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Comment by jonatron | Hacker News Reader

Do you know where the night demand comes from? I expected to see a bigger drop at night

UK has some tariffs with a cheaper electric charge at night called Economy 7. This is used to heat storage heaters for properties without gas central heating.

Industrial load will also play a factor, as will lighting homes during the dark hours.

The biggest industrial users - those on half hourly metering - also get discounts to move usage offpeak, and there's some tariff options that turn off or restrict those highest users during peaks. Partly so the grid don't have to keep waking up Dinorwig. :)

To save others googling: https://en.wikipedia.org/wiki/Dinorwig_Power_Station - cheers for the interesting read!

Wow. When notified in advance, Dinorwig can go from 0MW to 1800 MW power delivery in 16 seconds. Unprepared, looks like it takes a couple of minutes.

https://www.youtube.com/watch?v=McByJeX2evM

Absolutely breathtaking inside that place.

Rimmer: We can’t afford to take any chances. Jump up to red alert.

Kryten: Are you sure, sir? It does mean changing the bulb.

Seems puny compared to the twin plants on the Niagara in the USA/Canada (both are pumped-storage hydro):

2,675 MW: https://en.wikipedia.org/wiki/Robert_Moses_Niagara_Power_Pla...

1,997 MW: https://en.wikipedia.org/wiki/Sir_Adam_Beck_Hydroelectric_Ge...

You're comparing apples to oranges. They're not pumped storage stations.

Technically, they're actually both:

"Water enters the forebay via tunnels from the Niagara River controlled via the International Control Dam upstream of the natural falls. Water in the forebay is then either pumped up into the upper reservoir or immediately sent down over the escarpment downstream of the natural falls into the Robert Moses Power Station turbines."

So, it's like more like Malus pumila (Domestic Apple) to Malus sieversii (Wild Apple).

Also https://en.wikipedia.org/wiki/Cruachan_Power_Station

Worth a visit https://www.visitcruachan.co.uk/ and if you go by train it's discounted

And lighting the outdoors, streetlights etc. One of the few things you really can see from space.

I can't find firm material on exactly what explains the night usage — I'm sure the National Grid have details on this somewhere. Even so, the price of electricity reduces at night and so industry uses it a lot during that time. A lot of people leave appliances on overnight too, like washing machines.

And people on economy 7 tariffs heating storage heaters, although in the summer months that wouldn't be usual.

I expect that if solar becomes a dominant source of electricity, time-insensitive industrial uses (eg, aluminum smelting) will happily become daylight operations.

Aluminium cells can only be powered down for 4-5 hours before they become very expensive bricks. They can be (and they already are) used to smooth out grid fluctuations, but not on the scale of day to night.

In theory, could the cells reside in a high temperature resistant vacuum flask (Dewar flask)? Made from quartz perhaps?

It might need supports between the inner and outer walls, causing heat to leak, and hence multiple layers of vacuum with supports to be required for containing the heat...

In some part, what you're seeing on the demand side is underestimated during the day, due to solar not being centrally metered, and offsetting some of the true demand. As the mouseover on the solar gauge says, you can see this in the demand drop around noon.

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