peter green p10link.net> writes: > > I'm not a chem engineer, but a friend that /is/ tells me fossil fuels > > require four times the yield of energy to recover it from the earth > > and process it. > then ask him where the hell that energy comes from. > > I'm not saying that all fossil fuel recovery that happens is positive in terms of usefull energy output to > usefull energy input but on average they must be otherwise fossil fuels could not be the dominant > contributor to our supply of usefull energy. When the extraction and pumping gear on an oilfield run on power supplied by the products of the field (which are used untaxed in situ, after slight refining and removing things that go bang inside engines and boiler burners) the cost (price-wise) is simply un-computable. I suppose they write it off as 'wastage' or something like that. I have no idea what it takes energy-wise from the bottom of a borehole to a liter of diesel in a truck's tank on another continent, but this would be an interesting calculation to do. If anyone has a pointer, please post it. I just doodled that lifting 1 gallon of something out of the earth from 500 meters down alone costs 15kJ before flow resistance is calculated (and at 500 meters flow resistance for a viscous fluid is enormous). Peter -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist