Biomass is the material derived from plants that use sunlight to grow which include plant and animal material such as wood from forests, material left over from agricultural and forestry processes, and organic industrial, human and animal wastes.
In nature, if biomass is left lying around on the ground it will break down over a long period of time, releasing carbon dioxide and its store of energy slowly. By burning biomass its store of energy is released quickly and often in a useful way. So converting biomass into useful energy imitates the natural processes but at a faster rate.
Sources of Biomass
Biomass comes from a variety of sources which include:
- Wood from natural forests and woodlands
- Forestry plantations
- Forestry residues
- Agricultural residues such as straw, stover, cane trash and green agricultural wastes
- Agro-industrial wastes, such as sugarcane bagasse and rice husk
- Animal wastes
- Industrial wastes, such as black liquor from paper manufacturing
- Municipal solid wastes (MSW)
- Food processing wastes
Biomass Conversion Technologies
Biomass can be transformed into clean energy and/or fuels by a variety of technologies, including thermal and biochemical. Biomass can be converted into energy by simple combustion, by co-firing with other fuels or through some intermediate process such as gasification. The energy produced can be electrical power, heat or both (combined heat and power, or CHP). The advantage of utilizing heat as well as or instead of electrical power is the marked improvement of conversion efficiency – electrical generation has a typical efficiency of around 30%, but if heat is used efficiencies can rise to more than 85%.
Biochemical processes, like anaerobic digestion, can also produce clean energy in the form of biogas which can be converted to power and heat using a gas engine. In addition, wastes can also yield liquid fuels, such as cellulosic ethanol, which can be used to replace petroleum-based fuels. Algal biomass is also emerging as a good source of energy because it can serve as natural source of oil, which conventional refineries can transform into jet fuel or diesel fuel.
Advantages of Biomass Energy
Biomass energy technology is inherently flexible. The variety of technological options available means that it can be applied at a small, localized scale primarily for heat, or it can be used in much larger base-load power generation capacity whilst also producing heat. Biomass generation can thus be tailored to rural or urban environments, and utilized in domestic, commercial or industrial applications.
Biomass conversion reduces greenhouse gas emissions in two ways. Heat and electrical energy is generated which reduces the dependence on power plants based on fossil fuels. The greenhouse gas emissions are significantly reduced by preventing methane emissions from landfills. Moreover, biomass energy plants are highly efficient in harnessing the untapped sources of energy from biomass wastes.