Conversion losses and evaporation losses are two different types of losses in pumped hydroelectric energy storage, and their magnitudes differ.
Conversion losses occur during the pumping and generating processes due to inefficiencies in the pumps, turbines, generators, and associated equipment. These conversion losses impact the round-trip efficiency of the system, which typically ranges between 70% and 80% (or sometimes reported up to 85%)—meaning that about 20-30% of the energy is lost during conversion from electrical to potential energy and back again. These losses primarily include hydraulic friction losses in pipes and mechanical/electrical inefficiencies in pumps and turbines.
Evaporation losses refer to the water volume lost from the open reservoirs due to evaporation over time. These losses reduce the amount of stored potential energy, as some water is lost and must be replaced or results in a net loss of stored energy. Although evaporation represents a continuous loss during the storage period, it is generally much smaller compared to conversion losses. Evaporation losses are somewhat analogous to self-discharge in batteries, but their magnitude is relatively minor in the overall energy efficiency context of pumped hydro storage.
In summary, pumped hydroelectric storage typically experiences:
- Conversion losses responsible for roughly 20-30% energy loss per cycle, limiting round-trip efficiency to about 70-80%.
- Evaporation losses are smaller but represent a persistent loss over time and can vary depending on climate and reservoir surface area.
Therefore, conversion losses are the dominant factor in efficiency reduction, while evaporation losses are secondary but still relevant for long-term water loss and operational considerations.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-do-conversion-losses-compare-to-evaporation-losses-in-pumped-hydroelectric-energy-storage/
