Availability
Sunlight is by far the world's largest energy resource. A 1993 report by the DOE found that available domestic resources from solar represented 586,687 Quadrillion BTUs (Quads), out of a total of 667,597 Quads, with coal representing the second largest resource, a distant 38,147 Quads.[2] By comparison, the total annual energy consumption of the United States in 2007 was approximately 100 Quads,[3] less than 0.5% of that available from sunlight.
