Research into the use of anaerobic digesters in Manitoba proves that challenges exist

Project provides insight into the system’s viability for Manitoba farmers

When a complete mix anaerobic digester was installed on Sweetridge Farms—a large dairy farm near Winkler—as part of Manitoba Hydro’s Bioenergy Optimization Program, certain challenges were expected. Anaerobic digesters can be significantly affected by environmental factors and the systems are quite technical in their operation and logistically difficult to maintain.

 

Over the course of five years, the Prairie Agricultural Machinery Institute (PAMI) provided engineering and technical support with the goal of understanding the financial and technical challenges of operating anaerobic digestion systems in Manitoba. In the end, PAMI would transition the operation of the system over to Sweetridge Farms.

 

 

“This is a complex system and one we’re unfamiliar with in Manitoba,” said Lorne Grieger, assistant vice-president of Manitoba Operations, PAMI.

Used widely in parts of Europe and the United States, anaerobic digestion has addressed livestock and manure management concerns by being an effective tool for manure management, biomass recycling and energy production.

A complete mix anaerobic digestion system works by heating organic material (such as manure and woodchips) until bacteria breaks it down, creating energy. This process can also concentrate nutrients in the manure such as phosphorus, into a reduced volume but does not remove or diminish the overall amount of such nutrients. The energy created by this process is then stored to be used by the farm or sold, and the remaining nutrient dense material is applied as an organic fertilizer to the land. 

Digesting the results

The efficiency and benefits of an anaerobic digester are highly dependent on certain local factors including cost and reliability of electricity, ability to use and transport generated energy, available feedstock and the climate.

Manitoba’s cold and fluctuating temperatures negatively impacted the digester’s operation. Since the system had been designed for the milder weather conditions in Ontario, the move to Manitoba meant the system needed several changes and upgrades that were not possible within this application due to budget, scope of work and the uncertainty of its viability on the farm. Consequently, the system did not operate at full capacity, affecting its efficiency and benefits.

The fact that Manitoba has relatively low energy costs also meant that the anaerobic digester’s main benefit—the production of energy to be stored or sold—was not fully realized.

“We’re very fortunate to have such affordable electricity rates in Manitoba,” said Van Doan, an Agri-Ecosystems Specialist with Manitoba Agriculture. “Digestion systems can be useful in places like Ontario where electricity rates are considerably higher--they can help offset some of those costs. But here those costs are already low.”

The project also determined that anaerobic digesters can only be viable in Manitoba with properly trained technicians to install and service them due to their complexity.

Overall, after the operating costs versus savings and revenue were taken into account, it was determined that the digester system would perform at an annual loss and, to be fully functional in Manitoba, an investment of nearly $100,000 would be needed to adapt the system, with a significant degree of risk that it would ever fully perform reliably.

Moving science forward

The results from the project further contributed to amendments made in Manitoba’s regulations surrounding anaerobic digestion systems and bioenergy production. Prior to this demonstration, digesters had been a requirement for pig farms in Manitoba—such farms could not build or increase unless they had digestion systems. This policy has now changed, allowing farmers to develop without having a digestion system in place.

“This is another example of why research is so important,” Grieger said. “This change in policy may not have been a direct result of the digester project but the results have some bearing on better informing policy-makers and the decisions they make which ultimately affect all Manitobans.”

Despite these conclusions, the digester demonstration enabled researchers and students at the University of Manitoba to undertake new and innovative research and collect findings crucial to future research projects.

“We were trying to see if these systems are stable in this environment and can produce consistently,” said Nazim Cicek, a professor at the University of Manitoba in Biosystems Engineering. “Our goal was to carry out research that would help farmers better understand their own systems, run them more reliably and do some basic genomic science on the reactor’s microbial population at the same time.”

The demonstration helped the researchers understand the challenges involved, how to possibly make it fully operational in the future and what the costs would be.

“Research is not about whether the systems are successful or not. It’s the process you take and the knowledge gained that is really beneficial—knowing what does not work is just as useful as knowing what does,” said Grieger.


Transition to the Canadian Agricultural Partnership

Growing Forward 2 expired on March 31, 2018. The Canadian Agricultural Partnership is the new federal-provincial-territorial agriculture policy framework which replaces Growing Forward 2 and will continue until March 31, 2023.