Which Is Smarter: Photosynthesis or Photovoltaics? | WPN World People News

Scientists recently compared the efficiencies of real photosynthesis in plants to that of using man-made solar cells to harvest the energy of the sun. The results showed that even under ideal conditions, the difference was two to three times better for one over the other. Which would you bet on winning?

Plants such as corn (left) use photosynthesis to convert sunlight and water into fuel in a manner similar to using photovoltaic cells (right) to drive electrolysis that splits off the hydrogen from water for fuel.

If you guessed plants, you would be wrong. Their conclusion was that man-made photovoltaic-driven energy harvesting of sunlight was always at least twice as efficient as living photosynthesis systems, Not only that, but the team speculated that the higher efficiencies obtained artificially could be used as "rational design" criteria for a new era of enhanced plant-life.

Because photovoltaic systems directly produce electricity, whereas photosynthesis produced biofuels, the researchers compared artificial photosynthesis systems that use photovoltaics to drive electrolysis which splits off hydrogen from the H2O molecules in water. The hydrogen produced by artificial photosynthesis is thermodynamically equivalent to the sugar (adenosine triphosphate) produced by plant photosynthesis, and as a result, the researchers could directly compare the energy of the biofuels produced by plants to the hydrogen fuels produced by artificial photosynthesis. The resulting discrepancy showed conclusively, they claim, that photovoltaic-driven artificial photosynthesis is the winner.

According to the researchers, plant photosynthesis is similar to other evolutionary adaptations that are not optimized for any one function, such as energy production, but rather evolved merely to enable plants to maintain their self-contained systems that include growth, repair and reproduction. As a result, the team speculates that by using rational design techniques that mimic photovoltaics, it should be possible to use breeding techniques, such as selection, to boost the energy production of plants. Not only could these efforts enhance natural biofuel production, but they also could help stave off environmental catastrophes and perhaps even mitigate world hunger.

For instance, plants only produce enough biofuel to manage their own solitary existence, with very little storage capacity. Leaves in full sunlight typically use only about 20 percent of the energy they absorb, dumping the rest to avoid overly energetic internal chemical reactions that could damage its delicate mechanisms. Plants selected for their energy production, however, could boost that percentage.

The researchers hope to enhance an emerging technology called "synthetic biology" that combines re-engineered living plant biology with modern findings about the optimization of biofuel production for artificial photosynthesis. Their modest goal is to boost the current 133 trillion watts (terawatts) that plant photosynthesis produces today to power the biosphere--life on Earth--to about 150 terawatts without affecting the nitrogen cycle, carbon cycle, available fresh water, available land or the rate of biodiversity loss.

Lending credibility to their endeavor, this research team congealed contributions from organizations led by Washington University (St. Louis), including contributions from Argonne National Laboratory, Massachusetts Institute of Technology (MIT), Yale, Imperial College London, University of California, Berkeley, City College of New York, Donald Danforth Plant Science Center, Michigan State University, National Renewable Energy Laboratory, Colorado, University of Illinois, University of Osnabrück, University of Pennsylvania, University of Washington and ExxonMobil.

Source : Smarter Techonology