Disclosed are a method and a device for utilizing supercritical subsurface steam as combined supercritical thermal and hydraulic power stations at an efficiency of 50 percent, using molten bath superdeep drilling technology, a hydrofrac process, and the special properties of the supercritical subsurface steam, such as the drastic increase in the thermal capacity, reduced viscosity, and inorganic solubility. The multifunctional use of said technologies and physical properties of supercritical subsurface steam in the inventive method allows a supercritical subsurface boiler to be tapped rapidly and at a low cost at a great depth while making it possible to produce electricity, power, process steam, and heat almost anywhere at one tenth of the cost of conventional fuel technologies and comparable expenses. The supercritical process steam obtained from a closed forced subsurface-nature circuit is used in supercritical power stations featuring state-of-the-art steam turbine technology while the remaining pressure in the subsurface fluid is used for directly generating power and/or electricity after dissipating heat via hydraulic turbines.