The relevance is that you would have a base load to keep the system hot which is separate from the electricity that does the work. I think at a steel smelter,

The relevance is that you would have a base load to keep the system hot which is separate from the electricity that does the work. I think at a steel smelter, since the heat does the work, they aren't as easily separable. You would still use less energy at the times when you processed less metal. Aluminium smelters were traditionally some of the biggest loads on the grid. They were built near hydroelectric dams and had contracts with electricity providers to absorb excess energy and to pause operations on short notice when other demand is high. In exchange for this they get it very cheap, which is good because they need a lot of it. Variable energy supply is not new to them. Now I've never worked at either and I'm just spitballing ideas on the internet, but you haven't either and you are too.