Sure, any individual server: but amortized over 1000s? You'll develop an average just from traffic, and it'll be a lot higher then the bottom end - since otherwise why have the datacenter? Why not use spare capacity in your other datacenters?

The trick is that you sign a contract with the utility to guarantee a particular type of usage - and utilities love people who burn Watt-hours rather then Volt-Amps (i.e. a power factor near 1) since they're a lot easier to service, and people who promise to use power fairly consistently.

The utility says "we'll give you a lower overall rate, provided you promise to consume at least this much electricity" - in practice of course, you could consume less but you'll pay for it no matter what.

But compute is great for this model: it's fast to move applications onto and off servers, so hitting that minimum is easy.

> You'll develop an average just from traffic, and it'll be a lot higher then the bottom end - since otherwise why have the datacenter? Why not use spare capacity in your other datacenters?

Because when the sun is up over the Pacific ocean, everyone is asleep, and all of your datacenters are quiet.

That's when your batch jobs are running. Partially kidding but companies will wait until there's lower demand to take advantage of spot pricing.

Or routing latency insensitive traffic there. Do I care where my backups are stored? No. (well, I kinda do for geological/weather reasons, but put it on Mars for all I care)