I've heard of gravity batteries, but they are not a proven technology for utility-scale storage (yet). Can you please elaborate on what utility-scale storage will take the place of our current system whereby production generally scales up and down with demand, which will be more difficult with energy sources that can only produce intermittently like solar and wind? Hydro and wave energy generators look promising for baseline load, but those won't alleviate the need for utility-scale storage altogether, right?