September 22, 2008 | General

Small-Scale Digester Boosts Farm Economics

BioCycle September 2008, Vol. 49, No. 9, p. 46
Two dairy farms near Ottawa, Ontario, Canada – one that milks 130 cows and another that milks 70 – installed small digesters and cogeneration units to manage manure and reduce power costs.
Graeme Millen

WHEN George and Josef Heinzle left Austria with their parents 26 years ago, they came to Canada to purchase some land and help their father establish a small farm. Today, they are among the most widely recognized names in the province of Ontario’s agricultural community as a result of their success with biogas technology.
George and his younger brother Josef own and operate Terryland and Pinehedge Farms, respectively. The two dairy farms back onto one another in the rural community of St. Eugene, Ontario, roughly one hour east of Ottawa. Terryland Farms milks 130 cows while Pinehedge milks 70 and operates an on-farm organic yogurt factory. Terryland Farms has a 1,000 m3 digester and a 180kW cogeneration unit; Pinehedge Farms has a 500 m3 digester and 100kW cogeneration unit.
The Heinzle brothers’ interest in digesters started at a young age. While still in Austria, the Heinzles had a neighbor with a successfully operating biogas system, something not unheard of in that country, even in the 1970s. With a familiarity and interest in the technology, it was an idea they wanted to try for themselves.
“Since we got here it was something that was percolating in my mind,” says Josef. “It was when a friend was visiting from Switzerland and mentioned that a digester would be a good idea [at Pinehedge Farms] that I said to myself, he’s right!”
In 2005, Terryland and Pinehedge Farms had achieved enough economic stability to undertake the development of their own biogas systems. They enlisted the services of Genesys Biogas Inc., a local biogas development company, to design and oversee the installation of the project.
The systems on both farms are completely mixed, continuously fed Genesys Biogas anaerobic digesters operating mesophilically, or at roughly 40°C. The circular tanks are built with insulated foam blocks and use a flexible membrane roof that doubles as biogas storage. Biogas is fed into a custom-designed generator set supplied by Martin Machinery.
Terryland and Pinehedge Farms both have pasteurizers installed to facilitate the pretreatment of certain off-farm waste, as required under Ontario regulations. Terryland Farms receives off-farm materials on a regular basis, including grease trap waste, collected and delivered by Organic Resource Management, Inc. This material – which is stored in an underground tank and then held at 70°C for one hour in the pasteurization tank – is fed into the digester at a rate of roughly three tons per day, not including manure. The receipt of off-farm materials dramatically increases biogas production, allowing for the operation of Terryland Farm’s 180kW cogeneration unit at full capacity.
Pinehedge Farms has not received any off-farm waste due to the challenge of retaining its organic certification. Josef Heinzle was initially informed by his certifier that he could retain the farm’s organic status if he received off-farm organic waste. Over the course of project development, however, this certifier was replaced and the new certifier deemed that Pinehedge’s organic certification would be revoked if any off-farm wastes were processed. “It’s disappointing” he says. “But even with our digester running on just manure, we’re still proud to say that we probably make the most environmentally friendly yogurt in Canada.” As a result of its current inability to receive off-farm waste, Pinehedge has yet to reach full electricity generation capacity.
When evaluating a feedstock for digestion, the Heinzles were advised to consider the total solids content, or TS. When too high, agitation and pumping could be an issue. When too low, it is likely that there isn’t very much energy potential in the material. The feedstocks used at Terryland Farms, when blended, have an average TS of roughly 12 percent.
One of the most prominent challenges overcome by the Heinzles was the development of an alternative grid protection scheme to the utility-proposed “Transfer Trip” system. A transfer trip works by having a transmitter device at the generator and one at the local substation to detect line failures to ensure that the generator is taken offline quickly in order to prevent the grid and consumers from any electrical damage. At a price tag of roughly $250,000, the Heinzles couldn’t afford such a device. Advice from their electrical engineer, Dr. Aidan Foss, convinced them that a simpler, less expensive system would be just as effective.
Working with Dr. Foss, Genesys Biogas and Natural Resource Canada, a “relay system” alternative was developed, with more than adequate response times and reliability. This system costs only a few thousand dollars and can be built with mostly over-the-counter parts. After a series of tests, the local utility accepted the alternative protection scheme, opening the door for other small-scale generators to adopt similar technology.
While the Heinzles both dedicated considerable time during the early stages of the digester projects, they note that the systems require little maintenance. Both brothers say that they spend no more than 15 minutes/day on system maintenance. Digesting manure has significantly reduced odors and pathogens. Outputs from the system are used as fertilizer on the farms.
Having worked their way through the hurdles on their farms – from the grid connection to getting certificates of approval to receive the off-farm wastes – the Heinzle brothers are actively involved in the Agrienergy Producers’ Association of Ontario (APAO), a nonprofit organization dedicated to promoting the development of farm-based renewable energy production in the province of Ontario. APAO has been a driving force in the lobbying effort to increase the profile of agrienergy technologies, specifically biogas.
Graeme Millen is Project Coordinator with Genesys Biogas, Inc., based in Ottawa, Ontario (

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