Iceland utility Landsvirkjun began operating the first of six units of the 700-MW Karahnjukar hydroelectric project on November 5. Two more units were operating by November 14 in Fljotsdalur Valley of eastern Iceland.
Landsvirkjun said all six units would be operating by the end of the year. The utility said the critical path was the completion of a 40-kilometer headrace tunnel, excavated by tunnel-boring machine from Halslon Reservoir to the power station. (HNN 9/4/07)
Finishing works were completed by mid-October and full pressure of the tunnel achieved by the end of October. A part of the tunnel and the vertical pressure shafts were filled ahead of schedule by using groundwater seepage into the tunnel. That allowed early testing of the units to accelerate final start-up.
Impounding of Halslon Reservoir began in September 2006. The 198-meter-tall concrete-faced rockfill Karahnjukar Dam, saddle dams on each side, and an overflow spillway on the west bank were completed in the summer of 2007. Landsvirkjun said the reservoir is full and the spillway has been operating for a few weeks.
The six Francis turbine-generators in the power station were supplied by VA Tech Hydro. They are designed for the high head of 600 meters and equipped with high efficiency splitter blade runners.
Work continues on the project, including an eastern side diversion with further tunneling and dam construction to be completed by late 2008.