Uppsala University has developed a directly driven generator for tidal/instream applications. The turbine in operation is a vertical axis turbine with five blades (could be three/four bladed) and a radius of ca 3m and a height of ca 3.5m. On its tripod the turbine reaches 4m above the riverbed. Rotation speed: 15 (max 20) rpm at velocities of 2 m/s.
Located in the municipality of Söderfors, in the river Dal, 50 km north of Uppsala. The turbine is placed in a tributary part of the river, at 7m depth, and 200m downstream a hydropower dam. This enables experimental approaches including the possibility of controlling and changing velocity. The turbine is connected to a measuring station located on the shore, 50m away, by a feeding cable. The facility is prepared for grid connection.
Early discussions in 2011-2012 with regional authorities resulted in the decision that the project, due to its small scale and only including one turbine, would be considered as a “small project”. Thus, it would not need a formal permit, only consent from the regional authority, the county of Uppsala. A small project description was produced, and consultations were held with a limited number of stakeholder (e.g. the local municipality, land and fishing right holders, and the utility company Vattenfall, owner of the nearby and upstream hydropower station). The current consent became affective in 2013, when the turbine was launched, and lasts for five years. A new consent will be applied for during 2018. The consent was conditioned with fish studies, mainly with focus on Salmonidae.
Key Environmental Issues
Although the project was not considered to cause environmental problems, Uppsala University planned environmental studies, especially concerning the eventual effect of the rotating turbine on fish per the request of authorities and other stakeholders.
No long-term environmental monitoring was required by the consenting authority, partly because the part of the river is regulated above the hydropower station, and absence of fish (Salmonidae) migration. However, effect studies, such as turbine fish interactions, were required. In 2015 Uppsala University performed test fishing in order to establish fish species assemblage in the waters. In 2017 the research group at Uppsala University, together with researchers from Chalmers University of Technology and in cooperation with the Swedish University of Agricultural Sciences (SLU), started to plan fish-turbine interaction studies. In September 2017 the first study was initiated, the release of salmons nearby the turbine in order to study behaviour – turbine passes, avoidance, deterrence. Fish (salmon and trout), obtained from a nearby fishery (SLU) were released upstream the turbine. Observations were recorded with the help of a sonar system. The data is presently (2021) under analysis with intentions of publication in 2022 (Bender et.al – in prep.). However, no fish appear to have passed through the turbine and only passed through, or near, the turbine when not operating. In 2018 a laboratory study was performed at the nearby fishery, at Älvkarleby, operated by SLU. In a small-scale indoor brook aquarium, a model vertical-axis turbine was used for similar studies on Salmonidae smolt (Berry et.al 2019). In 2019 complementary studies were performed. No collisions were observed and smolt only passed near or through the turbine when not operating. Both projects had ethical and other necessary approvals for the respective study.
Baseline Assessment: Söderfors Project
|Receptor||Study Description||Design and Methods||Results||Status|
|Physical Environment||Velocity measurements||Up to three acoustic doppler current profilers (ADCPs) used.||Ongoing|
|Physical Environment||General baseline information – river bed structure, depths and velocities||Baseline information||Completed|
Post-Installation Monitoring: Söderfors Project
|Stressor||Receptor||Study Description||Design and Methods||Results||Status|
|Collision||Fish||Release of smolt (salmon and brown trout) in vicinity of turbine||Passive sonar monitoring||Ongoing|
|Collision||Fish||Laboratory/aquarium brook study – salmon and brown trout||Visual and video recordings. Different turbines, varying rpm, velocities, diurnal/nocturnal etc.||Planned (2018)|
|Noise||Fish||Measurements taken in 2015||Hydrophone recordings||Much background noise so hardly “audible” and of no concern||Done|