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by zeristor·8y ago·view on hn ↗
One use of cheap power is to do very energy intensive operations. Egypt powered fertiliser plants from the Aswan dam, and Iceland uses hydropower to smelt aluminium.

Saudi Arabia is building a huge aluminium smelter, I had thought it would be solar powered, but they would need far, far more power, and of course it couldn't run at night.

http://www.bechtel.com/projects/ras-al-khair-aluminum-smelte...

So I assume this is gas fired power, which seems strange.

4 comments
Natural gas is effectively free for the Gulf states as it’s a byproduct of oil drilling.

Compared to oil it’s harder to store and transport, and there aren’t any gas pipelines from the Gulf to neighbouring areas (unlike say Russia). If you fly over the Gulf at night, you’ll see the sea lit up from oil rigs just burning it off, so it makes sense to use it to fuel heavy industry.

The primary constituent of natural gas is methane, which has a much worse greenhouse effect than CO2, so it’s ‘greener’ to burn it rather than just releasing it into the atmosphere.

The Ma’aden Aluminium refinery and smelter complex is the world’s largest, lowest cost fully integrated aluminum facility.[1] The smelter as well as the alumina refiner have been operational since 2014.[2] [1] http://www.maaden.com.sa/en/business/aluminium [2] https://www.alcoa.com/saudi-arabia/en/default.asp
It's interesting that we don't favour the idea of something only running in the day when transitioning to renewables. Would it be such a bad thing and would there be other operations they could happen during the night ?

I know it might mean less money or whatever, but the universe doesn't seem to run on money so it's weird logic sacrifice the environment over something like operational uptime.

There are some processes where equipment lifetime is more determined by total usage than by start-stop cycles. Those processes can more or less seamlessly transition to intermittent renewables as long as the time value of money isn't very high. Given persistently low inflation rates despite years of QE, I think we might be there already. EDIT: actually, even if the processes are tolerant of frequent stop-start, the associated labor scheduling may not be. Not knowing when you'll have a shift scheduled sucks for workers. Not knowing if your regularly-scheduled workers will have favorable weather to do useful work when they show up at the plant would suck for employers.

Other processes are intolerant of complete shutdown/startup cycles. Modern aluminum smelting is one of them. If everything freezes up in the production cells because of too little power for too long, it causes damage and it takes a long time to start up again. To make aluminum smelting more cycling-tolerant would require rethinking the whole plant design. Even then the cost savings from cheap but non-dispatchable renewables may not be enough to compete with existing plants powered with dispatchable electricity.

> Not knowing when you'll have a shift scheduled sucks for workers. Not knowing if your regularly-scheduled workers will have favorable weather to do useful work when they show up at the plant would suck for employers.

I'm not sure if this is such a huge problem. Modern operations require very few human operators, and they do not contribute too much to the actual costs. Worst thing is that you'll just have some people doing nothing waiting for cheaper energy.

> If everything freezes up in the production cells because of too little power for too long, it causes damage and it takes a long time to start up again.

It takes much less power to keep the aluminum hot than it takes to smelt it, so if power becomes too expensive for smelting, you just use a fraction of it to keep it hot in the cells.

The Great Wikipedia[0] says "power must not be interrupted for more than 4-5 hours, since the pots have to be repaired at significant cost if the liquid metal solidifies."

[0] https://en.wikipedia.org/wiki/Aluminium_smelting

If you can go on standby and use say 5% of power indefinitely that's still a lot of flexibility.
Here's a crazy idea - can't you smelt aluminium using a giant magnifying glass?