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Hog Farm Converts Manure to Electricity

An Alberta, Canada Hutterite colony burns methane from hog manure to produce electricity.

An Alberta, Canada Hutterite colony burns methane from hog manure to produce electricity.

The Iron Creek Hutterite Colony, near Viking, Alberta spent more than $250,000 (Can$) for power in 2001 — but they haven't paid an electrical power bill since.

But, there's no need to hide from creditors. In 2001, the colony invested $2 million (Can$), roughly $1.33 million in U.S. dollars ($1 Can = $0.70 US), in the first Biogem Power System installed in a hog barn in North America. The biogas electrical generation system burns methane generated from intensive livestock waste to produce electricity.

“Biogem's (Power Systems) literature says the system will pay for itself with electricity sales to the power grid alone in 5-6 years,” says colony spokesman Andy Hofer. “Our payback will be even shorter if you add in what we save by reducing our $100,000 water bill. We have no water on our farm, so we have to buy it from a pipeline from Edmonton, 80 miles away.”

The Biogem system recaptures up to 95% of the water from the slurry inputs after it has been through the digestion process. This water is then processed back to usable, clean-quality status, so it can be either reused in the barns or used to fill other farm water needs.

“We use the water for spraying,” Hofer says. “It is perfectly clean water. It is supposed to be fit for human consumption, but we haven't done that yet.”

Additional savings are realized by using some of the heat produced by the system to warm the colony's hog barns. Heat is recovered through a series of exchangers, which use the heat of the engine exhaust, turbos and cooling system to then heat water. About 2% of the total thermal energy produced maintains the temperature in the anaerobic digestion cycle, with the other 96-98% available for other uses.

“We use 30-40% of the heat in the barns, but we still have 60-70% of it going up into the air,” Hofer says. “In the future, there are plans to add a greenhouse operation to take advantage of it.”

How the System Works

“Our system will operate on any biodegradable organic waste,” explains Grant Miekle with BioGem Power Systems in Ponoka, Alberta.

In the colony's operation, manure from their smaller, 600-sow barn and their other livestock operations is brought into a receiving tank, where it is mixed, pre-warmed and delivered into a cutter-pump assembly to be chopped into uniform sizes and pumped into anaerobic digesters. In the digesters, methane gas is produced naturally as part of the decomposition and fermentation process.

The digesters, about 50 ft. in diameter and 20 ft. deep, have an expandable bladder made of a special heavy-duty rubber cap to trap the methane gas. “For lack of a better term, it looks like a balloon,” explains Miekle.

The trapped biogas is then transferred to a piston engine, which generates electricity and thermal energy. The size of the generator needed depends on the amount of input (manure). “A 1,200-sow operation, for example, would produce 80-100 cubic meters (104-130 cu. yd.) of slurry a day, enough to run a 350-kw system,” he says.

“Our plant will generate 350 (kw/hr) of electricity,” Hofer says. “We use half of it to meet the colony's electricity needs and sell the other half to the power grid.”

The colony draws electricity from the power grid during off-peak hours, such as midnight to 6 a.m., when low demand means electricity is practically free. Then they sell electricity during the day, when demand pushes up the cost.

Power generation and consumption are recorded in detail by a computer throughout the day. The colony is paid the difference between the value of the electricity they use and the value of what they sell.

“Typically, our plants cost 1.5¢/kw to operate but on the open grid the average kilowatt sells for 5¢, so you have a pretty good spread,” Miekle says. “This is what makes our plant feasible. There are a number of other plants out there that aren't (feasible) because the cost per kilowatt hour is too high.”

Hofer says their power generation profits vary. “Last year we sold our average kilowatt for 18¢; this year it has only been 7¢.” Still, it adds up. In 2002, the colony earned $110,000 (Can$) selling electricity to the grid.

Manure Volume Reduced 80%

While the colony has benefited from the money the plant has saved and earned, Hofer feels the real advantage has been how it simplified their manure handling.

“We have lots of pigs, lots of manure and lots of smell,” Hofer explains. “We have barns 15 miles apart, and our land (for injecting manure) is up to 25 miles away. We spent a lot of money hauling manure. The digester has eliminated more than 80% of our manure volume. It reduced 10 million gal. to two million gal. and the residuals still have a nutrient value as fertilizer.”

All organic waste generated on the colony is fed into the system year-round. The outputs from the system are clean, re-usable water and a dry, organic, nutrient-rich material, which is about 4% of the original volume and has a consistency similar to peat moss. Since this organic material contains all the residuals from the process, there is now no need for a liquid, manure-spreading program at this site.

For nine months of the year, Hofer cycles material back through the digester to break it down further. “Theoretically, you could completely eliminate the manure by putting it back into the digester until it completely breaks down, and have a closed-loop system. We haven't tried this since we are concerned about a buildup of salt,” he says.

The Real Bonus — Less Odor

Perhaps the best byproduct of all is odor reduction. Since the Biogem system burns off the methane to produce electricity, and has a proprietary system to eliminate sulfides, the system eliminates the odors usually associated with hog manure.

“You are burning the smell,” Hofer says. “If you smell anything, you have a leak in the system and you are losing energy.”

“Odor control is a big selling point,” Miekle says. “All producers want to be good community citizens. If they can find a solution to the odor problem that takes care of some of the environmental and community complaints and pays for itself in the long run, we feel it is a win-win situation. Many producers agree.”

Biogem Power Systems has the North American distribution rights to the Romain Welter & Sons system from Luxembourg. Currently, there are 130 biogas electrical generation systems operating in Europe. The colony is currently adding a second system at their 1,200-sow barn 15 miles away from the main site.