A Chinese dairy farm is installing the world's largest system to turn manure from 60,000 cows into enough electricity to power thousands of homes, it was reported today.

Huishan Dairy has installed four Austrian GE Jenbacher 420 gas engines to generate electricity from biogas. The system will produce 5.6 megawatts of power.

The dairy, based in Liaoning province, northeast China, imports 3,000 cows from Australia every month just to sustain its massive stock of 250,000 cows - about double the number of dairy cows in the entire state of Florida.

The operation at Huishan is 10 times the size of the typical systems for generating electricity from cow manure. Its massive scale could help make the project more economical. GE, which is supplying the project's gas-powered generators, also hopes it will act as a showcase for the technology.

Huishan is gathering manure from 20 farms located close together near Shenyang, China, to feed into its massive digesters. Thomas Elsenbruch, marketing program manager for Jenbacher engines at GE, says larger systems can supply enough gas for a one-plus-megawatt engine. Such engines are more efficient than the 300- to 500-kilowatt systems used in many farms in Europe or the U.S.

Ann Wilkie, associate professor of environmental microbiology at the University of Florida told Technology Review said that this project could draw attention to the possibilities of biogas.

At the University of Florida they have developed a  new system, called a fixed-film anaerobic digester, it is up and running at UF’s Dairy Research Unit north of Gainesville after about four years of development, said Ann Wilkie. The project is an interdisciplinary effort between the soil and water science department and the departments of animal sciences and agricultural and biological engineering.

Wilkie, who developed the system, said it is capable of reducing odors by about 90 percent.

“Bacteria in the digester convert organic matter in the animal waste into methane and carbon dioxide,” said Wilkie. “At the same time, the microbes convert material that cause odor into nonoffensive compounds, so when the processed wastewater leaves the digester it can be applied to the land without the problem of nuisance odor.”

Wilkie said the new anaerobic digester is faster and more efficient than previous designs because dozens of plastic pipes have been added inside the 100,000-gallon tank. That gives the bacteria more surface area on which to degrade smelly or harmful compounds.

“Normally, bacteria just flow into a digester with the animal waste and then back out again,” Wilkie said. “We retain the bacteria inside our system on the plastic pipes.

“There are miles of surface area inside the tank covered with the bacteria that are the workforce of this system,” she said. “Since there are more bacteria per cubic foot inside the digester, the system has the ability to do more work.”

Wilkie said wastewater remains inside the digester only two days, compared with about 25 days for previous anaerobic digester designs or about 60 days when wastewater is treated in anaerobic lagoons.

She said this is the first time this type of technology has been applied to animal waste management. Similar systems have been used by the pharmaceutical and liquor distilling industries, Wilkie said.

UF researchers said the ability to control odors is becoming increasingly important as more and more rural land is converted to urban uses.

“The dairy farmers benefit because they are able to stay in business,” Wilkie said. “And their neighbors will be happy because they are not going to be sitting in their backyards smelling cow manure.”

But improving the smell of animal enterprises is not the only benefit of the new system. The farms also get a clean and free source of energy in the process.

“This particular system addresses several environmental issues,” Wilkie said. “These include the reduced odor, the reduced release of greenhouse gases that can cause global warming and reducing our dependence on fossil fuels.”

One byproduct of the digestion process is biogas, a mixture of methane and carbon dioxide. Wilkie said the fixed-film digester produces biogas that is 82 percent methane, where existing units reach only about 65 percent methane. The methane currently is being used to heat water for the Dairy Research Unit, with plans to use it this winter to fuel the space heaters in the milking parlor as well.

Additionally, the system will result in less water use, Wilkie said.

“We also are able to treat the wastewater to the point where it can be recycled back into the barns, allowing increased water conservation,” she said.

As regulations on animal enterprises increase, greater pressure will be placed on farms to manage their waste output effectively, said David Armstrong, the farm manager at the Dairy Research Unit. The digester will allow farms to take a waste product and turn it into something useful, he said.

“This system will become more economically feasible as the cost of energy goes up,” Armstrong said. “We can use the gas it produces to heat water or we can generate electricity with it that we can either use onsite or sell to the power cooperatives, giving us another income stream.”

Wilkie said a digester like the one at the 500-milking cow UF dairy could be built for about $150,000. Once the technology is licensed and put into commercial production, the cost should come down, she said. Also, for larger animal enterprises, economies of scale will come into play, she said.