The paper aims in examining and evaluating the state of the art in technological concepts towards zero-emission coal-fired power plants. The discussion is based on the evaluation of a novel concept dealing with the carbonization-calcinations process of lime for CO2 capture from coal-fired power plants, compared to the integration of CO2 capture in the Integrated Gasification Combined Cycle power plants. In the novel concept, coal is gasified with steam and lime. Lime absorbs the CO2 released from the coal, generating limestone. The produced gas can be a low-carbon or even a zero-carbon (H2) gas, depending on the ratio of lime added to the process, and can be used in state-of-the-art combined cycles for electricity generation, generating almost no CO2 OR other harmful pollutants. The limestone is regenerated in a second reactor where pure CO2 is produced, which can be either sold to the industry or sequestered in long-term disposal areas.
Results from thermodynamic simulation dealing with the most important features for CO2 reduction are presented concerning both technological options, including the operating characteristics and the main figures of the plants heat balances. An economic comparison is made, taking into account investment and operating costs, in order to assess the electricity cost related to the two different technological approaches.
The cycle calculations were performed with the thermodynamic cycle calculation software ENBIPRO (ENergie-Bl1lanz-PROgram). ENBIPRO is a powerful tool for heat and mass balance solving of complex thermodynamic circuits, calculation of efficiency, exergetic and exergoeconomic analysis of power plants. The software code models all prices of equipment that usually appear in power plant installations and can accurately calculate all thermodynamic properties (temperature, pressure, enthalpy) at each node of the thermodynamic circuit, power consumption of each component, flue gas composition etc. The code has proven its validity by accurately simulating a large number of power plants and through comparison of the results with other commercial software.