(732a) Process Sustainability Metrics Based on the Safe and Just Operating Space for Humanity

Sustainability assessment methods aim to relate the environmental, economic, and social dimensions of sustainability to help with decision making in process designs. Sustainability assessment methods use metrics and indicators to quantify impact and performance of specific parameters to provide comprehensive information that can be communicated to decision makers. These metrics are critical to identify the shortcomings and allocate resources to improve process performance and design.

Integrating sustainability assessment in chemical process design has gained interest due to the major role of chemical industry in economic, societal, and environmental sectors. The chemical industry is considered one of the primary consumers of natural resources and generators of waste and emissions, which impose significant stress of ecosystem goods and services.

The triple bottom line concept (TBL) recognizes the environmental and social dimensions in sustainability assessment have been popular in the assessments of engineering decisions. Popular sustainability assessment frameworks in the chemical engineering literature such as the indexes developed by AIChE¹ and IChemE², and the GREENSCOPE³ tool. These methods and tools evaluate different indicators based on the TBL dimensions separately, and then compare the alternatives in an aggregated manner.

One of the major shortcomings of these methods is ignoring the interactions and links between the different sustainability dimensions. That includes the true hidden costs of extracting resources and their impact on the natural ecosystems and social aspects such as justice and equity. Most methods only consider the demand of natural resources and ignore the capacity and limits of ecosystems to provide these goods and services, which can lead to the degradation of the ecosystems. Existing methods also do not consider social issues related to equitable access to resources and economic disparities.

The important role of ecosystems goods and services in sustainable process design have been discussed in the literature, and several efforts to quantify and include the supply and demand of ecosystems in process design have been developed^4,5. Other frame works such as the planetary boundaries^6,7, which defined the “safe space” and upper limits of earth systems processes, have been implemented in assessment studies on a global scale. An extension of this framework which introduced the social dimension in terms of the “just space”, propose lower limits that is necessary to meet the minimum social requirements for human wellbeing from natural resources⁸.

Since most of the design decisions are made on a process level, assessment methods need to be implemented on this scale. This ensures correct evaluation with comprehensive information and identifies the direct stakeholders. The planetary boundary framework fails to identify the safe space on finer scales and downscaling of the framework does not provide proper assessment results. There is also a challenge in identifying the connection between the “just space” and the “safe space” due to the knowledge gap between disciplines.

Ecosystems provide goods and services that represent the foundation of all economic activities that is utilized by societies. This connection is key to protect natural resources and improve the quality of human life. This work proposes boundaries to identify the “safe space” in terms of the capacity of ecosystems to provide the related goods and services. This ensures no degradation of ecosystems and provides the flexibility to be applied on a local and service shed scales.

To achieve sustainability, basic human needs from ecosystems must be met, this includes water, food, and energy. Similar to the safe space, this work proposes boundaries to identify the “just space” in a way that insures human basic rights from ecosystem services are fulfilled without causing any stress on ecological systems. These needs can be quantified by assessing the goods and services stakeholders need from the ecosystem. For example, basic demand of water for drinking, cooking, and sanitation can be calculated based on the population utilizing a watershed. This demand is then subtracted from the supply of the ecosystem represented in the “safe space” to form a more comprehensive “safe and just operating space”.

By considering the capacity of ecosystems, this work proposes sustainability metrics that combine the ecological and social boundaries to identify a sustainable design space that respects nature’s limits and ensure essential human demands are met. This work does not attempt to quantify the minimum social demand for the objectives proposed by the just space framework, like gender equality and voice. However, this work does quantify the social objectives that are related to ecosystems goods and services, such as food, water, and energy required to meet basic human needs.

This work broadens the scope of current assessment methods to include the social dimension of sustainability. The developed metrics can be utilized by assessment methods to help with process design on different scales. These metrics will be applied on case studies of chemical manufacturing processes to demonstrate the applicability of the assessment methods on multiple scales, and to identify improvement or alternatives of the process design. The results from this work can assess the performance of chemical process and provide a communication tool to stakeholders on different scales and help in the decision-making process. This can be applied to evaluate existing designs, or to assess new technologies and more sustainable processes. This effort provides a big step towards holistic sustainability assessment by accounting for the minimum social requirements while respecting nature’s limits, which contributes to human wellbeing and the prosperity of ecological systems.

References:

1- Calvin Cobb. The AIChE Sustainability Index: The Factors in Detail | AIChE. Technical report, 2009.

2- Inst. Chem. Eng. Sustainability Metrics: Sustainable Development Progress Metrics Recommended for Use in Process Industries. Technical report, Warwickshire, UK, 2014.

3- Gerardo J. Ruiz-Mercado, Raymond L. Smith, and Michael A. Gonzalez. Sustainability indicators for chemical processes: II. Data needs. Ind. Eng. Chem. Res.,feb 2012.

4- Bhavik R. Bakshi, Guy Ziv, and Michael D. Lepech. Techno-ecological synergy: A framework for sustainable engineering. Environ. Sci. Technol., 49(3):1752-1760, feb 2015.

5- Anders Bjorn, Manuele Margni, Pierre Olivier Roy, Cecile Bulle, and Michael Zwicky Hauschild. A proposal to measure absolute environmental sustainability in life cycle assessment. Ecol. Indic., 63:1-13, apr 2016.

6- Rockström, J., Steffen, (2009). A safe operating space for humanity. nature, 461(7263), 472-475.

7- Steffen, W., Richardson, K., Rockström, J. (2015). Planetary boundaries: Guiding human development on a changing planet. Science, 347(6223).

8- Raworth, K. (2012). A safe and just space for humanity: can we live within the doughnut?. Oxfam.