The fossil fuel grid has always needed load to function because of the load's variance. To keep large coal fired power stations operating overnight there needs to be consistent load. Back in the very old days industry didn't run 24/7. It was much more variable and that's why there was some pumped hydro built. That's why we used to have things like night rate hot water heating etc in order to provide some load overnight. As industry, such as steel making became 24/7, the overnight load became larger which is a benefit to the system generally in terms of efficiency and response.
In a renewable system it can be a bit different however having a steady consistent load is still a good thing even though it's for a different reason. Storage is key to a renewable energy system. Without it the system won't work for grid distribution. However, the question is how much storage do you need ? If you can use that excess energy rather than store it in the first place you get better value as I alluded to earlier. If you can use things like aluminium smelters as giant batteries you are getting a double benefit rather than building just storage. You can use the energy as it's created but you can manipulate the smelter when generation is a bit short.
So, having smelters in the system might not just be important for making steel locally, it might be important for grid management which benefits everyone.
Btw. The Portland smelter was a deal done to somewhat justify the construction of Loy Yang B power station. Loy Yang A construction was nearing completion and it was employing thousands on good money. The government of the day was keen to keep this going but there was an argument over whether the state needed more generation. Given the efficiency of sharing mine facilities etc with Loy Yang A, it made a lot of sense to add Loy Yang B. My understanding was that the government gave Alcoa a 30 year deal on cheap power if they built the Portland smelter. That was also very good for the Portland area as it meant further development of the port etc.
There's lots of reasons why we do these things. Employment, infrastructure and prosperity are often mixed in different ways.
Now, 35 years later, the roles appear to be swapping around.
