They can use wasted curtailed "renewable" power, and might even be paid to take the power.
Thermal storage allows us to learn how to make big hot corrosive things that take on and put out huge amounts of energy – thermal storage is a molten-salt reactor without the moderator and fuel.
Overbuilding solar and wind energy creates an abundance of electricity during daylight hours. Curtailing power means shutting off or disconnecting solar and wind power when they generate more than the electrical grid can handle.
California alone generates a lot of solar and wind power that has to be curtailed. At least 34,000 megawatt hours needs to be curtailed every month and some months (March to May) can go as high as 550,000 megawatt hours per month. Sometimes, during the middle of the day, California's renewable resources can generate more electricity than is needed. During these periods of surplus energy, the ISO's (Independent system operators) market automatically reduces the production of energy from renewable resources, or "curtail" generation. In rare instances, when economic bids from generators are insufficient, ISO operators manually curtail production to maintain the balance between supply and demand.