A biomass power plant typically produces steam through combustion. The steam can be used for industrial processes or to produce electricity. Alternatively, the heat from combustion could be directly used in an industrial process. Another variation is a co-fired power plant fueled by coal or natural gas combined with a biomass source.
Solid-waste fuel would typically be stored in an outdoor pile in quantities adequate to fuel the power plant anywhere from 60 days to several years. Agricultural waste fuel would be stored in silos. Agricultural products such as switchgrass, hybrid poplars, or cottonwood trees would be stored in barns or storage domes on site. Depending upon the type of boiler, the fuel is either transported directly to the powerhouse via a belt conveyor, or first processed in a chipper/grinder to produce a finer texture.
Municipal solid waste is deposited into pits where cranes mix the refuse and remove any large, non-combustible items; sometimes, it is further processed to remove ferrous materials, glass, and other non-combustible materials. In a fluidized bed boiler, the fuel is suspended on high-pressure jets of air during the combustion process.
This does not only allows combustion at relatively low temperatures and higher efficiency, but it also decreases the production of nitrogen oxide, an air pollutant.