A PROTOTYPE TURBINE designed to minimise fish injury at hydroelectric plants was unveiled to government, industry and environmental officials on 11 September 2001.

Developed by Alden Research Laboratory and Concepts NREC, both from Massachusetts, US, the design project was supported by the Department of Energy and the Hydropower Research Foundation.

To minimise fish injury only three blades are used with the new design, compared with six to ten blades in conventional turbines. As a turbine with fewer blades requires substantially longer blades to extract energy from water, the Alden/Concepts NREC design has wrapped the blades around the central hub in a corkscrew shape. This geometry gradually reduces pressure and minimises sudden changes in flow velocity which could injure fish. Predicted efficiency of the new design is only a few percent lower than a conventional turbine.

After computer modelling showed the new design was feasible, a full scale test facility was then built at Alden. In May 1999, detailed designs for the pilot turbine were created, which included a 2.6m closed loop piping system (1-1.7m in diameter); a 2000hp test loop pump; a 109,000 litre fish collection tank; test and control fish injection systems; and an air cooled water chiller. In May 2000, construction of the test facility begun and it became operational in August 2001.

Biological testing of the new turbine, using rainbow trout, is scheduled to run through the spring of 2002. In the autumn Alden will test other species including small or largemouth bass; golden shiner; American Eel; Chinook or Coho salmon; American shad; shortnose lake or white sturgeon; and white sucker.

The new turbine is expected to be used as a replacement for existing turbines and in fish diversion systems installed near the main turbines. The cost of the new fish friendly turbine is expected to be comparable to existing hydraulic models.