Yeah, I'd be curious about this, as well. A garden-variety 1U server sitting in a rack somewhere could be pulling 80W at idle and 1KW at load.
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.
Because when the sun is up over the Pacific ocean, everyone is asleep, and all of your datacenters are quiet.