Abstract
Producing ethylene from atmospheric CO2 using renewable electricity offers a carbon-negative alternative to conventional steam cracking. This study examines the economic feasibility of integrating a KOH based direct air capture (DAC) plant with a membrane electrode assembly (MEA) CO2 electrolyzer and downstream separation for a plant designed to output 75 kt of ethylene annually. The resulting levelized cost of ethylene produced at this facility was estimated to be $9.64/kg or approximately ten times more than the price of ethylene currently being produced using petrochemical processes. Combined costs associated with operating the electricity generation systems and operating the DAC system account for greater than 70% of the total annual expenditure. Parametric studies were performed and results indicated that single pass CO2 conversion rate, electricity tariff and cost of capital have the greatest impact on the economics of this process. Under current economic conditions, a break-even carbon removal credit of about $700/t CO2 would need to be established for this project to be viable. Advances in DAC technology, improvements in design for electrolyzers and future carbon pricing policies may make the effective production cost of ethylene produced from CO2 by electrolysis competitive with that of ethylene produced from fossil sources by the late 2040's.