The proposal isn’t to use the dam’s excess power to pump the water back uphill. They want to use excess power from other solar and wind plants to effectively s

The proposal isn’t to use the dam’s excess power to pump the water back uphill. They want to use excess power from other solar and wind plants to effectively store any excess energy that they produce. Since these alternative sources cannot consistently produce energy 24 hours per day, and the times that they are able to produce it do not necessarily match up with consumer demand, they need to store it somehow. This is being proposed as a more efficient and cost effective form of storage than batteries (though I am curious how much energy will be lost due to evaporation after the water has been pumped in Hoover dam’s hot climate and other inefficiencies).