Updating Parameters for Comprehensive Life Cycle Assessments (LCAs) of Biopolymers
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Navigating the complexities of Life Cycle Assessment (LCA) for biobased materials illuminates a landscape marked by significant debate among stakeholders. At the heart of this discourse are the conflicting findings from various LCA studies, many of which do not consider environmental pollution, micro- and nanoplastics generation, and the long-term effects on the environment and human health, but are nonetheless being used for environmental policy making. In this “Policy & Insights” piece we will do a closer examination of the limitations and challenges inherent in LCA studies, while also carefully considering their benefits.
LCA is a systematic method widely employed to evaluate the environmental impacts of plastics and assess the efficacy of interventions aimed at mitigating plastic pollution. It involves the comprehensive analysis of environmental aspects and potential impacts associated with a product, process, or activity over its entire life cycle. This life cycle encompasses key stages such as raw material extraction, manufacturing, transportation, product use, and end-of-life disposal or recycling. Importantly, LCA is a versatile tool that can be applied to assess either entire products or specific materials and processes within a product's life cycle. The scope of an LCA is adaptable, contingent upon the specific goals and boundaries defined for the study.
The LCA process involves several steps:
Goal and Scope Definition: Clearly defining the purpose of the assessment and specifying the system boundaries, functional unit, and the environmental impact categories to be considered.
Inventory Analysis: Collecting and quantifying data on inputs and outputs for each life cycle stage, including energy consumption, raw material use, emissions, and waste generation.
Impact Assessment: Assessing the potential environmental impacts associated with the identified inputs and outputs, considering categories such as climate change, resource depletion, and human health.
Interpretation: Analyzing and interpreting the results to draw conclusions and identify areas for improvement or optimization.
Whether examining the overall environmental footprint of a product or focusing on specific materials or processes, the primary goal of Life Cycle Assessment (LCA) is to provide a comprehensive understanding of the environmental profile of a system. This information, in turn, facilitates informed decision-making aimed at minimizing environmental burdens. LCAs often play a pivotal role in shaping policy, and this has been evident through its integration into the European Union's Product Environmental Footprint (PEF) initiative. A notable example is the LCA analysis conducted to guide the EU Packaging and Packaging Waste Directive (PPWR). The assessment identified coffee pods as a product category requiring a mandatory shift towards compostable materials. Subsequently, the EU Commission incorporated these findings into the PPWR proposal, advocating for a compulsory requirement for certain products, including coffee pods, to be made of compostable materials. Looking forward, the importance of LCA is expected to extend globally, particularly with the impending UN Global Plastics Treaty. This international initiative is poised to utilize LCAs to assess the viability of biodegradable and compostable materials as substitutes for traditional plastics. Hence, addressing any discrepancies in these methodologies is crucial to ensure accurate and impactful decision-making in environmental policymaking.
Rethinking LCA: A Call for Evolution in Approach
Comparative assessments between fossil polymers and biobased materials in LCAs often encounter challenges due to the inherent disparities between these diverse materials, likened to comparing "apples" and "oranges." These evaluations lack a level playing field, leading to potentially misleading conclusions. A common discrepancy arises when comparing mechanical recycling, preserving carbon but leaking microplastics, with the biodegradation process of biobased products, releasing biogenic CO2. Instances, such as plastic straws outperforming sustainable alternatives or single-use plastic bags appearing more sustainable than cotton bags, underscore the need for a nuanced approach.
The root cause lies in the non-comparability of studies within LCAs, stemming from varying foundational rules and technological contexts. An essential shift in perspective is required, urging the comparison of the recycling processes of conventional plastics with those of biopolymers. Both can undergo mechanical, chemical, and biological recycling, with biopolymers having the added advantage of being home and industrially compostable, as well as biodegradable in the environment.
While the traditional LCA focuses on the production, use, and waste management phases, it often neglects the long-term fate of materials after disposal. This critical phase involves understanding what happens to plastics—whether they are landfilled, leaked, exported, or recycled—beyond their initial life cycle. There is currently a scarcity of discussions around the long-term fate of plastics, except in the context of mismanagement and marine littering. Notably, no significant particulate matter issue has been reported for alternative materials like paper, glass, wood, or metal, emphasizing that the unknown impacts of this extended life cycle step are unique to the behavior of plastic materials. This insight underscores the need for a more comprehensive and forward-looking approach to life cycle assessments, ensuring a holistic understanding of a material's environmental impact throughout its entire existence.
The current application of LCA also faces challenges in adequately incorporating particulate plastics. The environmental consequences of particulate plastics in the long-term fourth key phase, including issues related to landfilled, leaked, or exported plastic waste, are often omitted. The inclusion of particulate plastics in LCA is practically non-existent due to insufficient scientific understanding to conduct a comprehensive risk assessment. Presently, there is a lack of standardized characterization factors for the environmental or human health damages caused by, for instance, microplastic pollution, which further limits the ability of LCA to account for particulate plastics' short- and long-term effects. Addressing this gap in knowledge is vital to enhance the comprehensiveness and accuracy of LCA studies, particularly in the evolving landscape of plastic pollution.
LCA of Biopolymers
LCA proves instrumental in directing the development of PHA production processes, as evidenced by Koller et al.'s study on a whey-based PHA pilot plant. Utilizing the Sustainable Process Index (SPI), the study highlights the ecological disadvantages of PHA against polypropylene, primarily due to electricity consumption. However, identified optimization measures, such as increasing PHA yield and reducing fermentation energy demand, suggest the potential for PHA to become ecologically competitive with polypropylene (Koller et al., 2015).
In another study by Shahzad et al. (2016), exploring a bio-refinery system generating PHA from animal residues, LCA demonstrates the clear ecological advantage of PHA over fossil competitors. The study, also using the SPI methodology, emphasizes the distribution of ecological pressures across multiple products within the complex bio-refinery system. Furthermore, it underscores the significant influence of energy provision systems on PHA's ecological footprint, highlighting its dependency on the energy sources of respective countries. These examples underscore the pivotal role of LCA in providing valuable insights for optimizing processes and supporting decision-making during the early stages of technological development.
| Aspect | Insights from LCA |
|---|---|
| Comparing Different Raw Material Options | LCA offers a comprehensive perspective on the ecological impact associated with various raw material options, summarizing ecological pressures across the entire life cycle. |
| Identifying Ecological Hot Spots | LCA studies can pinpoint steps in both the life cycle and the process itself that substantially contribute to the overall ecological impact. These insights provide starting points for process optimization. |
| Estimation Optimization Potential | Assessing technological optimizations for ecological hot spots aids in estimating the potential reduction in ecological impact during full process development. It also allows for an evaluation of the ecological competitiveness of products. |
| Supporting Decision About Location and Size of Plants | LCA studies contribute to decisions about the site and size of production plants by considering the energy system and logistical structures, both highly contingent on spatial context. |
| Parameter | Strategies for Mitigating Ecological Impact |
|---|---|
| Raw Material | Crops like corn and sugar beet impose significant ecological impacts during cultivation. Utilizing PHA from by-product and waste flows inherently provides an ecological advantage. |
| Development Status of Technology | PHA production processes, typically in early technological development stages, can significantly enhance ecological performance by maximizing potentials in yield and energy efficiency. |
| Energy Provision | PHA processes could consume substantial process energy and electricity. Prioritizing the provision of clean electricity can dramatically reduce the ecological impact of PHA production. |
| "Refineries" Production Processes | Implementing more intricate process schemes that generate a broader product portfolio and fully utilize raw materials can decrease the ecological impact allocated to individual products. |
| Raw Material Logistics | For processes utilizing wastes, agricultural, and industrial by-products, optimizing raw material logistics is pivotal in enhancing ecological performance. Optimizing plant size and resource logistics is crucial to reduce life cycle-wide ecological impacts. |
Although standardized by the International Standardization Organization (ISO), LCA's flexibility allows for diverse interpretations, leading to disparate conclusions even within the same thematic studies. The varying outcomes in LCA studies are often rooted in differences in normative foundations. Lacking a universal ecological norm, evaluation methods exhibit normative orientations, relying on indicators like Global Warming Potential (GWP) or benchmarks such as Carbon Footprint. Combining indicators or using aggregated measures like the Sustainable Process Index (SPI) aims for a comprehensive view but introduces normative biases. Some limitations that occur when LCA assesses biopolymers are:
Societal Aspects: Critics argue that LCA may not fully capture broader social implications, overlooking aspects such as social equity and socio-economic impacts.
Land-Use Change: Indirect effects of land-use change, particularly in bio-based materials, are challenging to quantify in LCA.
Ecosystem Services: Essential benefits from ecosystems may be under-addressed in LCA, neglecting impacts on water purification, pollination, and soil fertility.
Incomplete Consideration of Externalities: Gaps in considering externalities can lead to underestimating environmental and social impacts.
Temporal Considerations: LCA's static view might not capture dynamic ecosystem changes, especially concerning slow-release materials like plastics.
Micro and nano-plastic creation: The consequences of plastic ingestion, as it degrades into micro and nanoparticles have been largely overlooked and underestimated in LCAs.
Normative disparities contribute to varying LCA results even with identical eco-inventories. Differences in process limits, eco-inventories, and functional units compound variations. The diversity in raw materials for bio-polymers, notably PHA, further challenges clear-cut outcomes in their LCA studies compared to fossil-based counterparts.
The inherent normative diversity in evaluation methods significantly impacts the outcomes of LCA studies. Addressing these challenges is crucial for a more nuanced understanding of the ecological performance of bio-polymers, especially concerning their comparison with fossil-based alternatives. The fight against plastic pollution necessitates navigating the complexities of raw material diversity, methodological variations, and a more comprehensive consideration of socio-environmental factors in LCA frameworks.
| Critical Aspect | Significance |
|---|---|
| Normative Base of Valuation | Every assessment inherently carries a normative standpoint, molding perceptions of "ecologically desirable" processes. Comparing assessments rooted in different norms becomes intricate. |
| Functional Unit | Studies evaluating end-use products (e.g., carrier bags, appliance housing) often merge manufacturing processes and material properties. This synthesis can lead to notable variations in results. |
| Development Status of Technology | PHA production processes, often on the cutting edge of innovation, hold substantial optimization potential. Hence, LCA places them at a systemic disadvantage compared to fully optimized processes producing competing fossil materials. Evaluating such processes based on pilot plant/laboratory data has limited significance. |
| Raw Material | The raw materials for PHA production exhibit considerable diversity. Agricultural crops (corn grains, sugar beet, etc.) can have some ecological impacts during cultivation, while by-products and waste flows present distinct considerations. |
| Spatial Context | The spatial context defines energy provision patterns and logistical structures, exerting significant influence over the outcomes of LCA studies. |
Future Directions: Advancing LCA
LCAs for biobased materials reveal a landscape marked by debate. Despite being a valuable tool for understanding environmental impacts to some degree, challenges arise in comparing diverse materials. The exploration of PHA production processes demonstrates a valuable role that LCAs play in guiding development and optimizing ecological performance, but also often fail to acknowledge that numerous suitable substitute materials like PHA outperform their fossil-based counterparts. Particularly when biopolymers make use of renewable energy, and industrial and ecological waste carbon as feedstock. As we move forward, addressing the normative and contextual disparities and incorporating a more comprehensive approach in LCA frameworks is essential. More research is required to develop life cycle analyses that take into account circularity measures, multiple end-of-life options, and the complete life cycle indicators to assess the performance of biopolymers.