Researchers at the Tokyo Institute of Technology have partnered with engineers from Sanoh Industrial to develop "stabilized heat cells" technology that should replace typical geothermal power plants. It eliminates their main drawback - the need to use a coolant with a temperature of about 180 ° C, water vapor, which spins the turbines of the generators. Heat cells are said to work well below 100 ° C, generating electricity directly from heat.
The cell is based on a three-layer structure - a germanium semiconductor, an electron transport layer, and a copper-based solid electrolyte source. On both sides, two electrodes are adjacent to the structure, which form a closed circuit with fasteners under load. Now, if the cell is heated, electrons from germanium will rush through the transport layer to the electrode, forming a movement of particles or an electric current. Having passed through the load and wasting some of the energy, the electrons will reach the electrolyte and, with the help of redox reactions, will return to the semiconductor.
Such a battery has a fundamental flaw that Japanese physicists have been able to turn into an advantage. As you work, copper ions will be scattered throughout the system and the resource for redox reactions will be exhausted. But if you apply an external voltage, then the movement of electrons will resume, and most of the ions will return to the electrolyte. The result is a stable system with a long service life and minimal maintenance costs.
Technology diagram from developers
The developers are not yet ready to create a prototype of a geothermal battery, the technology is experimental. There are questions about the safety of the multilayer structure during temperature fluctuations, and the main component, germanium, cannot be called cheap. But there is zero emissions, there is no harmful radiation and, in theory, heat cells can be used wherever there is an excess of heat. For example, as a "symbiont superstructure" on various large energy-consuming mechanisms.