Better biofuels through beefed up photosynthesis is being explored by the National Renewable Energy Laboratory (NREL). In a recent feasibility study, the NREL-sponsored group compared the energy capturing efficiency of photovoltaic solar cells to that of plants. Plants lost. But could photosynthetic efficiency be improved through genetic engineering? By capturing and storing a larger percentage of the sun’s energy, such super-plants would not only be a more robust food source but also a more practical biofuel.
Solar cells can capture energy across the spectrum, but plants mainly absorb reds and blues, reflecting the greens. Even that much light can be too much. Sometimes more electrons get excited than the chloroplast can handle. Then surplus energy must be dissipated to keep the plant from burning up. This bottleneck is often due to a rate-limiting enzyme involved in processing carbon dioxide. So far, no way has been found to get this enzyme to respond to higher carbon dioxide levels.
The research team is seeking ways to apply photovoltaic principles to reengineer photosynthesis. They suggest that geneticists try to integrate genetic information for pigments that absorb energy from neglected parts of the spectrum such as the infrared region. But without ways to deal with energy overload, the plant would still cook itself. Therefore they must also find a genetic way to improve enzyme efficiency. The NREL team’s calculations indicate that even in the best case, plant efficiency will never equal that of a solar cell, but it could be significantly improved.
Blaming evolution for the inefficiency inherent in plants, the authors write, “The photosynthetic apparatus are limited by the need to operate within a living organism, for which they were tailored by evolution.” They believe that plants inherited biochemical processes from non-photosynthesizing forbears and just got stuck with them. Furthermore, they say, “Photosynthetic organisms in the wild are selected through evolution for reproductive success, not for high biomass production.”1
Historically, mankind has applied common sense genetics to the practical problems of food production with great success. Careful manipulation of the genetic material that God created to develop practical renewable fuel sources is the modern extension of that process.
We might want to borrow their statement but change one word: the photosynthetic apparatus are limited by the need to operate within a living organism, for which they were tailored by God. Plants do devote a great deal of energy to growth and reproduction, and we are thankful they store enough surplus energy to provide food for our end of the food chain. Historically, mankind has applied common sense genetics to the practical problems of food production with great success. Careful manipulation of the genetic material that God created to develop practical renewable fuel sources is the modern extension of that process. Engineering better biofuels is a way to be good stewards of the world God gave us.
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