Opportunities of consequential and attributional modelling in life cycle assessment of wastewater and sludge management

Heimersson, Sara; Svanström, Magdalena; Ekvall, Tomas

doi:10.1016/j.jclepro.2019.02.248

Cited by 24 publications

(11 citation statements)

References 26 publications

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“…There are cases where the economic value does not reflect a causality, because the processes are not driven by the expected profit but by concern for, e.g., the environment. These include noncommercial processes such as municipal wastewater treatment plants [30] and landfills. In these cases, the economic value is less valid and might not even be possible to use as basis for the allocation.…”

Section: Partitioning In Attributional Lcamentioning

confidence: 99%

Attributional and Consequential Life Cycle Assessment

Ekvall¹

2020

Sustainability Assessment at the 21st Century

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An attributional life cycle assessment (ALCA) estimates what share of the global environmental burdens belongs to a product. A consequential LCA (CLCA) gives an estimate of how the global environmental burdens are affected by the production and use of the product. The distinction arose to resolve debates on what input data to use in an LCA and how to deal with allocation problems. An ALCA is based on average data, and allocation is performed by partitioning environmental burdens of a process between the life cycles served by this process. A CLCA ideally uses marginal data in many parts of the life cycle and avoids allocation through system expansion. This chapter aims to discuss and clarify the key concepts. It also discusses pros and cons of different methodological options, based on criteria derived from the starting point that environmental systems analysis should contribute to reducing the negative environmental impacts of humankind or at least reduce the impacts per functional unit: the method should be feasible and generate results that are accurate, comprehensible, inspiring, and robust. The CLCA is more accurate, but ALCA has other advantages. The decision to make an ALCA or a CLCA should ideally be taken by the LCA practitioner after discussions with the client and possibly with other stakeholders and colleagues.

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Section: Partitioning In Attributional Lcamentioning

confidence: 99%

Attributional and Consequential Life Cycle Assessment

Ekvall¹

2020

Sustainability Assessment at the 21st Century

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“…Yet, it is hard to even consider a world without any multifunctional process and thus it has become a general systematic issue of concern. The multifunctionality issue does not only relate to the functions of product flows but also the function of waste treatment [79]. See also the work of Schaubroeck et al [80] for a broader overview, including a coverage of waste valorization as multifunctionality issue.…”

Section: How Multifunctionality Is Dealt Withmentioning

confidence: 99%

Attributional & Consequential Life Cycle Assessment: Definitions, Conceptual Characteristics and Modelling Restrictions

et al. 2021

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To assess the potential environmental impact of human/industrial systems, life cycle assessment (LCA) is a very common method. There are two prominent types of LCA, namely attributional (ALCA) and consequential (CLCA). A lot of literature covers these approaches, but a general consensus on what they represent and an overview of all their differences seems lacking, nor has every prominent feature been fully explored. The two main objectives of this article are: (1) to argue for and select definitions for each concept and (2) specify all conceptual characteristics (including translation into modelling restrictions), re-evaluating and going beyond findings in the state of the art. For the first objective, mainly because the validity of interpretation of a term is also a matter of consensus, we argue the selection of definitions present in the 2011 UNEP-SETAC report. ALCA attributes a share of the potential environmental impact of the world to a product life cycle, while CLCA assesses the environmental consequences of a decision (e.g., increase of product demand). Regarding the second objective, the product system in ALCA constitutes all processes that are linked by physical, energy flows or services. Because of the requirement of additivity for ALCA, a double-counting check needs to be executed, modelling is restricted (e.g., guaranteed through linearity) and partitioning of multifunctional processes is systematically needed (for evaluation per single product). The latter matters also hold in a similar manner for the impact assessment, which is commonly overlooked. CLCA, is completely consequential and there is no limitation regarding what a modelling framework should entail, with the coverage of co-products through substitution being just one approach and not the only one (e.g., additional consumption is possible). Both ALCA and CLCA can be considered over any time span (past, present & future) and either using a reference environment or different scenarios. Furthermore, both ALCA and CLCA could be specific for average or marginal (small) products or decisions, and further datasets. These findings also hold for life cycle sustainability assessment.

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“…These two contradictory product system definitions in the ISO standard can hence be related to the difference in ALCA and CLCA. Studies have showcased the considerably different outcomes that can be obtained between ALCA or CLCA for the same studied product (Wardenaar et al, 2012;Weidema, 2017;Heimersson et al, 2019;Schaubroeck et al, 2021a). In the context of ISO 14040-14044, the inconsistency of the product system definition in general and the need for a differentiation between attributional and consequential thinking has already been highlighted by Weidema (2014), although the definitions presented in latter article are not in line with UNEP-SETAC (2011) definitions, and are presented without reference and without consensus.…”

Section: Inconsistencies Concerning Product System and Multifunctiona...mentioning

confidence: 99%

“…Most notably, inconsistencies and/or lack of clarity concerning the aspects of product system definition and multifunctionality, similar to those present in the ISO standards and possibly originating from them, can also be found in LCA guidance documents, LCI databases and case studies. For example, many studies still apply partitioning to address multifunctionality problems at the level of production processes (following attributional thinking) in combination with the substitution approach for the multifunctionality of waste valorization (following consequential thinking), which is inconsistent if the aim is to conduct either ALCA or CLCA (Schrijvers et al, 2016;Heimersson et al, 2019;Schaubroeck et al, 2021a). Such a combination addresses an unclear and commonly not specified research question, in between consequential and attributional thinking.…”

Section: Multifunctionality Solution Typesmentioning

confidence: 99%