Challenges and opportunities in assessing sustainability during chemical process design

The need for incorporating sustainability principles as a design goal rather than a constraint has prompted major changes in chemical process design and engineering in recent decades. In this regard, sustainability assessment via economic, environmental, and social dimensions, a triad referred to as the triple bottom line (TBL), is becoming not only an accounting tool but also a means to re-evaluate the design of a given process or product. Nevertheless, the inherent complexity of sustainability assessment by considering the TBL gives rise to a variety of challenges that should be addressed at each stage of process design. At the outset, the design problem is open to interpretation and information is scarce; thus, the metrics for the sustainability dimensions cannot be easily implemented. In subsequent design stages, when detailed information is available, the potential for sustainability enhancement is constrained by the preliminary decisions made on the process design. This indicates that distinct sustainability metrics should be deployed at the various stages of the design task to capture and quantify the impacts derived from a process, or product, thereby facilitating their reduction. Thus, this work aims at summarizing recent developments on sustainability metrics and classifying them according to the stages of the process design at which they could be utilized.