With the term "biomass" must be understood as "the biodegradable fraction of products, waste and residues from agriculture (including vegetal and animal substances), forestry and related industries, as well as the biodegradable fraction of industrial and municipal waste".

The definition includes a wide range of materials, virgins or residual working agricultural and industrial, that can present in various physical states, with a broad spectrum of calorific values. Depending on the type of biomass, and then the most appropriate technology for its energy, as well as depending on the size of interest and the final uses of the energy produced, thermal and/or electrical, you can move toward a plurality of system solutions.