Cleaning used water is an energy-intensive process.

To manage our operating costs and reduce the environmental impact of our energy use, we implement several energy efficiency projects each year and also generate our own energy from renewable sources. Thanks to our partnerships with the Energy Trust of Oregon and Oregon Department of Energy, we have saved enough energy to power about 400 homes per year. 

Combining the methods below, Clean Water Services generates more than 19 million kilowatt-hours of electricity each year, which meets about 40 percent of electricity needs at its facilities.

Digester Gas

Methane gas is created during the breakdown of organic material in the wastewater treatment process. Although the gas is simply burned as a flare at many wastewater treatment facilities, we use it to produce energy in a cogeneration system at our Rock Creek and Durham facilities. The cogeneration system produces electricity and heat for use in our treatment facilities.


At our Rock Creek facility, 30 percent of the energy needs are met through cogeneration. At our Durham facility, 60 percent of the energy needs are met through cogeneration. Energy production at the Durham facility is enhanced using 70,000 gallons of fats, oils and grease (FOG) delivered weekly from local restaurants. FOG, also known as “brown grease,” is cleaned out of restaurant grease traps and interceptors at regular intervals. In the past, this significant energy source was disposed of in landfills, but it is increasingly being used as feedstock to produce energy. Clean Water Services received a $3 million grant from the Energy Trust and a $2.8 million tax credit (net value) from the Oregon Department of Energy to offset the Durham cogeneration facility’s construction cost.

Solar Energy

Through a public-private partnership with SolarCity, a national provider of clean energy systems, solar panel projects at our Durham and Rock Creek facilities produce more than 500,000 kilowatt-hours of electricity per year.

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