Concept of socio-economic aspects of energy supply systems. Techno-economic, socio-economic and environmental aspects of energy supply; the current situation, trends and projections at the global, EU and Latvian context. Investment project cycles. Public regulation of energy supply. Basic aspects of pre-investment study. Market institutions and technological change, its impact on the technical and economic studies; the entrance and exit barriers. Content of the technical-economic study. The basic principles of calculation of capital investments, financial analysis of energy project and investment analysis. Calculation of long-term marginal cost of electricity production. Activities of the energy supply companies in a competitive environment. The external costs in economic calculation. Socio-economic figures for energy projects.