Biomass is organic matter that was recently living, such as wood, straw, crops, algae, sewage sludge, animal litter or other biological waste.
In general biomass in the domestic sector almost always refers to wood fuel, which is only sustainable if it comes from renewable forest sources.
Biomass systems can have high levels of efficiency, typically 60-80% in ranges, pellet stoves, log stoves and log boilers.
Biomass fuel usually takes the form of wood pellets or wood chips.
The burning of wood is considered to be a carbon neutral process since the CO2 released when energy is generated, is balanced by that absorbed during the fuel’s production (i.e. replacement tree growth).
It is most cost effective when a local fuel source is used, which also helps to reduce transport pollution which might otherwise be associated with the solid fuel.
One consideration, however is the physical size and installation cost of the fuel storage and delivery system. A 20kW thermal boiler typically consumes 0.6m3 of wood chip daily in winter, and the volume of one tonne of dried wood is about 6m3.