Essentially its a resource that is available all over at a national scale. For some numbers (approximated) : 100 million exajoules are needed to power the USA and 14,000,000 million exajoules are available.
It could provide renewable power at all times at a consistent rate all over. Way to explore google.org. keep it up
I also recently read a story about someone taking advantage of the highway system, parking lots, and other large paved areas for their heat retention and expulsion. Maybe that was google too?