Thermo-economic analysis of a solar-coal hybrid power plant

Abstract

Today when global environmental change is posing a growing challenge to the world's economy and creating doubts to survival of humanity, coal thermal power plants are under pressure to satisfy rigorous environmental regulations into attaining worldwide set millennial objectives for alleviating the effect of emission gases on the atmosphere. Owing to its abundance, it is unlikely to see the use of coal completely missing from the global energy mix within the next hundred years to come. While innovative emission reduction technologies are evolving for the better, trendy technological solutions which require reintegration of these coal plants with alternative greener fuels are growing at the moment. The hybridization of the solar power plants with fossil-fired power plants is one of the most important aspects of solar thermal utilization. Retrofitting existing power plants is a low-cost option for solar thermal projects because the steam turbine investment is no longer needed helping solar energy to expand more quickly. Among these solutions, the present paper establishes that the fuel saving in coal-fired power plant by integrating solar energy to increase the temperature of the feed water entering the boiler is an effective and economical method. An extensively used solar thermal technology i.e. parabolic trough collector has been introduced at different locations in the steam power plant to heat boiler feed water. The proposed modification in the plant saves substantial fossil fuel input. In the present investigation, the steam extracted from high pressure turbine is replaced by solar field for increasing the temperature of feed water; thereby reducing amount of heat input from the boiler considerably. The integration of the solar field also enables reduction in coal consumption as well as CO2 emissions. Solar field model that represents the actual PTC modules has been proposed, and then integrated into the coal-fired power plant. An algorithm based upon the innovative proposed model is developed in MATLAB. This model predicts useful heat input and thermal losses that occur in the tubes of the solar collector. An economic analysis exposes the benefits of using solar thermal energy to augment the electricity production of a conventional power plant along with reduction in carbon emissions and used fuel in boiler.