Pump as Turbine for Grid Flexibility in Uruguay Optimal Scale & Performance Prediction

Abstract

Renewable variable generation incorporation to the national electric system like wind and solar brought the requirement for more flexibility in the grid. Storage technologies can contribute to it, being pumped storage the most used globally for this purpose. While traditional pumped storage trend to be more feasible at larger scales (above 250 MW), Uruguayan power system appears to need only between 10 and 30 MW to balance variable generation. Small turbines could be used for this purpose but their high price makes it many times prohibitive. Using a pump in reverse rotation, acting as a turbine generating electricity, could be a more economical alternative in order to filter generation peaks and demand fluctuations. Remarkably, any kind of pump “off the shelve” can be used as a turbine. Performance remains almost same as in pump mode, and it can be improved with small modifications such as blade tip rounding, or replacing intake for a specially deigned square section diffuser.