Developing a systematic framework for consistent allocation in LCA

Abstract

Purpose Multifunctionality in life-cycle assessment (LCA) is solved with allocation, for which many different procedures are available. Lack of sufficient guidance and difficulties to identify the correct allocation approach cause a large number of combinations of methods to exist in scientific literature. This paper reviews allocation procedures for recycling situations, with the aim to identify a systematic approach to apply allocation. Methods Assumptions and definitions for the most important terms related to multifunctionality and recycling in LCA are given. The most relevant allocation procedures are identified from literature. These procedures are expressed in mathematical formulas and schemes and arranged in a systematic framework based on the underlying objectives and assumptions of the procedures. Results and discussion If the LCA goal asks for an attributional approach, multifunctionality can be solved by applying system expansion-i.e. including the co-functions in the functional unit-or partitioning. The cut-off approach is a form of partitioning, attributing all the impacts to the functional unit. If the LCA goal asks for a consequential approach, substitution is applied, for which three methods are identified: the end-oflife recycling method and the waste mining method, which are combined in the 50/50 method. We propose to merge these methods in a new formula: the market price-based substitution method. The inclusion of economic values and maintaining a strict separation between attributional and consequential LCA are considered to increase realism and consistency of the LCA method.Conclusions and perspectives We identified the most pertinent allocation procedures-for recycling as well as coproduction and energy recovery-and expressed them in mathematical formulas and schemes. Based on the underlying objectives of the allocation procedures, we positioned them in a systematic and consistent framework, relating the procedures to the LCA goal definition and an attributional or consequential approach. We identified a new substitution method that replaces the three existing methods in consequential LCA. Further research should test the validity of the systematic framework and the market price-based substitution method by means of case studies.

Life Cycle Management Approaches to Support Circular Economy

“…It was also pointed out that one of the main challenge to overcome in the LCA field, within the circular economy context is the quantification of the benefits from recycling, both in terms of substituted materials and quality of the secondary material [16][17][18][19][20]. It was also noticed that an important contribution to solve the related issue of multi-functionality and substitution of primary material has been provided by the Product Environmental Footprint (PEF) pilots initiative through the definition of the Circular Footprint Formula [21].…”

Life cycle assessment of low temperature asphalt mixtures for road pavement surfaces: A comparative analysis

“…In order to understand the potential environmental advantages and disadvantages related to the use, 10 in wearing courses, of low-temperature asphalt mixes with and without RAP content, the reference 11 pavement structure ( Figure 2) constituted by layers made of conventional HMA without RAP content 12 was compared to four alternative structures with equal geometry, but in which the wearing course of 13 the initial structure, and subsequent M&R treatments, was made of WMA produced according with two 14 different technologies (i.e., foaming and CECABASE ® additive) to lower the manufacturing 15 temperature, and with and without the adding of RAP. Furthermore, the set of alternative mixtures was 16 completed with the consideration of a conventional HMA with a RAP content equal to 50%, thus rising 17 to 6 the total number of pavement sections to be analysed and compared. The inventory data required to perform a LCA study are classified into two categories: primary 4…”

“…French processes and conditions were used as inputs and outputs when modelling the processes covered 10 by the several sub-components integrating the system boundaries. Specifically, the primary data include 11 mainly: (1) the composition of the mixtures; (2) the annual fuel consumption (FC), production and life 12 period of asphalt mix plants; (3) Regarding the secondary data, they are mainly related to the inventory analysis of (1) raw 15 materials, (2) fuels, and (3) construction, transportation, and on-road vehicles operation, and they were 16 obtained from existing publicly available reports and the ecoinvent database version 3.2, but modified 17 whenever possible and suitable to best approximate French conditions by using French energy 18 inputs/mixes. 19 20 The life cycle inventory (LCI) stage consists of the real data collection and modelling of the system.…”

“…14 In one of the WMA production technologies considered in this study, CECABASE ® was used as a 15 chemical additive. According to the scarce information available, this additive is made up of fatty acids, 16 namely tetraethylenepentamine polyamides 17…”

“…procedures and sustainability assessment methodologies to certify the sustainability of the studied 15 technologies to the benefit of the European community. Some of the promising sustainable technologies 16 commonly mentioned in the literature and studied in the framework of this research project are the 17 asphalt mixes requiring lower manufacturing temperatures, such as (1) warm mix asphalt (WMA) 18 (Kristjánsdóttir et warm mix asphalt (HWMA) and (3) cold mix asphalt technologies (FHWA, 2016). 21 WMA is the name used to designate a set of technologies by which the traditional HMA is allowed 22 to be manufactured, transported, placed and compacted at lower temperatures.…”