they all are, but indirectly. I challenge you to find any manufacturing plant that's powered by a direct energy source instead of grid power - it's simply not efficient to manage demand peaks and valleys yourself when there's a huge amount of infrastructure already dedicated to doing exactly that.
Interestingly, I live in rural Japan and went on a trip with some of my neighbours. One of them brought her son along who is a buyer of natural gas for Fuji film. I asked how they are set up. He told me that they generate all of their electricity onsite from natural gas generators. It seems that they also need the waste heat for some other processes so it makes sense for them. I asked him about solar and wind because I know that both are fairly good bets here (more than 200 days of sun per year at 34 degrees latitude, coastal position with near constant moderate wind). He said that because of the waste heat that they need, it's still much cheaper for them to go with natural gas and figured that it would continue for some time (though... I suppose he might be biased given his job ;-) ). Unfortunately my Japanese isn't quite good enough to understand what they were using the waste heat for. Fuji film makes a lot more than film -- they do a lot of electronics too, so I'm not quite sure what they are doing. I also know a few people who work for automobile parts manufacturers (suppliers for the big car companies here) and most of them also use primarily natural gas, apparently (which surprised me greatly). I did notice that a few years ago quite a few factories in the area have covered their roofs with solar panels, so I think it's moving slightly.
I suspect that in many parts of the US, the national grid is so cheap that it makes sense to use it. But at least here in Japan it seems to be common to generate at least some of the energy yourself.
Note that he's not using a carbon price. It's definitely the case that using waste heat from a thermal plant is a big plus. But using natural gas in Japan, which imports all of its natural gas under high-priced long-term contracts, is not cheap.
Energy wise, nothing is cheap, which is why I was quite surprised that Fuji Film weren't already moving over to renewables. Japan basically has no other energy resources. Natural gas, oil, coal, uranium: basically whatever small supply they had is already gone. I suspect the reason for factories using natural gas is because it is on demand and the capital cost for the generators is relatively small. Probably long term Japan will use geothermal for baseload, but a lot depends on how the recent test plants perform and especially how they are perceived by the public.
This isn't strictly true, but isn't strictly false. Power plants are often built to supply power to aluminum smelters, like in New Zealand [1], Oman [2], and Iceland [3], but they're usually connected to the grid in the end. Iceland has a grid circling the island [4], Oman is upgrading its grid and building out interconnects [5][6], and in New Zealand, Manapouri went from exclusively supplying the Tiwai Point smelter to being a power station of the South Island grid.
The generators are connected to the grid, both for buying & selling but it is absolutely not true they don’t manage the ebbs & flows. Quit the opposite it’s a major part of their business
Until someone puts in a tie line from Roxburgh to Benmore Manapouri's power is really only available to the lower third of the South Island. Mind you the sooner we shut down the smelter and redeploy that power to locally owned industry the better
Alcoa has a whole division for energy generation. Their energy plants are collocated with aluminum plants, most like the Warrick operation are coal but they do have a hydro plant.
The Lochaber Hydro Electric scheme in Scotland was privately built and is still privately owned and feeds water to power the aluminium smelter in Fort William.
