Methodology for the Life Cycle Assessment of Various Process Design Options in Alternative Fuel Production

Abstract

Sustainable transport fuels provide an essential alternative to fossil fuels when aiming to reduce greenhouse gas emissions in the EU transport sector, especially for the transport that is difficult to electrify. The production can be achieved via multiple process routes and even different process designs within one route. Hence, the question arises how to easily and comparably assess such a variety of process designs from a techno-economic and ecological perspective. Within DLR the in-house tool TEPET+ was developed to perform semi-automated techno-economic analyses (TEA) as well as life cycle assessments (LCA) of chemical processes and technologies. Both TEA and LCA build upon a rigorous energy and mass balance of an Aspen Plus® simulation. By combining TEA and LCA in one tool a consistent assessment (same boundary conditions, functional unit etc.) of different process designs is enabled and economic and ecological trade-offs can be quantified. The application of the tool and methodology regarding the LCA and combined evaluation is demonstrated for a Biomass-to-Liquid process with two biomass sources (bark and straw) and three process configurations. While there are slight differences in environmental impact between the two biomass types, the variances between configurations are more prominent. In dependence of the major impact contributors the configuration without external electricity demand or the one with a lower biomass input to product output ration has the lowest impact. The combination of economics and ecology in the greenhouse gas abatement cost reveals a trade-off that favours the configuration with the lowest cost but medium global warming potential. Semi-automated LCAs enable the easy and comparable assessment of multiple process designs while the combination of LCA and TEA in one tool allows for a consistent sustainability assessment from both an economic an ecological point of view. Although this methodology was only illustrated for one sustainable fuel production process, it can be applied for various other chemical processes as well.