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The often-criticized methane gas produced by livestock operations is being harnessed in a new process that has potential to light homes in towns and cities across the country.

A pilot plant in north-central Alberta, which may become the first of many in North America, is expected to draw considerable attention later this summer as it begins processing solid feedlot manure to produce electricity.

The Integrated Manure Utilization System (IMUS) will process manure from Highland Feeders' 36,000 head feedlot near Vegreville, Alta., to produce power and other value-added byproducts. Initially, the plant will extract methane from raw manure to fuel electrical generators that will produce one megawatt (one million watts) of electricity and has capacity to scale up to produce about three megawatts, typically that's enough power to supply electricity to a town of more than 5,000 people.

First solid system

The dry solid byproducts of the process are useful as an environmentally friendly fertilizer, while the liquid component will be recycled as irrigation-quality water.

The project is believed to be the first co-generation plant of its kind in North America that uses solid feedlot manure to produce energy. Another similar project at the Iron Creek Hutterite Colony in Viking, Alta., has been using liquid hog manure to generate power since 2002.

The IMUS technology, which has been licensed to Highmark Renewables, a wholly-owned subsidiary of Highland Feeders Limited, was developed by the Alberta Research Council in a $7.9 million project funded by federal and provincial governments as well as industry investors. It has also been established as a demonstration project under the federal Greenhouse Gas Mitigation Program for Canadian Agriculture (GHGMP).

"The idea is to demonstrate the technology in this feedlot scale pilot project and eventually market the technology nationally and internationally," says Mike Kotelko, president of Highmark Renewables.

Value-added revenue

The concept is aimed at solving or reducing a number of the environmental challenges associated with handling large volumes of feedlot manure. At the same time, products resulting from the process will provide value-added revenue that covers the capital cost of the IMUS system, and provides a revenue stream for the operation.

Raw feedlot manure is a valuable nutrient source, but it presents a range of social and environmental challenges for feedlot operators. It produces odour, releases greenhouse gases when improperly handled, is expensive to haul, and presents challenges to the maintenance of ground and surface water quality.

The pilot project involves construction of a $6 million IMUS processing plant at Highland Feeders. Main components include two 1,500 cubic metre capacity concrete tanks which serve as anaerobic digesters. The tanks, 15 metres in diameter and 11.2 metres high, are capped with a heavy rubberized material.

In the process, raw manure is placed in a hopper and fed into the digester tanks. Water is added to create a manure slurry. "It is a continuous feed system," says Dr. Xiaomei Li, Alberta Research Council, the lead research scientist on the IMUS project. "Fresh manure can be added on a daily basis or as it is collected." It takes about 14 days for manure to work its way through the system.

Methane and carbon dioxide produced in the digester is drawn off and fed into a co-generation plant. The methane is used to power a reciprocal engine generating electricity for the feedlot. Surplus power will be to the Alberta power grid. Surplus gases will be eliminated through a flare stack.

Once the gas has been removed, the slurry is fed into a solid/liquid separator. The dry solids produce a nutrient rich fertilizer. Nutrients can also be recovered from the liquid, leaving irrigation-quality water that can be reused in the IMUS process.

"The whole process provides several significant benefits for operations and the agricultural community," says Li. "The manure is dealt with in an efficient and odourless manner, and the technology provides several value-added products." The pilot project is expected to be fully operational by August.

Generating bio-fertilizer and electricity

IMUS is designed as a modular system that can be expanded to meet increased manure capacity simply by adding more components. Highmark's pilot project is geared for a 7,500 head feedlot, while a commercial IMUS system is targeted for a minimum 20,000 head-capacity feedlot. At that scale, it is estimated the system can produce 13,200 metric tonnes of bio-fertilizer annually with a value of $660,000 and 14,480 megawatts of electricity worth $1.01 million.

The process will also offset greenhouse gas emissions. It is estimated IMUS technology will reduce the amount of carbon dioxide produced through land application of manure by 36,000 metric tonnes annually. As a national system is developed to reward producers for carbon reduction - often referred to as carbon credits - this could be a bonus revenue source worth an estimated $360,000 annually.

"IMUS provides environmentally safe and sustainable manure management," says Li. "And looking at the big picture, it addresses some of the critical issues associated with our expanding livestock industry. By reducing manure volumes, it could reduce the land base required for livestock operations, and by eliminating much of the manure odour, it could reduce the minimum separation requirements between intensive livestock operations and other land owners."

For more information on this and other projects related to reduction of greenhouse gas visit the Canadian Cattlemens' Association's Web site at www.cattle.ca and click on the "Stewardship" section.

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Turning manure into power

First solid system

Value-added revenue

Generating bio-fertilizer and electricity