Spatial-temporal variations and reduction potentials of volatile organic compound emissions from the coking industry in China

Coke production is a significant source of ambient volatile organic compound emissions; thus, stringent control measures must be applied. We fully characterized the trends in volatile organic compound emissions by the coking industry in China between 1949 and 2016 based on a factory-based database and process-specific emission factors. We then projected the reduction potentials in these emissions if different control policies were implemented in 2020 based on three emission scenarios. The results indicate that: (1) the emission factor of volatile organic compounds for coke plants under uncontrolled conditions was 3.065 g/kg coke, and benzene, toluene, and acetone were the most abundant emission species. (2) The annual volatile organic compound emissions from the coking industry increased by an order of magnitude from 3.38 Gg in 1949 to 1376.54 Gg in 2016. The emissions show distinct spatial characteristics, with significantly higher emissions in northern China than in other areas. (3) Compared to the uncontrolled scenario, if basic or more stringent control measures were fully implemented in China in 2020, then volatile organic compound emissions would be reduced by 59% or 82%, respectively. (4) Controlling coke oven flue gases through efficient combustion, sealing and cleaning the openings of coke ovens, and using gas blanketing or carbon absorbers in by-product facilities were the most effective technologies for controlling volatile organic compound emissions from coke production.