These are products derived from solid biomass that are capable of direct use in energy conversion processes derived from biomass via transformations, usually physical, such as chipping, grinding and drying. Solid biofuels made from castor beans are biomass pellets and briquettes, the combustion of these is used to generate heat or steam in heating homes and producing electricity in combined heat and power. The production of electricity from renewable sources of biomass does not contribute to the greenhouse effect as carbon dioxide released by burning biomass is equal to the carbon dioxide absorbed by the biomass during its growth.