First of an foremost -- I am not a plumber or HVAC person by trade. I study allot of this information out of interest and deal with with HVAC, plumbers, pipe-fitters for a large condo association (our mechanical systems are more like commercial buildings than residences).
The hot mineral springs -- it sounds like you want to use this as an open loop system and pump the hot water through the radiant flooring to heat the home. Three issues --
- The 100 degree temp is hot, but you would be using allot of water to get the floor to the home to a decent temp.
- What are you going to do with all that water? The mineral water could be used at other areas of the home, but it sounds like you would need a second well to pump the water back into the ground -- (open loop geothermal systems do the same thing).
- Long term concern would be the maintenance of that system -- hot mineral water typically has lots of minerals in them that would cling to inside of your piping material and eventually slow the flow, or clog piping.
Solar panels sound like a much better way to go. Closed loop, treated water to lower maintenance costs, etc.
Good luck with the "guerrilla economics" building tactics.