A Coal-Fired Power Plant With Zero Atmospheric Emissions

Abstract

This paper presents the thermodynamic analysis of a coal-based zero-atmospheric emissions electric power plant. The approach involves an oxygen-blown coal gasification unit. The resulting synthetic gas (syngas) is combusted with oxygen in a gas generator to produce the working fluid for the turbines. The combustion produces a gas mixture composed almost entirely of steam and carbon dioxide. These gases drive multiple turbines to produce electricity. The turbine discharge gases pass to a condenser where water is captured. A stream of carbon dioxide then results that can be used for enhanced oil recovery, or for sequestration. This analysis is based on a 400 MW electric power generating plant that uses turbines that are currently under development by a U.S. turbine manufacturer. The power plant has a net thermal efficiency of 42.6%. This efficiency is based on the lower heating value of the coal, and includes the energy necessary for coal gasification, air separation and for carbon dioxide separation and sequestration. The paper also presents an analysis of the cost of electricity (COE) and the cost of conditioning carbon dioxide for sequestration for the 400 MW power plant. Electricity cost is compared for three different gasification processes (Texaco, Shell, and Koppers-Totzek) and two types of coals (Illinois #6 and Wyodak). Cost of electricity ranges from 5.16 ¢/kWhr to 5.42 ¢/kWhr, indicating very little sensitivity to the gasification processes considered and the coal types used.