As the search continues for more cost-effective energy sources that also are environmentally safe, companies are getting more creative. Many are looking toward utilizing things that were once relegated to the waste stream, even including organic animal waste.
But while some companies have found success in building animal waste-to-energy facilities, the strategy is facing challenges.
“I think the concept of using animal manures and livestock wastes as a feedstock for bioenergy systems is becoming more topical, but has not gained the relevance it deserves,” says William “Gus” Simmons Jr., P.E., director of bioenergy at Cavanaugh & Associates. “The U.S. has tremendous organic waste resources that may be used to generate renewable fuels and electricity, but we have been slow to realize this great potential.”
Cavanaugh is a Winston-Salem, N.C.-based consulting firm that develops programs that optimize water efficiency and waste-to-energy. In 2006, Cavanaugh partnered with the Nicholas Institute at Duke University to develop a system for harnessing energy from swine manure. That system was commissioned in 2011 through the Loyd Ray Farms Project in Boonville, N.C.
“The project originated as the state of North Carolina contemplated a set of renewable energy and energy efficiency goals … which included specific requirements for electric utilities that serve North Carolina to generate a portion of the renewable energy obligation from swine and poultry farming wastes,” says Simmons. “The Loyd Ray Farms Project was a first-of-its-kind, commercial-scale demonstration project that presented a way in which the energy value from agricultural wastes may be beneficially derived.”
The project currently has nine barns housing 8,640 swine and that produces 50,400 cubic feet a day in biogas, which generates 65kW of electricity, according to AgSTAR. AgSTAR is an outreach program designed to reduce methane emissions from livestock waste management operations by promoting the use of biogas recovery systems. It is a collaborative effort of EPA, the U.S. Department of Agriculture, and the U.S. Department of Energy.
AgSTAR reports that there are 247 farms with operating systems processing animal manure in the U.S. But that pales in comparison to other countries like Germany, which has close to 8,000 in operation.
Converting animal waste into energy “provides a renewable energy source and reduces the strength of greenhouse gases emitted from animal operations,” says Joe Kramer, senior project manager for the Energy Center of Wisconsin. “The primary challenges are that the systems are expensive, and owners often rely on sales of electricity generated with biogas to help make their systems economical whereas Wisconsin utilities are not enthusiastic about buying the energy.”
Dairyland Power Cooperative Senior Resource Planner John McWilliams agrees that financial strain is one challenge keeping converting animal waste into energy from maintaining its initial push.
“Converting animal waste into energy gained momentum about 10 years ago as a means for large dairy operations to manage manure issues. However, high capital costs and significant maintenance requirements for digesters are challenges limiting the addition of new digesters,” he says.
The Dairyland Power Cooperative, based in La Crosse, Wis., is a Touchstone Energy Cooperative that provides wholesale electricity to 25 member distribution cooperatives and 17 municipal utilities in 62 counties in four states (Wisconsin, Minnesota, Iowa and Illinois). It has digester project operations at two dairy farms, a food processing plant waste water treatment facility and a combination hog and beef cattle operation.
“Economics continue to be the greatest challenge,” says Simmons. “Implementation of energy harvesting systems on U.S. farms means additional infrastructure at the farm, and quite often for the utilities and businesses that wish to take advantage of the energy produced.”
Misunderstanding how the systems operate can lead to policy hurdles, as well, says Simmons. “While, in most cases these hurdles are not insurmountable, they contribute to higher development costs, as time must be invested on a project-by-project basis to inform policy makers, regulators, and the public,” he says.
Animal manures and wastes are processed biologically, such as through anaerobic digestion, or through a thermal process such as gasification and pyrolysis when converted into energy sources, says Simmons.
“In a nutshell, the manure is collected and heated, creating the natural byproduct of methane gas. That biogas is the fuel used to power the generators and create renewable electricity,” says McWilliams.
Converting other sources of organic waste into energy is gaining momentum in the U.S. but not as quickly as Simmons says he thinks they should.
“A great opportunity exists to create partnerships that increase the efficient use of existing waste management infrastructure used by industry, cities, towns, and states while providing economic opportunities for farmers and organic waste managers. If it is organic, it has energy potential,” he says. “The U.S. should embrace the tremendous resources we have available ‘above the dirt’ in the form of organic wastes, and work to develop more innovative, financially attractive ways of repurposing these materials from a ’waste’ into a ‘resource’.”