What does that number really mean?

I have found that in science we often use really big or really small numbers but we don't often relate that to something we intuitively know or have experienced. So I'm going to be putting out numbers and what they "really" mean.

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

1 BTU = British Thermal Unit = energy needed to raise 1 pound of water 1 degree Fahrenheit.

So let's now see what we can do with these numbers. While we only get about 22.7% of our energy from coal (22.8 Quads) If you wanted to haul all of this coal in one train it would have 11 million cars and be 104,000 miles long. This train would be long enough to go around the world a little over 4 times. And that's just in one year.