Biomass is an energy source that is derived from crop waste and wood, but it is also derived from garbage, manure, sewage sludge and other organic waste that society continuously produces. It is for this reason that biomass is considered to be a natural and renewable source.
The concept that regrowth can eventually replace the plant material used also supports the concept that biomass is renewable. The carbon emitted and obtained from burning the gathered biomass is absorbed by plants and is considered as a part of the carbon cycle. This is plausible if the amount of trees and plant material harvested for biomass is replenished as soon as the wood is burned. New plants and trees absorb the carbon dioxide produced through combustion, maintaining the carbon cycle and establishing an renewable energy source.