CYCLE DIAGRAM OF GEOTHERMAL ENERGY

Link for citation: Yankovsky S.A., Lavrinenko S.V., Tsibulskiy S.A., Yankovskaya N.S., Gamov D.L. Cycle diagram of geothermal energy. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр. 122-136. In Rus. The relevance of the research is caused by the need to develop alternative and environmentally friendly energy sources in conditions of global warming. The development of geothermal energy will make it possible to produce thermal and electric energy without emissions of CO2 into the environment and reduce the dependence of the energy sector on hydrocarbon raw materials. The main aim of this study is a comprehensive analysis of the features of geothermal power plants, including the existing technologies for converting geothermal energy to provide consumers of electric and thermal energy. Objects: diagrams of geothermal power plants operating in different geographical and climatic conditions, as well as their working fluids. Methods: analytical review of thematic publications using the materials of the databases of the RSCI, Scopus and Web of Science, a comparative analysis of the effectiveness of geothermal power plants for various indicators. Results. Currently, there are about 400 geothermal power plants in the world. The active development of geothermal energy is caused by environmental friendliness, low cost of energy produced, minimal operating costs, lack of dependence on atmospheric influences, and the absence of the need to burn fuel, etc. At the same time, most of the world's geothermal power plants use the energy of a geothermal source with a water temperature of 100–200 °C. Among the main thermodynamic cycles and thermal schemes implemented, it is possible to single out direct cycle geothermal power plants with one-stage and two-stage separation of a geothermal source, with direct supply of dry steam to the turbine, binary and combined versions. The analysis shows that direct cycle geothermal power plants have the lowest cost of installed electrical power due to the relative simplicity and high thermal efficiency, but require high parameters of a geothermal source. On the other hand, binary geothermal power plants have the highest unit cost, but can be implemented on geothermal sources with relatively low water parameters, which was the main reason for their greatest spread in the world. At the same time, the implementation of a binary geothermal power plant with a Organic Rankine сycle has a number of advantages compared to the thermodynamic cycles of Kalina, Stirling and Brighton, among which the main ones are relative ease of adaptation and application, as well as low maintenance costs.