Reducing CO_2 Emissions of a Coal-Fired Power Plant via Accelerated Weathering of Limestone: Carbon Capture Efficiency and Environmental Safety

摘要

Reducing CO_2 emissions is a key task of modern society to attenuate climate change and its environmental effects. Accelerated weathering of limestone (AWL) has been proposed as a tool to capture CO_2 from effluent gas streams and store it primarily as bicarbonate in the marine environment. We evaluated the performance of the biggest AWL-reactor to date that was installed at a coal-fired power plant in Germany. Depending on the gas flow rate, approximately 55% of the CO_2 could be removed from the flue gas. The generated product water was characterized by an up to 5-fold increase in alkalinity, which indicates the successful weathering of limestone and the long-term storage of the captured CO_2. A rise of potentially harmful substances in the product water (NO_2~-, NO_x~+, NH_4~+, SO_4~(2-), and heavy metals) or in unreacted limestone particles (heavy metals) to levels of environmental concern could not be observed, most likely as a result of a desulfurization of the flue gas before it entered the AWL reactor. At locations where limestone and water availability is high, AWL could be used for a safe and long-term storage of CO_2.