content: no, they're saying if they have 100 watts of solar/wind energy being produced and only 30 watts of it being used, they want to use 70 watts to pump water above the hoover dam.  Then they'll have more water above the dam for times when solar/wind is only producing 100 watts and they need 130.  THey're just trying to answer what do you do when you have renewable creating more energy than needed.