Jun 2, 2013

Biogas as a Renewable Energy Source

The world is in need of a sustainable, efficient, carbon-neutral fuel source. Biogas, harvested from agriculture and food industries, not only fits this criteria, it is readily available and affordable for people around the world. Also known as biofuel, natural methane holds promise for the future.

History of Biofuel

According to the Regional Biomass Energy Program's publication Methane Recovery from Animal Manures The Current Opportunities Casebook (United States Department of Energy 1995,) it has been known for perhaps thousands of years that decomposing organic matter can produce a flammable gas. The first documented modern use of methane as a source of power was in 1859, at a leper colony in India.

England followed suit in 1895. Faced with a surplus of sewage and nowhere to put it, authorities allowed the waste to anaerobically ferment and harvested the resulting gases to power gas streetlamps. The availability of fuel was exploited throughout the UK as well as Germany, particularly during World War II when fuel was scarce.

In the 1930s, an agricultural model was designed to intentionally harvest methane from animal manure. The concept was a source of experimentation in India as well as China throughout the sixties and into the eighties, reaching a peak during the first oil crisis.

Unfortunately, once oil prices returned to previous lows, the idea was seen as uneconomical and mostly abandoned. Recently, however, there has been a resurgence of interest in biogas as a readily available, renewable, carbon-neutral source of fuel.

Green Fuel Makes a Comeback

In India, where overpopulation has resulted in massive deforestation and fuel shortages, biogas is the target of intense research. Already, in India and Nepal, biogas technology is used as an economical and attainable source of household fuel. As outlined in the Biomass Energy Resource Assessment Handbook, there are currently millions of household biogas systems in operation worldwide, with 3.8 million operating in India alone (Maithel 2009.)

In developed countries, biogas technology is chiefly used on the industrial scale to power large farming operations, landfills, and so on. Throughout Europe, centralized digester systems are utilized, in which manure, agri-food waste, and other organic industry waste products are shipped to a central processing unit. These systems produce electricity on a large scale for domestic as well as commercial applications.

Currently, government subsidies exist to encourage the development of biogas systems in India, Germany, Sweden, and parts of Canada. With continued research and public encouragement, biogas holds enormous promise for reducing greenhouse gasses, treating waste products, and providing a renewable source of carbon neutral fuel.

Renewable Energy from Manure

Most biogas is produced within the confines of an anaerobic digester, an oxygen-free, air-tight container that is capable of processing a variety of organic waste products. In the publication Generating Methane Gas from Manure Fulhage et al describe the following process for converting manure to usable biogas (University of Missouri 1993):
  1. Acid-forming anaerobic bacteria break the material down into a simple organic liquid.
  2. Methane-forming bacteria digest the liquid effluent, creating methane, carbon dioxide, and a low-odor, nutrient-rich liquid as by-products of digestion.
  3. The gas products can then be tapped and used as biogas.
  4. The waste matter is treated for possible contaminants and usually spread as fertilizer.
Using this method, the same publication estimates that the manure of three beef cattle are capable of producing enough energy each day to power a refrigerator, and a small herd of 72 animals could produce enough heat energy to heat an average-sized home.

Advantages of Biogas

In Biogas From Waste and Renewable Resources: an Introduction, authors Deublein and Steinhauser explain that biogas is predominantly methane, a hydrocarbon gas typically produced by microorganisms during anaerobic digestion of organic matter. Once contained, biogas can be used in much the same way that natural gas is used for home heating or electricity generation (Wiley-VCH, 2008.) Biogas offers a number of advantages over conventional fuel sources, including:
  • Reduction in Greenhouse Gasses: methane is a significantly more powerful greenhouse gas than carbon dioxide, with greater potential for increasing global warming effects. Containing methane and converting it to CO2 will neutralize its effect on global warming.
  • Biogas is Carbon Neutral: Because CO2 is returned to the atmosphere via incineration at approximately the same rate it is taken up during photosynthesis, biogas is generally considered to be carbon neutral.
  • A Renewable Resource: As biofuel is the product of recently consolidated atmospheric carbon, it is also considered to be a highly renewable resource.
  • Reduced Organic Waste: The digestate waste product leftover from biogas production is of significantly reduced volume. In most cases, the low-odor digestate is treated for contaminants and spread as organic fertilizer.
A renewable, carbon-neutral substitute for fossil fuels is the stuff that dreams are made of. While manure may not be a romantic subject, it is hard not to fall in love with biofuel.


Deublein, Dieter and Angelika Steinhauser. Biogas from waste and renewable resources: an introduction. Weinheim: Wiley-VCH, 2008.

Fulhage, Charles; Dennis Sievers and James R. Fischer. "Generating Methane Gas from Manure." University of Missouri Extension. October 1993. University of Missouri. 2 April 2010.

Maithel, Sameer. "Biomass." Solution Centre for Renewable Energy Cooperation Network for the Asia Pacific. September 2009. Asian and Pacific Centre for Transfer of Technology. 2 April 2010.

Regional Biomass Energy Program. Methane recovery from animal manures [microform] : a current opportunities casebook Regional Biomass Energy Program, U.S. Dept. of Energy, Washington, D.C. : 1995


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