Project uses compost to generate free heat for organic farm
CLEMSON — Clemson University researchers and educators are finding ways to turn up the heat without turning on a heater.
And it’s free — via nature.
Shawn Jadrnicek, farm manager for the university’s Student Organic Farm, is combining food waste from Clemson’s cafeterias and wood mulch from local producers to heat water to warm the farm’s greenhouses and for a variety of other purposes. The heat is produced by the decomposition of long, thick compost piles, which reach internal temperatures that can be astoundingly hot. In fact, Jadrnicek has to be careful not to build the piles too high. Otherwise, they can literally catch on fire.
“There is bacteria and fungi in there, and as they feed on the compost material, they generate a massive amount of heat,” said Jadrnicek, who has been working jointly with Clemson University recycling organics and biofuels project coordinator C. David Thornton. “Our system usually peaks out at 160 degrees, but it stays over 150 for more than two months. You can extract heat for months and months. We had a pile last year that was still 120 degrees a year after it was built.”
Jadrnicek has helped develop an intricate system of tubing that winds through the compost piles like capillaries. Water flowing through the pipes is then heated by the decaying concoction.
“The techniques we’re developing here are new, and we’re constantly improving and learning as we go, ” said Jadrnicek, who has written a book on the subject that will be released soon. “We’re working with teachers on campus who are modeling the system, and we’re working on different pipe configurations to see how we can improve our heat extraction. Biosystems engineering classes at Clemson are doing a lot with these classes right now, as well.”
The Jadrnicek/Thornton project is also exploring the potential financial savings to farmers, nursery owners and even homeowners. In addition to producing free heat, the decaying process disposes of waste. And the compost eventually decomposes into an organic fertilizer that is extraordinarily rich in nutrients.
“We’re taking waste that would normally be thrown away in the cafeterias, so we’re saving the cafeterias money because now we don’t have to throw that waste away at a landfill,” said Jadrnicek. “And then we’re using the nutrients in our fields. Anyone who has access to a waste stream can use it for heat. Some really big farms with livestock that produce a lot of manure can use it in their compost piles. Dairy operations might need hot water for animals. The water can even be used to heat fishponds. It’s all integrated.”
A South Carolina Department of Health and Environmental Control report said that the state’s local governments spent more than $330 million on solid waste management in fiscal year 2013.
“We’ve diverted about 150 tons of food waste from (Cherry Crossing Research Facility) last fiscal year and anticipate more than 250 tons this fiscal year,” Thornton said.
The compost is sold to the Student Organic Farm, the South Carolina Botanical Garden, campus housing, campus landscaping and to the public. Thornton said the compost piles at the organic farm take about 45 tons of waste to construct.