Scientific American has an article on the use of fracking to develop geothermal power projects - Fracking Could Help Geothermal Become a Power Player.
Here's another use for fracking: expanding access to hot rocks deep beneath Earth’s surface for energy production. In April Ormat Technologies hooked up the first such project—known in the lingo as an enhanced geothermal system, or EGS—to the nation's electric grid near Reno, Nev.
"The big prize is EGS," enthuses Douglas Hollett, director of the Geothermal Technologies Office at the U.S. Department of Energy (DoE). "The key is learning how to do it in a reliable way, in a responsible way."
By some estimates, the U.S. could tap as much as 2,000 times the nation’s current annual energy use of roughly 100 exajoules (an exajoule equals a quintillion, or 1018 joules) via enhanced geothermal technologies. With respect to electricity, the DoE concludes at least 500 gigawatts of electric capacity could be harvested from such EGS systems. Even better, hot rocks underlie every part of the country and the rest of the world. Australia's first enhanced geothermal system, spicily named Habanero, began producing power in May, and Europe has brought three such power plants online.