Andrew Sloat, operations manager of Green Cow Power in Goshen, explains how power is generated at its biogas plant. Green Cow converts farm waste into enough energy to power 1,900 homes for a year. SBT Photo/BECKY MALEWITZ [Additional photos available via link below.]
Company converts farm and organic waste into energy
Posted: Sunday, January 31, 2016 6:00 am | Updated: 12:01 pm, Sun Jan 31, 2016.
GOSHEN — A Goshen business is turning poop into power.
Green Cow Power Energy Center has two anaerobic digesters that turn the waste from the 1,500 cows on a nearby dairy farm into electricity.
In April, Green Cow Power turned on its first engine at 24130 County Road 40, said Andy Sloat, the plant's operations manager. It is the largest waste-to-energy facility in Elkhart County and it is believed to be the eighth such operation in the state.
Brian Furrer, who operates another digester in Reynolds, Ind., just north of Lafayette, and Brent Martin, of Goshen, who owns a local dairy farm, collaborated on the project.
"They wanted to add more cows and as you add more cows you get more manure," Sloat said. He explained that there are restrictions to the amount of manure that can be spread on fields and, of course, neighbors complain about the smells. The anaerobic digesters help cut down on the odor and turn the manure into other products like biogas, mulch and a liquid fertilizer.
The project cost at least $7 million when it was built nearly a year ago. But the company expects to see a return on that investment in about six years.
As of last March, there were about 247 operational anaerobic digester projects nationwide, according to the Environmental Protection Agency. At least 13 more were under construction.
Green Cow Power is not the only local digester. Culver Duck Farm in Middlebury uses duck parts that are not salable — blood and innards of the nearly 6.5 million ducks it processes each year — to power a $4 million facility that generates about 1.2 megawatts of power, which it sells to Northern Indiana Public Service Co. That's enough energy to power about 500 homes per year.
Since October of 2013, Homestead Dairy in Plymouth also has used a digester to generate about 1 megawatt of electricity, which it sells to NIPSCO.
How it works
The 1,500 cows produce close to 100,000 gallons of manure in a day, Sloat said. It gets sent next door to Green Cow Power, where it is added to the tanks — which hold a total of 5 million gallons — and blended with other biodegradable waste.
"We accept all kinds of organic waste," Sloat said. "Factories make everything from corn dogs to multivitamins and they will have waste streams throughout the process of making it. A lot of that we're diverting from the landfill. They are paying to dump it in here, but we charge typically less than the landfill."
For example, a truckload of pancake batter recently arrived. An animal had gotten into the truck and the producer had to throw away all of the product. Another time, a company printed its maple syrup labels upside down and it cost too much money to repackage them, so the syrup was sent to Green Cow Power.
Basically, anaerobic digesters are like a giant stomach, Sloat said. The tanks are kept void of oxygen and at about 101 degrees. They contain bacteria, which break down the manure and other biodegradable material over the course of 30 days and turn it into a black sludge that resembles oil.
The digester usually receives about 160,000 gallons of waste per day and is fed every four minutes.
But Sloat has to be careful to balance its intake. For instance, if a jelly factory brings loads of jelly, he has to make sure that the digester doesn't get a sugar overload.
"It got upset once, so I didn't feed it much, gave it a lot of water and let it rest a couple of days and then it was good to go again," he said.
Electricity and other byproducts
During the anaerobic process, the methane gas rises to the top and is piped off.
"Methane is what you smell. It's the stinky part of manure," Sloat said. "In its purest form, it's pretty much natural gas."
There is too much gas for the plant to store. Instead, it uses the gas to power three engines that produce 3 megawatts of electricity. It transfers enough energy to power 1,900 homes for a year to NIPSCO's substation in Wakarusa.
NIPSCO buys the power through its Feed In Tariff program, which currently has 112 participants, including biogas, wind and solar. The program's first year, the utility bought about 6,200 megawatts of electricity from participants' renewable sources. That number increased to 96,000 megawatts in 2015, said Kathleen Szot, a spokesperson for NIPSCO.
But electricity isn't the only byproduct of the waste. Nothing at Green Cow Power is trucked to a landfill.
Solids from the waste, which no longer smell like manure once the methane is removed, are dried and used as bedding for the cow barns. A truck load is picked up twice each day from Green Cow Power and returned to the dairy.
"We used to use sawdust to bed the cows," Sloat said. "That was a $1,200 a week deal, which is now zero because we recycle all this."
The solids can also be sold as a compost, or mulch. In the past 50 years, use of manure as a fertilizer has declined because it is bulky and costly to transport, and synthetic fertilizers are cheaper, according to a University of Minnesota extension study. However, post-digestion compost is popular with greenhouses, Sloat said, because it contains the nutrients of manure but has less odor and eliminates the problem of weed seeds being mixed into the soil.
Leftover liquid is also used. It is sent into a 25-million-gallon open lagoon, where it is stored until the dairy farmers can spread it on crops as fertilizer. It's not very smelly because the fatty acids, which cause the most odor, are removed in the digester, but it still contains nitrogen, phosphorus and potassium.
Sloat said Green Cow Power sold 19 million gallons during the fall, which went to different farmers.
The plant even uses the heat the engines produce, to warm the plant and dairy and to provide hot water for the farm.
Some operations similar to Green Cow Power are beginning to add greenhouses, Sloat said, because they have fertilizer, compost and heat. They can even pump pure CO2 into tomato gardens if they want.
It's a good way to reduce greenhouse gas emissions — methane is the most common greenhouse gas — and make farming more sustainable, Sloat said.
"We aren't reinventing anything," he said. "We took something that is already happening. All we did was put a roof over it."
Benefits of anaerobic digestion
In 2014, anaerobic digesters on livestock farms throughout the United States generated 948 million kilowatt hours of equivalent energy and reduced greenhouse gas emissions by 3 million metric tons.
This is the equivalent of:
- the annual carbon emissions of 631,000 passenger cars,
- more than 16,000 rail cars full of coal,
- 6.9 million barrels of oil.
SOURCE: AgSTAR data provided by the U.S. Environmental Protection Agency