Environmental assessment and extended exergy analysis of a “zero CO2 emission”, high-efficiency steam power plant

Aim of this paper is to analyze the performance of an innovative high-efficiency steam power plant by means of two “life cycle approach” methodologies, the life cycle assessment (LCA) and the “extended exergy analysis” (EEA). The plant object of the analysis is a hydrogen-fed steam power plant in which the H2 is produced by a “zero CO2 emission” coal gasification process (the ZECOTECH© cycle). The CO2 capture system is a standard humid-CaO absorbing process and produces CaCO3 as a by-product, which is then regenerated to CaO releasing the CO2 for a downstream mineral sequestration process. The steam power plant is based on an innovative combined-cycle process: the hydrogen is used as a fuel to produce high-temperature, medium-pressure steam that powers the steam turbine in the topping section, whose exhaust is used in a heat recovery boiler to feed a traditional steam power plant. The environmental performance of the ZECOTECH© cycle is assessed by comparison with four different processes: power plant fed by H2 from natural gas steam reforming, two conventional coal- and natural gas power plants and a wind power plant.