By Zach Hagadone
Idaho Business Review
Idaho Falls-based engineer Ted Sorenson has designed or built hydroelectric projects around Idaho. Now he’s extending his expertise into Montana, where his companies, Sorenson Engineering Inc. and Turnbull Hydro, are building a $12 million hydro plant on an irrigation canal near Fairfield, Mont.
Expected to go online in 2012, the power from the 13-megawatt Turnbull Hydroelectric Project will be sold to Montana utility NorthWestern Energy, according to a purchase agreement announced Nov. 10.
The deal will run for 20 years and, according to NorthWestern officials, will help the utility meet its state-mandated goal of 25 percent renewable energy by 2015.
Sorenson, who founded Sorenson Engineering nearly 30 years ago, has built hydro projects as large as 30MW, and is currently working on a 15MW project at the base of the Arrowrock Dam near Boise. Turnbull Hydro is a Montana company he founded with two partners about a year ago specifically for the Turnbull project.
He said utilities are attracted to small hydro because of its light construction footprint and low environmental impacts.
"The main advantage to this kind of system is that a lot of it’s already there. Another thing is this is very environmentally benign – we’re not using any water that’s not already there, we’re not drawing down or disrupting the stream flow,” he said.
The Turnbull project consists of building two generating facilities located at canal drops, which are concrete structures that control the flow of water over steep grades. Water released for irrigation from the Pishkun Reservoir would be diverted into pipelines built parallel to the drops, which measure between 97 and 146 feet.
As water is forced into the pipeline, pressure builds up. That pressure is captured at the bottom of drop and used to power electrical turbines, which Sorenson said will be purchased from Boise-based Far East Engineer. After passing through the turbines, water is then routed back into the existing canal system for use by irrigators.
Sorenson said the generating project would run during the summer months when water is released to feed crops but lie dormant during the winter. If it’s a low-water year, the plant won’t generate as much electricity. If it’s a high-water year, the plant will easily meet its 13MW capacity. Regardless, irrigation users won’t notice any changes in water output from the plant.
"We hope for plenty of water,” Sorenson added.
NorthWestern spokeswoman Claudia Rapkoch said the project is attractive because of its reliability and low-risk.
"What we look for in a project that we purchase output from is cost effectiveness for our customers, reliability and stability in terms of risk. Right now there’s a great deal of risk associated with carbon, and looking at renewable energy is a priority,” she said. "This project is a way to get both the benefit of the water for irrigation, and the electricity that will be used for irrigators in the area.”
Sorenson said he expects to break ground on the project in fall 2010, and during construction employ as many as 90 workers both on- and off-site. During operation the plant will require "one full-time job,” he said.