Archives

Engineering progress makes “biogas” appealing energy alternative

Engineering advancements in “biogas” generation technology could make liquid and semi-solid manure produced on Canadian farms a feasible source of heat and electricity, says a Project Manager with Alberta Agriculture, Food and Rural Development (AAFRD).

“This is a technology that has been around for a while, but engineering improvements have sparked renewed interest in biogas,” says Project Manager Brian Sexton. “Currently, several biogas systems are being built in Western Canada and 25 systems are fully operating in the U.S. Since biogas must be used as it is produced, its greatest potential is in combination operations, such as a pig barn/greenhouse operation.”

Biogas is produced by bacteria during anaerobic (oxygen-free) digestion of organic material, says Sexton. Producers can generate biogas on site with a digester – a large sealed container that holds the manure and collects the biogas as the manure breaks down. Producers can then use the biogas for everything from water and space heating, to fuel for compressor engines and electric generators.

“Basically, manure is fed into the digester, where it is heated and kept for several days under oxygen-free conditions,” he explains. “Because of our climate, heat usually has to be added for this process to take place. Anaerobic bacteria thrive in this environment and break down the manure to produce biogas.”

Sexton, along with engineers from the AAFRD AgTech Centre in Lethbridge, recently completed information releases for producers on biogas and other alternative energy sources.

The practicality of biogas production on a number of factors including the type of livestock, manure management system, as well as heat and/or electricity requirements, he says. “Producers must carefully evaluate their operation to determine if biogas is a viable energy alternative.”

Biogas systems range in sophistication and price, he says. “In the southern U.S., ‘low-tech’ anaerobic digesters, such as plug flow digesters, are technically feasible. But because of our climate in Canada, ‘high tech’ systems, such as sequence batch and complete mix digesters, are required. This makes biogas production more expensive for Canadian producers.”

To incorporate biogas production, manure systems should be liquid, slurry or semi-solid, he says. “Manure must be collected daily and delivered to the digester free of bedding and stones.”

Based on United States Department of Agriculture figures, Sexton says that biogas is most viable for larger livestock operations. For example, a dairy with a minimum of 300 head, or a hog operation with at least 2,000 animals.

Matching the heat and electricity demands of an operation is the only way to make biogas cost effective, he says. “That is why combination operations where there are substantial energy needs throughout the year are ideal candidates for this technology. Otherwise, biogas that can’t be used or sold in the warmer months must be flared off, wasting energy.”

For livestock producers, anaerobic digestion has several manure management benefits. Once digestion is complete, the digested manure, or effluent, is released from the digester and can be stored until it is land applied. The digestion process breaks down many of the solids contained in manure. As a result, the effluent causes less stress on pumps and agitation equipment than undigested manure.

“Effluent left over from the process contains fewer weed seeds and pathogens,” Sexton says. “Anaerobic digestion also converts the nutrients found in manure into a form more readily available to crops. But if a digester means changing the operation’s current manure management system, it may be less feasible because of the increased capital and operational costs of new equipment and infrastructure.”

As well, operating and maintaining biogas systems requires time, along with specialized training and skills, says Sexton. “Biogas is explosive, requiring special handling using proper safety procedures and equipment.”

To receive more information on biogas and other alternative energy sources, or to get the November 2001 edition of the AgTech Innovator newsletter, which also examines biogas, contact the AgTech Centre. Phone: (403) 329-1212. Fax: (403) 328-5562.

© 2002 Meristem Land and Science
Meristem® is a registered trademark of Meristem Information Resources Ltd. All rights reserved.
Legal Disclaimer