BIOMASS BOILERS use an organic, plant based material (usually wood) as fuel to heat your home. The three most common fuels are pellets, wood chip and logs. Biomass is viewed by many as the most important source of renewable energy and is carbon neutral from sustainable sources. Woody biomass is an effective way to heat your home as it produces high water temperatures which is ideal for older, not easily insulated houses particularly in rural areas as fuel storage is an important factor.