BRAINERD (AP) — Brainerd officials are looking at an unconventional place for a future energy source: the sewers.

Brainerd-based Hidden Fuels began working with the city and the school district in 2009 and later installed sensors in the sewers. For more than a year they measured the temperature and the amount of sewage running through them.

Peter Nelson, of Hidden Fuels, says they found enough energy to heat hundreds of homes. He says the next step is converting it into usable energy, but it's challenging.

Earl Wolleat, director of buildings and grounds for the school district, says he's confident Hidden Fuels can pull it off, but it will take years before it's cost effective.

Low energy prices are a roadblock for many alternative and renewable energy projects.

Copyright 2012 The Associated Press.