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Converting Sunlight Into Liquid Fuel With a Bionic Leaf

Posted by Soulskill on 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.

5 of 68 comments (clear)

  1. Animal, not plant by MrLogic17 · · Score: 4, Informative

    The headline implies that we have a machine replicating the process of a plant. The summary indicates that what they have is a vat of bacteria that are making alcohol. Not nearly as attention grabbing, considering mankind has been using yeast & bacteria to make alcohols of various forms since the dawn of time.

    If they have a more efficient process with simpler (cheaper) inputs, kudos to them. But this ain't no artificial leaf.

    1. Re:Animal, not plant by gstoddart · · Score: 5, Insightful

      The summary indicates that what they have is a vat of bacteria that are making alcohol

      Hmmmm ... are you sure?

      Their work integrates an "artificial leaf," which uses a catalyst to make sunlight split water into hydrogen and oxygen, with a bacterium engineered to convert carbon dioxide plus hydrogen into the liquid fuel isopropanol.

      So, they're clearly doing more than just making alcohol with yeast.

      "This is a proof of concept that you can have a way of harvesting solar energy and storing it in the form of a liquid fuel

      In fact, I'd say it sounds quite different.

      --
      Lost at C:>. Found at C.
    2. Re:Animal, not plant by jdschulteis · · Score: 3, Insightful

      If it is so good, why not just store the hydrogen for fuel? Wouldn't it be cheaper/easier to skip the last steps?

      Hydrogen is difficult to store in a lightweight, compact system. One good way to store hydrogen is to chemically combine it with carbon and oxygen and put the resulting liquid in tanks at ordinary temperatures and pressures.

  2. energy balance doesn't work out by Noah+Haders · · 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.

    1. Re:energy balance doesn't work out by gstoddart · · Score: 3, Funny

      Hmmmm .... 100 square kms ... producing flammable alcohol.

      Have you seriously thought about this?

      The first guy to realize he can light a match and have hilarity ensue will probably create something visible from orbit, and get himself a Darwin award.

      Actually, scratch that ... bring it on! That would be funny.

      --
      Lost at C:>. Found at C.