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

Reducing CO 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 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 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. A rise of potentially harmful substances in the product water (NO, NO, NH, SO, 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.