This is a common and easily available technology for residential and commercial applications. With a closed-loop system a 4-ton HVAC system requires roughly 60

This is a common and easily available technology for residential and commercial applications. With a closed-loop system a 4-ton HVAC system requires roughly 600ft of 3/4-inch pipe as vertical wells. That typically means 4 wells maybe 15-20 feet apart. You need a decent about of property to support these systems, enough room for a well driller, appropriate drilling conditions, permits for drilling, etc. There are other systems for people with the land which may be less expensive which don't require drilling. I spent several summers installing these systems, they are surprisingly simple and effective. https://en.wikipedia.org/wiki/Geothermal_heat_pump https://en.wikipedia.org/wiki/Geothermal_heat_pump