Integration of Sustainability Assessment and Global Optimization for Sustainable Production of Biofuels and Chemicals

Nowadays Chemical Engineers are faced with the challenging task of designing chemical processes that are not only technically viable and economically attractive, but also environmentally benign and socially acceptable. In order to develop more sustainable chemical processes – and therefore contribute towards a sustainable development – sustainability principles must be embed throughout the conceptual and development stages of the design, e.g. design appraisal. Existing methods such as superstructure-based optimisation enables to maximize economic potential or minimise costs of processes. Whilst these improvements can lead to more environmentally friendly processes through a more efficient use of raw material and energy resources, other sustainability aspects such as process safety fall outside the scope of current methods developed for process design. For example, traditional methods for developing superstructure-based process for the sustainable production of biofuels and chemicals consist of a sequential rather than integrated approach, were life cycle assessment is used to quantify the environmental impacts of an already “optimised design”, i.e. maximum profit or minimum costs. Such approach can only inform on the current environmental sustainability performance of a design without guaranteeing to be the most sustainable option. Recent studies have addressed part of this problem through the development of optimization models that consider environmental and economic criteria simultaneously. However, these models tend to rely on single environmental metrics such as global warming potential. In order to contribute towards the design of more sustainable processes, this project aims to develop an optimization-based framework that integrates sustainability metrics relevant to the bio-based fuels and chemicals sector.

The selection of relevant sustainability criteria and corresponding metrics will be carried out along with the development of an optimisation model capable of integrating such metrics together with process models, often resulting in a mixed-integer nonlinear programming model. Different methods and tools will be developed and used for these purposes, including life cycle assessment and global optimization techniques. Whilst the methodology will be applied to a specific bio-based chemical production, it will be generic and applicable to the production of a wide range of bio-based fuels and chemicals. The outputs of the project will aim to guide chemical engineers and the chemicals sector to identify the most sustainable routes for producing biofuel and bio-based chemicals, as well as to determine the most sustainable pathways for specific feedstock including biomass.