Fracking with water (which is what geothermal would do) has pretty limited environmental concerns, and has enormous gains in increasing surface area and reach,

Fracking with water (which is what geothermal would do) has pretty limited environmental concerns, and has enormous gains in increasing surface area and reach, so it almost certainly what we're going to end up doing. Iirc this is part of Quaise's plan: drill 20km down then frack the bottom to get a really big volume and surface area at those very high temperatures.