Unpacking LCAs in Advanced Recycling: Methodological Insights and Sustainability Considerations
What are the essential elements, best practices and uncertainties when conducting LCAs involving advanced recycling?
LCAs are widely used to evaluate potential environmental impacts of goods and services, including chemical recycling technologies such as pyrolysis, depolymerization, and dissolution. They have been standardized internationally in the ISO 14040 series since 1996, with subsequent series standards on carbon and water footprinting, organizational LCA, and Type III Environmental Declarations.
Conducting an LCA requires a comprehensive, transparent, and science-based approach to assess a comprehensive range of impact categories, as available. Best practices include clearly defining the goal, scope, system boundary, functional unit, allocation approaches, transparency in choices and assumptions used in modeling, ensuring consistent methodologies, and incorporating high-quality and relevant data to capture the full life cycle from raw materials to end-of-life management.
LCAs can offer valuable insights into improved product and process design, uncover operational and resource efficiencies, and identify bottlenecks and hotspots. They also have limitations and uncertainties that can influence the results and their interpretation. These derive from the diversity and inconsistency of definitions, frameworks, methodologies, standards, guidelines, and databases with baselines and averages that may not align geographically or temporally with the study in question. Further complexities include the discretionary and subjective choices made by LCA practitioners, which can result in vastly different LCA outcomes even when assessing the same product or technology within the same industry or sector located in the same region.
How do LCAs Support Understanding of Product/Technology Impacts?
Understanding LCA results requires context. For example, ISO 14044 mandates that whenever LCA results are shared with any third parties in any form, a third-party LCA report needs to be made available to those parties. If the LCA study further intends to support comparative assertions, i.e., conclusions on the overall environmental superiority of one product over a competing product, which are intended to be communicated to the public, then the report further needs to undergo a critical review by a panel of no less than three independent experts. Such critical review is meant to protect interested parties such as material or technology providers, customers, and the general public from bad decisions based on biased, incomplete, or otherwise faulty data and conclusions.
To reduce variability when communicating LCA results in a B2B or B2C setting Type III Environmental Product Declarations (EPD) were developed in 2006 (ISO 14025). Thereafter, consensus-derived Product Category Rules (PCR) define things like the functional or declared unit, the system boundary, allocation approaches, and life cycle impact assessment methods to maximize comparability across EPDs and improve decision making in procurement and consumer choice. These EPDs have gained traction in the building & construction (B&C) sector, with sector-specific standards ISO 21930 and EN 15804 adding even more specificity to ISO 14025. A similar path for the products of chemical recycling could be considered.
Despite their complexity, LCAs are the predominant tool to support product and technology environmental sustainability claims and can be one source of information to support decision-makers in product development, marketing, procurement, business strategy, and finance. Due to current limitations, LCAs are not suitable as the sole determinant for financial decisions, policymaking, or substantiating sustainability. Examples of such analyses may include Environmental Impact Assessment (EIA), Life Cycle Costing (LCC), Social LCA (sLCA), or Risk Assessment (RA).
Understanding the Scope of an LCA
Many LCAs are narrowly scoped with boundaries unrepresentative of the actual life cycle, and often focus on a limited set of metrics, for instance, climate and emissions, while overlooking broader environmental impacts (e.g., water use, toxicity, biodiversity effects) and economic and social factors (e.g., job creation, affordability, community health and safety, safety of products) that are critical for understanding systems-level impacts. A narrow scope may provide strong information on a dimension of performance, but it can also lead to misleading conclusions about the benefits and risks throughout actual life cycles, creating rebound effects, shifting risks across supply chains, and potentially misguiding the public and policymakers about the actual sustainability of a given product, technology, or process.
To align with the principles of sustainability—balancing economic, social, and environmental dimensions—it is essential to incorporate a broader range of environmental impact categories and address the social and economic factors. Without these additional considerations, conventional LCAs cannot serve as a standalone tool for evaluating sustainability. As LCAs are increasingly viewed as a core element in policymaking and investment decisions, it is more important than ever to understand and address the challenges and uncertainties they present. The lack of proper contextualization, accurate scoping, and transparency about a study’s limitations and assumptions may distort the life cycle benefits as well as the risks.
How do “Avoided Emissions” Factor into LCAs for Pyrolysis, Depolymerization and Dissolution?
In LCAs for advanced recycling “avoided emissions” refer to greenhouse gas reductions that occur when these processes displace more carbon-intensive alternatives, such as virgin plastic production, landfill disposal, or incineration. Including avoided emissions can add valuable context and insights to an LCA in understanding the net environmental benefits of chemical recycling. However, avoided emissions must be applied transparently, with clearly defined assumptions, methodological rigor, and well-established baseline scenarios and system boundaries. Full-system comparisons are essential to prevent misleading conclusions, as key factors such as conversion rates, energy and process efficiency, end market substitutions, and regulatory and market dynamics significantly influence overall calculated avoided emissions.
From a sustainability perspective, LCAs should expand beyond avoided emissions and encompass a broader range of environmental factors, including the economic and social dimensions of sustainability. A comprehensive life cycle approach ensures that chemical recycling is assessed not only for its climate and emissions benefits but also for its broader impact on system-wide sustainability, helping to prevent risk-shifting or unintended trade-offs elsewhere in the value chain.
How are “avoided emissions” considered in a particular product LCA?
The use of “avoided emissions” is somewhat controversial in the context of an LCA for a particular product. In fact, that phrase is not defined or used by any product-level accounting standard in the ISO 14000 series. Instead, it is borrowed from organizational carbon accounting where it denotes a "greenhouse gas emission reduction that occurs outside the organizational boundaries of the reporting organization as a direct consequence of the use of its products” (ISO 14050, 3.9.16), which aligns with WBCSD’s Guidance on Avoided Emissions . However, according to ISO’s Net Zero Guidelines, these reductions “cannot be included in claims of progress towards Scope 1, Scope 2, and Scope 3 targets” , and ISO 14067 on Carbon Footprints of Products doesn’t mention avoided emissions at all.
Regardless, avoided emissions may find their way into product-level assessments, most frequently under the monikers "counterfactual credits” or “upstream system expansion”, where one subtracts something that doesn’t happen from that which does happen instead. In advanced recycling, this may mean that you model the environmental footprint of a recycled product made from waste feedstock (A), and then subtract the emissions associated with the avoided waste treatment of the same amount of waste feedstock (B).
There are variety of conceptional and practical challenges here:
As indicated by the word “consequence” in the above ISO definition, these avoided emissions are a form of “consequential LCA” that aims to calculate the overall increase or reduction in environmental loads due to a move away from the status quo, e.g., by diverting a waste stream from incineration to advanced recycling.
This is different from the “environmental footprint” of a recycled product by itself, which is based on “attributional LCA” that is only concerned with what happens rather than with what does not happen.
While there are cases in attributional LCA where emissions can be subtracted, it is generally done to eliminate real, physical co-products rather than anything counterfactual.
True consequential LCA would need to model how the emissions of conventional waste management would change when a certain waste fuel is diverted to recycling. A more simplistic avoided emissions calculation implies that, e.g., waste incineration emissions would decrease proportionally, thereby discounting the possibility of operators simply switching to another waste fuel to make up the difference.
If the goal is to calculate the percentage reduction in, e.g., GHG emissions, of moving from the status quo to advanced recycling, then the status quo would need to be represented by the sum of virgin/fossil material production (C) and conventional waste management (B) as these two are both part of that status quo.
If one instead subtracts B from A, any percentage reductions will be higher than they should be even as the absolute emission reduction stays the same. (Footnote: If A=2, B=1, and C=3, then A/(B+C)-1=-50% whereas (A-B)/C-1=-67% reduction).
This becomes even more problematic when (A-B) results in a negative number, which can be misinterpreted as, e.g., a negative carbon footprint (which it is not) and lead to claims of emission reductions >>100%, which are not meaningful. (Footnote: If A=2, B=4, and C=4, then (A-B)/C-1=-150%).
As such, avoided emissions need to be scoped, justified, applied, and communicated with caution. But even then, results may be taken out of context and misrepresented, whether intentionally or accidentally. As such, most EPD program operators today do not allow for avoided emissions to be included in Type III EPDs.