A 1D model will be established (in-house MatLab code) for the power plants under investigation, with the possibility of switching on and off the presence of ACUR. A prescribed operation plan is then simulated (as an example 30 starts and stops), and iterations on what technologies (air compressors, pistons, switching of valves) is necessary and how to govern the ACUR for the desired mitigation of discharge fluctuations will be performed. What a ‘desired mitigation’ is, must be determined in a feedback loop working with the personnel in Task 5.2 and Task 5.3 using the models to investigate the influence on river eco systems, using power plant discharge as an input to the models. The power companies (Statkraft and Vattenfall) will provide restrictions on the design from practical perspectives. The work with ACUR will be performed by a Post-Doctoral research fellow and permanent staff at the Waterpower laboratory, NTNU, with input from LTU, Statkraft and Vattenfall. If there is no current technology available for obtaining a working concept, an industrial partner that can develop the technology needed will be sought for. In addition, passive ways to mitigate fluctuations will be evaluated based on the flow scenario modeling.