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CO2 To Ethanol In One Step With Cheap Catalyst (sciencedaily.com)
Reader networkBoy writes: Boffins at ORNL (Department of Energy's Oak Ridge National Laboratory) have discovered a simple and cheap catalyst that can take CO2 (Carbon Dioxide) dissolved in solution with water and at room temperature convert it to ethanol with 60%+ yields. They envision it as a way to store surplus power from green energy plants and then burning it to fill in lulls in supply.From the report:The team used a catalyst made of carbon, copper and nitrogen and applied voltage to trigger a complicated chemical reaction that essentially reverses the combustion process. With the help of the nanotechnology-based catalyst which contains multiple reaction sites, the solution of carbon dioxide dissolved in water turned into ethanol with a yield of 63 percent. Typically, this type of electrochemical reaction results in a mix of several different products in small amounts. "We're taking carbon dioxide, a waste product of combustion, and we're pushing that combustion reaction backwards with very high selectivity to a useful fuel," Rondinone said. "Ethanol was a surprise -- it's extremely difficult to go straight from carbon dioxide to ethanol with a single catalyst."
His/her question is good, and the summary is incomplete. It converts CO2 to CH3CH2OH at a yield of about 63%, but what CO2 concentration in the water are they assuming? Average soda concentration is about 0.12-0.15 M (moles per liter) at about 4 bar. That would mean you'd get 0.05 M alcohol (2 carbons per EtOH from one carbon in CO2, 0.5*0.63*0.15), which is 0.05 moles EtOH/55.5 moles water or about 0.08 percent alcohol by volume. That's a lot less than the ethanol conversion you'd get from corn.
It did not mention the catalyst materials cost, nor the materials processing required to make a nanomaterial.
So we'd have energy costs by compressing CO2, then converting it using the catalyst, then there would be ethanol separation costs (with requisite electricity/natural gas from the distillation columns) from water that far exceed normal ethanol separation, and the ethanol would still have about 10% water because it is an azeotrope,so then you'd need another liquid-liquid extraction...
As is the case with the other carbon dioxide conversion schemes, it's really cool chemistry, looks good in summary, but the details render it ineffective for practical use.
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Hmm, it seems the laws of thermodynamics are being overlooked here...
Nah, we don't normally care if yeast die by the billions, and they're exceedingly unlikely to initiate an armed revolt to avoid starving to death.
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