Biomass is the name for a range of organic materials which can be used to produce energy, an example of biomass which are often used to generate energy is wood. As the biomass grows, it absorbs CO2 from the atmosphere and traps the carbon in the tree. This is then harvested and burnt in a biomass boiler, in order to provide heat for a home. Because the carbon is being trapped, the CO2 emissions are minimal. Furthermore the the fuel is being replaced by new trees, making the process sustainable. The co2 emissions from processing and transportation can be offset by growing more biomass than is required for fuel.