PAMI Develops Anaerobic Biodigester

REGINA - Oct 2/06 - SNS -- The Prairie Agricultural Machinery Institute (PAMI) has developed an anaerobic biodigester system at its facilities in Humboldt, which has the potential to turn common waste into heat and electricity.

The system is essentially a set of tanks, boilers and specialized equipment that creates a controlled environment to enhance a natural phenomenon: the decomposition of organic material by bacteria, which produces biogas in the process.

According to Patricia Lung, PAMI's Project Leader for Energy and Processing, this biogas contains a mixture of about 70% methane and 30% carbon dioxide, with trace amounts of hydrogen sulfide. The methane is capable of being burned in generators to produce electricity.

The versatility of the biodigester may be one of its strongest assets. Feedstock for the device can essentially be any organic material, including manure, plant matter, seeds, grain, fat or a combination thereof.

"The objective of our pilot system has been to test different feedstock recipes and different operating conditions, such as temperature and retention times," Lung said.

"In essence, we have been able to go to a client and take what they would like to feed into a biodigester, test it for them and give them an idea on how much gas that they can get off of it."

Lung noted that a biodigester demonstration project is in operation in Cudworth, as a partnership between SaskPower, Clear-Green Environmental Inc. and the Cudworth Pork Investors Group.

The project converts hog manure into biogas to run four 30-kilowatt microturbines that are plugged right into the provincial distribution grid, generating enough electricity to power 30 to 40 homes. The waste heat produced by the microturbines is captured and used to heat the biodigester. The remaining solids from the biodigestion process are spread on surrounding fields as a compost-type organic fertilizer.

Lung said this ability of the biodigester to interconnect well with other components in a broader operation has people thinking about some very promising opportunities.

"Discussions at the moment within both Alberta and Saskatchewan are with respect to eco-clusters. That's a cluster of your ethanol facility, your biogas facility and your biodigester facility, and they more or less feed off each other," she stated.

Looking into the future, the biodigestion process offers other intriguing potential that could some day be applied here in Canada.

"The biogas can be cleaned up and used as natural gas. It can be run through a hydrogen sulfide stripper and a carbon dioxide stripper, and put right into a natural gas grid. They're doing it in Europe," Lung said.

"The natural gas used in North America is generally 86 to 95% methane, so we use it to heat homes, do our cooking and stuff like that. Biogas has that capability, as well. It's just not as concentrated, but it can be cleaned up to be that concentrated."

Experimentation with different feedstock has also opened the door to another possibility: energy from common household waste.

"PAMI's system is a liquid system. We can handle up to 12% solids," Lung stated. "But there are designs which are being used in Europe to process everyday organic garbage to generate power. That's another opportunity for recycling potential. It's just a matter of it being economical to do it."

She added, "There's a lot of potential right now regarding any aspect of bio-energy: biodiesel, ethanol and biomass. The biodigester project focuses on biogas, and it is right along this same line of thinking. We've got a lot of exciting promise here."