| Abstract |
According to the European-Green-Deal, the share of renewable energy sources (RES) in electricity generation is increased by e.g. solar/wind. This requires the deployment of effective energy storage solutions to compensate the fluctuating network supply of RES. A well-developed storage technology is pumped hydro energy storage (PHES), but especially in lowland countries, e.g. Denmark, typical high-head plant locations are missing. Therefore, new developments in low-head hydraulic turbomachineries and smart operation schemes are needed to shape LH-PHES towards a viable future technology through maximizing performance and minimizing investment costs. Hence, this study demonstrates a novel design of contra-rotating, variable-speed, reversible pump-turbines (CR-VS-RPT) for low-head operation with a peak efficiency above 90 % in pump/turbine mode. The results comparing shaft-driven with rim-driven CR-VS-RPT show the influences of chosen RPT type on the reservoir size/investment. The study also proves that hydraulic losses due to the bulb for shaft-driven CR-VSRPT have a decisive impact on the head range, and thus on the required dam material volume. Despite the slightly less efficient performance of rim-driven CR-VS-RPT, the absence of the bulb increases the efficiency during operation at low LAT s . However, the LAT is the key factor for CR-VS-RPT type selection to minimize the investment for LH-PHES. |
