to hijack the efficient electron generators in plants to generate electricity for people. But to build a working solar panel using proteins, he had to stabilize the proteins on the surface so that they perform just like they do in cells. And he had to attach enough of them to generate a measurable current.

Mershin harvested one type of light-collecting protein complex from photosynthetic bacteria. Suspended in a stabilizing solution, the photosynthetic protein complex maintained its shape and function.

He painted the protein solution on a glass slide covered with nano-sized rods of zinc oxide, a common ingredient in sunscreen. The rods hold more protein than the flat surfaces commonly used to make photosynthetic solar panels — enough to give the panel a faint green tinge.

The bio-solar cell converted about 0.1% of sun’s energy into electrical energy — 10,000 times more efficient than previous biosolar cells. Mershin says his plant-based solar cells will never match the conversion efficiencies of commercial solar panels. But even increasing the efficiency to 1% could make these plant-powered panels useful for people in the developing world who have no electricity, he adds.

Mershin hopes other labs around the world will start experimenting with these green solar panels to improving their efficiency and lifetime. His method and results are freely available from a paper published in the journal Scientific Reports.

Instead of throwing plant trimmings or grass clippings onto a compost pile, perhaps one day we’ll set some aside to make solar panels too. It’ll be a whole new way to DIY solar.

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Category: Energy, Engineering, Environment

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Melissae Fellet

About the Author ()

Melissae Fellet is a freelance science writer obsessed with electrons, atoms and molecules. Writing about chemistry, physics and technology, she hopes to reveal how the invisible building blocks of matter influence things like plastics, perfumed shampoos and the speedy computer chips we use everyday. She holds a BS in biochemistry and microbiology from the University of Florida and a PhD in chemistry from Washington University in St. Louis. She spends sunny days at her home in Santa Cruz either watching otters in the bay or tromping around the redwood forests.
  • Terri Sweeney

    There are two statements which seem at odds with each other.

    "These plant proteins are tuned to maximize the sun’s energy. Practically all of the sunlight that hits them gets converted to electrons. Commercial solar panels struggle to match this efficiency because they can’t absorb all wavelengths of visible light."

    AND

    "The bio-solar cell converted about 0.1% of sun’s energy into electrical energy — 10,000 times more efficient than previous biosolar cells. Mershin says his plant-based solar cells will never match the conversion efficiencies of commercial solar panels."

    So the bottom line is that these photo-chemical cells will NEVER begin to approach even 10% of the efficiency of the cheapest photo-voltaic cell. Essentially useless.

    • TFox, plant biologist

      The critical point is the potential for cheaply making these panels once the technique is established, independent of efficiency. Photosynthetic bacteria happily grow with water and simple mineral nutrients.