Brainerd taps sewers for energy

May 25, 2012

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BRAINERD, Minn. When people in Brainerd run the dishwater, or take hot showers, they not only use energy, they create it.

The water they use and the waste they flush down toilets all flows to the sewer, which not surprisingly can be a pretty warm place - and heat can generate energy.

Brainerd officials say that unconventional source of energy to heat holds huge energy potential for heating and cooling buildings, likely starting with the city police station and a school building.

Under the right conditions that could save the city, the Brainerd School District and residents money.

"Everybody heats water," said Scott Sjolund, technology supervisor for Brainerd Public Utilities. "That's potential energy that could be extracted."

The idea for the project comes from Brainerd-based Hidden Fuels, a company that has been creating a thermal energy map of the city. In 2009, the company began working with the city and the Brainerd School District to seek a $45,000 grant from the federal stimulus package.

In 2010, a team led by Peter Nelson a principal of Hidden Fuels, installed sensors in the city's sewers. For more than a year they measured the temperature and the amount of sewage running through them.

"...There's a significant amount of energy -- literally enough to heat hundreds of homes within the streets of the city of Brainerd."

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Brainerd taps sewers for energy