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.