Anaerobic Digesters and Biogas
In a world almost completely dependent on fuel for many everyday luxuries of life, there is steady headway towards a more personalized solution to the fuel shortage problem in many parts of the world. Biogas is an alternative that allows people to produce their own fuel using waste. It also allows for a cleaner burn then wood making it a viable solution for developing countries that have excessive indoor air pollution.
Introduction
A constant hunt for alternatives to a world powered by unsustainable oil has yielded possible small and large scale solutions to the current issues in the industry. It also allows a way for developing countries to escape dependence on foreign infrastructure and imports that they do not have the means to pay for. One place this technology is taking root is in rural china, which still uses biomass such as wood and crop residue, as well as coal, for everyday needs. India is yet another country taking steps in this direction. There are individual projects pushing this technology, but they are largely academic primarily because this technology is still being spread. There are large-scale projects and companies that are using this technology, but the people using the technology are not generally buying kits or products; they are building their own. This is promising because in order for the fuel source to actually be taken advantage of, it has to be widely accessible to a wide variety of people. The actual digesters that create the biogas may be different in appearance, but they all tend to use the same general concepts.
History
This is, by no means, a new technology as is typical with many sustainable alternatives explored today. Possibly the earliest known usage of biogas was in the 10th century BC for heating bath water in Assyria (Harris). The first person known to show that decaying organic matter created flammable gas was Jan Baptita Van Helmont in the 17th century. Bombay, India has the first claim of a functioning digestion plant in 1895 by a leper colony. Biogas was even used by England as a source of fuel for street lamps in Exeter around 1895. We can only go off of documented accounts to get a comprehensive picture as to how biogas usage evolved, but what can be concluded is that it is and has been a viable fuel source for Centuries.
Context
Biogas is still an emerging technology for many countries around the world, but the two countries that have seemed to delve the deepest into this field are rural India and China. The Appropriate Rural Technologies Institute and Biotech appear to be major contributors to domestic fuel alternatives and waste usage in India. Many Chinese build their own systems but private industry is also there to lend a hand. Among them are Chongqing Wangliyuan Agricultureal Development Co. and Shenzhen Puxin Science & Technology Co. These companies not only sell digester parts and systems, they also sell a large variety of appliances that run off biogas. Another prominent group advocating a lot of this sort of technology and should be mentioned is The Global Alliance for Cookstoves. The goal of the alliance is to outfit 100 million homes by 2020 and they are partners with profit, non-profit, and public groups (including their biggest supporter: Shell).
The major reason in both countries for a switch to Biogas is indoor air pollution. Dung cakes used in India release toxins when they are burned to cook food (Tewari). This has lead to serious health problems including tuberculosis and lung cancer. According to the World Health Organization, “Burning traditional fuels indoors produces harmful smoke that contributes to an estimated 420,000 premature deaths each year in China.” (Peach). Women and children are most often affected by this plight and it leads to a death somewhere in the world every 20 seconds (WHO). The time spent cooking over a fire is most directly related to this statistic, which is why biogas should be considered for cook-stove use. There was debate as to whether the possible methane leaks would create even more problems with global warming, but after testing it was concluded that even with a few methane leaks anaerobic digesters, over a span of 20 years, would create up to 54 percent less warming then traditional fuels (Peach). The other issue that is true of all fuels is the fact that biogas is extremely flammable and is therefore a hazard if not used correctly. Social trends pushing the general population away from oil and towards independence on a personal level (as well as a public level) will spread biogas technology. Prices for current fuel options may also play a part in the shift.
Anaerobic digestion is the process leading to the creation of biogas. The general process starts by feeding organic wastes, and feces into the main chamber of the digester and allowing fermentation to take place (Spuhler). This is simply the change from non-soluble to soluble organic compounds. There is no oxygen in this process and the optimal temperature is 97 degrees Fahrenheit (Climatelab). Natural microbes aid in the breakdown and conversion of the material. The second step is acidification where the soluble organics become volatile fatty acids and carbon dioxide (Spuhler). They are then convert into acetate and hydrogen. The methane is formed last leaving a mixture of methane and carbon dioxide as the finished product. There are two different main types of digesters: dry or wet. The byproducts besides biogas include the water that went into the process as well as residual organic material that can fertilize crops. China tends to use a CFD or China Fixed Dome and India uses IFC or India Floating Cover (Climatelab). Maintenance cost is low, and the general cost is anywhere from 120- 600 dollars depending on the climate of the location. It is more expensive to build in a place like china because of the temperate climate. In general, this explanation applies to domestic units but holds true for other systems as well.
The gas can then be stored and used to fuel cook stoves. This solves a lot of the original issue because the fuel burns so much cleaner then wood or coal. The Global Alliance for Cookstoves reports that using biogas lowers emissions by 95 percent and cuts energy usage up to 70 percent. This is just one solution to the “1.9 million premature deaths annually, with women and young children the most affected (The Global Alliance for Cookstoves).
Analysis
China
Chongqing Wangliyuan Agricultureal Development Co. is a private company that sells to a great number of countries and sells a wide variety of products dealing with biogas. The Biogas Test Center of Agricultural Academy tests their products. Among their products they sell biogas digesters, enamel biogas anaerobic reactors, biogas appliances, fittings, generators, storage tanks, and more. They are located in Chongqing, China and employ engineers and chemists for the advancement of their product. They delve into environmental management, product design and macromolecule materials.
Shenzhen Puxin Science & Technology Co. is another private company who sells many of the same products as Chongqing Wangliyuan Agricultureal Development Co. and has many of the same goals. They also employ a similar staff with similar credentials. The goal is to find new energy that incorporates environmental protection. They are located in Gaungdong, China and have been up and running since 2001.
India
Appropriate Rural technologies Institute developed their domestic biogas plant in 2003. They are located in Maharashtra and are run by scientists and social workers. It is an academic group that started out with 9 original projects. Their products are not sold by them and are distributed instead by Samuchit Enviro Tech Pvt Ltd. Their goal is to raise people’s standards of living. They accept donations but there is no actually information on where the majority of their funding comes from that is easily accessible.
Biotech was established in 1994 and spreads awareness as well as training people to help others in various fields. Their focus is on renewable energy; development, and research. They are located in Kerala, India. There overall purpose appears to be to spread information; particularly there anaerobic digester systems.
Conclusions
Overall the options in India that I was able to find deal more with non-profit systems that share information for the greater good. All I could find out about the Chinese approach was through Private industry. All four groups I looked at wanted the same thing to some degree. It is relevant to look closely at both China and India because they are the prominent users of this technology. In this project I feel that most of the information is not actually recorded because so many people build there own digesters and do not look at the consumer world at all. The biggest problem is distribution because the companies that offer their products cannot offer them for free. If the impoverished cannot afford the consumer solution it makes sense that they would just build their own and bypass the middleman all together. This technology is extremely important and will continue to gain importance as time goes on, but it may be more of a cultural movement focused on the spread of the information rather then selling a product.
Works Cited
"Domestic Biogas Plant." Climatelab. MindTouch Enterprise,
2009. Web. 12 Apr 2011.
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Harris, Paul. "A brief History of Biogas." Beginners Guide to
Biogas. The University of Adelaide, 04 Nov 2011. Web.
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"Indoor air pollution and health." World Health Organization.
WHO, 2011. Web. 12 Apr 2011.
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"Overview." Global Alliance For Cookstoves. Global Alliance
For Cookstoves, 2011. Web. 27 Feb 2011.
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Peach, Sarah. "Greening China's Indoor Fuel Use." Chemical &
Engineering News. American Chemical Society, 07 Mar
2011. Web. 12 Apr 2011.
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Spuhler, Dorothee. "Anaerobic Digestion (Organic Waste)."
Sustainable Sanitation and Water Management. SSWM,
2011. Web. 12 Apr 2011.
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Tewari, Ritika. "Significance of Anaerobic Digestion in Rural
India." AltEnergy eMaqazine. LJB Management Inc., 2011.
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Companies Cited:
http://cqwangliyuan.en.alibaba.com/
http://puxinbiogas.en.alibaba.com/productgrouplist-202675376/Biogas_home_appliances.html#products
http://www.arti-india.org/
http://biotech-india.org/Domestic_Biogas.aspx
Images Cited:
http://pubs.acs.org/cen/news/89/i11/8911scene.html
http://www.sswm.info/category/implementation-tools/wastewater-treatment/hardware/solid-waste/anaerobic-digestion-organic-
http://image.made-in-china.com/2f1j00FvRaNnurEycz/Biogas-Stove-JZZ-1A3-.jpg
http://image.made-in-china.com/2f1j00IvmEDchlAPqK/Biogas-Stove-Double-Burner.jpg
http://cleancookstoves.org/wp-content/uploads/2011/04/SNV_Building_viable_domestic_biogas_programmes.pdf
source: http://sustainablebydesign.wikispaces.com/Anaerobic+Digesters+and+Biogas 
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