Upgrades help Sheboygan wastewater facility generate energy to be self-powered

From an article by Dan Benson in the Sheboygan Press:

Thanks to improvements made in recent months, the Sheboygan wastewater treatment plant is one of the few facilities of its kind — perhaps the only one in the nation — capable of generating enough energy to fully power its operation.

In fact, on weekends, when less equipment is operating and fewer people are working, the plant has generated an excess of electrical energy, which it sells back to Alliant Energy, according to Dale Doerr, wastewater superintendent.

"About a month ago, we were producing 115 percent (of the plant's energy needs)," Doerr said. "It turned the meter 'backward' for a time."

The city treatment plant is able to do that with the help of two 200-kilowatt micro turbines, which were installed in December with the help of a five-year $1.2 million loan from Alliant Energy's Shared Savings Agreement and $400,000 in grants from Alliant's Focus on Energy program.

The turbines run on "biogas" — methane gas generated by treated sewage. Exhaust from running the turbines also is used to heat water, buildings and the digesters at the plant, 3333 Lakeshore Drive.

The new turbines are part of a $4.5 million construction project to upgrade the plant, which includes improving the overall energy efficiency of the plant. In all, the plant is realizing energy savings of 17.5 percent, or 1 million kilowatts, and up to $221,000 a year.

Those funds are used to pay back the Alliant Energy loan, Doerr said.

That makes the Sheboygan treatment plant the only secondary treatment facility in the nation capable of generating enough power to meet all its energy needs, officials say.