Integrated gasification combined cycles and repowering of local thermal power plants

In this study, technoeconomic analysis of power generation via gasification of coal, repowering electrical and environmental performances of thermal power plants and applying gasification technologies to the repowering applications are performed. For this purpose, Soma A thermal power plant, deactivated on 2010, was examined. Onsite examinations performed to observe the current status in Soma A thermal power plant. According to the design parameters obtained from power plant a model was constituted in THERMOFLEX software. Comparison of performance repowering alternatives of Soma A thermal power plant were carried out. As alternatives for performance repowering; feedwater heating, hot windbox, parallel repowering and gasification technologies are compared with in terms of technically and economically different gas turbine power ratios. A hybrid solar assisted power plant formed to investigate the effects of feed water preheating and direct steam production on the performance of thermal power plant. Solar energy is utilized by parabolic trough type solar collectors and thermal energy storage is ignored because of increasing first investment cost. In the case of implementing gasification technologies the effects of gasification with air and oxygen to the performance of power plant is investigated. In the case of gasification with oxygen lower heating value of syngas is higher than the gasification in the air. However, in this case first investment and operational costs of power plant increases. Within the scope of clean coal technologies CO2 capture and storage systems are examined in case of gasification by air. According to the results, implementation of gasification technologies increase the installed capacity of the power plant while due to the increased auxiliary consumption of the plant the net electric efficiency is decreased. In the case of entrained gasifier application the net electric efficiency of the power plant calculated more than current situation. The cheapest specific repowering cost is found in parallel repowering application. In contrast, in the case of the unit electricity price hot windbox repowering application has the lowest cost. When considering CO2 prices, post combustion CO2 capture application with the highest first investment cost is able to compete with other alternatives.As a general result, installed capacity increment and CO2 emission per installed capacity decrement in short term is obtained by repowering with gas turbines in current coal fired thermal power plants. It has a vital importance that gasification technologies and CO2 capture systems take part in future 10 years energy projects and implementation of these technologies to a pilot plant in the terms of utilizing local energy sources and decrement in foreign-source dependency.Keywords :Repowering, Integrated gasification combined cycle, gasification, clean coal technologies, CO2 capture