System Uses Heat From Composted Manure

System Uses Heat From Composted Manure ENERGY Miscellaneous 32-1-3 An innovative Canadian company says it has come up with a cost-effective way to extract heat from composted cattle manure and bedding and put it to use on the farm. (The compost is a by-product that can be used or sold.) Aerobic decomposition of the waste produces hot water vapor, and the system extracts the heat energy, transferring it into an insulated bulk storage water tank where the heated water can be directed elsewhere for various hot water applications. "The system is self-powered, with the exception of a small amount of electricity needed to power four 120-VAC motor-driven, inline air blowers, using 1/8 hp motors," says Acrolab president Joe Ouellette. "The energy output last winter routinely reached 5 million BTUs per 24 hour period." The company worked with the USDA and the State of Vermont to set up a commercial-scale prototype at a dairy cow replacement farm near Enosburg Falls, Vt. The system provides radiant floor heating in a 49 by 184-ft. calf barn. "The composting facility consists of a 2-bay barn with an enclosed hallway between the bays. Each of the composting floors (or bays) is about 52 by 60 ft. and will permit active composting of between 700 and 800 tons of materials at one time," Ouellette says. "The four windrows in each bay are mechanically turned regularly. The compost produces temperatures of 120 to 165¦ F for four to eight weeks." The steam that's produced is captured by an array of special "vapor collector" pvc pipes (top slots are cut open along their length), that are recessed into the insulated concrete floor and protected from vehicle traffic by heavy-duty mesh screen. According to Ouellette, the fans draw the hot vapor from the floor collectors into insulated ducts, which are attached to a collection of "Isobar" superthermal conductors that heat water in a converted 800-gal. bulk milk tank. (The insulated ducts are wrapped with a "TekFoil" material which raises the insulation value around the pipes to approximately R50 or R60.) The Isobars are 3-in. dia., sealed, stainless steel tubes containing a proprietary "working fluid". They function like a wick to transfer heat, says their inventor, Ouellette. They don't require any outside energy source to work, and they transfer heat about 10,000 times faster than copper. The "Agrilab Isobars Heat Transfer System" raises the tank water's temperature to 75¦ F at the outlet valve and maintains the un-insulated calf barn floor at a comfortable 51¦ F. When the water returns to the tank, it's 57¦ F. With the American prototype operating so well, Ouellette is hoping to set one up in Canada for demonstration also, and eventually sell the system to farms everywhere. He says it will be an investment that pays off quickly, with a price tag of roughly $50,000. Contact: FARM SHOW Followup, Agrilab Technologies Inc., 7475 Tranby Ave., Windsor, Ontario, Canada N8S 2B7 (ph 519 944-5900; fax 519 944-9141; info@ acrolab.com; www.agrilab.org).

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