Optimization of pumped hydro energy storage design and operation for offshore low-head application and grid stabilization

Abstract

The increasing share of renewable energy sources in the global electricity generation defines the need for effective and flexible energy storage solutions. PHES with their technically matured plant design and wide economical potential can generally match those needs. But especially for lowland countries, where low-head PHES applications are needed, the current turbomachinery technologies offer no viable solutions for LH-PHES to be a competitive energy storage technology in the context of realizing the European Green Deal.The new developments in low-head hydraulic turbomachineries, smart operation schemes and powerful site identification algorithms can shape these plants towards a viable future technology. Therefore, this study demonstrates that, through a novel design of a contra-rotating, variable-speed, reversible pump-turbine especially designed for low-head operation, PHES can operate over a wide range of hydraulic heads and discharges at very high efficiencies. Additionally, it shows that, with the use of more than one CR-RPT unit in parallel action, different power settings can be selected to achieve high efficiency with fast reaction times.Furthermore, the newly developed operation simulation code is used to support the RPT design developments considering the most compact plant design, which is achieved by Prototype 0 at LAT of 31 m and dam diameter of 1600 m. Thus, the investment costs are minimized while the revenue is maximized through the delivery of grid services tailored to suit the market needs. Moreover, the novel development of a smart site identification algorithm, supports RPT design development at high potential offshore sites (in the Greater North Sea).