On Sun, 21 Nov 2010 07:19:02 +0700, Bruce
wrote:

Frankly it sounds very much like a perpetual motion machine.

It's definitely not perpetual motion but it does depend on a number of
assumptions that may not hold true in the real world. Extracting
energy from spinning props is definitely possible under the right
conditions but my calculations show that the maximum power available
is relatively low, quite possibly enough to supply house loads, but
very unlikely enough to recharge a large battery bank.