While burning wood to heat or cook is one of the least efficient ways to use bioenergy, it remains the most important energy source for some three billion people. But there are better ways to use biomass.
 | Picture Gallery (click on the picture to start)A closer look at the primitive and modern ways to produce bioenergy (Photo: Reuters) |
Legend has it that fire was given to mankind by a demi-god who pitied our vulnerability. Fire has been the most important form of bioenergy for thousands of years, but there are many other ways to extract energy from dead or harvested biological matter, such as generating gas from waste or producing liquid biofuels from crops.
Worldwide Importance and Future Trends
Biomass currently supplies a little over ten percent of primary global energy supply making it the most important renewable energy source. According to the World Energy Council, around half of this is produced from burning wood fuels - mostly fuelwood, charcoal, and black liquor - which an estimated three billion people worldwide still rely on for heating and cooking.
Developed countries have found more efficient ways to use biomass - mainly burning it to generate electricity.
Around 4 percent of electricity in the European Union comes from biomass, but the EU's Biomass Action Plan plans to double this share by 2010. The plan would reduce oil imports by 8 percent, prevent greenhouse gas emissions worth 209 million tons of CO2-equivalent per year, and create up to 300,000 new jobs.
Some experts say that biogas alone could supply up to 10 percent of Germany's electricity needs by 2020.
Liquid biofuels made from rapeseed, corn, sugar cane, palm oil, and a number of other sources are poised for future growth if oil prices stay high. Research firm Global Insight predicts that by 2030, more than 100 billion gallons of biofuels will be produced globally, enough for about 15 percent of the world’s motoring fuel needs.
Although fossil fuels still account for over 95 percent of the global transportation fuel market, climate and energy security concerns are pushing annual biofuel production growth rates, mostly in ethanol and biodiesel. Global ethanol production has doubled since the year 2000. In 2008, total EU biodiesel production increased by 35 percent.
 | Belching BiogasBelching cows produce massive amounts of methane, a potent greenhouse gas. Using manure to produce biogas neutralizes some of the gas and turns it into a renewable energy source (Photo: Reuters) |
Global Resources and Producers
The estimated energy potential of the world's terrestrial biomass each year could be equivalent to three Zettajoules, which is several times global annual energy consumption. Only around two percent of this is currently used for energy, which theoretically leaves a big potential for growth. Not all of what remains, however, can be used for energy sustainably.
In terms of Terawatt hours, the world's leading bioenergy electricity producers are the United States, with 30 percent of the world's total in 2005, Germany, and Brazil. Other significant players are Japan, Finland, Canada, and the UK.
Brazil and the United States are by far and away the world's two largest biofuel producing countries, sharing 80 percent of production in 2007 between them. Germany is the global leader in biodiesel production, accounting for around half of world production, mostly from rapeseed.
Energy Output
Biomass is mainly used to produce electricity in three ways: direct-firing, co-firing, and gasification.
Direct-fired systems burn biomass to produce steam. Co-firing systems simply replace parts of the coal burnt in existing power plant furnaces with biomass, which emits less toxic and greenhouse emissions than coal. The most efficient way of using biomass is gasification. Most biogas plants produce 500 kilowatts of power or less, though one planned plant in Germany will have a capacity of 4 Megawatts (MW).
Biofuels for transportation vary significantly in their net energy output; it depends on the crops from which they are made and if they have to be shipped a long way from producers to consumers.
Corn, which is the biggest ethanol crop in the United States, is not considered very efficient, because the energy gain from producing corn-based ethanol is relatively low. By comparison, crops like sugar cane, jatropha, and palm oil are considered more efficient in terms of net energy gain.
Environmental Impact and Drawbacks
There has been some debate over the environmental and social benefits of biomass as an energy source.
Growing corn to produce ethanol is one of the most controversial because it is not yet energy efficient, represents only a marginal reduction in net greenhouse gas emissions from petroleum, and competes with food and livestock production. The massive increase of corn production for fuel purposes has driven the price of corn beyond what many poorer consumers can afford.
The future development of cellulosic ethanol production, which makes better use of crop residues and byproducts, may help make corn-based ethanol more sustainable.
The expansion of other biofuel crops, however, has also drawn scrutiny. Booming global demand for biofuels has led to rapid growth of sugar cane and palm oil production in Brazil and southeast Asia, respectively, which has led to alarming levels of deforestation, soil erosion, and pollution.
editor: Valdis Wish
last updated: September 16, 2009
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wowo
there should be more info on other energy sources and not just biomass and bio gas. that is bad info and if some one is to use that info i would take there grade down.!