[elliottkember]

I think it's that a thousand terawatts is equivalent to one petawat. So this is 10.7PWh.

[PittleyDunkin]

Ah so the complaint is of moving the last order of magnitude onto the quantity rather than the unit. I can't imagine this affects readability that much (although I can understand why you'd want to enforce consistency in an academic context).

Sometimes it's useful to distinguish these, though. And after many do have the inexplicable "MM" suffix (ie s thousand-thousand) to suffer through which seems much worse.