Is biomass clean

It is not clean if clean is defined as sanitary.

It is clean if considered as environmentally clean, as it produces less harmful effects thatn fossil fuels.

Biomass is considered a renewable resource because of the ability of plant's to regrow. It is actually the number 1 renewable resource used in the world. Although the creation of this energy also causes pollution with-in the atmosphere from the release of the CO2 and Carbon Monoxide.