Leafy Green Power: Spinach is Key Ingredient in Solar Breakthrough0

Ysabel Yates | Thu Sep 20 2012

This month, a breakthrough at Vanderbilt University brought us closer to achieving solar power efficiencies on par with plants.

By adding the photosynthetic protein in spinach to silicon, researchers created biohybrid solar cells with much greater power output than previous designs.

The Biohybrid Breakthrough

Biohybrid solar cells are part biological molecule, part electrode material.  “In our case, those molecules are Photosystem I proteins, which drive photosynthesis in green plants,” said Kane Jennings, professor of chemical and biomolecular engineering at Vanderbilt, who led the study with David Cliffel, an associate professor of chemistry.

The research on using Photostream 1 (PS1) proteins in solar cells began over 40 years ago, when scientists discovered PS1 proteins could function even after they were removed from plants. Because PS1 converts sunlight into energy with nearly 100 percent efficiency, research groups began working with the protein in hopes of creating more efficient solar cells.

Biohybrids could be cheaper and greener to produce than traditional solar cells

The results of this initial research were cells that couldn’t produce very much electrical current, and began to deteriorate after only a few weeks.

The latest advancement addresses both of these problems. The new and improved cells can produce almost a milliamp of current per square centimeter at 0.3 volts – nearly two and a half times more electricity than previously developed biohybrid cells.

In addition, the Vanderbilt researchers have been working for years to improve the cell’s longevity; back in 2010, the team was able to keep a PS1 cell working for nine months with no deterioration in performance.

Cheaper, Greener Solar

Commercially viable biohybrid solar cells would be a manifold breakthrough for solar power; their key components are abundant and renewable, so producing them would cost less and be better for the environment than traditional solar cells.

Furthermore, by harnessing the photosynthesizing abilities of plants, biohybrid cells could also greatly increase solar panel efficiency.

However, the cells still have far to progress before they can compete with established solar technology.

“Currently, these biohybrid cells are not competitive with traditional solar cells,” Jennings explains. “They represent a significantly less mature technology, less than ten years of history for these cells versus fifty years for traditional silicon photovoltaics.”

Jennings emphasizes the need for more research into biohybrids, which “could be much cheaper and greener to produce than traditional solar cells because the key biological components are vastly abundant and renewable in nature.”

The research is currently being carried out, and groups like the Environmental Protection Agency are starting to take notice of the potential. Earlier this year, a group of Vanderbilt chemical engineering seniors won three awards for the cells at the EPA’s National Sustainable Design Exposition in Washington, D.C. The demonstration earned them a grant to develop the concept further.

Through funding by the EPA and the National Science Foundation, the team is now working to further optimize the cells to maximize power output, and to “take this published design from the laboratory scale to a more technologically relevant size scale,” says Jennings.

Top image courtesy Flickr user Scott Robinson.