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At the Soldier Canyon Filter Plant in Fort Collins, Colo., U.S., Tri-Districts was looking for ways to reduce operating costs.
This plant pulls water from the nearby Horsetooth Reservoir. Raw water enters the filter plant from a buried pipeline, passing through a sleeve valve that regulates the incoming pressure and flow rates as needed to match demand and maintain plant operation. Treated water leaving the plant is then distributed to North Weld County, East Larimer County, and Fort Collins Loveland Water Districts, commonly referred to as the Tri-Districts.
Tri-Districts decided to explore the potential to install a hydroelectric turbine at the plant inlet in parallel with the sleeve valve to generate electricity from the incoming water supply. A feasibility study revealed that potential generation available would exceed the plant’s electricity needs. Furthermore, the local electric utility allows for power producers to generate up to 125% of their annual bill and will compensate them for any excess generation. Not only could the plant eliminate its electricity bill, but Tri-Districts could actually use a hydro turbine as a means of revenue generation.
After reviewing several options, Tri-Districts decided to install a 208-kW In-Line Turbine (ILT) manufactured by Canyon Hydro to recover the energy being lost across the sleeve valve at the Soldier Canyon Filter Plant. They chose the ILT because it provided the highest power output, came in a small footprint and had a lower cost than conventional options.
The ILT is a traditional Francis turbine with a reconfigured layout to have in-line flanges to simplify installation for water system applications. Aside from the simplified layout and compact footprint, a couple of major advantages of the ILT over other energy recovery technologies are its variable flow capabilities and adjustable power output. Power output is adjusted by opening and closing the turbine’s internal wicket gates, precisely controlling the flow rate through the turbine. This allows plant operators to dial power production in to meet demand.
Tri-Districts then needed to decide where to install this turbine. The existing sleeve valve vault did not have room to house additional equipment, so it became apparent a new structure would be necessary. Because of the complex underground pipe network, it also became apparent that both space and locations for the new structure were limited. Canyon Hydro and the filter plant owner together decided the turbine would be supplied inside a fully equipped pre-cast vault that would sit just inches from the existing valve’s vault.
While designing the new vault, Tri-Districts had the foresight to install a second set of pipe headers and leave room for another set of controls. This will allow them to add a second hydropower turbine without difficulty in the future, meaning the plant can double its generation capacity, ensuring its power demands will be met for the foreseeable future. A scheduled plant expansion in the coming years will increase both electricity demand and water use.
Receiving the turbine in a pre-cast vault provided several advantages for the filter plant. One of the biggest advantages was savings of on-site installation costs by reducing installation time, as most of the work was done off site. Additionally, the equipment installation took place over the winter inside heated facilities, when on-site work would have been affected by snowfall and freezing temperatures. The turbine, controls and switchgear were all installed into the vault and the assembly was delivered to the job site with wiring and plumbing already complete.
Tri-Districts excavated a hole, installed new pipe connections for the vault and then dropped the complete assembly in place.
Soldier Canyon’s turbine has been operational and generating power for more than four months. Overall, the installation has been a success, but there have been lessons learned from the installation as well. Because the new vault was placed directly next to the existing sleeve valve, vibration from the valve is transmitted directly to the turbine vault. While it is still within the reasonable limits, the transmitted vibration interferes with Tri-Districts getting accurate readings on the turbine’s vibration monitor. If Tri-Districts were to plan a similar installation again, they would either specify a heavier vault or try to separate the two pieces of equipment with more distance.
Tri-Districts looks at the Soldier Canyon Filter Plant project as a way to reduce annual operating costs. By installing the turbine, they have been able to fully eliminate their electricity bill for years to come. The installation has no impact on plant operations and allows seamless power generation from a previously untapped source.
