November 10, 2022 – What is the ecological impact of a TEO installation on aquatic life? Water managers would like to know this, so that they can make a good assessment of what they will or will not allow. Much knowledge has already been developed about this from the research program WarmingUP, STOWA and water managers (Rijkswaterstaat and the Union of Water Boards).

During this day, this knowledge was presented and it was outlined which knowledge gaps still exist and what is needed to fill them.

STOWA has developed a first version of an assessment framework for cold discharges in 2021 to support licensing authorities in this regard. Because much is still unknown about the ecological effects of TEO and because every situation is unique, the assessment framework offers room for individual interpretation. Various studies have been carried out to refine and further substantiate the criteria in the assessment framework.

Ghada Sukkar of the Union of Water Boards outlined the dilemma facing water managers and how they work on model policy. Ida de Groot-Wallast of Deltares outlined the research questions that were worked on within WarmingUp and the NIOO and the current state of knowledge. Several researchers pitched the results of recent studies.

During two sessions, researchers shared the latest knowledge on the various topics and discussed which knowledge questions still remain.

During the first session, the effects of the technique were examined. What are the consequences for plants and animals that pass through filters and heat exchangers in the water that is drawn into a TEO installation? Anton de Fockert of Deltares discussed the operation of 4 different TEO systems. Then his colleague Miguel Dionisio shared what is already known from the literature on the effects on aquatic life. Hoogheemraadschap Hollands Noorderkwartier, Hoogheemraadschap Rijnland and Waternet investigate the extent to which different filters cause damage to zooplankton and told about their approach. Finally, Sven Teurlincx of NIOO shared how possible damage to zooplankton and phytoplankton will play out at ecosystem level, based on an ecological modeling of a TEO installation at a small lake.

During the second session, the effect of the cold discharges from the system on the ecology was discussed. What do we know about how the cold spreads in the receiving surface water and what impact this has on the ecology? Roland Vlijm from Deltares showed to what extent we can model the cold plume and his colleague Ida de Groot-Wallast then discussed the effects on ecology, based on recently conducted studies of the literature and ecological modeling of the effects.

After we all had a clear picture of what is and is not known about the ecological effects of cold discharges, we entered into a discussion about the remaining knowledge questions. Which are they and which should be dealt with first in order to be able to better assess permit applications? All participants could add their questions to the open questions.

Our input was “What is the effect of cold discharges on – in our case the Linge – if aquathermal energy is applied not only in Enspijk, but also in the adjacent village centers on the Linge, which may lead to a different outcome about the effect of that cold discharges“

Published by STOWA: links to report and presentations on 10 November