Energy, exergy and economic analyses of new coal-fired cogeneration hybrid plant with wind energy resource

A novel configuration of a coal-fired cogeneration plant is proposed in this paper. This novel system is composed of combustion chamber, Rankine cycle, absorption chiller, alkaline electrolyzer, and methanation plant. In the proposed configuration, the heat of exhaust gas from the combustion chamber can be used in a Rankine cycle to produce electricity. The heat of exhaust gas also powers the absorption chiller to provide cooling. The exhaust gas flows through a sulfur extraction unit to separate sulfur from CO2 gas. To supply electrical power, wind turbines alongside the Rankine cycle are considered. A part of the produced electricity from both the Rankine cycle and the wind turbines can be used by an alkaline electrolyzer to produce hydrogen and oxygen. The CO2 gas from sulfur unit and hydrogen gas (H-2) provided by the electrolyzer can be delivered to a methanation unit to produce syngas (CH4) for different applications. The oxygen from the electrolyzer is injected into the combustion chamber to improve the combustion process. Results show that by using 80 units of 1 MW Nordic wind turbine to generate electricity, all of the CO2 in the exhaust gas is converted to syngas. The whole system energy and exergy efficiencies are equal to 16.6% and 16.2%. The highest and lowest energy efficiencies of 85% and 30.1% are related to compressor and steam power plants. The energy and exergy efficiencies of the wind turbine are 30.7% and 11.9%. The system can produce 40920.4 MWh of electricity and 180.5 MWh of cooling. As CO2 is consumed to produce syngas, the proposed system is capable of avoiding a significant amount of 2776 t CO2 emissions while producing 1009.4 t syngas annually. Based on economic analysis, the payback period of the system is 11.2 y, and internal rate of return is found to be 10%, which can prove the viability of the proposed configuration. (C) 2020 Elsevier Ltd. All rights reserved.