Over the years, proponents of some forms of geothermal energy have suffered from a bit of an identity crisis. There is, of course, Big G which generally refers to hydrogeothermal resources of the type that create geothermal electrical generation common to northern California, Nevada, Indonesia, etc. and shown below in the new Hudson Ranch I system that recently went online in the Salton Sea of California.
Big G also commonly refers to geothermal resources used for direct use as in hot springs resorts and the district heating system in Pagosa Springs, Colorado.
Then there is "little g" which refers variously to geothermal heat pumps (GHP), geoexchange, or, more appropriately, ground source heat pumps (GSHP) -- a fundamentally different energy resource and technology than Big G. It doesn't help that both Big G and little g, and which both suffer from a bit of a Rodney Dangerfield complex, are often discussed at the same conferences which only further confuses the two. Rather than a resource for electrical generation or direct use heating, ground source is better looked at as an energy efficiency device that can provide both heating and cooling for space conditioning (I won't go into the details here. Interested readers might want to start out with the Wikipedia entry).
The basic problem with ground source is the high first cost of installing the loop field. While improving technology has increased the efficiency and cost effectiveness of the heat pump component of the system, there has been little improvement in the cost of installing the loop (see the excellent article by Tom Konrad in Forbes here). Thus, for residential systems in particular, GSHP remains at a competitive disadvantage -- especially in light of low natural gas prices.
I have long argued that ground source deserves more recognition in utility demand side management/energy efficiency programs, most of which focus on weatherization programs (good) and nothing more sophisticated than rebates for kitchen appliances and compact fluorescent light bulbs (questionable). Some states have enhanced their renewable energy standards with new thermal energy standards. These have tended to focus more on solar hot water heating and, occasionally, biomass... still not much recognition for the only technology that provides both heating and cooling.
During this legislative session in Colorado, a group convened to attempt to foster greater recognition for ground source in a thermal energy standard that was being discussed. Unfortunately, the single paragraph that discussed geothermal or ground source in what became Senate Bill 12-180 was lost in what morphed essentially into a biomass/forest conservation bill. That the bill was introduced late in the session and was tagged with a large fiscal note did not bode well for its prospects and it was soon killed in committee. That was probably just as well since the bill was a mess and the best it would have done would have been to create a thermal energy working group. In the present economic environment, and with little support for new incentive programs, I suspect that ground source is going to have to continue to rely on technological advance and new financial innovations (similar to the PPAs that have fostered greater PV adoption) to reduce the first cost to consumers so that it can compete with more established space conditioning technologies.
