Identifying key environmental objectives for integrated process and fuel design

Abstract

Integrated process and fuel design enables tailoring renewable fuels for optimal production while simultaneously fulfilling desired fuel specifications. In this work, we extend the integrated process and fuel design framework from [A. König et al., Comput. Chem. Eng., 2020, 134, 106712] towards multiple environmental impact categories of the life cycle assessment methodology as additional objectives to “production cost” and “global warming impact”. We then apply the technique of [G. Guillén-Gosálbez, Comput. Chem. Eng., 2011, 35(8), 1469] to reduce the high dimensionality of the objective vector while still covering the major trade-offs of the optimization problem. Commonly, the input data required for this technique are normalized. We analyze the influence of normalization variants on the identification of the key environmental objectives. For the specific case of designing advanced spark-ignition engine fuels, our findings suggest that “land use” and “resource use of minerals and metals” represent key environmental objectives in addition to “production cost”. These key objectives hold for both current and future technologies for feedstock and utility supply as well as different normalization variants. Our subsequent multi-objective optimization with these key objectives demonstrates that the obtained renewable bio-hybrid fuels, produced from biomass and renewable electricity, can balance the benefits and drawbacks of both biomass- and electricity-based fuels.