TOKYO, Japan 6/11/12 (PennWell) -- The second of six 470-MW turbine-generator units is now in operation at Japan's Kannagawa pumped-storage hydroelectric facility, HydroWorld.com has learned.

The power plant, owned by Tokyo Electric Power Company (TEPCO), has been operating since December 2005, when Unit 1 was brought online.

TEPCO says Unit 2 was completed a month ahead of schedule, establishing the plant's total generating capacity at about a third of its eventual 2,820 MW total.

Kannagawa is one of nine pumped-storage plants owned by TEPCO.

The company says Units 1 and 2 are the first in the world to use a "split runner," which enables simultaneous operation of both the pump and turbine blade. Co-developed with Toshiba, the technology increases the output by 20 MW per unit.