In conventional geothermal energy, the aim is to drill into water-bearing layers underground in order to pump the warm deep water to the surface.
In contrast, with the Eavor-LoopTM the heat from the rock is used directly. Boreholes are drilled in the dense subsoil and cased or sealed in the deeper area. There is therefore no physical exchange with the environment, apart from the transport of heat. A water-based working fluid circulates in a closed system of deep boreholes underground, absorbs the heat from the rock and rises to the surface again.
Since heat is always present underground, energy dissipation is safe and predictable. The thermosiphon effect, based on temperature and density differences in the fluid, causes it to rise automatically. This is comparable to a lava lamp: The mass heats up at the bottom of the lamp. The warm mass rises. The medium cools down and sinks to the bottom again. A closed system cycle is created.
Casing is only used in the two vertical boreholes, which in Hanover are around three kilometers deep. The section where the heat exchange takes place is sealed along the horizontal boreholes using a patented process developed by Eavor.