The environmental burdens of the ethylene oxide production processes are becoming more and more important due to the release of very harmful chemical components as well as its high-energy demand. One way to moderate its environmental burdens within the energy transition period is the natural gas/biomass-based scenarios. However, this Life Cycle Assessment (LCA) study reports that natural gas is not a right alternative for this special case, where natural gas-based scenarios are less sustainable than the residual fuel oil-based scenarios particularly concerning fossil depletion (93%), freshwater ecotoxicity (76%), marine ecotoxicity (59%), human ecotoxicity (53%), terrestrial acidification (51%) and particulate matter formation (40%). On the other hand, the LCA study shows that without revamping the heart of the process technology, the reduction in the environmental burdens is possible through biomass. The biomass-based scenarios reduce the burdens from 4.40 to 4.36 MJ (equivalent of non-renewables) according to Cumulative Exergy Demand or from 2.18E-04 to 1.85E-04 (dimensionless normalized results) in accordance with ReCiPe, preparing the way to a sustainable ethylene oxide process within the energy transition period where revamping the heart of the process technology is not desired. Graphic abstract