Jones wrote: <snip> 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.
MC: This is not simple. You have to capture the maximum energy from the wind at all speeds. For the pump, it is also a matter of torque as well as strokes/second. In principle, if the wind speed is low, you can gear down the propellor shaft and get enough torque to compress the gas. There are variable ratio transmissions, but these are quite inefficient. With an electric generator and the right electronics there are various tricks you can use to extract energy at low speeds; the system doe not stall. Mike Carrell
