Petrol from Air


Stories are circulating about a UK company that has worked out a way to manufacture petrol from air. The BBC reports

Its sounds exciting, they are converting carbon dioxide into fuel, so what is the problem here. Well, it took them several months to get a couple of litres, but that is not the real issue, because what they have is just a concept, a demo to prove that it works. Can they scale it up? Given enough investment and the rising cost of fuel it might be economic in the long term … but then again perhaps not. The real problem is simple and revolves around the basic chemistry and also the Laws of Thermodynamics.

Carbon dioxide is almost completely energy-free: it is what you get from hugely exothermic (energy-releasing) reactions like burning fuel. Petrol on the other hand consists of long carbon chains of that are full of chemical energy, so if you want to convert carbon dioxide into fuel, you need to put all that energy back in. There is no magic here, it will take heaps of power to do this, so all you are really doing here is storing up energy and thus the fuel is simply a way to capture, preserve and transport that energy. So where will this energy come from … renewables, or nuclear perhaps, but it sure as hell will not be coming from burning more fuel, that would be utterly insane.

Still, it is an interesting step … if it takes off, it means we can capture energy in a renewable manner, then use it to manufacture fuel and so we get to keep our cars, and also lose the guilt trip about pumping carbon dioxide out, because to get that fuel we would be simply taking it back.

Final sanity check … yes, it is indeed a technical reality, but right now this is not a commercial reality, it is a heck of a lot simpler to simply drill and pump the stuff out of the ground. But in the years to come we might be tempted to turn to a technology like this once the oil starts to run out, then perhaps this does become a bit more interesting. Then again, this could simply be one of those ideas that simply do not scale up into something that could ever be commercially viable, because the amount of energy required to produce the fuel may prove to be far too much.

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