Converting Sunlight Into Liquid Fuel With a Bionic Leaf

Posted by Soulskill on Wednesday February 11, 2015 @05:29AM from the who-needs-dead-dinosaurs dept.

hypnosec writes: Artificial leaf techology made waves the moment it was announced by Daniel Nocera back in 2011. His latest research, published in PNAS, involves gathering hydrogen from this artificial leaf, carbon dioxide from another source, and feeding it to Ralstonia eutropha bacteria to create liquid fuel. Once the materials are fed to the bacteria, "An enzyme takes the hydrogen back to protons and electrons, then combines them with carbon dioxide to replicate—making more cells. Next, ... new pathways in the bacterium are metabolically engineered to make isopropanol." Researchers say the same process could be used to make vitamins.

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energy balance doesn't work out by Noah+Haders · 2015-02-11 05:59 · Score: 3, Interesting

The energy balance doesn't work out here. Max solar intensity is 1 kw / m^2, or 1 kj per square meter every second, or 3.6 MJ per square meter per hour. A gallon of gasoline is 120 MJ. So assuming 100% efficiency and 100% peak sunlight, it would take 30 hours to make a gallon of gas from one square meter of artificial leaf. Considering the average solar intensity is about 10% the max, and any process involving the sun is max 20% efficient, it starts to take a very long time to make one gallon of gas. Not even including the energy requirements of the leaf / enzyme process.