The work related to this proposal is part of the EU ALPHEUS project. ALPHEUS has the aim to develop new types of hydropower pump-storage solutions intended for low-head applications. Two different types of counter-rotating pump-turbine concepts are evaluated in work carried out by Chalmers. Steady, unsteady, and transient operations are investigated for the two counter-rotating pump-turbine concepts. Chalmers has the responsibility to deliver both highly resolved numerical simulations of transient operations, as well as simplified steady-state simulations at various operating conditions.