Actually what I said here was (probably) wrong. Sort of like saying you can't get energy out of sugar in the absence of oxygen -- yeast would laugh in your face if you claimed such a thing.
If we start with something like gasoline, which is something like C8H18 (pure octane, I know it's not, but close enough), then the actual combustion reaction is something like this: 2*C8H18 + 25*O2 --> 16*CO2 + 18*H2O with who-knows-what intermediaries and such. Be that as it may, the point is the oxidation of the H's releases energy, all by itself (though I dare say the lion's share comes from oxidizing the carbon). So, in principle, it should be possible to start with gasoline, burn a little bit and use the energy for something you want to do, then burn a lot more and use the energy from the second burn to split the CO2 from both burns. Overall the reaction would look like: x*C8H18 + y*O2 --> z*Cw (some kind of graphite?) + q*H2O Without spending time with redox tables or the equivalent I'm not certain but I think the reaction is still energy-positive. In fact, if I don't miss my guess something close to this is done in charcoal production, where a large amount of wood is stacked up in such a way that it has rotten ventilation in the middle, and the pile is burned, very slowly. Certainly a lot of the heat driving the reaction comes from burning the well-ventilated wood on the outside of the pile but I'm not sure that does more than get the reaction started; once the stuff in the middle starts to go it's most likely self sustaining. Stephen A. Lawrence wrote: > > OrionWorks wrote: >> Frank's work brings up a wish-list: >> >> Wouldn't it be nice if there was an economical technology in existence >> that had the ability to separate CO2 back into its individual >> elements. Release the oxygen back into the atmosphere while >> simultaneously nano-manufacturing all sorts of interesting carbon >> nonotubes. > > But ... the problem is the energy balance. > > You got a lot of energy out when you let those O atoms glue themselves > to the C -- in fact, getting that energy "fix" is probably why you did > it. Now, to get them unstuck again, you're going to have to put just as > much energy back in. > > Kind of defeats the purpose, I would think. > > On the other hand, it could be useful if you're imagining using the > C+O2 --> CO2 --> C+O2 cycle as a convenient way of transporting energy > from point A to point B, or converting the energy from one form to > another. But then again that sort of puts you back where we started, > which is looking for some other source of energy. > > > >> Regards >> Steven Vincent Johnson >> www.OrionWorks.com >> www.zazzle.com/orionworks >> >
