Tokyo Electric Power Company (TEPCO) has used ultra high head, reversible pump turbines to cut unit construction costs at its latest pumped storage power station in Japan.

Developed by Hitachi, the units will lead to savings of 15-20%, or approximately US$2000 per kW.

The 2 x 400MW Kazunogawa station is located some 35km northeast of Mount Fuji in Yamanashi Prefecture. The two Francis-type turbines were commissioned in December 1999 and June 2000, respectively.

Cost savings were made as the pumped storage plant’s turbines eliminated the need for an intermediate dam between the upper 87m rockfill dam near Enzan, and the lower 105m concrete gravity dam near Otsuki. The underground power house is near the lower reservoir.

The design parameters for the Kazunogawa units are 728m maximum head and 412MW maximum power. At 714m, Kaxunogawa also has the world’s greatest effective head for pumped storage and the station can be expanded to 4 x 400MW as required.

The Francis-type, single stage, pump turbines can handle heads of up to 800m of either fresh or salt water. Smaller pump turbine units of the same design are installed at Okinawa’s Yanbaru pilot sea water pumped storage project and at Okawachi. Yanbaru has a maximum head of 170m and a 30MW maximum rated capacity variable speed pump turbine. The Okawachi variable speed unit has a 415m maximum head and 331MW rated capacity.

TEPCO now has eight pumped storage power stations. It is also planning a ninth 2700MW plant at Kannagawa but the development of the project has been delayed by a slow growth in power demand in Japan. The rapid growth of distributed gas-fired co-generation in the country’s recently liberalised market may also limit the demand for pumped storage.