Standard approaches to heat mining require the drilling of at least two boreholes, as illustrated in the drawing at right. The main problems with this approach are two-fold: (1) the hydraulic connection (fluid flow through cracks and pore spaces) either needs to be created (“enhanced geothermal systems”), which is a risky business (but getting less risky, through efforts of companies like Fervo and efforts of the Geothermal Technologies Office at the Dept. of Energy), or already exists and therefore cannot be controlled, and may be quite leaky; (2) the drilling and production phases are separate– a borehole cannot be operating– producing steam– and drilled at the same time. For the latter, new boreholes can be drilled while others are producing, but this process is costly and compounds uncertainty. All of these problems compound the deeper the target rock reservoir lies. At higher temperature, the more difficult becomes standard mechanical drilling and creation of crack networks. Our approach is quite different…