I'll start by talking about how much energy the US uses. According to the Department of Energy's report on the Energy Consumption of the US in 2006 we used 99.8 quadrillion BTUs (or as the energy industry says "Quads") of energy. Our usage for the first 9 months of 2007 projected a usage of over 100 Quads by the end of the year. Let's first define our terms.
1 quadrillion = 1x1015