For thousands of years, ever since we used wood for fuel, we have relied on biomass or bioenergy to provide heat and energy. Today we use many other sources of biomass in the form of plants, landfill fumes, agriculture and forest residues, and organic wastes from industries and cities.
Sources of Biomass
Biomass can come from a large variety of sources. Often, agricultural and forest industry by-products can be used, which include paper mill residue and lumber mill scrap. Municipal wastes and surplus crops can also be utilized. Dedicated energy crops, such as fast growing trees and grasses can be used as sustainable long-term sources of biomass.
Generating Energy from Biomass
Energy is produced from biomass by basically burning organic matter to release its stored chemical energy that it has accumulated through the process of photosynthesis. Using biomass contributes very little to the build-up of greenhouse gases. Although plants will release their stored carbon dioxide (CO2) when burned, that CO2 is recaptured and used by other plants as they grow. Therefore, theoretically there is no net gain of carbon dioxide because of a cycle of usage.
There are several ways of creating electricity from biomass, including direct-fired, co-firing, gasification, anaerobic digestion.
How Bioplants Work
There are several ways of generating biopower:
Direct-fired: the most common method of processing biomass. Biomass is burned to produce steam that is captured by a turbine and converted to electricity by a generator. The direct-fired system is similar to the process used in coal or oil plants.
Co-firing: by burning biomass in combination with fossil fuels on coal power plants, air pollution can be significantly reduced, especially sulfur emissions. Cofiring is probably the most economical choice at the present because it can be used with existing technologies.
Gasification: Gasification uses high temperatures to convert biomass into a gas within an environment lacking oxygen (a.k.a. an anaerobic environment). Gas is then used to turn a turbine and generator, creating electricity. Gasification is one of the most efficient and low polluting of the conversion technologies.
Anaerobic Digestion: Anaerobic digestion uses bacteria to decompose organic matter, especially waste products, in an oxygen-starved environment, producing methane gas. Methane gas may be used in several ways. Most facilities will burn it to create steam and run a generator. Methane can also be used in micro-turbines and fuel cells.
Biomass is a very viable alternative to replace fossil fuels. Already biomass can be used with conventional technologies. As a renewable, clean resource, that is becoming more increasing cost-efficient, biomass is a very feasible source of energy for the future.