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Researchers Seek Ways to Improve the Economics of Anaerobic Digestion on the Farm

by 5m Editor
11 August 2007, at 8:31am

CANADA - The use of anaerobic digestion as a means to convert manure into energy for use on the farm is expected to become increasingly appealing as the costs of more traditional energy sources continue to escalate.

Anaerobic digestion is a naturally occurring biological process which harnesses bacteria to break down a wide variety of organic wastes -- ranging from livestock manure, to the byproducts of food processing, to municipal sewage. The process creates biogas which consists primarily of methane and carbon dioxide with trace elements of hydrogen sulfide. When captured, the methane it contains can be burned to create energy, either directly for heating or to fuel turbines for the generation of electricity.

Anaerobic Digestion Technology Generates Interest Nationally

Doug Jackson, an agri-energy specialist with Manitoba Agriculture Food and Rural Initiatives, observes that there has been a fair amount of interest in this technology both in Manitoba and throughout Canada.

“Some of the main reasons that the province is interested in it is to gather information in terms of what effect the anaerobic digestion process will have on nutrients, on processing water, on reduction of pathogens and odours,” says Jackson.

The province is working with three proponents on the development and evaluation of three different systems in an effort to assess the economic feasibility of the technology in Manitoba.

Economics of the Technology Remain Questionable

Jackson notes, while the technology is not new, it is expensive. As a biological process that requires considerable maintenance the economics will depend on how much gas is produced and what kind of conversion rate is possible for the generation of electricity to offset electrical costs.

He observes, “The economics are, let’s say, a little questionable right now. But, as energy costs go up and as technologies improve, this could certainly be a thing of the future.”

Dennis St. George, Manitoba Hydro’s senior biosystems engineer expects the first use of biogas will be for heating.

Manitoba Hydro, the provincial crown corporation that supplies Manitoba’s electricity and natural gas, has promoted several successful initiatives aimed at helping farmers curb energy use. Currently the utility is involved in a number of projects which are looking at the use of anaerobic digestion for processing livestock manure.

Biogas Energy Expected to Displace More Costly Alternatives

St. George is confident the technology will reduce the need for high cost fuel sources for the customer while freeing up some of Manitoba Hydro’s capacity.

He explains, “A number of the livestock operations in the province, because we don’t have a large a natural gas supply, would rely on propane as their heat source. In some instances it’s electricity. First of all propane has become quite expensive and as well we’re trying to make customers more electrically efficient. If we can displace the electricity you purchase from Manitoba Hydro, we can potentially move that into our export markets for higher value so it actually nets a better benefit to the overall system that way.”

Proponent Calls for Public Policies to Support Use of Anaerobic Digestion

Phil Dorn, a civil engineer with Brandon based Sampson Engineering, would like to see public policy in Manitoba changed to make it more feasible for farming communities to utilize some of their waste and turn it into energy.

Samson Engineering is developing an anaerobic digestion at Riverbend Colony Farms near Carberry. Dorn explains, the process being used in that project begins by reducing the volume of water contained in the manure by approximately 75 percent. The remaining concentrate is digested anaerobically addressing some of the nutrient, pathogen, odour and solid issues while providing a substantial amount of gas production. The digestate that comes out is a very valuable and potentially highly marketable fertilizer, particularly for organic food crops.

The company is looking at implementing systems where by the biogas can be used on the farm, either for direct heating or secondarily for the production of electricity.

Hydro Generation Not Considered Economically Appealing

Dorn observes that the production of electricity isn’t that attractive because the rates Manitoba Hydro is prepared to pay for electricity do not make it economically feasible. Ontario pays 11 cents per kilowatt hour which makes it highly feasible to do that. “If Manitoba did some similar type of program it would be very attractive,” he says.

Lauren Wiebe, the owner-operator of Grunthal area based Topeaka Farms agrees, “We, as consumers, have been subsidized because we are blessed with this green energy called hydro done through water and subsequently we pay a lower rate than anybody else in Canada and subsequently that hinders the growth of the biogas industry here in Manitoba.”

Topeka Farms is looking at different technologies based on biogas production including the use of thermophilic digestion, where the digester operates at a higher temperature improving the efficiency of the process to collect more methane to produce more gas and to produce more electricity. Additional components would include the separation of solids from liquids for nutrient management and processing the water for reuse in the barn, hopefully reducing water consumption by between 40 and 50 percent.

Low Cost Hydro Caps Opportunity for Generation of Electricity

Wiebe says, “Our goal is to have government, not just Manitoba, but the Canadian government embrace this kind of technology and push it forward.”

He points out a number of programs have been put forward in Alberta where they’ve built some anaerobic digesters, in Ontario there’s some and there’s some in Saskatchewan.

“We’re just a little bit slower on that end of it because we do have such affordable electricity here in Manitoba,” he says.

Wiebe suggests, if electricity rates in Manitoba were similar to those in Alberta, it would put an additional billion dollars on the table to work with.

Bio-Terre Focuses on Improving Reliability and Cost Effectiveness

A third proponent, Bio-Terre Systems, is in the process of upgrading an anaerobic digester constructed at Cook Feeders near Teulon in 2003.

“We’re basically trying to figure out ways of making the system as reliable and cost effective as possible so that it can be marketed to farmers all across North America,” says Bio-Terre project coordinator Alex Singbeil.

He notes, Bio-Terre will be looking at different ways of utilizing the biogas including the use of low cost hot water heaters or boilers.

In addition to the system in Teulon Bio-Terre operates two other biodigester pilot projects in Quebec. “Our process is very reliable and stable and our efforts are going to be more in the areas of finding ways to lower the cost of the system itself and also looking at other alternative uses for the biogas,” says Singbeil.

He notes the company is looking at putting heat into the barn at Cook Feeders. It’s a feeder barn so they don’t have a high demand for heat.

He suggests the biogas might also be used in vehicles. “We’d like to maybe look at experiments with running the biogas as a vehicle fuel. That scenario that could offer potential because vehicle fuels are very expensive and therefore the value of the biogas would be very high if it could be used in that area.”

Bio-Terre Committed to Minimum of Two Years of Research

Singbeil says Bio-Terre is committed to operating the project for a minimum of the next two years to provide data to better define the research goals of both the company and the province so they can set policy in the future.

Benefits Extend Beyond Economics

Jackson acknowledges that while the economics of anaerobic digestion pose the greatest challenge, there are other benefits that are hard to put a dollar value on.

“Certainly in some situations, being able to treat the manure and re-use the water in the operation, those kind of things, particularly if you’re in a water shortage situation or with the reduction of odours. These can play a factor in terms of the economic viability and the social acceptability of livestock operations.”

5m Editor