Fig. 4: EFs for selected chemicals manufacturing processes using mass allocation and grouped by principal feedstocks.

a,b, Ethylene (a) and methanol (b) manufacturing processes using mass allocation and grouped by principal feedstocks. The contribution of each emissions source to the total cradle-to-gate EF is shown for each process. The cradle-to-gate EF shown by the black error bars is the sum of the four emissions sources. The uncertainty shown by the error bars corresponds to the 95% confidence interval as defined in Methods. The right axis shows the equivalent annual emissions from the product if all the product was manufactured using each single process exclusively. The gray shaded areas represent the uncertainty bounds of the feedstock-specific EFs for ethylene that are used later in this study when weighting ethylene EFs according to facility feedstock information as detailed in Methods. The specific processes for each bar are detailed in Supplementary Section 2.3 and a dataset containing all calculated EFs is available at https://doi.org/10.5281/zenodo.10532625. Note that the numbers at the top of each figure represent the number of chemical manufacturing processes.