Comparative Evaluation of Advanced Coal-Based Power Plants

The purpose of this study is to comparatively evaluate four types of advanced conceptual power plants based on coal. With efficiency, costof-electricity, and emissions as main criteria, the evaluation was made under consistent design conditions and economic assumptions. The plants considered are a supercritical steam power plant (SC 580◦C), an indirectly coal-fired power system (HIPPS), an advanced pressurized fluidized-bed combustion power plant (PFBC), and an integrated gasification-combined-cycle power plant (IGCC). Reflecting the technology standard of the current coal power plants, a conventional steam power plant (PCC) was chosen for comparison. Exergetic and economic analyses have been performed for each type of the plants, together with parametric studies. The main sources of thermodynamic inefficiencies as well as the dominating contributors to the cost of electricity are identified. Potential improvements of both the performance and the cost effectiveness are discussed, and the environmental impact of each plant is briefly presented. The HIPPS appears to be the thermodynamically and economically most viable option, capable of achieving a 48.5% overall exergetic efficiency while allowing a levelized cost of electricity (LCE) by merely 3.7% higher than that of the PCC power plant. If the HIPPS is fueled only with coal, the system efficiency is expected to decrease by 3.7% and the LCE remains basically unchanged. The PFBC has the second highest plant efficiency, 5.8% lower than that of the HIPPS, and the lowest LCE among the four. The IGCC power plant possesses an exergetic efficiency 11.0% lower than that of the HIPPS and the highest LCE. The SC 580◦C yields the lowest overall exergetic efficiency among all the plants, 19.3% lower than that of the HIPPS. Still, it is 9.4% higher than that of the conventional PCC plant. The LCE of this plant lies between that of the HIPPS and that of the IGCC. Further elevating the steam parameters to 700◦C and 365 bar promises an increase of 7.5% in efficiency, without a necessary rise in the LCE. As a conclusion, among the four technologies, the HIPPS is the best option for the power generation based on coal in the far future. While SC power plants can be the choice to meet the short-term needs of new capacity, PFBC and IGCC plants could provide solutions for both middle-term power generation and use of low-rank fuel feedstock.