Abstract <p>The article presents modern environmental requirements and the current state of the art in the field of cleaning flue gases from sulfur dioxide at thermal power plants in Russia and abroad. The most promising methods of flue gas desulphurization for implementation in the near future at thermal power plants in Russia are presented, and the experience of the All-Russia Thermal Engineering Institute (VTI) in the design and implementation of such installations is described. The experience of creating a domestic industrial highly efficient and waste-free installation for cleaning exhaust flue gases of thermal power plants from sulfur dioxide with a capacity of 1.5 million m³/h (under normal conditions) using ammonium sulphate technology, the final product of which is fertilizer, is considered. The technical solutions applied in the development of the basic design of this desulphurization system are presented based on the experience of developing a pilot industrial plant using ammonia-sulphate technology (AST) at the Dorogobuzhskaya TPP and taking into account the characteristics of the fuel being burned as well as the results of mathematical modelling of a device for introducing flue gases into a gas precooling apparatus (prescrubber). The article presents the results of the development of a project for a simplified “wet-dry” flue gas desulphurization unit with an efficiency of up to 50% for a boiler with a steam capacity of 670 t/h as well as the results of mathematical modeling of the process of injecting lime suspension droplets into the flue gas flow in the prechamber of an electrostatic precipitator and their evaporation. The article presents data on the preliminary feasibility study of the use of wet limestone desulphurization technology (WLDST) to reduce sulphur dioxide emissions taking into account the requirements of environmental legislation for a number of thermal power plants in Russia.</p>