Low-carbon power transition may shift mercury emissions from coal combustion to nonferrous metal smelting

Abstract

Rapidly transitioning to low-carbon energy sources is essential not only for reducing the direct emissions of toxic mercury (Hg) from coal combustion but also for fulfilling our commitments under the Minamata Convention. However, this shift could significantly increase the demand for nonferrous metals that are intensive in Hg, potentially negating the benefits of reduced Hg emissions. The effect of these nonferrous metal inputs on the overall effectiveness of Hg reduction efforts within the power sector's transition is an area that requires further investigation. Here, we evaluate the impact of China's low-carbon power transition on Hg emissions from coal combustion and nonferrous metal (mainly copper, zinc, and lead) smelting. We find that the low-carbon power transition will lead to a significant reduction (101.81 tons) of over 90% in annual Hg emissions originating from coal combustion during the period from 2021 to 2060. Unexpectedly, the pursuit of renewable energy, particularly in photovoltaic and wind power, is likely to result in a twofold increase in annual mercury (Hg) emissions from nonferrous metal smelting, totaling 5.07 tons, under current industry practices. The cumulative emissions from nonferrous metal smelting is estimated to be 370.44 tons during 2021–2060, including 65.80% power transmission equipment related and 34.30 % power generation equipment related emissions. Overall reduction through the adoption of coordinated measures in the power and nonferrous metals sectors could cut cumulative Hg emissions from nonferrous metal smelting by 57% (211.37 tons) during 2021–2060. The study emphasizes the critical need to manage emissions from metal production for a sustainable low-carbon energy transition.