Stanford, Calif. -- Pumped-storage hydropower projects may be the best means of storing solar and wind energy on the electrical grid, according to a paper published recently by Stanford University researchers.
The study, titled, "The energetic implications of curtailing versus storing solar- and wind-generated electricity", examines various options in dealing with excess power produced by intermittent renewables and the cost effectiveness of energy storage systems.
Curtailment -- or the practice of shutting down solar and wind generating systems to reduce the production of surplus power -- seems wasteful, the researchers noted, though their study showed existing battery-based storage systems (lead-acid, lithium-ion, sodium-sulfur, vanadium-redox and zinc-bromine) do not offer an attractive solution in terms of their "overall energetic cost".
The study defines the "overall energetic cost" as being the total amount of fuel and electricity to both operate and build an energy storage system, which, the researchers said, means the adverse by-products of large-scale battery production could actually negate the wind and solar farms they are meant to serve.
Pumped-storage hydropower offers not only one of the highest ratios in terms of "Energy Stored on Invested" (ESOI) of any storage system examined in the study, but also provides a number of ancillary benefits that make it an attractive means of capturing excess energy.