The 1.6MW Kosumo Shizuku Hydropower Station in Iijima Town, Nagano Prefecture, Japan, harnesses previously unused water resources in the upper reaches of the Yotagiri River using a horizontal shaft Twin Jet Turgo turbine supplied by Gilbert Gilkes & Gordon Ltd.
Named after nearby Mount Kosumo, the scheme was developed to make efficient use of the available hydraulic resource while integrating with wider hydropower developments within the catchment. Gilkes worked alongside Yamaura Corporation and Ashino Industrial Co., Ltd., with Ashino as the customer for the turbine supply.
The site has a net head of 108.5m and a maximum flow of 1800 litres/sec. Its single turbine has a 25-inch runner and operates at 720rpm, delivering up to 1.6MW.
The turbine requirements included efficient use of the available head and flow, reliable operation across varying seasonal flows, and suitability for direct coupling to a synchronous generator. The customer also sought a proven design capable of supporting long-term operation and high availability.
Gilkes’ scope of supply comprised the horizontal shaft Twin Jet Turgo turbine, two needle-controlled nozzles, a deflector control system, turbine casing and housing, and an inlet bend and branchpipe assembly. The package also included mechanical tooling and maintenance equipment, together with a factory assembly and inspection programme.
Kosumo Shizuku marks the sixth 25-inch Turgo turbine supplied by Gilkes to Japan. It adds to the company’s portfolio of Japanese Turgo projects, which range in capacity from 6kW to 6.7MW.
