When I read those things I always assume they're talking about megawatt hours.
Considering that the average american home consumes a little under 1000 kilowatt hours a month then the math starts to line up.
1000 KW hours is 1 megawatt hour. 1,000 megawatt hours is 1 gigawatt hour, so 1,000 months, while being a bit shy of 100 years, is still 83 years and change.