Sewer Energy: City to Use Sewage to Heat Homes

Sewer energy
Scott Sjolund of Brainerd's Public Utilities inspects a city sewer. Image via

The small city of Brainerd, located about 128 miles northwest of Minneapolis, MN, will soon begin drawing geothermal energy straight from the sewer to heat and cool area homes and businesses. No, it won’t make your home smell like sewage, but it does have the potential to cut the cost of heating a home by as much as 50 percent. Seems like a win-win.

A Brainerd-based company called Hidden Fuels recently received a $45,000 federal grant to get the project underway. The company is currently monitoring heat sensors installed in area sewers to find out hot spots and overall temperatures.

U.S. landfills currently use waste-to-energy technology to draw energy from rotting garbage. Modern technology enables landfills to capture methane gas for use as energy, as well as to burn trash and convert it to electricity. However, extracting geothermic energy from sewage water is relatively new in the U.S.

According to John Lund, a professor of civil engineering at Oregon Institute of Technology, using the existing sewer system for heating and cooling the city could cut overall utility expenses in half. He says the sewer water temperatures fall between 42 and 66 degrees, which is ideal for heating and cooling applications.

Peter Nelson of Hidden Fuels told NPR, "[Preliminary testing] shows that there's a significant amount of energy — literally enough to heat hundreds of homes — within the streets of the city of Brainerd.” The company plans to begin heating the city’s police headquarters by the end of 2012 and the high school soon after that.

The whole sewer heating and cooling process works similarly to other geothermal applications. Pipes draw sewage water from the sewers into circulation pipes to heat or cool buildings. It’s an efficient way to utilize waste for energy when it would otherwise just get sent to a treatment facility.

A similar type of heating technology was used at the 2010 Winter Olympics in Vancouver. Other cities across the world are using sewer energy, including Philadelphia and many cities in China where the technology is more advanced that it currently is in the U.S.

A company based out of Philadelphia, PA called Nova Thermal Energy launched the first U.S. project utilizing sewer water for heating and cooling. The Southwest Water Pollution Control Facility in Philadelphia features a one million BTU per hour heating unit that extracts heat from an area sewer channel. A ribbon-cutting ceremony was held back in April to launch the project.

Nova is currently working on similar projects in New Jersey and Texas. Sewer geothermal energy technology is sure to expand across the entire country as the technology progresses. It’s not only a green way to heat and cool a city, but it also substantially reduces the cost. In fact, Earl Wolleat, director of buildings and grounds in the Brainerd School District, states that just one sewer pipe provides enough geothermic energy to heat the entire high school, potentially saving tens of thousands of dollars every winter!

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