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