Thermodynamic analysis for definition of low-potential heat sources

This study presents a method for defining low-potential energy sources based on thermodynamic analysis. It defines low potential energy sources and presents the results of calculating temperature levels corresponding to the concept of a low potential energy source. A classification of energy sources by thermal level was carried out, including sources of cold, low-potential heat and cold at reduced temperatures, low-potential heat and cold at elevated temperatures, and high-temperature sources. The analysis demonstrates the correspondence between thermodynamic assessment and practical views of many researchers on low-potential energy sources. Conclusions about the influence of external factors on the temperature range for these sources are drawn. It is shown that factors affecting the range of low-potential temperatures include: the temperature potential of consumers, as a reference point for temperature, and the efficiency of local stations for converting heat into work or electricity. Narrowed assessment is presented based on optimal conditions for humans (22 °C), from −90 °C to 203 °C, and extended assessment based on limits of liquid water existence at atmospheric pressure and temperatures (0–100 °C) from −104 °C to 329 °C with an efficiency of heat conversion stations of 38 %.