Some, but not all geothermal energy processes, are widely available. However, the most generally and sufficient use of geothermal energy is only viable in or near volcanic areas. This new energy source is something that will hopefully be studied more in the future, so it can be used on a wider, more affordable, basis.
Geothermal energy is localized and unexamined to be able to be utilized for its highest potential. As it is solely available in abundant properties in the volcanic areas - it is hard to tell what ways will be most efficient in harnessing it and utilizing it. For the moment the studies are insufficient but the potential is there.