This energy would otherwise be wasted, and by selling electricity to the Public Service Company, we are able to reduce consumer water costs by as much as 8 percent. By producing nearly 20 million kWh of electricity with a renewable resource in 1996, Boulder replaced the use of 9,650 tons of coal for fossil-fuel generated electricity. Since the first plant went into operation in 1985, the city's facilities have generated more than 130 million kWh of electricity, replacing the use of more than 64,000 tons of coal. There currently are five city-operated hydroelectric plants with two new plants being planned, which will triple the Boulder's electrical energy production. The hydroelectric plants convert excess pressure in the city's municipal water supply system into electricity, which is then sold to Public Service Company.
Excess pressure results from most of the city's water descending from the mountains west of Boulder.
This pressure must be reduced in order to prevent damage to household plumbing and equipment, such as water heaters. The city also owns and operates one cogeneration facility, which is an operation utilizing waste energy to produce electricity. Methane, a by-product of the wastewater treatment process, is used as fuel for two engine generators that produce electricity and heat. The electricity is sold to Public Service Company, and the captured heat is used to the heat plant building and keep biosolids digestion tanks at an optimal temperature. By utilizing a renewable source to generate electricity, fossil-fuels are not needed for normal operation of the facility.