Poor Don, I suppose a 90% furnace makes you a bit nervous too. Let's bring back the days of 70% furnaces & 6 Seer A/C.
I've never met anyone so afraid of heating with refrigerant. It's OK to face your fears... heat pumps, whether air source, water source or geothermal, are here to stay & are much more efficient. psst... they're starting to bypass hot gas & inject it into the compressor & heating efficiencies are going even higher... Don't worry though, these systems won't out number the current "old" technologies til long after we're both dead. And expanding on your logic, I'd guess they're inherently bad because of that, & the fact that the ranchers in SoDak don't use them either... Progress moves at the speed of a hearse.
Since heating with Gas & Oils is a much older technology than the reversing valve in a refrigerant stream, I can understand why there are a few more of these systems around. Just because fireplaces are popular doesn't mean they're more efficient. Although if gas were the new kid on the block you'd, I'm sure, would be extolling the virtues of coal.
If Geothermal in Ill. has 1% of the homes, I say hooray... That's a huge number. Considering my metro area, I'd have to say we're well under 1%, adding in the outstate might bring the total up to 1%, but I can't say for sure, What I can say is geothermal is very affordable & will pay for itself, if you use your head. Geothermal in the Arctic might need some consideration, but then again I'm not an expert on the Arctic. Vertical bores through granite might cost more that sand, but even this can be done. Please, just stop using theoretical quotes based on what you would charge to install a system that you don't like & seem to know very little about. (Insert retort of your motorcycling to Engineering school at USC back on the GI Bill)
South Dakota has huge amounts of geothermal in operation as well as in construction. (I'm working on a campus project right now that serves all of the 40+ buildings needs for heat with geothermal.) Up until Hydron was bought out, South Dakota had one of the best Geothermal units in the world built in state, Time will tell if the new owners will maintain quality. SDSU in Brookings has been one of the leaders in the study of geothermal. Unfortunately for MN, our design temps are colder & frost lines are deeper, but our geothermal works just fine thank you. (And yes we're colder than parts of Canada too... big statement considering we're north of Toronto)
IF the cost of operation for a system is half of that of another, it will pay for itself, whether you base it on the total cost of the system or the cost difference between the two. Needless to say, in either case, the less efficient system will never pay for itself.
Now feel free to tell me I'm full of shit & don't know a damn thing. I'm a big boy & I don't fear your flames, or progress...
Merry Christmas to all.
goodluck geothermaljones st.paul,mn