The demand for electricity in the developed world is increasing every year, and consequently the need for the construction of additional power plants is imposed. The case of the Republic of Croatia and its electricity system is no exception in this case. Thus, in 2016, the project for the construction of a combined-cogeneration gas power plant on lake Peruća near the already existing Hydroelectric power plant Peruća was presented to the public. The project was presented as a strategic investment in the neglected Dalmatian Zagora, energy independence of Croatia and Dalmatia, and as a necessary necessity in the summer months when the tourist season is at its peak and electricity needs are many times higher than during the rest of the year. Immediately after the presentation of the project, controversy arose over the issue of the construction of a thermal power plant at the largest drinking water pool in the Republic of Croatia. The paper presents the energy efficiency of the Cetina River, the available technical data on the new power plant, the problem of shutting down gas power plants in Europe; analyses the impact of the power plant operation on the environment and people and questions the economic relevance of the project. Parallel to the construction of the thermal power plant, the construction of the Dugopolje-Peruća gas pipeline and the 440kV Peruća-Konjsko transmission line is envisaged. In addition to these two projects without which the thermal power plant is not feasible, a project for the construction of a reversible hydroelectric power plant on Peruća was presented, where the upper reservoir would be on the Dinaric plateau Ravno Vrdovo. By analyzing gas prices, electricity prices from imports, available pollution data, lack of some of the data presented, existing energy plants at Cetina, water supply sites, environmental impact study we get a realistic picture of whether there is a need for new large power plants electroenergy system of the Republic of Croatia.