The Cheyenne Board of Public Utilities in Wyoming is hosting an open house of its recently constructed 850 kW hydroelectric generation facility at the R.L. Sherard Water Treatment Plant.
Cheyenne BOPU said the project cost $7.5 million to design and construct. The project uses existing raw water pressure to generate electricity to save on electrical costs and prolong service during power outages. It was funded by a Drinking Water State Revolving Fund Green Project loan with a $750,000 principal forgiveness.
About 70% of Cheyenne’s municipal water supply comes from surface water stored in reservoirs. This water is conveyed through a series of reservoirs, pipelines and streams, ultimately reaching Crystal Reservoir. There, the water is diverted into pipelines and conveyed about 15 miles to the Sherard Water Treatment Plant.
The 525-foot elevation difference between Crystal Reservoir and the Sherard Water Treatment Plant generates 250 pounds per square inch (psi) of water pressure at the water treatment plant. The Hydroelectric Generation Facility uses this pressure to generate electricity.
Water entering the plant is diverted to a four-jet, vertical-axis Pelton turbine supplied by Gilkes, selected because it will provide the greatest power output at multiple flows. The unit is expected to produce about 4 million kWh annually. The turbine is housed in a steel frame building about 36 feet by 36 feet wide and at least 40 feet tall. The turbine, generator, switchgear, controls and ancillary equipment are located on the second floor. Water leaving the generator is collected in a basin about 25 feet tall, to provide enough head pressure to allow water to flow through the plant’s treatment processes.
Cheyenne BOPU said the generator will, at times, service all of the Sherard Water Treatment Plant electrical needs, which typically consumers 200 to 400 kW according to Gilkes, and allow for the excess generation capacity to be sold back to the service provider.