A biomass plant is a power plant that uses renewable energy obtainable from biomass by extracting it out through direct combustion of biomass by special processes meant to improve efficiency. The term "biomass" defines any organic matter (i.e. derived from the process of chlorophyll photosynthesis).

This definition covers an extremely heterogeneous variety of materials: these may be, for example, industry waste, residues from agricultural and forestry processing, firewood, scraps of the agri-food industry, dung and waste from farms, vegetable oils, municipal waste, but also cultivated vegetable species such as the poplar, miscanthus, or other fast growing and easily cultivating essences and species, suitable for this purpose.