A constructive systems approach to long-term energy development forecasting (for 30 to 40 years) is elaborated and the main methods and mathematical models for implementing it are proposed.  They are: 

-- An intersector model and method for long-term forecasting of basic indices of economic growth and national economic estimation of energy development strategies; 

-- An iterative scheme and optimization model for elaborating possible energy development strategies and comparison of tendencies in science and technology; 

-- A statistical model for forecasting final energy demand based on existing dynamics of the main indices of economic growth. 

These models and methods are tested on preliminary information.