(277b) Comparative LCA for Decarbonization of Petrochemicals Using Electrification, Biomass or CO2 As Feedstocks

Chemical industry decarbonization will require an in-depth analysis of direct GHG emissions (also known as Scope 1 emissions) to identify hot spots and the scope for mitigation measures. Furthermore, the chemical industry implies complex multiproduct value chains that will require systematic structural and performance evaluations for clear allocation of impacts in order develop strategies that also address scope 2 and 3 emissions (indirect emissions). To evaluate alternatives and strategies a life cycle approach needs to be adopted. In this work, the life cycle assessment (LCA) of alternatives for decarbonizing ethylene and methanol as major petrochemical products is presented. Ethylene and methanol are generally produced from fossil feedstocks using energy intensive and CO₂ emitting process technologies. In both cases the objective is to identify hot spots, impact trade-offs and reduction of life cycle GHG emissions (covering scope 1, 2 and 3 emissions). Because ethylene is the major petrochemical produced and thus a major contributor to greenhouse gas (GHG) emissions, its decarbonization is much needed. For this process, electrification of the crackers and the use of bionaphtha (from hydrodeoxygenation of vegetable oil) was considered. Compared to the use of fossil naphtha, the use of bionaphtha allowed a 15% decrease in GHG emissions reduction, while the electrification of the crackers using renewable energy allowed a 50% decrease. The reduction achieved by combining both decarbonization alternatives was 60%. However, trade-offs with impacts such as acidification and photochemical ozone creation were identified. A similar analysis was performed for the case of methanol and preliminary results will be presented. One alternative was the use of biomass gasification for syngas production and conversion into methanol. A second alternative included the use of CO₂ and green hydrogen as feedstocks. These alternatives are compared against the process using natural gas. Given the pressure on the chemical industry to set transparent targets, measure and monitor decarbonization, the approach and results presented can provide insights on the major bottlenecks and trade-offs of the decarbonization challenge from a whole system perspective.