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In ecology, biomass means the accumulation of living matter. It is the total living biological material in a given area or of a biological community or group. Biomass is measured by weight, or by dry weight, per given area (usually measured per square metre or square kilometer). In the energy industry, it refers to biological material which can be used as fuel or for industrial production. Biomass includes plant matter grown for use as biofuel, and also includes plant or animal matter used for production of fibres, chemicals or heat. Biomass may also include biodegradable wastes which can be burnt as fuel. It excludes organic material which has been transformed by geological processes into substances such as coal or petroleum. It is usually measured by dry weight.
Biomass is grown from several plants, including switchgrass, hemp, corn, poplar, willow and sugarcane. The particular plant used is usually not very important to the end products, but it does affect the processing of the raw material. Though biomass is a renewable fuel, its use can still contribute to global warming. This happens when the natural carbon equilibrium is disturbed; for example by deforestation or urbanization of green sites.
Biomass is part of the carbon cycle. Carbon from the atmosphere is converted into biological matter by photosynthesis. On decay or combustion the carbon goes back into the atmosphere. This happens over a relatively short timescale and plant matter used as a fuel can be constantly replaced by planting for new growth. Therefore a reasonably stable level of atmospheric carbon results from its use as a fuel.
Although fossil fuels have their origin in ancient biomass, they are not considered biomass by the generally accepted definition because they contain carbon that has been 'out' of the carbon cycle for a very long time. Their combustion therefore disturbs the carbon dioxide content in the atmosphere.
Other uses of biomass, besides fuel:
- Building materials
- Biodegradable plastics and paper (using cellulose fibres)
Plastics from biomass, like some recently developed to dissolve in seawater, are made the same way as petroleum-based plastics, are actually cheaper to manufacture and meet or exceed most performance standards. But they lack the same water resistance as conventional plastics.
The most successful animal, in terms of biomass, is the Antarctic krill, Euphausia superba, with a biomass of probably over 500 million tons across the world, about twice the total biomass of humans. Biomass may also be a measure of the dried organic mass of an ecosystem.
This is a summary of biomass data.
|BIOME ECOSYSTEM TYPE||Area||Mean Net Primary Production||World Primary Production||Mean biomass||World biomass||Minimum replacement rate|
|(million km²)||(gram dryC/sq metre/year)||(billion tonnes/year)||(kg dryC/sq metre)||(billion tonnes)||(years)|
|Tropical rain forest||17.0||2,200||37.40||45.00||765.00||20.45|
|Tropical monsoon forest||7.5||1,600||12.00||35.00||262.50||21.88|
|Temperate evergreen forest||5.0||1,320||6.60||35.00||175.00||26.52|
|Temperate deciduous forest||7.0||1,200||8.40||30.00||210.00||25.00|
|Mediterranean open forest||2.8||750||2.10||18.00||50.40||24.00|
|Woodland and shrubland||5.7||700||3.99||6.00||34.20||8.57|
|Tundra and alpine climate||8.0||140||1.12||0.60||4.80||4.29|
|Desert and semidesert scrub||18.0||90||1.62||0.70||12.60||7.78|
|Extreme desert, rock desert, sand or ice sheets||24.0||3||0.07||0.02||0.48||6.67|
|Swamp and marsh||2.0||2,000||4.00||15.00||30.00||7.50|
|Lakes and streams||2.0||250||0.50||0.02||0.04||0.08|
|Algal beds and reefs||0.60||2,500.00||1.50||2.000||1.20||0.80|
|Estuaries & mangroves||1.40||1,500.00||2.10||1.000||1.40||0.67|
- AllGreen Energy - Electricity Generation from Biomass
- Everything Biomass
- Michigan Biomass Energy Program
- BioMASS Laboratory at University of Illinois at Urbana-Champaign
- Forest Bioenergy
- Nicol S. & Endo Y. 1997 (1997). Fisheries Technical Paper 367: Krill Fisheries of the World. FAO. http://www.fao.org/documents/show_cdr.asp?url_file=//DOCREP/003/W5911E/w5911e00.htm.
- T.A. Volk et al Developing a willow biomass crop enterprise for bioenergy and bioproducts in the United States. In: Proceedings of Bioenergy 2000, October 15-19, 2000. Buffalo, New York.
- Oh, chicken feathers! How to reduce plastic waste. Yahoo News, Apr 5, 2007.
- Leith H. & Whittaker R H. 1975. Primary productivity of the biosphere. Springer-Verlag, Berlin. Ecological Studies, vol 14. ISBN 0-3870-7083-4