Avista Utilities is spending $35 million to upgrade its largest hydroelectric plant, 456-MW Noxon Rapids on Montana’s Clark Fork River.
When work on four 50-year-old units is complete in 2012, Avista expects the plant to provide about 28 MW of additional base load capacity for its system.
Avista said the upgrades also should extend the life of turbine and generator equipment, enable the utility to qualify for federal renewable energy tax credits, and help meet state renewable energy portfolio standards. Avista said the additional renewable, non-emitting generation from Noxon Rapids would help offset the utility’s need for new carbon-based energy sources.
Noxon Rapids is one of two plants in Avista’s Clark Fork project (No. 2058). (HNN 3/11/08) The other, 265-MW Cabinet Gorge, is about 20 miles downstream.
Avista initiated the Noxon Rapids upgrade with work on Unit 1, including installation of a new turbine runner built by Toshiba International and a rewind of the generator stator by Voith Siemens Hydro Power Generation. Work on the unit is scheduled for completion in April.
The refurbished turbine and generator are expected to produce a 5 to 6 percent increase in efficiency. The unit’s capacity is expected to increase 5 to 7 MW, the utility said.
Avista plans to complete similar work on Units 2, 3, and 4 over the next three years. Work on Unit 2 will begin in September and is to be completed in March 2010. Avista said work on Units 3 and 4 will begin in September 2010 and September 2011.
In addition to the upgrades, the utility plans to replace generator step-up transformers for all four units at a cost of $12 million.
Avista named Toshiba to supply runners for all four unit upgrades and Voith Siemens to do stator work. Other contractors include: Hydro Power Services, Ideal Machine, Industrial Repair Service, Iris Power Engineering, IRS Environmental, Kingsbury Bearings, Precision Machine &Supply, Purcell Painting, and VibroSystM.
Unit 5, installed in 1979, is not involved in the upgrade. In 2008, Avista replaced the stator in Unit 5’s generator to improve reliability. This work was smaller in scope than work on other units and did not change output, the utility said.
