Basically as much as I can from whatever I end up building. 2-3kw seems realistic with intermittent usage. It's definitely one of those projects where it's too hard to figure anything out without just trying stuff and learning as I go. So many variables involved... 

 I did some reading about it last winter and came to a similar conclusion. I'm curious about how much wood it consumes per kw hr produced. 

 Yeah, me too. I'm sure what kind of biomass and it's dryness makes a huge difference. I imagine the power output is going to vary drastically in my situation as I'll be using all sorts of different wood.