http://www.eurekalert.org/pubnews.php
Helium isotopes point to the best sources of geothermal energy
Unknown to most, the US has enough geothermal energy below its surface to supply three times the amount of energy that the US consumes annually. Up until this point no one has tapped this source because finding the geothermal hot spots is too expensive. Recently researchers discovered that surface indicators can predict if geothermal energy sources are below the ground -- now no more expensive drilling is required.