I'm not buying that...
I haven't seen too many homes in the real world that draw an average of 9 Kw, even during peak hours.
Like is said, MAYBE. In reality you have to have enough “spinning reserve” (a term for partially loaded generators even though fully loaded is the most efficient) to handle load surges.
9 megaWatt hours = 5.075913173 barrels of oil.
To generate 9 megaWatt hours of electricity from oil, you would probably need about 12 barrels of oil.
Here’s a handy-dandy converter: