One of Wisconsin's signature industries — food and beverage processing — is getting a cutting-edge flavor in a new renewable energy project scheduled to start operating this week.
The project, located in the Menomonee River Valley, just west of the Potawatomi Bingo Casino, will convert food wastes into renewable energy, with the power to be sold to We Energies.
The developer of the $20 million project: the Forest County Potawatomi. The digester will produce 2 megawatts of electricity — enough to supply about 1,500 homes — that will be sold to We Energies.
But the project is about more than producing power. The project is small compared with utility power plants or even large wind farms, but it accomplishes something important by producing energy from the waste left behind from food production. Wisconsin's roots in food and dairy run deep. An entire industry has sprung out of converting grain, milk and meat into products of value.
But food production creates a mix of waste that's either sent down the drain to a wastewater treatment plant or spread on farm fields as fertilizer. Meanwhile, pollution rules regulating what's going into rivers and lakes can make disposal alternatives costly and inhibit expansion for food producers.
"There's a lot of the feedstock that is available in any large metropolitan area that's currently being land-applied or being processed through the sewage utility districts. There are costs and problems associated with all of those disposal methods," said Jeff Crawford, attorney general for the Forest County Potawatomi Community. "This merchant facility is going to try to capture as much of that liquid organic feedstock as possible and make green energy out of it, instead of it just becoming a problem in the waste stream."
The project is somewhat similar to manure digesters that process cow manure into energy at dairy farms across Wisconsin.
But the system opening Monday a block west of Potawatomi Bingo Casino is much larger and more complex, said Charlie Opferman, owner's representative at Greenfire Management Services, the tribal business serving as construction manager on the project.
The digester is part chemical processor, part power producer. Its most visible feature: two 1.3 million-gallon tanks — the digesters — where the liquid food waste will be converted into a biogas.
The system involves the use of biotechnological processes using microorganisms, or "bugs," to convert wastes into a biogas that contains methane, Opferman said.
In recent weeks, as biomass feedstock began arriving at the plant, the work has been focused on getting the bugs into the right state for converting waste to biogas.
"It's a biological process," said Opferman. "You've got to grow your bugs, get them acclimated and feed them well, and make sure they eat a balanced diet."
The better the diet for those microorganisms, the better the end product of the conversion process.
Some of the wastes that will be trucked to the plant include bakery waste from making cookies, cheese plant waste and waste from production of soy, said Joe DeNucci of Advanced Waste Services, a hauler supplying feedstock to the plant.
Bioenergy experts have pointed to the food-processing sector as a key source of renewable energy for Wisconsin.
The Potawatomi project is one of three large projects being developed across the state, including the GreenWhey project that recently opened in western Wisconsin, as well as a large digester project planned at the Brakebush Brothers chicken processing plant in Westfield.
A study for the state of Wisconsin's energy office by the consulting firm Baker Tilly Virchow Krause concluded that Wisconsin can be a leader in the area given its prominence in the nation's dairy industry.
As the state looks for ways to help food processors expand to meet growing international demand, strict local wastewater permits and state environmental rules can hinder expansion plans.
The Baker Tilly study projected that Wisconsin could generate up to 40 megawatts of electricity — or about 20 plants the size of the one at Potawatomi — from a combination of cheese plants and large-scale dairy farms.
The Potawatomi project received $2.6 million in funding from the U.S. Department of Energy as well as a grant from the state Focus on Energy program.
Partners in the project include Greenfire Management Services, the tribal construction management company, Miron Construction, Symbiont Inc., Titus Energy and Rockwell Automation as well as bioenergy researcher Dan Zitomer of Marquette University.
General Electric Co.'s Waukesha engine plant manufactured the facility's two internal combustion biogas engines. The Potawatomi site is the first U.S. deployment of this more efficient engine model for use in continuous generation.
"This is a long time coming for us," said Crawford during a tour of the biodigester in advance of a grand opening the tribe will host Monday. He described the project as an outgrowth of the tribe's environmental mission statement.
"The goal of the tribe is to try to reduce its adverse environmental impacts, and one of the big things we can do is to produce our own green energy," he said.
The $20 million project is part of a series of capital projects with a total investment of $200 million in the region, including the hotel under construction adjacent to the Potawatomi Bingo & Casino and a $36 million data center built as part of the tribe's redevelopment of the former Concordia campus.
The renewable energy project is also linked to the casino, since excess heat from the waste-to-energy process will be used to heat the water for guests taking showers at the hotel or using the casino's bathrooms, Opferman said.
In addition, the tribe is exploring ways to supply the biogas project with food wastes from the casino and hotel restaurants, he said.
"We're looking at resolving things that we're doing within our own operations and improving the way we do things," Opferman said.
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