A Kennewick company has the go-ahead from Franklin County to pursue a power plant in an irrigation canal that could become the first in the nation to use a new hydroelectric power technology.
Franklin County commissioners unanimously approved a conditional-use permit Wednesday for Percheron Power's proposed small-conduit project on a canal two miles west of Mesa near Road 170 and Langford Road.
The company has many other regulatory waters to navigate before construction of the project would be possible. That may take three to five years.
Percheron Power is working toward obtaining the Federal Energy Regulatory Commission conduit exemption license needed for the project to move forward, said Jerry Straalsund, the company's president.
The conditional-use permit gives the company six years to apply for a building permit. A one-time extension of six months is possible, said Jerrod MacPherson, county planning and building director.
Percheron Power received a $1.5 million federal grant from the Department of Energy and Department of the Interior's Bureau of Reclamation in September to install the nation's first Archimedes Hydrodynamic Screw hydropower system in the Potholes East Canal. The entire project is estimated to cost about $5 million.
The project would harness the energy available in water in the canal, which flows at about 1,800 cubic feet per second and has an 18-foot drop at the existing check structure in the canal, Straalsund said.
With the project, water would be diverted from the canal using a bypass channel and would flow through screw-shaped turbines, which decline at an angle of 22 to 26 degrees, he said. The screw would turn relatively slowly, at 30 to 40 revolutions per minute, and the water would slowly drop down inside the turbine.
The current design includes four turbines but could decrease to three, Straalsund said.
Percheron Power has an exclusive option to buy 20 acres along the west side of the canal from Jay Wood of Othello, according to a Nov. 20 letter from Percheron Power. The land would remain in agricultural use until the hydroelectric project is constructed. Then, about five acres would be used for the project.
The existing canal system would continue to be operated by the Bureau of Reclamation and the South Columbia Basin Irrigation District.
The project would not change the water level in the canal, according to the company. More than 100,000 acres of irrigated farmland are served downstream of the station on the Potholes East Canal, the South Columbia Basin Irrigation District said in county documents.
The project would connect to Big Bend Electric Co-op's existing grid. Straalsund said the company is working with the electric co-op to determine what upgrades would be required for the plant to use its system.
An existing power line goes through the site, he said.
The two-megawatt plant could generate about 7,000 megawatt-hours a year, Straalsund said, enough to power about 500 homes.
The plant would run only during the irrigation season and likely would be dormant when water is shut off from October to March, he said. It is possible that one turbine could run in the offseason, because some water still flows in the canal. But at the moment, the company has no plans to do so.
Percheron Power already has preliminary applications for a similar project at two other sites along the Potholes East Canal. But both locations are on federal land, which complicates the permitting process, Straalsund said.