Conceptual design, energy, exergy, economic and water footprint analysis of CO2-ORC integrated dry gasification oxy-combustion power cycle

Abstract

Among various techniques for CO2 capture and sequestration from coal-fired power plants, Dry Gasification Oxy-Combustion (DGOC) is a promising technology due to its efficiency, in-situ sulphur capture, and low water usage. In this work, a novel DGOC power cycle integrated with CO2-Organic Rankine Cycle (CO2-ORC) has been proposed for power generation and carbon capture. This study presents Energy, Exergy, Economic, and water footprint analysis of DGOC and its integration with CO2-ORC for different operating pressures and with different types of coal using Aspen Plus simulator. Steam cycle and CO2-ORC have been optimized for the process. Integration of CO2-ORC not only reduces the penalty for CO2 capture but also improves the efficiency by providing extra power output. Integration of CO2-ORC shows improvements in energy, exergy, and economics. Energy analysis shows a maximum increase in efficiency of 6.92% points by integrating CO2-ORC with DGOC for Bituminous coal and a maximum increase of about 6.7% points for high ash coal. The highest thermal energy efficiency of about 41.63% was noticed for Bituminous coal DGOC with CO2-ORC. Exergy analysis shows a positive impact of CO2-ORC integration for all operating pressures with a maximum increase of 5.74% points and 5.87% points for bituminous and high ash coals respectively. Economic analysis shows that combining CO2-ORC improves the specific capital cost of the cycle by 13.17% and 13.27% for the Bituminous and high ash coal cases respectively. Levelized cost of electricity (LCOE) analysis shows an improvement of 12.94% for Bituminous coal and 12.69% for high ash coal by the addition of ORC. The water usage for the plant is also reduced significantly with the addition of CO2-ORC.