At 12:22 PM 2/15/5, Jones Beene wrote: >Anyway at the wind mill itself air can be compressed and then cooled and >recompressed however many times is necessary to give liquid air at an >optimum efficiency of 48 % of the torque. I disagree with Mike that this >process is not as efficient at low air speeds, but someone like Richard >who is a pump expert may be able to correct me, if this is wrong.
Your 48 percent assumption might be a bit out of line. Are you referring here to 48 percent of optimum Carnot effciency and not actual efficiency? I should mention that torque is not work. It is the equivalent of force. Torque times angular velocity is work. Maybe you mean shaft horsepower? Much more importantly, you have to keep in mind that gas compression is limited by Carnot efficiency, based on the difference in temperatures involved. It is a themodynamic process. Hydrogen generation and electricity generation are not limited in this way. There is much room for improvement for the latter two and not much wiggle room, even theoretically for the liquifaction process. The same argument applies to conversion of LN2 to shaft horsepower. This process is limited by the Carnot efficiency. Fuel cells are not so limited. You have totally ignored cost in the cost/benefit. Sure wasted energy is an important factor, but comparative cost of the service is also important. We don't really have cost numbers, other than maybe to compare the cost of a Linde plant to an electric generator of similar capacity. These are fairly meaningless numbers though in that the deisgn of either an electrolysis plant or liquifation plant for a wind application would be substantially different. Further the cost involved represent transport and storage costs. There is a cost/benetif tradeoff which depends on the cost of the source energy. Then there is the question of market preference. If there is a huge market generated for hydrogen then, like Betamax vs VHS, or token-ring vs CDMA, the production will eventually all go where the market is. Though this is all good discussion and the approach may yield practical results for a while, it is important to realize that wind can not solve all the worlds energy problems, and working on a new *source* of energy is the big problem. Regards, Horace Heffner
