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posted by Fnord666 on Thursday July 20 2017, @12:44PM   Printer-friendly
from the cue-the-fart-jokes dept.

Submitted via IRC for Bytram

The carbon dioxide we're currently dumping into the atmosphere started out as atmospheric carbon dioxide hundreds of millions of years ago. It took lots of plants and millions of years of geological activity to convert it to fossil fuels. One obvious way of dealing with our atmospheric carbon is to shorten that cycle, finding a way to quickly convert carbon dioxide into a usable fuel.

Unfortunately, carbon dioxide is a very stable molecule, so it takes a lot of energy to split it. Most reactions that do so end up producing carbon monoxide, which is more reactive and a useful starting material, but it's far from a fuel. Now, though, researchers have discovered a catalyst that, with a little help from light, can take CO2 and make methane, the primary fuel in natural gas. While the reaction is slow and inefficient, there are a number of ways it could be optimized.

The work started out with a catalyst that converts carbon dioxide to carbon monoxide when supplied with a source of electrons. The catalyst is a complex ring of carbon-based molecules that latch on to an iron atom at the center. The iron interacts with carbon dioxide, allowing hydrogen atoms from water to break one of the carbon-oxygen bonds, liberating water. The iron loses some electrons in the process, and these have to be re-supplied for the cycle to start again. Typically, that supply comes in the form of a separate chemical that readily gives up some electrons.

Source: https://arstechnica.com/science/2017/07/cheap-catalyst-takes-sunlight-and-carbon-dioxide-makes-methane/


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  • (Score: 2) by kaszz on Friday July 21 2017, @05:26AM (1 child)

    by kaszz (4211) on Friday July 21 2017, @05:26AM (#542206) Journal

    Solar cells are likely to suck for these kinds of applications. The economical ones are at circa 16% efficiency and then you got to add MPPT and DC/AC conversion boxes. High efficiency is at ~43% but they make little economic sense. The better approach is to focus enough sun radiation to cook the CO2 at circa ~2500 ⁰C. This will split the C from the O2. To make CH4 one needs to grab a H4 somewhere.

    A burnable gas can be made into liquid through liquification processes. They seem to do it by lengthening the chemical bonds. Which of course consumes energy, no free lunch..

    To store carbon, maybe it's better to just keep the C like it is. Other compounds can maybe be used to bind it. But then coal etc all seem to work out just fine. Dig it down under a layer of clay and it will not circulate for quite a while.

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  • (Score: 2) by HiThere on Friday July 21 2017, @04:54PM

    by HiThere (866) Subscriber Badge on Friday July 21 2017, @04:54PM (#542449) Journal

    1) Sorry, my (GP) reply was almost a joke.
    2) For this application you wouldn't need any inverter, just design it to run on DC.
    3) This had better a low voltage, low current requirement, or the entire process is worse than just stupid. Even if it is, I'd expect auxiliary costs to swamp any benefit.

    FWIW, I expect that plants of some sort (I'm including microbes within plants as long as the convert CO2 to carbohydrates) would, or could be engineered to, do the job both better and cheaper. Except in special circumstances, such as, perhaps, on board a nuclear sub.

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