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Colorado rancher takes waste-to-energy to new level

An above-ground stainless steel tank, like this one built by American Structures, Inc. , is the key to making the Teague biogas generator project profitable. (Photo by American Structures, Inc.)

A resource is an asset that lies ready for use, while “resourceful” is the ability to deal with a problem promptly and effectively. The two meanings intersect at Teague Diversified, Inc.; a Ft. Morgan, Colo., cattle feeding business; where resourcefulness is turning waste into a valuable resource.

Owner Gary Teague is joining a small but growing group of feedlot operators who generate electricity from manure, and he will do it with cutting-edge technology. Instead of the conventional covered pit, the innovative technology employs an above-ground, stainless steel tank that processes waste in a quarter of the usual time. “That’s what makes the project profitable,” said Teague.

After several years of phased development, the completed system could produce as much as 8 MW of electricity, and up to $2.5 million in annual income from energy and compost sales.

Teague knows a thing or two about turning waste into profit. For the past 10 years, he has disposed of the manure from his 20,000 to 25,000 head of cattle by composting it. His operation is also the only one in the area that accepts animal carcasses from other feedlots. Local farmers and Denver landscaping companies buy more than 153,000 cubic meters of high-quality, organic compost from him each year.

Innovation changes technology economics
It is no wonder, then, that the condensate rising off the compost piles got Teague to thinking about extracting another product from waste—energy. About 40 confined animal operations in the United States, including a hog farm in nearby Lamar, Colo., convert animal waste to methane with anaerobic digesters, and use the gas to fuel electricity generators.

Teague knew enough about the technology to know that in-ground, plug digesters take 20 days to turn waste into methane. He had also heard about potential problems the systems had with releasing the liquid byproduct. Still, he decided to attend a meeting on anaerobic digesters hosted by the Colorado Governor’s Office of Energy Management and Conservation last spring.

The meeting focused on setting up digesters in rural communities to accept different types of waste streams, recalled OEMC Senior Deputy Director Ed Lewis. “We also talked about a digester vessel that cut the hydraulic retention time from 20 days to five,” he said. “That got Gary ’s attention.”

To learn more, Teague visited the Center for Profitable Uses for Agricultural Byproducts at Utah State University where Center Director Conly Hansen had developed the technology.

Unlike conventional plug digesters, where the mixing occurs around the top of the lagoon, the tank churns the waste vertically. “It keeps the bacteria in contact with all the material, so it processes much faster,” explained Lewis.

As project grows, issues change
Another advantage of the above-ground units is that they are cheaper to build because no excavation is necessary to install them. Teague is financing the first six units himself with OEMC contributing the first stainless steel tank. Over the next few years, he plans to scale up to 12 units.

The modular approach will allow him to work bugs out of the smaller system and negotiate a contract to sell excess generation. “I don’t envision selling power before the first of the year,” said Teague.

The first units are expected to produce one to two MW—well beyond the 500 kW Teague’s operation consumes. Teague pays his utility, Morgan County Rural Electric Association, the retail price of 6 to 8 cents for the 500 kW of electricity farm operations use. Tri-State Generation and Transmission Association, MCREA’s wholesaler, will pay Teague 3 to 4 cents per kWh for the electricity his system generates.

MCREA is installing a net meter and upgrading the power line to the ranch. If the completed system generates the anticipated 8 MW, the utility will have to build a new substation, as well.

Continued research boosts profitability
The feedstock will be a major factor in determining the system’s capacity. In addition to manure, Teague is accepting waste from local breweries and dairies and paunch material from slaughterhouses. Even the animal carcasses may eventually find their way into the digester. As might be expected, different wastes decompose at different rates. “Some materials break down slower than others,” Teague noted. “Everything is compared to manure—that’s the baseline.”

Teague sends waste samples to Hansen who has cooked up “recipes” for the optimum breakdown rate. “Milk and brewery waste enhance the performance,” said Teague.

The USU research team is also experimenting with genetically-modified bacteria and different quantities of bacteria to lower the retention time to two to three days. Different mixing machinery could also speed up the process. “That would really improve the cash flow,” Teague observed.

Researchers from the Colorado State University Agricultural Sciences Department are helping Teague develop rates at which another product, the liquid digestate, could be applied to fields. The slurry enters the digester containing 12 to 15 percent solids, and leaves it with 4 to 6 percent solid content, 90 percent less noxious odors and no pathogens or toxins. The solids go to the compost heap, while the liquid, which contains a little nitrogen and phosphorous, can be applied directly to crops.

A fertilizer that adds moisture to the dry Colorado soil will have a lot of value to local farmers. Having gone to the trouble of extracting the energy and dry nutrients from so many materials, a resourceful businessman like Gary Teague is not about to let one last product go to waste.