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posted by cmn32480 on Wednesday September 20 2017, @04:41AM   Printer-friendly
from the can-we-make-vodka-too? dept.

Scientists at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) have harnessed the power of photosynthesis to convert carbon dioxide into fuels and alcohols at efficiencies far greater than plants. The achievement marks a significant milestone in the effort to move toward sustainable sources of fuel.

Many systems have successfully reduced carbon dioxide to chemical and fuel precursors, such as carbon monoxide or a mix of carbon monoxide and hydrogen known as syngas. This new work, described in a study published in the journal Energy and Environmental Science, is the first to successfully demonstrate the approach of going from carbon dioxide directly to target products, namely ethanol and ethylene, at energy conversion efficiencies rivaling natural counterparts
....
For this JCAP study, researchers engineered a complete system to work at different times of day, not just at a light energy level of 1-sun illumination, which is equivalent to the peak of brightness at high noon on a sunny day. They varied the brightness of the light source to show that the system remained efficient even in low light conditions.

When the researchers coupled the electrodes to silicon photovoltaic cells, they achieved solar conversion efficiencies of 3 to 4 percent for 0.35 to 1-sun illumination. Changing the configuration to a high-performance, tandem solar cell connected in tandem yielded a conversion efficiency to hydrocarbons and oxygenates exceeding 5 percent at 1-sun illumination.

The ethanol-fueled rejoice.


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  • (Score: 5, Insightful) by jmorris on Wednesday September 20 2017, @05:16AM (2 children)

    by jmorris (4844) on Wednesday September 20 2017, @05:16AM (#570533)

    Basically, when you strip away the propaganda included to get the next round of funding you are left with an improved device to crack CO2 into very simple hydrocarbons. it is only "solar" in the sense you can use a photoelectric cell to get the electricity to drive it, but ANY source of electricity would work equally well.

    And it is only 5% efficient. I'm assuming that is driving it with solar power, taking into account the efficiency of the solar cells used (read most exotic they could get) and the losses of the device itself. On the surface that is pretty dismal, but it IS storing energy in a useful form, readily transported, etc. Since you can get over 40% from current research cells, the device in question is losing most of it. Still, offer up a panel with an attached gadget that craps out liquid fuel all day into a holding tank and you wouldn't have to pitch it on "saving the Earth" grounds unless it was insanely expensive. Lots of places that sort of thing would be handy.

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  • (Score: 5, Informative) by c0lo on Wednesday September 20 2017, @06:33AM

    by c0lo (156) Subscriber Badge on Wednesday September 20 2017, @06:33AM (#570544) Journal

    Basically, when you strip away the propaganda included to get the next round of funding you are left with ...

    And it is only 5% efficient.

    Only about a week ago [soylentnews.org] - under the title "Researchers Make Alcohol Out of Thin Air" (granted, that one was on research in Netherlands, this one is in USA. Does that "next round of funding" and the low efficiency smells somehow of desperation?)

    Anyway, the PhD thesis defense for the Dutch guy was scheduled on Sep 14 - I couldn't not find the thesis itself. However, as any PhD thesis, there should be a large number of articles accepted for publishing.

    Here's one of them - free access "Controllable Hydrocarbon Formation from the Electrochemical Reduction of CO2 over Cu Nanowire Arrays" [researchgate.net].

    Page 2, figure 2 show a graph of faradaic efficiency of conversion of CO2/water into: C2H4 (ethene), C2H6 (ethane), CO (carbon monoxide), HCOOH (formic acid), ethanol, n-propanol, and H2.
    Excluding H2 (obtainable without CO2 and containing no carbon) and the formic acid (doesn't burn directly - or it's not advisable anyway), the faradaic conversion efficiency to "fuel like chemicals" is around 30-35%.
    Including the formic acid as well, the efficiency climbs to 50-55%. Including all the products, the faradaic efficiency is well over 90%.

    --
    https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
  • (Score: 0) by Anonymous Coward on Wednesday September 20 2017, @08:34AM

    by Anonymous Coward on Wednesday September 20 2017, @08:34AM (#570559)

    Also confusion, contrast and compare

    efficiencies far greater than plants

    suggesting a >> b

    at energy conversion efficiencies rivaling natural counterparts

    however a = b or even slightly less...