Assessment and Enhancement of the Energy Supply System Efficiency with Emphasis on the Cogeneration and Renewable as Main Directions for Fuel Saving

The paper presents methods for assessing economic, resource and environmental efficiency of cogeneration plants (CPs) and energy supply systems as a whole and ways of its improvement, the main of which are the development of cogeneration and renewable energy sources (RES). The problem of allocating fuel and financial costs at the combined production in accordance with the criterion of equal profitability of supplied energy products is solved. The methods allow determining specific indicators of supplied energy products. The technology of introducing RES-based power plants to the energy supply systems by means of using unstabilized RES-based power for direct fuel substitution in thermal cycles of gas-turbine (combined cycle) and steam-turbine plants (the wind is viewed as the most promising type of RES). Connection of wind power plants to an electric grid through thermal power plants allows us to avoid solving the problems of maintaining power quality and operating reserve of the wind power plants capacity in the power system and also to use wind energy at the plants of combined heat and high-quality electric power production, small ones included. The technology can promote smooth transition to hydrogen energy. It is shown that the cogeneration saves more than 20% of fuel, and its combination with wind power station – more than 50%.