Well, you could use chicken manure as a biomass fuel. It'd be derived from a living animal...
When I was a kid, there was a nutcase chicken farmer living near me who ran a motorcycle on buiogas derieved from rotting chicken manure and straw.
One of my dad's best friends collected vintage motorbikes, and the two of them (chicken farmer man and m'bike collector) were good friends.
Apparently the collector was pretty simple, just a big vat of stinky manure with an airtight lid.