I did some more looking around on peltiers. These guys:
Using a peltier to generate electricity - HomeBuiltAirplanes.com
were playing with the same idea. Turns out peltiers are around 10% efficient. Not too good then.
Now, with the turbo alternator, i think a stumbling block is in getting a generator that goes as fast as a turbo. If we gear down from turbo speeds, we are losing efficiency. I'm trying to find out more about switched reluctance motors as they seem to be whats used. Apparently they are very cheap to make. Doesn't mean they'll be cheap to buy though...
ollie