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Canadian bio-digester report

Increasing support and a variety of technologies are resulting in increasing numbers of digesters across Canada.

Manure bio-digesters are increasing in number across Canada due to increasing interest in the benefits, rising electricity costs, and technology adaptable to different environments and purposes. Farming operations are using digesters both for manure management and electricity production. Many predict that once digester cost-returns are achieved and electricity production provides much-needed farm income, a new rural ‘green’ economic boom will result.

Of all provinces, Ontario leads the way in terms of total number of manure digesters, with five so far. This is due to two major factors, says Bruce Bowman, a retired Agriculture and Agri-food Canada (AAFC) scientist who created the AAFC’s web site, Manure Net. One factor is the release of Ontario Power Authority’s unique Renewable Energy Standard Offer Program Contract and Option Agreement in late 2006, available to anyone generating renewable energy.

Bowman says the other factor pushing bio-digesters forward in Ontario is a recent funding program for biogas projects from the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), which will fund construction for about 20 digesters. Don Hilborn, OMAFRA’s agricultural by-product management specialist, says that while it’s hard to estimate how many digesters will eventually be constructed throughout the province, “Germany has 4000, so we could have 500 to 1000 here.”

Dairylane Systems is putting the finishing touches on an Induced Blanket Reactor (IBR) digester – designed by Andigen – at Stanton Farms, located near London, Ontario. Manure from the farm’s 2000 dairy cows will be separated and solids pumped into the bottom of the digester, working its way through the eight tanks in as little as five days.

What will accelerate bio-digesters even more in Ontario, says Hilborn, is the on-going evolution of the technology used to physically ‘hook-up’ a digester to the electricity grid so that it is both safe and affordable to do so. However, probably most significant of all in the spread of digesters, notes Hilborn, is the streaming of off-farm food sector resources (mostly fats and oils from restaurants) into digesters, which boosts electricity output considerably.

Recently, the Klaesi families, who share a digester between their dairy farms near Cobden, Ontario – northwest of Ottawa – finally received a certificate of approval from Ontario’s Ministry of the Environment, which allows them to accept off-farm food wastes into their digester. Receiving the permit took more than a year and a half, although that process is currently being streamlined. The Klaesi digester inputs electricity into the grid during part of the day, and the farm draws from the grid at other parts of the day (during milking), so that the farm is billed only for net power used. The heat from the generator also provides supplemental winter heat to buildings on both farms.

St. Eugene, Ontario dairy farmers George and Linda Heinzle, whose digester became operational in August, are still waiting on their certificate of approval. George says their unit can power about 30 homes plus the farm using manure from the farm’s 260 cattle, but that the addition of off-farm wastes will result in power production for 100 homes. Linda says they currently accept corn syrup from an ethanol plant into their digester, but this does not require approval as the material is food-grade and not considered waste.

“We’ve signed a 20 year Standard Offer Program contract, locked in to receive 11 cents per kilowatt,” she says, adding the family hopes the government will change the contract and offer more in the future. Pressure is mounting in the province for this to occur. The attachment of their digester to the grid was delayed, Linda adds, due to a dispute with Hydro One (the company which distributes electricity in Ontario) over the electrical transferring equipment. The issue was eventually cleared up in March 2007.

Powerbase Automation Systems Inc. of Carleton Place, Ontario, has developed a fully automated, modular technology for monitoring, generating and interfacing with the grid from digesters and other renewable power generation systems for dairy, hog and cash crop farming operations. Sales and marketing manager Dave Robinson says they are involved in the construction of three new digesters in Eastern Ontario.
In Thunder Bay, Ontario, EEC Energy designed and constructed a digester at a dairy farm in spring 2003. EEC engineer Keith Wilson says because the farm recently switched to beef, they are currently rebuilding the manure feed system. It is a thermophilic, horizontal plug-flow digester that accepts high amounts of solids. The generator produces hot water heating for both the farm and the digester during the winter.

“If we can make it work here in Thunder Bay, we can make it work anywhere,” Wilson says.

In Ilderton – near London, Ontario – Dairylane Systems is putting the finishing touches on a digester for Stanton Farms, which is operated by Laurie and Sandy Stanton and their children. The digester’s Induced Blanket Reactor (IBR) design is the brain child of Andigen, a company based in Utah. Garry Fortune, Stanton Farm’s renewable energy consultant, says manure from the farm’s 2000 dairy cows is separated and solids are pumped into the bottom of the digester. This material works its way through the eight tanks in as little as five days, in comparison to many other digesters which take 30 days to break down material. Fortune says this acceleration is due to the bacterial culture being boosted at the start of digester operation.

“Plans to manage the biogas produced by the Stanton Farms digester operation include electricity generation, on-site heat use and natural gas upgrading,” Fortune adds.

The Stanton digester will also be using other on-farm waste (and eventually, off-farm waste) in addition to manure in order to optimize gas output. “Part of the key is to get the right recipe,” says Fortune. He says that in addition to input flexibility and accelerated speed, another benefit of the Andigen digester design is its modularity; additional tanks can be added, and it is not necessary to shut down digester operation to do maintenance on any given tank.

In Quebec, Bio-Terre Systems Inc. has installed hog manure digesters on two farms, one in St-Edwidge-de-Clifton in 2001 and the other one in St-Odilon-de-Cranbourne in 2004. Steve Boivin, project manager, says the digester’s low temperature technology helps promote sustainable agriculture by providing optimum use of wastes on the farm, and of the nutrients and biogas produced. Bio-Terre Systems digesters use batch operation with a 14 day cycle and give methane yield similar to higher temperature technology.

There are no digesters as of yet in British Columbia, but Electrigaz Technologies Inc. of Harrington, Quebec, has completed a digester feasibility study in the Fraser Valley, sponsored by B.C. Bio-products. PlanET Biogas Solutions, poised to construct several advanced high biogas yield digesters in Ontario, has also done a feasibility study in British Columbia.

Doug Jackson, an agri-energy specialist with Manitoba Agriculture Food and Rural Initiatives, says his agency is providing partial funding for three digesters projects on three private pig farms in that province. Two digesters – one thermophilic and one mesophilic – will begin construction this fall. A third low temperature Bio-Terre Systems digester in Teulon, constructed in 2004, is undergoing modifications to allow the future operation of a co-generation unit. Jackson stresses that the operation of all three digesters is focused on manure management and providing heat for producing pigs rather than electricity production, and that there are plans for only one to produce electricity.

Jackson explains that digesters accepting pig manure must be both designed and handled differently than cow manure digesters. “Pig manure has less solids content [and more water] which impacts gas production, meaning less gas,” he says. “Dairy manure has more of an optimum solids content, so a plug-flow system, in and out, can be used. Pig manure requires automatic mixing.”

This difference in digester design and operation with regard to manure type has created some challenges in Falher, Alberta, for Peace Pork Inc. However, the company has decided to move ahead with retrofit of their digester which has a 500 kilowatt generator and will process 20 million gallons of pig manure a year, says controller Wes Anderson.

Also in Alberta, the Iron Creek Hutterite Colony in Viking has operated a vertical, wet digester since 2001 that accepts hog manure and other feedstocks, says Josh Meikle, marketing manager for Adam Integrated Industries Inc., the current affiliated company.

In Vegreville, Alberta, Highmark Renewables constructed an IMUS-1 digester over two years ago, designed to process approximately 15 percent of the manure from a 36,000 head feedlot. It has been processing nearly 100 tonnes of manure daily. The digester is a 1MW co-generation facility fuelled by ‘polished’ biogas, which is raw biogas cleaned of moisture and hydrogen sulfide, containing only high proportions of methane and some carbon dioxide. Trevor Nickel, Highmark’s technology commercialization manager, says the moisture and hydrogen sulfide in raw biogas shortens the life of generators.

“A lot of generators are at risk for higher maintenance costs because of this,” he notes.

The Highmark design is also unique in that it features a mechanical separation system that removes debris from the feedlot manure, which Nickel says is a cause of failure for a lot of feedlot digesters. This design is thus suitable to handle materials such as food processing wastes and municipal solid wastes.

Highmark is currently quadrupling the size of the Vegreville facility, and will be coupling it with an ethanol plant. Nickel says ethanol plant operation is one of the best ways to use the large amounts of excess heat from a digester. They have immediate plans for several more digesters across U.S. and Canada.

In Saskatchewan, Clear-Green Environmental Inc. constructed a mixer digester of concrete and steel designed by Kriegfischer for Cudworth Pork in Saskatoon in 2003, although it is currently non-operational.

Anna Crolla, a researcher at University of Guelph’s Alfred campus – located east of Ottawa – continues to investigate various aspects of digesters with federal and provincial funding. She and her colleagues are studying energy production from on-farm anaerobic digesters, gas production performance of different substrates, and the environmental impacts on air, soil and water associated with the land application of digested versus raw manure (odor, greenhouse gas emissions, pathogens). This research, along with that conducted by private companies and individuals, will support further expansion of bio-digesters in Canada. -end-