The term biomass generally really applies to a fuel source rather than a specific generation technology.
Biomass fuels are combustible organic materials which can vary dramatically in form. For example, agricultural by products such as wood chips, almond shell, and municipal solid waste are examples of materials which could be combusted with little processing to generate electricity. Cogeneration can utilize biomass fuels, or the material may be combusted directly in a boiler.
Biomass as a fuel source also includes “biogas’ fuels. For example, methane recovered from landfills can be combusted to produce electricity. This technology reduces fugitive methane releases (a major greenhouse gas) and produces a useful commodity. Another source of biogas are farms; dairy waste products (manure and other material) can be placed into a “digester” where microbacterial decomposition produces combustible gases. This technique can also be applied at waste water treatment facilities.
Cogeneration is the simultaneous production of two or more forms of useable energy from a single fuel source.
By using the fuel “twice” this technology has greater efficiencies than using the fuel to solely generate electricity. Possible primary fuels include biomass materials (explained below), and fossil fuels like natural gas, coal or oil. Most systems are designed to produce electricity (which is used in-house or sold to an electric utility) as well as thermal energy for industrial processes (such as steam).
Cogeneration is especially useful for Thermally Enhanced Oil Recovery (TEOR) projects which extract thick oil from older fields. Over 80% of the world’s TEOR recover oil comes from California. Cogeneration systems can range in size to fit the users’ needs. For example, cogeneration is used at hospitals, food processing facilities, universities, housing projects and shopping centers.