The Vast Potential of Geothermal Energy in the United States and an Approach to Extract It

Geothermal energy is a vast source of energy that is stored in the Earth's interior. Compared to fossil fuels, which eventually will be depleted, geothermal energy is essentially inexhaustible, and unlike the intermittent availability of solar and wind energies, its availability is constant. Here, by using a set of thermal energy calculations, we demonstrate the magnitude of this energy's potential and an approach to extract it.

We have calculated the total thermal energy of various size cubes of the crustal rocks at various depths and under different background heat flows. Our calculations show that the thermal energy stored in these cubes is a function of both background heat flow and the depth at which they are located. The higher the background heat flow for particular terrain and the deeper the subsurface location of the cube, the higher the total thermal energy. Additionally, we calculated the energy generated by various power plants for a period of 40 years and compared their energy production with the thermal energy of the cubes. The results (Fig. 1a-c) reveal the great potential of geothermal energy in producing a sustainable energy.

In the United States, more than 10% of the land has higher heat flow values than the global average of ~87 mW/m² (Fig. 1d). The thermal energy, stored in the rocky upper 1 km of these regions, is equivalent to 5000 years of energy consumption at current energy usage rates in the United States. This value, however, is an upper limit since not all of the geothermal energy is accessible or extractable yet.

Previously, we have developed and presented a novel approach for extracting geothermal energy called Radiator Enhanced Geothermal Energy (RAD-EGS), the strength of which is in mimicking the natural hydrothermal systems. RAD-EGS is capable of a sustained high-energy production over deep sedimentary aquifers with adequately high background heat flow. We posit that the meticulous implementation and operation of RAD-EGS is fundamental in introducing the world to a virtually endless source of energy, conveniently located just under our feet.