Abstract
The need for research in the field of energy efficiency and the ecological aspects of primary energy use is currently receiving considerable attention in the framework of European Union policy as well as in the Slovak Republic. It is necessary to deal with this issue not only for the needs of normal operations, but especially in the current situation, when due to the threat of the COVID-19 virus, the requirements for thermal energy are increased. A suitable way to achieve this is the use of renewable resources, in Slovakia mainly biomass, solar, wind, water and geothermal energy. Ambient air, ground heat, heat contained in groundwater and various other waste heat from technological processes represent a huge potential for the use of low-potential energy. The article is focused on solving the problem of conversion of primary energy into heat using thermodynamic cycles and compressor circulation with working substance (refrigerant) CO2.