A scientific framework for sustainable hydropower with improved fish passage

Hydropower is a crucial renewable energy source with numerous advantages beyond clean energy, including improved river navigation, increased reliability of the grid, and access to water for agriculture. As many turbines reach their expected lifetimes, there is an opportunity to not only increase power, but to generate improved fish passage (IFP). In 2019, a one-of-a-kind stainless steel IFP fixed-blade runner, optimized for both improved fish passage and power efficiency, was installed in Ice Harbor Dam's Unit 2. Over two decades of research guided the turbine design to benefit juvenile salmon and generated advanced in situ methods of understanding the impact of turbine passage on fish. The new Unit 2 turbine water passageway was characterized at three operating points set around a 1 % drop from peak power generation efficiency—Lower 1 % (lower discharge than peak efficiency), Peak Efficiency, and Upper 1 % (higher discharge than peak efficiency)—using autonomous Sensor Fish technology. Nadir pressures below 101.7 kPa (atmospheric pressure) near the runner can harm certain fish species, such as salmonids, with increasing effects at nadir pressures below 86.2 kPa, dependent upon migration depth and acclimation pressure (i.e., gas volume in the swim bladder). For the new Unit 2, the characterization revealed both improved nadir pressures and reduced instances of high acceleration. In conclusion, the new IFP fixed-blade turbine successfully achieved the primary design objective of enhancing fish survival while improving power generation efficiency by approximately 4 %. This study demonstrates a firm scientific framework for future turbine replacements at aging hydropower facilities.