In this Final work, a technical-economic comparison was made between the construction of a new block of Plomin Thermal Plants named Plomin C. The values of the cost-effectiveness of the construction of the thermal power plant on gas and coal were compared. The existing thermal power plant is located in Luka Plomin and consists of two blocks, TE Plomin 1 (built in 1969) and TE Plomin 2 (built in 2000). Plomin thermal power plant is a two-block condensing thermal power plant, each with a boiler and one steam turbine. The fuel of both blocks is charcoal. The total power of the thermal power plant is 325 MW. As noted in the paper, the cost-effectiveness of the construction of the Plomin C thermal power plant at gas or coal will be compared. The total power of the new thermal power plant is 500 MW and the initial project is to build a new block on the coal fuel. For the purpose of assessing the feasibility of the construction of the new block in this paper, two ways of construction, coal fuel and propane gas are compared. The paper analyzes the unit cost of electricity produced for both variants and also analyzes in detail the environmental impact and the prevention of harmful gas emissions. For the purpose of environmental impact analysis, the current values of exhaust emissions with future values are compared to the construction of the new block are compared.