First of all;, systems are designed to match the loop field to the particular system design for particular buildings.<quoted text>
Sparse use is practical. Where it breaks down is in the cooling mode, and too many facilities are dissipating heat into the same geologic member. The heat fro mone facility is carried to the location of the other facility.
Eventually, enough heat from enough facilities dissipate enough heat into the geologic member to create a steady-state equilibrium temperature.
Heat can only travel from a higher temperature to a lower temperature. Tricks can be imployed, like forcing a "coolant" through a nozzle, creating a change in pressure of the "coolant" which changes it's specific capacity to hold heat. In an air conditioning system, high pressured "coolant" absorbes heat, then is forced through a nozzle where on the other side the pressure is much less and the heat capacity is reduced, causing the heat absorbed in the high pressure side of the nozzle to be dissipated in the low pressure side of the nozzle.
Ultimately, the surrounding environment can dissipate only so much heat. If enough facilities dissipate heat into the same thermal reservoir, then the temperature difference becomes negligible, and heat transfer ceases, resulting in a thermal equilibruim state.
Geothermal cooling is very complicated.
Thus, it isn't free, like these dupes think.
Second, no one said geothermal was free.