Biogas Digesters

A biogas digester is a sound and ecologically sustainable solution to present problems in energy supply, and in many rural areas it also has the great advantage that a digester can be purchased by individuals. This means that they themselves are in control of the means on which they rely for their basic needs.

While being a sound investment for the people who need it, the digester is, of course, also an interesting entity of interest for capital investors. This is especially the case in developing countries where under the Kyoto protocol the digester developer may be able to obtain carbon credits for the carbon emissions saved by the digester during its lifetime.

Factors such as deforestation put a great pressure on local households to find alternative fuels for cooking, and this pressure releases a consumer demand for a technical solution which biogas from a digester when used for cooking can easily provide.

Once the digester has provided gas for cooking it can also provide the owner with cash to spend. A biogas digester generator program using, for example manure derived methane from certain agricultural facilities, is sufficient to generate electricity for the facility's own use and to produce enough additional energy to send the excess back up to the distribution grid.

In many countries this option to feed electricity back into the grid is not available for reasons of supply monopoly, and simple bureaucratic inertia. However, in many forward looking nations, parliamentary bills are being planned, or have been prepared, that will permit payment to be made by the local electricity utility company for electricity fed into the grid by digester operators.

Hundreds, if not thousands, of poultry and livestock facilities will be able to generate electricity for the facility's own use. They will also be able to send the excess to the distribution grid with payment made for this, by the local electricity company.

Digester Facts

A biogas digester with a 3 cubic meter capacity is enough to meet the cooking needs of a family of five and costs approximately 188 sterling. A digester with a 2 cubic meter capacity - enough to meet the cooking needs of a family of five - costs approximately $350. The costs of inputs are minimal assuming the household has a water supply and at least five cows - the minimum necessary to supply a small plant.

These generating facilities must for the sake of safety meet all applicable safety and performance standards established by the appropriate National Electrical Code, and the country's Institute of Electrical and Electronics Engineers best practice guidance.

Gas is consumed at a rate of about 15 to 20 cu ft per hour per horsepower generated by these plants. If you can find a small enough water cooled engine and the digester is large enough the engine can run constantly to keep up with the production of gas.
Very successful biogas digesters can be operated when using cow and buffalo dung as the main feedstock. Biogas generation consumes about one-fourth of the dung, but the available heat of the gas is claimed to be about 20 per cent more than that obtained by burning the entire amount of dung directly. This is said to be mainly due to the very high efficiency (60 per cent) of utilization compared to the poor efficiency (11 per cent) of burning dung cakes directly.

Gas and biogas is inherently better for space heating and cooking than electricity. There is no transmission or generating loss when biogas is used for heating on the premises where it is made, and it gives a convenient and immediate heat.

Also, gasoline engines may be run on alcohol, natural gas or biogas, so why not use it for this purpose as well.

Small scale fishermen in rural areas could easily be made self sufficient in alcohol and methane gas fuels if they digested their fish waste.

We think that you will agree after reading this article so far that biogas digestion is a truly useful process. If you have a farm or access to some of the feedstocks mentioned in this article and wish to consider the possibility that you might build a digester yourself, we recommend that you visit our web site Anaerobic Digestion Com

Inside a Biogas Digester

Anaerobic digestion consists of a series of reactions which are catalyzed by a mixed group of bacteria and through which organic matter is converted in a stepwise fashion to methane and carbon dioxide. Polymers such as cellulose, hemicellulose, pectin, and starch are hydrolyzed to oligomers or monomers, which are then metabolized by fermentative bacteria with the production of hydrogen (H2), carbon dioxide (CO2), and volatile organic acids such as acetate, propionate, and butyrate. Anaerobic bacteria naturally present in the digestive system of mammals digest the feedstock sludges. Several different levels types of bacteria digest the waste products of one another.

There should be more companies filling this void and making biogas digesters of a multitude of sizes and shapes so that everyone, from big factories to small homes, can take advantage of this latent energy, most of which is completely untapped at present. Why not campaign for more use of biogas. Join our Newsletter here for regular updates and hints on how you can get involved.

Biodigester Output Products

Digesters are really good at producing non-toxic fertilizers in addition to the clean energy already discussed. These are produced from the solid and liquid outputs from digesters and created by the bio-organisms in the reactor which feed on the materials put into the digester which are composed mainly of carbohydrates with some lipids and proteins.

Conclusion

Development of household biogas digesters in rural areas (eg many communities in China) and integrated use of agricultural wastes, has changed the structure of rural household energy consumption for the better in high uptake areas.

It has greatly increased the application of highly efficient organic fertilizer, improved soil fertility and promoted sustainable agricultural development. The use of digesters can also have a very positive impact on household energy consumption in rural areas, and provide a cash income for the owner as well.

Biogas digesters have a proven record as an environmentally sound technology and find considerable acceptability in China and India. They can be used to dispose of many things in addition to manure, for example food scraps, cut hair, grass clippings, leaves, etc can also be added in moderation. Bananas which are of poor quality of over-ripe (like most waste fruits), produce a large amount of biogas in a short amount of time.

Local people are no longer using wood for cooking where the biogas systems are in use. This is allowing trees and undergrowth to return, protecting the soil, lessening the threat of flooding and freeing people, particularly women and children, from backbreaking, destructive labor. It is also reported that local groups are now producing a surplus of food crops. This has even been so successful that in some instances the local markets are insufficient to purchase all the goods produced, and the over-supply has caused some price reductions in food costs. While this is not good for the local farmers their total revenue is up and the community is at least wonderfully well fed.

Biogas Digestion needs your understanding and support in order for society to properly appreciate and then utilize this wonderful process to the benefit of so many poor people.

Please consider whether you could install, or finance, or even just use the products from a Biogas Digester. Please do Vote in our Poll below, and visit our Anaerobic Digestion Blog at Anaerobic Digestion News at Blogger where we recommend you also join our Email Newsletter (just add your email adress into the form in the right sidebar, on the blog page).