There is a $300 federal tax credit for biomass fuel stoves (used for heat or water heating) placed in service between January 1 and Dec 31, 2009. The stoves must have a thermal efficiency rating of at least 75%.

There is a $300 federal tax credit for biomass fuel stoves (used for heat or water heating) placed in service between January 1 and Dec 31, 2009. The stoves must have a thermal efficiency rating of at least 75%.

The law defines "biomass fuel" as any plant-derviced fuel available on a renewable or recurring basis, including agricultural crops and trees, wood and wood waste and residues (including wood pellets), plant (including aquatic plants), grasses, residues, and fibers.

The Pellet Fuels Institute  may have more details.