Life Cycle Assessment & Circular Economy

Life Cycle Assessment (LCA)

• Comprehensive analysis of a product’s entire life cycle to evaluate sustainability and environmental effects.
  • Tracks impacts from raw-material extraction → energy production → manufacturing → use → reuse/maintenance → disposal/end-of-life.
  • Sometimes phrased as “cradle-to-grave” (linear) or “cradle-to-cradle” (circular).
• Cannot yield a perfectly precise result; instead offers a comparative decision-support tool.
• Key motivations
  • Identify & quantify environmental “hot spots.”
  • Find alternative processes that lower $\text{CO}_2$ emissions, water use, toxic releases, etc.
  • Provide evidence for marketing claims ("green" products) or for third-party certifications.
  • Enable goal-setting for corporate & governmental climate policies.

Standard LCA Framework

• Goal & Scope Definition
  • Clarify why the study is done and what product/service is assessed.
  • Define functional unit & system boundaries (temporal, geographical, technological).
• Inventory Analysis (LCI)
  • Compile a flow model of all inputs (resources, energy) and outputs (emissions, waste) across the life cycle.
• Impact Assessment (LCIA)
  • Translate LCI flows into impact categories (e.g., climate change, eutrophication).
  • Assess magnitude & significance of each impact.
• Interpretation
  • Evaluate results in context; identify limitations & uncertainty.
  • Provide actionable recommendations; iterate if needed.

Environmental Impact Categories (common set)

• Climate change / global warming potential
• Acidification (formation of acid rain)
• Eutrophication (N & P release → algal blooms)
• Cumulative energy demand / energy loss
• Radiation exposure
• Land-use change
• Air pollution (particulates, $\text{NO}<em>x$, $\text{SO}</em>x$, etc.)
• Resource depletion (minerals, fossil fuels)
• Water use & stress
• Ecotoxicity (toxic releases harmful to biota)

Benefits & Applications of LCA

• Process & product design: redesign for lower footprint.
• Marketing & claims: substantiate “eco-friendly” labels.
• Continuous improvement: hotspot analysis pinpoints priority actions.
• Verification/certification: e.g., Environmental Product Declarations (EPDs).
• Policy support: quantifiable metrics for $\text{GHG}$ targets and circular-economy mandates.

Linear Economy Model

• Sequence: Take → Make → Use → Dispose.
• Relies on finite resource extraction and produces waste at end-of-life.
• Common term: “cradle-to-grave.”
• Example (construction industry):
  • Manufacture (cement, steel) → Use/operation (building lifetime) → Demolition waste
  • Generates high carbon footprint and landfill burden.

Circular Economy Model

• Sequence: Make → Use → Recycle/Reuse/Repair → Make … (closed loops).
• Aims for zero waste; every residual stream becomes a resource.
• Relies on renewable energy; energy itself cannot be recycled (2nd law: $\Delta S_{\text{isolated system}} \ge 0$).
• Systems thinking: considers short- & long-term impacts across the entire value chain (needs LCA integration).
• Guiding principles
  • Eliminate waste & pollution.
  • Circulate products & materials at highest value.
  • Regenerate nature (restore soils, biodiversity).

Technical vs. Biological Materials

• Technical (synthetic, non-biodegradable): plastics, metals, fossil fuels.
  • Strategy: maintain → reuse → refurbish → remanufacture → recycle to retain value.
• Biological (organic, consumable): food, wood, cotton, water.
  • Strategy: compost / anaerobic digestion → return nutrients (N, P, K) to soil.
• Butterfly Diagram visualises the two parallel cycles and flow paths.

Circularity ≠ Sustainability

• Circularity focuses on material loops; sustainability covers people, planet, profit.
• A circular process may still have social or ecological downsides if, e.g., powered by fossil energy.
• Alignment with UN SDGs: circular strategies contribute to SDG 12 (Responsible Consumption & Production), SDG 13 (Climate Action), etc.
• Current consumption: humanity uses ≈1.75 Earths worth of resources per year → urgency for circular thinking.

Examples of Circular-Economy Practices

• Plastic pyrolysis: converts mixed plastics to chemical feedstocks → new plastics.
• Lithium-ion battery recycling: recovery of critical minerals (Li, Co, graphite) to secure supply chains.
• Circular food systems:
  • Food loss/waste currently ≈$\frac{1}{3}$ of production, contributing ≈30 % of global $\text{GHG}$ emissions.
  • Solutions: redistribute surplus, compost by-products into bio-fertilisers, adopt regenerative agriculture.
• Fashion & textiles:
  • Sector emits ≈8 % of global $\text{GHG}$.
  • Actions: recycled fibres, design for durability, rental & resale models.

Practical & Ethical Implications

• Resource justice: extending material life reduces demand for conflict minerals and protects vulnerable communities.
• Corporate responsibility: transparent LCAs discourage green-washing.
• Policy alignment: carbon pricing & extended producer responsibility (EPR) schemes use LCA data.
• Innovation driver: encourages eco-design, modularity, and service-based business models (e.g., product-as-a-service).

Study & Assessment Aids

• Further reading
  • https://pre-sustainability.com/articles/life-cycle-assessment-lca-basics/
  • https://ecochain.com/knowledge/life-cycle-assessment-lca-guide/
  • Ellen MacArthur Foundation CE overview: https://ellenmacarthurfoundation.org/topics/circular-economy-introduction/overview
• Quizzes
  • Footprints-Science LCA quiz: https://www.footprints-science.co.uk/index.php?quiz=Life cycle assessment (2)
  • Quizizz LCA: https://quizizz.com/admin/quiz/5e5acfab79c348001b64cb07/life-cycle-assessment-lca
• Key academic references
  • Geissdoerfer et al. (2017) “The Circular Economy – A new sustainability paradigm?” $\textit{J. Cleaner Prod.}$ 143:757–768.
  • Garcés-Ayerbe et al. (2019) “Is it possible to change from a linear to a circular economy?” $\textit{Int. J. Environ. Res. Public Health}$ 16(5):851.

Core Terms & Definitions

• Functional Unit: quantified performance of a product system for comparison.
• System Boundary: processes included/excluded in the LCA.
• Hot-spot Analysis: identification of stages with largest impacts.
• Cradle-to-Gate: partial LCA from resource extraction up to factory gate.
• End-of-Life (EoL): stage where product exits use phase; options: recycling, energy recovery, landfill.
• Circularity Indicator: metric expressing % material retained in productive loops.