(20a) A Detailed Strength, Weakness, and Opportunity Analysis of Existing Sustainability Metrics and the Case for Process Safety Inclusion

As the human population grows and continues to industrialize, the strain on resources and the environment grows exponentially. Sustainable practices are therefore necessary to protect the planet as well as preserve the standard of living of those inhabiting it. As the process industry allows for such a large-scale impact on both people and the planet, the quantification of sustainability is vital to monitor and regulate industry practices. From publication data, it is also clear that there is a rising demand for various tools to measure the sustainability of a process. Therefore, it is necessary to understand the development of the field of sustainability quantification.

Frameworks such as life cycle assessment, impact assessment, and the triple bottom line provide approaches to quantify, understand, and implement sustainability concepts. Many studies have expanded on these frameworks to provide a variety of methods to quantify sustainability in industry, with various strengths and weaknesses for each. The key strengths, weaknesses, and resulting opportunities of these various methodologies will be discussed. To determine the validity of existing metrics, the consistency of their results must be compared. When utilizing existing sustainability indices, significant variation was found both in the final quantification of sustainability for a single process, and in the determination of a more sustainable process when comparing two processes. These inconsistencies imply the need for additional considerations within the various indices. From the analysis of existing indices, it was determined that sustainability metrics for process industry sustainability to this point have lacked an inclusion of safety, time dependence, and quantification of the interrelations between sustainability pillars.

As process safety incidents are so intricately tied to process economic feasibility, environmental impacts, and societal acceptance, it is clear that process safety is a key aspect of process sustainability that has been disregarded until recently. This work proposes that process safety is on par with the economic, environmental, and societal aspects of sustainability for the process industry, and therefore sustainability metrics in the area should expand the triple bottom line for the basis of their methodologies. Additionally, when a process is impacted in one of these four key aspects of sustainability, the impact on other aspects should be quantified. In the case of a process safety incident, key indicators in the economic, environmental, and societal sustainability of a process will be impacted, and any sustainability metric should reflect these cascading effects. It has been well documented that implementation of process changes in the design stage leads to less cost and better results than the retrofitting of processes. In order to provide the most impactful results, a sustainability metric should therefore be usable during the process design stage, allowing for the most successful implementation of any required design changes and inherently safer design principles. Finally, due to the continuous impact from processes and due to the need for constant improvement to enhance sustainability, time dependence within the measurement is necessary. Therefore, an interrelated, time dependent quadruple bottom line methodology that can measure the sustainability of a process at the design stage is necessary to provide a thorough assessment of the sustainability of a process.