Long-Term Energy Storage Solution Has Been Here All Along
The most efficient energy storage technology may be as close as the nearest hill, according to former Energy Secretary Steven Chu, and almost as old.
“It turns out the most efficient energy storage is you take that electricity and you pump water up a hill,” Chu said Tuesday at the Stanford University Global Energy Forum.
When electricity is needed, you let the water flow down, spinning generators along the way. Pumped hydro can meet demand for seasonal storage instead of the four hours typical of lithium-ion batteries.
“There’s been a resurgence and a new look at pumped storage because it is the one thing we do have, and we know it works and lasts a long time,” Chu said, highlighting it first in a review of energy-storage technologies.
Pumped hydro takes advantage of the efficiency of converting electricity to mechanical motion using an electric motor, and converting it back again using generator.
“Round-trip efficiencies can reach as high as 85 percent,” he said. “In terms of energy storage it’s really one of the best.”
Chu has been touting pumped hydro as a backup for renewable energy at least since he served as President Obama’s first energy secretary in 2009. It can help renewables dominate the grid, he said, at least to 80 percent.