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University of Missouri

Geothermal Heats Chicks Cheaper

An MU engineering professor is pioneering a way to make geothermal profitable.

turkey

©istockphoto.com

Energy-efficient geothermal heating and cooling might never be in every home, but Yun-Sheng “Shawn” Xu, research associate professor of civil and environmental engineering, is putting it in as many farms, industrial plants and large commercial buildings as he can.

In the Midwest, Xu focuses on poultry farms, where he says heating is the biggest cost to growers. Baby birds grow best at temperatures between 90 and 92 degrees, which means a furnace is on almost year-round.

Geothermal systems usually involve drilling down hundreds of feet to where the ground temperature is a constant 55 degrees. When surface temperatures soar in the summer and sink in the winter, that difference in temperature below ground can be exploited.

But drilling is expensive. It can take years — even decades — to recoup the installation costs. Alternatively, geothermal systems can lie horizontally near the surface. But because temperature differences are smaller there, they require larger, more expensive heat-transfer pipes spread over a large area, which involves digging up a field of earth. In the end, it still takes more than a decade to recoup the initial investment.

Xu found a better way.

Hot and cold temperatures seep into the ground at predictable rates, and in six months, they haven’t gone far. Based on soil composition, Xu can determine where that six-month level is. By placing his horizontal system there, it will be sitting in dirt warmed by last summer’s sun while it’s snowing up top, and it’ll be cooled by last winter’s freeze during the dog days of August. He also uses reclaimed waste heat ventilated from the poultry house to “reheat” the ground around his geothermal system, further reducing the size and cost of the pipes and the area needed.

Xu estimates installation costs could be recovered in six or seven years, which makes for happy farmers — and cozy chicks.