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Biomimicry isopropanol bionic leaf (artificial leaf)

Published on February 12th, 2015 | by Tina Casey


Harvard Scientists Invent A Bionic Leaf That Makes Rubbing Alcohol

February 12th, 2015 by  

The last time we checked into the whole “bionic leaf” thing, it involved making hydrogen fuel from sunlight and water. Now a team of Harvard researchers have come up with a new twist: a bionic leaf that throws bacteria into the mix.

The result goes one step beyond hydrogen to produce a steady stream of… rubbing alcohol! So, what does that mean from a cleantech perspective?

isopropanol bionic leaf (artificial leaf)

Rubbing Alcohol From A Bionic Leaf

To produce its new bionic leaf, the Harvard research team brought together the Faculty of Arts and Sciences, Harvard Medical School, and Wyss Institute for Biologically Inspired Engineering for this biomimicry project.

The bionic leaf is an integrated system, and the first part draws from previous research undertaken by fellow Harvardian Daniel Nocera. He’s the brains behind the first “artificial leaf,” a small, leaf-sized solar device that is submerged in water to produce hydrogen.

Currently, the primary source of hydrogen fuel is natural gas, so being able to produce hydrogen in a more sustainable way is a big deal.

If you’re feeling a touch of déjà vu, last year we noted that our friends over at Lawrence Berkeley National Laboratory were working on amped-up version of the artificial leaf concept, which they called a “bionic leaf,” but it seems that they didn’t call dibs on the name “bionic” because now Harvard has it.

As long as we’re on the topic of producing hydrogen from artificial and bionic leaves, there’s another interesting project under way at Oak Ridge National Laboratory, that involves producing hydrogen from an actual leaf (hint: Popeye would love this).

Where were we? Oh, right. The Harvard team started with the artificial leaf to produce hydrogen, and they combined that system with a bacterium that munches on a combination of hydrogen and carbon dioxide to produce isopropanol.

The bacterium in question is a specially engineered strain of Ralstonia eutropha. If you check out the team’s paper, “Efficient Solar-to-Fuels Production from a Hybrid Microbial Water-Splitting Catalyst System,” published earlier this week by the National Academy of Sciences, you can see that the key factor is how to keep your bacteria alive and functioning as efficiently as possible in an artificial environment.

The image above shows an improved survival rate for the bacterium when exposed to an improved catalyst.

So far, so good. The team is already nearing the 1 percent efficiency mark, which is almost equivalent to the natural photosynthetic rate for converting sunlight to biomass. The goal is 5 percent.

Many Uses For Isopropanol

For those of you who know your rubbing alcohol, it’s plainspeak for the isopropanol alcohol, or isopropanol for short. Isopropanol is a petroleum-derived product based on propylene (aka propene), a byproduct of gasoline refining. Propene can also be derived from coal.

There are quite a few uses for isopropanol aside from rubbing, so as with hydrogen, getting it from renewable resources is a big step forward for replacing petrochemicals and other fossil-derived substances.

The Harvard team seems particularly excited over the potential for producing sustainable isopropanol fuel, but we’ll keep our pom-poms down for now in that regard. Our new best friends over at Adventures in Stoving certainly don’t recommend isopropanol as a fuel, at least not in portable open-flame camp stoves, because it is “usually a sooty mess to burn.”

On the other hand, the Harvard research was funded by the Air Force Office of Scientific Research and the Office of Naval Research along with the National Science Foundation, and isopropanol has a number of applications in aviation, so there’s that.

Isopropanol is also used as a component in antifreeze, so if you’re looking forward to the day when your gasmobile will run on renewable biogasoline, you’ll might have some renewable antifreeze to go with it.

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Image Credit: Proceedings of the National Academy of Sciences, in “Efficient Solar-to-Fuels Production from a Hybrid Microbial Water-Splitting Catalyst System.

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About the Author

specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.

  • Steven F

    “Our new best friends over at Adventures in Stoving certainly don’t recommend isopropanol as a fuel, at least not in portable open-flame camp stoves, because it is “usually a sooty mess to burn.”

    the only stoves in which alcohols are used as fuel are hand made stoves frequently madefrom alumium cans. There is no control of the air buel mixture. in aplications where the air fuel mixture is controlled (cars) it works very well although you might have to change some seals in the fuel system.(especially on older cars made before 1980)

  • ThatEnergyFreakGuy

    Wait, I thought that antifreeze was methanol?

    • Steven F

      Methanol is sometimes used to as an antifreeze but mostof the time it is not since it is very flamable and very poisons. the most commonly used antifreezes are ethylene Glycol (poisons), propylene glycol (less poisonous), and Glycerol (safe, not poisonous). Many other chemicals can also be used, some are corrosive,some are toxic, some are very expensive. In some cases water is replaced with a synthetic chemical such as Flourinert.

  • shecky vegas

    “The result goes one step beyond hydrogen to produce a steady stream of… rubbing alcohol! So, what does that mean from a cleantech perspective?”
    I’ll tell you what it means — PAAAAAAARTYYYYYYYY!!!!

    • RamboSTiTCH

      Please don’t try to drink rubbing alcohol straight. It is a highly potent alcohol. You will gag, cough, and throw up. One drop of isopropanol (isopropyl alcohol) in a soda will make someone drunk or buzzed. A cap-full in 2 liters is too much and will make one puke. It breaks down to acetone in the body, which has some toxicity. Ye be warned.

    • Steven F

      Methanol, isopropanol, and butanol are all toxic alcohols. Only ethanol is safe.

  • Marion Meads

    It would be nice to know the exact calculations and assumptions in that 1% efficiency. Currently, the main reason why plants only have 1% efficiency is that it is the energy value of the fuel product divided by the solar radiation intercepted by the planted area for the period of time the land is prepared for growing until post-harvest operation when the land is prepared again for the next crop. This is the correct standard of efficiency computation. Get the energy value of the fuel produced artificially divided by the total solar energy intercepted per the same unit time.

    • Joseph Dubeau

      I read about this other day on Science Daily.
      “Their goal is 5 percent efficiency, compared to nature’s rate of 1 percent efficiency for photosynthesis to turn sunlight into biomass.”

      Bionic leaf: Researchers use bacteria to convert solar energy into liquid fuel

      “We’re almost at a 1 percent efficiency rate of converting sunlight into isopropanol,”

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