This paper presents the results of elaboration of long-term national energy plans. The most important aim was reduction of CO2 emissions. Long-term national energy plans can be worked out with special computer programs, such as MARKAL, which is one of the well-known programs in this field. MARKAL is a dynamic linear programming "bottom-up" model, which finds the optimal development of the energy system under given technological characteristics and boundary conditions. Estonia differs greatly from other countries in the world. Oil shale is the most important fuel for power stations in Estonia.