Abstract - This paper is dedicated to the task of energy supply planning in the market environment. The possibilities of forming coalitions between companies competing within energy production, distribution and sales are considered. In this case, for justifying the decisions and distributing the gains a cooperative game theory is used. Various methods of forming a coalition and distributing additional gains are described in this paper. The example of Riga district heating system planning presented in the paper shows the rationality and efficiency of using the considered approach. A number of power supply planning tasks where application of the cooperative