EAST LANSING, Mich. In a head-to-head battle of harvesting the sun's energy, solar cells beat plants, according to a new paper in Science. But scientists think they can even up the playing field, says researcher David Kramer at Michigan State University.
Plants are less efficient at capturing the energy in sunlight than solar cells mostly because they have too much evolutionary baggage. Plants have to power a living thing, whereas solar cells only have to send electricity down a wire. This is a big difference because if photosynthesis makes a mistake, it makes toxic byproducts that kill the organism. Photosynthesis has to be conservative to avoid killing the organisms it powers.
"This is critical since it's the process that powers all of life in our ecosystem," said Kramer, a Hannah Distinguished Professor of Photosynthesis and Bioenergetics. "The efficiency of photosynthesis, and our ability to improve it, is critical to whether the entire biofuels industry is viable."
While photosynthesis is less efficient on a pure energy basis, it has the advantage of producing high-energy liquid fuels. (It also makes all of our food, and is thus essential for life). The paper summarizes several specific approaches to improving photosynthesis, some likely achievable in the short term, some more involved.
In truth, the competition really isn't fair unless the term "efficiency" is first defined. At a bare minimum it isn't fair to compare plants that package the sun's energy in handy little stored-fuel vessels (carbon-based molecules) to solar cells that just take the first step of converting the sun's energy to jazzed-up electrons. Fairer would be to compare plants to solar cell arrays that also store energy in chemical bonds.
The point of the comparison is not to make us throw plants on the compost pile, the researchers said. For one, efficiency is only one consideration among many in the choice among energy technologies.
|Contact: Layne Cameron|
Michigan State University