Your arguments in “energy payback” apply to any form of geothermal energy.
No:
Drilling normally uses much less energy than vaporizing rock.
Using liquid drilling fluid uses much less energy than compressed air for deep holes.
Pumping out existing hot water isn’t limited by thermal conductivity, and conventional geothermal does that.
All of your calculations assume that the rock has to be vaporized. I don’t see why it wouldn’t suffice to melt the rock, or even just heat it quickly enough that it shatters while remaining in the solid state.
Quaise Energy is a startup that is specifically about vaporizing rock with microwaves.
Melting rock doesn’t help get it out of a hole. (What are you going to do, try to pump it?) And thermal cracking is pointless when you can use a normal drill. But yes, you can drill rock while keeping it in the solid state.
No:
Drilling normally uses much less energy than vaporizing rock.
Using liquid drilling fluid uses much less energy than compressed air for deep holes.
Pumping out existing hot water isn’t limited by thermal conductivity, and conventional geothermal does that.
Quaise Energy is a startup that is specifically about vaporizing rock with microwaves.
Melting rock doesn’t help get it out of a hole. (What are you going to do, try to pump it?) And thermal cracking is pointless when you can use a normal drill. But yes, you can drill rock while keeping it in the solid state.