Researcher amplifies effectiveness of solar electrodes — with spinach

Popeye claimed that spinach was the key to bulging biceps, but researchers at Vanderbilt University have just found a new use for the super-vegetable — harnessing the power of the sun.

Kane Jennings, who teaches chemical and biomolecular engineering at Vanderbilt University, and his colleague Professor David Cliffel developed a new way to use proteins found in spinach to generate solar power.

“What we did was extract out a key protein found in spinach and all other green plants known as photosystem 1,” he said. “We placed photosystem 1 on a surface, it’s able to capture incoming light, much like it does in photosynthesis — both current and potential — to power a solar cell.”

Jennings said it was a natural evolution to consider harnessing photosynthesis to generate power. Plant photosynthesis generates eight times more power than all of the power generated by fossil fuels today, he said.

The spinach-solar collector is built with the photosystem 1 protein layered atop a silicon electrode. It generates 2,500 more times than when the protein was put on a metal electrode and six times more power than the silicon electrode alone.

But solar panel owners shouldn’t expect to run out to the grocery store immediately to pick up some spinach. Jennings said what his group is building is different from the typical photo-voltaic arrays that you might find on your neighbor’s roof.

“What we’re looking at here is more of a wet-based solar cell. More like kind of a solar battery,” he said of his new creation.

They’re not quite ready to take on the more capable photovoltaic cells, he added, but they’re on a good path.

“What we have shown is that we’ve increased the power output on these simple liquid-based solar cells by a million-fold in the last five years. If we stay on this same trajectory, we’ll be very close to those more traditional photovoltaics in about three years,” he said.

But, of course, spinach is also widely used as an important food source in the human diet. So, using spinach to make energy raises many of the same concerns that turning corn to ethanol raises.

So Jennings is working to shift away from deriving photosystem 1 from spinach and instead extract it from kudzu, an invasive, rapidly growing vine that covers many millions of acres in the southeastern United States.

“I would say that we are about, in the neighborhood of five to ten years, of having commercially marketable solar cells based on bio-hybrid technology,” Jennings said. “We need to make performance improvements to get us much closer to what traditional photovoltaics are giving out right now.”