Monday, December 14, 2009

Using Waste Energy For High Tunnel Production

December 11, 2009
Waste energy to be captured for winter crop production
WEST LAFAYETTE, Ind. - Using water generally lost through evaporation from Purdue University's power plant, a researcher believes he can heat the ground during winter months and grow produce under cover that would taste better and cost less at local markets.
Cary Mitchell, a professor of horticulture, is one step closer to building a high tunnel structure that could affordably allow for out-of-season growing in Midwestern states. The tunnels, like greenhouses, would trap heat and moisture while water used to cool Purdue's coal-fired boilers would be piped underground beneath the tunnels to heat the ground to a suitable temperature for growing.
"That energy, the hot water created by cooling boilers, is usually just vented into the air," Mitchell said. "This would put that energy to use."
Mitchell, who hopes to build at least one 30-by-96-foot tunnel near the Wade Power Plant this spring or summer, on Friday (Dec. 11) accepted a $75,000 grant from Walmart to aid in his work.
Later phases of Mitchell's research would add heat-pump technology to increase air temperatures in the tunnels and heat engines that could convert low-grade heat to electricity for supplemental LED lighting.
Larry Whitlow, Walmart market manager for the Lafayette area, said the company is interested in the research as a way to cut some of its costs and benefit local communities.
"The high tunnel research ties right into two of our company's initiatives: sustainability and encouraging local economic growth," Whitlow said. "We're finding that with sustainability, there's a cost savings. By selling local produce in our stores, there is less freight and shipping cost, and that keeps prices low for our customers."
Mitchell said produce grown in high tunnels could be left to ripen on vines instead of ripening during the shipping process, increasing the quality.
"We'll be able to do locally what they do 1,500 miles away," Mitchell said. "We pay so much for shipping, and the produce sits in a truck degrading for a week."
The Walmart grant puts Mitchell over the halfway mark for the project, which is difficult to raise money for because many funding agencies do not support infrastructure development.
"Hopefully this Walmart initiative will help catalyze the rest of the funding we need," Mitchell said.
Writer: Brian Wallheimer, 765-496-2050,
Sources: Cary Mitchell, 765-494-1347,