Dirty deeds aren’t done dirt cheap when it comes to manure biodigesters

Manitoba hog farmers aren’t failing to build manure biodigesters because they’re stupid, says a researcher involved in trying to make them work in prairie conditions.

They aren’t building them because they’re good at financial math.

“There’s a reason we don’t have many around,” said University of Manitoba bioengineering professor Nazim Cicek.

“If they made economic sense, believe me, farmers are very smart. They pick up technology quickly and they make it work, but our environment just isn’t very conducive at the moment.”

Manitoba hog farmers aren’t allowed to build new hog barns unless they feed their manure through biodigesters, which turn much of the material into gases.

However, only a couple of hog barns in the province are experimenting with some sort of digestion system, and the most advanced on-farm biodigester is on a dairy farm and still being commissioned.

Biodigesters are widely used in some jurisdictions, such as Wisconsin just south of the Manitoba border, and they are “a mature technology” in Europe.

However, Cicek said two main problems make biodigesters non-starters for most prairie farms: practical design challenges and economic realities.

The practical design concerns seem to be the less serious challenge. Biodigesters are expensive, but keeping them warm enough during harsh prairie winters can be done.

Building hog barns isn’t cheap if each farm needs to have its own dedicated digester. Cicek said some facilities in Wisconsin service a number of farms, and some of those farms can have 2,000 to 3,000 cows.

The dairy farm he’s working with outside Winkler, Man., has 300 cows. Bigger digesters can take advantage of economies of scale.

However, Cicek said operating biodigesters in a way that can make money, or at least not lose a lot of money, is a bigger challenge.

“It’s far from being self-sustaining economically at the moment,” said Cicek.

The challenges are many.

Biogas produced by biodigesters can’t be sold for much, especially in Manitoba.

“Energy prices here are low,” said Cicek, noting that the six cents per kilowatt hour that Manitoba Hydro offers producers compares badly to 19 cents per kilowatt hour offered in Ontario and up to 40 cents in Germany.

“You need to find other sources of revenues or other reasons to do it,” said Cicek.

The dairy industry takes advantage of its need to buy bedding by turning the solids left at the end of the digestion process into a valuable product.

The solids are squeezed dry with a screw press and the material can be used to bed the animals. However, bedding isn’t used in most prairie hog barns.

Hog manure is thin gruel for a digester. Unlike dairy manure, which can be six to nine percent solid matter, hog manure is only three percent solids. It means the digester has to work twice the amount of liquid to consume the same amount of solid manure.

Manitoba farmers don’t receive carbon credits or substantial greenhouse grass mitigation benefits like they do in Europe.

Government departments and agencies such as Manitoba Hydro have supported small test projects like that on the Sweetridge Farm near Winkler, which Cicek is working on, but places like Germany offer big capital grants to cover much of the cost of construction.

“That’s the reason we don’t have much on-farm digester presence in Western Canada,” said Cicek.

Contact ed.white@producer.com

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