Vortexes, louvers and bubble-walls were some of the suggestions put forward when HydroCen researchers discussed possible new solutions to prevent fish from entering power stations and embarking on the often fatal turbine passage.
Previous research has shown that scaring fish is an inefficient way of influencing fish behaviour, so HydroCen invited several experts from various disciplines to brainstorm new ideas.
— Fish and turbines are a bad combination, and we need to take a broader and more interdisciplinary approach to solve this problem, says senior researcher Torbjørn Forseth who lead the meeting.
Researchers have tried several methods before, such as different repulsion measures and small bar-spacing racks. Both methods have their limitations.
— We’ve tried some really conspicuous, blinking, LED-lights, but salmon smolts are extremely motivated to reach the ocean, so they won’t scare, says Forseth.
The racks in front of the power station inlet are primarily made to prevent debris and driftwood from reaching the turbine. Replacing these with racks that fish cannot pass has several challenges.
Small-bar racks are both difficult to clean and maintain, and they can cause reduced power production. In addition, the racks must be larger, and can be both costly and hard to replace in existing power plants.
Can fish be guided?
Instead, researchers now want to investigate methods for guiding fish past the power station inlet. The question is whether fish can be guided or tricked? The answer is most likely «yes», but we need to understand a lot more about fish behaviour to be able to answer «how».
— Fish can feel all variations of the water flow all over its whole body, , says researcher Ana Silva.
She is one of the best in the world at understanding why fish do what they do.
— Water velocity, acceleration, turbulence, intensity and pressure – it all influences fish behaviour, she says.
Interdiciplinary approach for new innovation
One of many challenges is that different species and even individuals of the same species but of different sizes use hydraulics in different ways , which lead to specific behaviours and swimming performances.
So, researchers need to think new.
— I believe that it is important to combine knowledge of biology, hydraulics, physics and engineering to solve these issues, an interdisciplinary approach is the best way to succeed, she says.
That may well be the recipe for success. During the group discussions principles from turbine research where combined with biological knowledge, engineering and experience from partners in the hydropower industry. Several of the ideas will now be elaborated and explored within HydroCen.