> But because they fracture the rock instead of vaporizing it, there's essentially gravel/sand leftover which is hard to evacuate from a deep vertical shaft, h

> But because they fracture the rock instead of vaporizing it, there's essentially gravel/sand leftover which is hard to evacuate from a deep vertical shaft, hence their focus on power/fiber trenches not geothermal. Getting cuttings out of the borehole is a solved problem with present drilling technics used in the Oil & Gas industry or geothermal. The drilling fluidsbrings them back. One needs the drilling fluids (mud) to avoid the well to collapse, I guess Petra is staying clear of deep borehole drilling because they can't operate their technology with drilling mud present. Also the deeper you go, the smaller the hole and they may face miniaturizion issues too.