(96h) Integrated Environmental, Economic, & Social Lifecycle Assessment: A Novel ‘Hub & Spoke’ Methodological Framework

Sustainability is best viewed as being underpinned by three constituent impact areas, or ‘strands’: environment, economics, and society. Despite this, methodology development in life cycle assessment initially focussed purely on environmental aspects, predominantly utilising the ISO 14040 standards, while neglecting economic and societal aspects. A fully harmonised and integrated assessment framework remains elusive, preventing a detailed and holistic assessment of impact burden shifting between the environmental, economic, and social strands.

In recognition of this, the work presented herein outlines a novel ‘hub and spoke’ framework for the holistic life cycle assessment of chemical value chains. Its modular structure maximises utility in the context of chemical value chains, with hubs representing core process under an organisations control, and spokes representing competing feedstock generation routes and suppliers. In many application cases a significant number of possible hub and spoke permutations will be present. Through the incorporation of a novel aggregation procedure these are assessed simultaneously, removing the need for manual evaluation of each possibility. As with traditional methodologies, aspects such as system boundary specification, indicator selection, and allocation procedures are left at the practitioner’s discretion.

The framework’s underpinning methodology is ISO 14040 aligned across all three strands, building upon a strong methodological backbone in which a majority of practitioners are already well versed. Furthermore, it is compatible with broadly utilised characterisation methods such as ReCiPe, TRACI, and CML. Additionally, parallel integration of multi criteria decision making (MCDM), in the form of hybrid AHP-TOPSIS, weights and aggregates the assessed impact indicator results to generate a single overall ‘sustainability score’. Consequently, value chain recommendations are tailored to the commissioning organisations priorities. These overall value chain scores for each permutation are presented in parallel to the traditional objective indicator results, framing the subjective MCDM derived value chain scores and providing much valued reporting transparency.

Methodological validation was carried out through a proof-of-concept study, examining value chain performance across 19 environmental, economic and social impact indicators. The study focused on the production of soda ash in India via the Hou process, considering 35 alternative routes for feedstock production. This verified significant efficacy, reducing practitioner workloads by up to 68% and simultaneously assessing 14,580 value chain permutations. Recommendations from the model were checked against the parallel objective result, confirming that AHP-TOPSIS can be used within lifecycle assessment to screen large decision spaces without compromising scientific validity. Furthermore, it has been demonstrated that the developed lifecycle inventory structure facilitates a ‘plug and play’ philosophy in which seamless re-use in subsequent assessments is possible.

Implications of this work are far reaching, benefiting stakeholders throughout value chains, beyond improvements in environmental performance. Organisations can better inform strategic decision making around sustainable development, minimising risk of unintended secondary economic or social effects associated with planned projects or initiatives. Meanwhile, consumers benefit from the inclusion of both economic and social aspects. The increased cost of goods, often associated with more environmentally sustainable processes, are minimised, while safeguarding against impacts on quality and quantity of life.

In summary, the holistic life cycle assessment methodology presented in this work offers a robust and versatile tool for the identification of sustainable value chains. Two major advancements presented include the integration of AHP-TOPSIS and the modular approach to life cycle inventory structure.