Biomass to Energy

Biomass is organic matter that can be processed into energy for heat, liquid fuels or power generation. Sources of biomass include wood, plants, agricultural residues, animal waste, and the organic components of municipal and industrial wastes. Biomass can be combusted directly to produce steam for electricity or it can be converted into a gas to power a turbine. It can also be converted into a fuel oil substitute called bio-oil.

Biomass power can be generated at stand-alone power plants, cogeneration power plants or in microgeneration applications. A biomass power or cogeneration system typically consists of a combustor or a gasifier and a prime mover that uses steam from a boiler or combustible gas from a gasifier to produce heat and/or power. Installations range in size from less than .75 MW electric capacity to over 50 MW.

Learn more about how agricultural waste can produce heat and power an by reading about the Colorado Pork project.

Biomass can be converted to thermal energy, liquid, solid or gaseous fuels and other chemical products through a variety of conversion processes:

Direct Combustion
Generating electricity and/or useful heat energy is most frequently done by direct combustion of biomass in a boiler. Energy content, moisture content and chemical makeup are among the most important biomass characteristics affecting combustion processes.

Pyrolysis
Pyrolysis is the process of heating biomass at a high temperature in the absence of oxygen. It is broken down into three main products: liquid oil, char and a combustible gas.

Gasification
Gasification converts biomass to what is commonly called a "producer gas" by heating the raw material at high temperature with a controlled amount of oxygen. The resulting producer gas can be combusted to generate electricity, heat and liquid fuels.

Anaerobic Digestion
Anaerobic digestion involves the decomposition of biomass solids into gas (primarily methane and carbon dioxide).

Fermentation
Fermentation can be used to produce ethanol from biomass. In this process, starch from plants is converted to sugar and fermented into ethanol, which is then distilled in its pure form. If cellulosic biomass materials are used instead of traditional feedstocks (starch crops), the end product is called bioethanol.

Transesterification
Transesterification is the process used to produce biodiesel made from fats or oils. In this chemical process, a catalyst causes the exchange of the alkoxy group of an ester by another alcohol.

Hydrolysis
Hydrolysis involves extracting simple carbohydrates from complex carbohydrates found in cellulose and hemicellulose. Extracting the carbohydrates may involve "steam explosion" of the cell walls, or dissolving the organic constituents with acids, enzymes, or organic solvents. Sugars resulting from hydrolysis can then be converted into ethanol through microbial fermentation.