Testing “dancing rods” in practise

The solution has been tested in Vattenfall’s large-scale laboratory for hydropower-related environmental and hydraulic experiments (Laxeleratorn) on two previous occasions with promising results. 

In its first field trial, a 12 meter barrier with 80 “dancing rods” was installed in Stångån in Linköping. The location is ideal due to its well-known fish populations, including species such as asp and eel, but also because it has an already installed fish counter and a strong collaboration with Tekniska verken, who are the owner of the power station. “Dancing rods” are flexible rods that move with the water flow and they are designed to be a barrier that guides fish toward safe passages past the power station.

The barrier was monitored using cameras to study fish behaviour and determine whether fish follow the rods and choose an intended opening for passage or if they attempt to pass directly between the rods and through the barrier. While the current prototype used plastic foam material, Vattenfall is now exploring biodegradable options with the company Cellufy.

The goal is to find effective, commercially viable solutions that support migrating fish while minimising impact on fossil free hydropower production. During 2026 Stångån power station is out of service due to repairs and the trials in will continue in 2027. During 2026 the field tests continue at Vattenfall’s power station Stämmemad in the river Viskan. A 15-meter-long barrier is placed across the powerplant’s intake channel, with the intention of guiding fish to a small nature-like stream providing a safe passage.

Different types and designs, e.g. different choice of material and dimensions of rods, will be tried through the year, hopefully leading to a better understanding of effectiveness during different flow and weather conditions.