reply to disconnected
Re: Wood-Fired Steam Engine to Drive Generator? Don't put your hopes too high. You're not going to be able to make an efficient-enough steam engine, definitely not without getting into levels of pressure and temperature that cannot be controlled in the backyard.
And then you have another issue - inability of controlling the output power in a timely fashion. You will have to be able to increase the output power by a factor of 10 or more in a fraction of a second when a load is being added. Even with a giant flywheel, that's not going to help as it will take maybe a minute to be able to increase the fire intensity to the needed levels.
Edit: I'd be extremely surprised if you got more than 3% efficiency. Generating 15kW of electricity, even disregarding any generation losses, would require about 15*3413/0.03 = 1.7mil BTU/h. That's nearly 1 cord of wood for 10hrs of use...