Interesting topic. My first thought is that most hot springs in the United States are scattered throughout several western states -- Hot Springs, Arkansas being a notable exception. That would suggest that that the viability of geothermal is limited to relatively few parts of the country.
That said, as a small piece of the renewable energy puzzle, geothermal is an interesting topic.
The following links about small scale geothermal heating projects in Idaho are interesting.
http://www.idwr.idaho.gov/energy/En_News/Sept%2005%20Energy%20Buzz.pdf“Idaho’s underlying geology, roughly from McCall south, consists of fractured rocks and faults, which allow a constant supply of hot water to flow to the surface or close to it. Early settlers recognized the potential uses over a century ago. Resorts like Lava Hot Springs in Eastern Idaho were established, and homes were heated and still are along aptly named Warm Springs Boulevard in Boise. In fact, the Idaho Statehouse is the only capitol building in the nation heated with geothermal water.”
http://adm.idaho.gov/about/fact_sheets/MallGeothermalProject06.pdf“STATE OF IDAHO
The Capitol Mall Geothermal Energy Project
Providing low-cost space and hot water heating for the Capitol and adjacent state office buildings”
…
“The system, was built at a cost of
$1,850,000, and has produced through
natural artesian pressure, low-cost
space and hot water heating (750,000
square feet) for the Idaho Statehouse and
eight other major state buildings for
nearly 20 years.”
…
“The existing natural gas heating system
is retained as a backup to the geothermal
system and for supplying additional heat
requirements on extremely cold days.”
