The project is expected to be complete in 2009, and will result in higher efficiency, a greater range of stable operation and reduced maintenance costs. Currently, the two units at Mossyrock generate about 40% of Tacoma Power’s energy.

GE will replace the existing vertical Francis hydro turbines with its patented X-blade technology, designed to offer improved stability over large ranges in flow and head, strong cavitation behaviour, low-pressure pulsation levels, and higher part-load and overload efficiency levels. The upgraded units will each have unique performance curves to enable them to more efficiently cover the full operating range of the plant, resulting in increased energy production for Tacoma Power.

In addition, GE will replace the wicket gate seals, rotating exciters and generator stator. GE also will refurbish the rotor and modernise the governor with a new digital control system.