PAMI develops manure recipes to make energy

Trials successful Researchers show how various solid organic materials can produce heat or electricity from biogas

Researchers in Saskatchewan are making energy out of a few tonnes of culled potatoes and manure.

It’s the latest ‘recipe’ officials with the Prairie Agriculture Machinery Institute are testing inside the organization’s solid state anaerobic digester.

At a pilot-scale facility at PAMI’s Termuende Research Ranch near Lanigan, Sask., Joy Agnew is documenting how various organic materials could be used to produce a biogas that could generate heat, electricity or be fed into a provincial grid in the future. Successful trials have been running since last year.

Eventually, the project could provide the livestock industry with a new source of power and a better way to manage manure.

“We’re becoming more socially aware of how much waste we’re putting on the Earth and what it’s doing to the Earth and we’re trying to extract as much value and nutrients out of it as possible,” said Agnew, project manager of agricultural research services at PAMI.

Anaerobic digesters are already employed in Europe and parts of Canada, but PAMI’s is unique. Biodigesters more commonly require manure to be collected, diluted and liquified.

PAMI’s works with the material in its solid state, which would allow it to be more easily employed in manure management systems in prairie feedlots, where cattle aren’t on cement floors.

Agnew said a solid state system would be smaller, simpler and less costly. She said a full-scale system could cost $5 million to $10 million, still cheaper than others, allowing industry to see a return on investment in a fraction of the time.

She said PAMI will be looking to scale the project up into a larger facility for proof of concept.

“We have space to landfill and we have the space to land apply (manure), so we do, but if there are more strict requirements on nutrient recycling and energy use and energy production and if there’s incentives for green energy production then this kind of technology does make economic sense,” said Agnew. “But that could be 20, 30, 40 years down the road.”

She is researching ways to optimize the process with the right mix of feedstocks.

Current tests are using 10 tonnes of material at a time, mostly manure from the neighbouring Pound-Maker Agventures feedlot along with other organic materials like straw or culled potatoes, loaded into an air-tight container.

As microorganisms break down the material — a process kick started with an inoculum and before the whole thing is heated — researchers capture the emerging gas, a mixture of methane and carbon dioxide.

Pilot scale results indicate manure from a 40,000 head feedlot could heat approximately 58 homes or power 180 homes. The material that remains inside can be composted and used as a fertilizer.

“If you only put a dollar value on the gas itself, it’s not going to make economic sense,” said Agnew.

“You have to put a value on that spent material, which we call digestate, as well, because that material is where all the fertilizer nutrients are in and can be used for land application for growing crops.”

That digestate, which resembles normal compost, is cheaper to transport, easier to spread and has a more uniform nutrient composition than solid manure.

At Pound-Maker, a scaled-up solid state digester could make use of the facility’s manure, as well as material from the company’s on-site ethanol facility.

The facility already composts to cut down on bulk, but this system would allow it to move more manure year-round, even in the winter.

“We’re a long ways away from really being able to commercialize this, but I think the promise is so great that it’s worth the effort,”said Brad Wildeman, president of Pound-Maker.

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