What is biogas?
Biogas is a form of biofuel
produced from anaerobic breakdown of organic matter. This could be plant or animal waste, dung, kitchen waste or any other kind of biological waste. It is often referred to as “digester gas”. It is a renewable energy source produced from a combination of animal dung and human sewerage. Biogas is an increasingly popular alternative fuel source, especially in the developing world.
Biogas is made up of methane and carbon dioxide. It may also contain oxygen, moisture and hydrogen sulphide. When oxygen, moisture and hydrogen sulphide are removed, biogas can be converted to ‘bio-methane’, a renewable form of natural gas
. This gas can then be liquefied to produce liquefied natural gas (LNG)
, for use in a wide variety of applications.
How is biogas used?
Biogas is an efficient way to combat energy supply problems in remote communities, while also combatting hygiene and waste management issues. Developing countries use biogas as a renewable source of fuel for lighting, cooking and heating homes.
In these systems biogas is produced in a small ‘digester’, typically using animal dung and human sewerage as feedstock. The gas is then delivered to cooking, lighting and heating appliances through a series of pipes and valves. The leftover slurry is used to fertilise crops. Such systems are very popular because they are inexpensive and require very little maintenance.
Compressed biogas is increasingly used to fuel internal combustion engines for vehicles such as cars, buses and trains. Biogas refining is becoming a popular way to produce natural gas, known as ‘bio-methane’, because it is both renewable and already produced in abundance as a by-product of human waste disposal. Bio-methane can be compressed and used for the same purposes as LNG.
Who uses biogas?
The search for renewable sources of energy has seen biogas use increase rapidly across the globe. Traditionally biogas is a popular source of fuel for households in developing nations.
In China, the government began supporting the at-home biogas industry in 1958. By 1970 at least 6 million domestic biogas digesters were installed in China. The Chinese government continues to offer subsidies for at-home biogas digesters. As a result over 35 million digesters are currently operating in the country. The Chinese government plans to increase this number to 80 million digesters by 2020.
In India, the at-home biogas industry has been supported by the government since 1982. It was estimated to have at least 4 million domestic biogas production plants operating in 2004. Similar systems are popular in other developing nations in Asia, Africa and South America.
The use of biogas as a fuel for internal combustion engines is increasingly popular in Sweden, Switzerland and Germany. An estimated 12,000 vehicles world-wide were fuelled by compressed biogas in 2007.
Where does biogas come from?
Aside from home-producers, biogas is also produced on a commercial scale.
The largest single facility for producing biogas is the Liaoning Huishan Cow Farm project in China, which produces 38,000MWh of electricity each year. China is the world’s largest producer of biogas, with commercial production in China topping 5 million cubic metres in 2010. This does not include production in the nation’s 35 million at-home biogas digesters.
India and Pakistan are also major producers of biogas. In Europe biogas has been produced as an alternative fuel since the 1920s. The most significant biogas producer in Europe is Germany. By the end of 2006 about 3,500 commercial biogas plants were in operation in Germany.
Development of biogas in advanced nations lags behind developing nations like China and India, for whom the gas is a primary fuel source. This is due to the widespread availability of electricity and natural gas infrastructure in advanced nations, who produce biogas primarily as a renewable alternative to traditional hydrocarbon fuels.
Interesting facts about biogas:
- Evidence suggests biogas was used to heat bath water as long ago as 10BC in Assyria.
- The first digestion plant to produce biogas from wastes was built in Bombay, India in 1859.
For more information, visit our Alternative Energy section.