From American City and County (Todd Briggeman, David Egger, Bruce Duncan and Pat Sullivan):
Often hydropower is associated with large-scale projects such as dams and reservoirs or major river diversions. However, small conduit hydropower can be installed potentially anywhere pressure must be reduced in a conveyance system, such as at the headworks of water treatment plants, wastewater treatment plant outfalls or at any pressure-reducing station. Small hydropower projects do not need to be located near a river or dam.
Several communities recently have begun creating energy at existing water facilities. They are locating hydropower turbines at pressure-control facilities to take advantage of energy that would otherwise be lost and channel it to power the facilities or sell it back to the grid. The projects are saving money and improving energy efficiency at water facilities…
The Project 7 Water Authority wholesales potable water to municipalities and rural areas in Colorado’s Uncompahgre River Valley. The authority owns and operates a raw water reservoir, raw water pipeline, water treatment plant, and 30 miles of potable water transmission piping.
For a decade, authority officials knew that they had several potential hydropower opportunities at locations with existing pressure-reducing valves. However, hydraulic constraints and complications with delivering the potential power back to an active grid kept them from creating a renewable energy project until 2007. That was when the authority decided to update its water treatment facilities, and plans called for increasing the raw water-delivery capacity. Additional pressure would be needed for delivery and to meet future plant peak demands, but it would be necessary to dissipate the additional pressure during normal flows, which created the possibility to capture the excess hydraulic energy.
To tap that energy, the system had to be optimized for turbines of two sizes: 60 and 110 kilowatts (kW). The turbine generator units were designed to fit within the new flow-control facility that increases the raw water capacity to the plant. Power generated from the new units is connected and consumed through a net metering agreement with the Delta-Montrose Electric Association (DMEA), a rural electric cooperative in Montrose, Colo., which allowed Project 7 to consume the energy within its own facilities. That allowed Project 7 to bypass a complicated connection to the nearby grid while maximizing the value of the recovered energy.
Colorado municipal electric utilities, such as the DMEA, are required to use renewable energy, including hydroelectric power, and energy recycling to account for 10 percent of retail sales by the year 2020. The incentives to comply with that standard, as well as advances in small turbine manufacturing, have made it more feasible to capture energy in raw water delivery networks. Project 7 placed the new turbine-generator units online in November 2009.
Project 7’s renewable energy facility produces approximately 1,400 kilowatt-hours (kWh) per day of energy. Although the authority does not receive any revenue directly from the energy generation, it is saving approximately $4,000 per month on its electricity bill — 85 percent of total plant-wide electricity costs. Locating the renewable energy project on the existing water treatment plant site allowed the project to become financially viable, not only because there was adequate space for the new turbine-generator units, but also because the power delivery method was greatly simplified. Authority officials expect to fully recover the investment in hydropower within seven to 10 years.
Project 7 Assistant Manager Adam Turner credits some of the project’s success to flexibility and support from the region’s electric utility. “We have some high power demands, especially during the summer months,” he says. “We can run the smaller unit to generate up to 60 kW much of the year and run the larger unit to generate 110 kW in the summer. We got a killer deal by getting credit at the same high rate we’d pay for it, so ours is probably rosier than the average small hydro project picture.”
