Waste not, want not: maxim in action

In new experiment, dairy farm recycling manure into energy to produce ethanol

By Norm Heikens

August 17, 2006

FAIR OAKS, Ind. -- Nothing about Fair Oaks Dairy Farm is small.

With 14,000 cows, it's the largest dairy east of the Mississippi River. Each unit of 3,500 cows is housed in barns that stretch a quarter-mile.

Generators fired by methane recovered from cow manure could light all the houses in a small town if they weren't powering milking machines, fans to keep the cows cool and other equipment

Now Fair Oaks is embarking on another big project. The dairy hopes to use the methane to heat an ethanol plant that could produce 40 million gallons of the fuel a year.

If successful, the plant would demonstrate that factory farms could cut the United States' dependence on fossil fuels and make the farms themselves more efficient.

"The technology is better than it's ever been," said Ron Turco, a Purdue University agronomist with a specialty in animal waste. "Anything you can do that can capture energy from waste is good."

Part of the project is standard: The plant would turn bushels of corn into ethanol much like other plants throughout the Midwest. What's new is where the plant would gain its heat.

Fair Oaks wants to power the plant with methane produced by manure because it makes both economic and environmental sense, said Mike McCloskey, a Fair Oaks owner. "This captures what I need. It does it at a reasonable cost," he said.

The principles of producing methane are well-known, Turco said. In India, for instance, waste from food, animals and humans has long been placed in covered pits. Methane collected from the pits is used to fire cook stoves.

Technology being tested at Fair Oaks produces gas with content upward of 75 percent methane, Turco said. Traditionally the gas is about half-methane and half-carbon dioxide, a mixture that doesn't burn cleanly.

Here's how the process would work:

Manure collected from barns is gathered into a device called a digester that captures methane.

Methane will heat a boiler that turns water into steam. The steam will heat corn mash in the ethanol plant. It also will heat a still that removes the ethanol.

The ethanol will be sold to petroleum distributors to be mixed with gasoline.

Mash left over from the ethanol-making process will be fed to cows in the nearby barns. That eliminates burning natural gas to dry the mash that formerly was hauled away.

Manure is removed from the digester and reduced to a fiber smelling like garden compost with a faint livestock odor. It is spread on fields to fertilize crops. The material is more compost than manure -- so much so that Stoermann doesn't hesitate to ram a hand into a pile and emerge with a fistful to show a visitor.

Water remaining after the process is piped to fields to irrigate crops.

In the future, bacteria that break down manure in the digester might be extracted as a form of protein to feed fish, poultry or other noncattle species.

It's a new wrinkle in technology, some say. "They're doing an excellent job of capturing energy with waste," said Purdue's Turco.

Fair Oaks Dairy is using technology owned by Bion Environmental Technologies, a New York bioenergy firm, to reduce air and water emissions from the digester.

To produce 40 million gallons of ethanol a year, the plant will need manure from 40,000 cows. To reach that goal, Fair Oaks will need to add more cows, and form partnerships with neighboring dairies, McCloskey said.