In a state that has led the nation in the movement toward greater reliance on renewable energy, Los Angeles itself has been a leader. Just last year, the Los Angeles Department of Water of Power (LADWP) announced that it had reached the state mandated goal of 25 percent of all energy sales from renewable power. That was a dramatic jump from just 6 percent 10 years earlier.

Now, Los Angeles is in the spotlight again with a proposal to use the massive Hoover Dam for solar energy storage. The New York Times reports that the LADWP wants to equip the dam with an underground pipeline and a pump station powered by solar and wind energy.

The pump station, to be located about 20 miles downstream, would send water back up the pipeline to be deposited behind the dam and harnessed later for more hydro generation. By using solar and wind power to recycle the water, the project would turn the dam into a massive pumped hydro-storage facility.

Currently, the dam only operates at about 20 percent of capacity due to low water levels caused by drought and to avoid inundating downstream communities with excess flows. The project would allow the dam to increase its generating capacity without changing downstream flows, and it would not require any costly changes to the dam or to the 17 power generating turbines located within it.

The project is estimated to cost about $3 billion and is scheduled for completion in the year 2028.

Calling it a "a once-in-a-century moment," Los Angeles Mayor Eric Garcetti is optimistic about the project and its ability to help the city meet its renewable energy needs.

"There’s no bigger battery in our system than Hoover Dam," Garcetti said.

Despite its potential, the project faces a myriad of hurdles before it can be launched. It will require buy-in from the Bureau of Reclamation, the Department of the Interior and the National Park Service, environmentalists and neighboring state and local officials.