Turning Wastewater Into Clean Energy

Oct. 5, 2004 -- — One day, when you flush a toilet or rinse those dirty dinner dishes, you could be doing more than just washing waste down the drain. Soon you could be helping to produce watts of energy for your home and those in your neighborhood.

With fuel costs rising, many cities and local municipalities are increasingly looking for cheaper ways of producing electricity — including recovering energy from waste material such as sewage.

For now, many municipal water-treatment plants produce enough "biogas" — a methane-rich fuel derived from decomposing organic waste — to energize the plant's operation. But some researchers say there's a lot more potential power in wastewater that's being, well, wasted.

David Bagley, an engineering professor at the University of Toronto, along with graduate student Ioannis Shizas recently studied the waste from three local water-treatment plants. They determined that there was enough organic material in the wastewater to possibly produce up 113 megawatts of electricity — enough to power a small town for a year.

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"Most [treatment] plants are not recovering the energy from biogas completely," said Bagley. "They use it to heat the water that aids in the waste-treatment process and maybe to heat the building, but that's about it."

From his research, Bagley believes wastewater could contain nine times the energy that typically is captured and used in a water-treatment plants. And to capture all that wasted potential energy, Bagley and other researchers believe new treatment processes will have to be used.