Use of coal as a main fuel at thermal power plants (TPP) and significant wear of TPP boiler equipment cause the relevance of environmental aspect consideration when organizing rational energy supply to consumers. Hence, the purpose of this study is to propose a methodical approach for planning the development of regional thermal power plants in terms of environmentally friendly energy supply. The proposed approach is oriented at using the best available technologies, based on expert appraisals and estimation methods of investment project efficiency. The object of research is described. A multistage algorithm of regional TPP development planning is presented in terms of environmentally friendly long-term energy supply. This algorithm is designed to be built in the system of economic and mathematical models for predicting the development of the fuel and energy complex. A methodical approach ensuring environmentally friendly long-term energy supply has been proposed for planning the development of regional thermal power plants.