Life-cycle assessment

Question 1

List the four phases that we distinguish in LCA.

Answer 1

• Goal and scope
  
  • Goal? Why?
    
    • Identify environmental bottle necks in a product system
    • Compare product systems with the same service
    • Assess different improvement options for a product
    • Compare different product designs
    • To label/evaluate products
    • Identify prospects of a new product system to predict environmental feasibility
  • Methodological choices that should be made are:
    
    • What product, process and function?
    • What is the functional unit as basis for comparison?
    • What are the system boundaries?
    • Which environmental impacts are being considered?
• Inventory: A list of environmental interventions required for your functional unit. Interventions are exchanges with nature, e.g. emissions to air, soil or water (CO2, CH4, Particulate Matter, Lead etc.); Resource extractions (materials, energy, land, water).
  
  1. Identify processes (flow diagram)
  2. Identify interventions per unit process + quantify
     
     • Manually for foreground
     • From databases for background
     • Allocation may be necessary
  3. Quantify relation of processes to function unit
     
     • How much of each process do I need?
  4. Sum total interventions over all processes per FU
• Impact assessment
  
  • We have a list of environmental interventions, so what’s next?
    
    • Depending on the goal of the study one can assess one or a few interventions of interest
    • Or
    • Quantify impact per impact category: Life Cycle Impact Assessment ( LCIA) methods. Choose the impact category using a midpoint indicator for a particular problem.
  • One inventory item may contribute to multiple impact categories! E.g. NOx contributes to photochemical oxidant formation; aquatic toxicity; terrestrial acidification. So to calculate use Score impact per impact category :
    
    • S = sumx of ( Ix*Qx), where S = impact score, I = Intervention ( kg), Q = Characterisation factor
• Interpretation
  
  • Interpret your study in relation to the study goal
    
    • Evaluate the robustness
    • Draw conclusions and make recommendations through:
      
      • Contribution Analysis
        
        • What is main environmental impact?
        • What is the most important life cycle stage?
      • Analysis towards assumptions
        
        • Sensitivity analysis (assumptions)
        • Uncertainty analysis
      • Improvement options
        
        • Possible changes in design, material or product use

Question 2

What is Life Cycle Assessment?

Answer 2

• LCA is a systematic method to quantify and evaluate potential environmental impact of product systems by:
  
  • compiling the environmental inputs and outputs
  • evaluating their potential environmental impacts ( broad range of environmental impacts)
• Throughout the entire life cycle of a product system (i.e. from cradle to grave)

Question 3

What can LCA be used for?

Answer 3

• Product development and improvement
• Public policy
• Marketing:
  
  • Eco-labelling scheme
  • Environmental claims
  • Environmental product declaration

Question 4

What is functional unit in LCA?

Answer 4

• Serves as the basis for your LCA
• Represents the function of the product or service you assess
• All inputs and environmental impacts are expressed on the basis of this unit
• E.g. transport of 1 person over 1 km

Question 5

What is the problem of allocation?

Answer 5

• Occurs in multifunctional processes: multi-output processes ( co-production); multi-input processes; recovery and recycling processes
• Hard to decide where and how much of the burden (emissions) should be allocated

Question 6

What are the different types of allocation?

Answer 6

• Causal relations ( e.g. consider heat as a free by-product, so 0 burden to heat

Question 7

What are the examples of midpoint impact categories?

Answer 7

• Resources:
  
  • Abiotic resources
  • Biotic resources
  • Land use
  • Water use
• Pollution:
  
  • Climate change
  • Ozone depletion
  • Human toxicity
  • Ecotoxicity
  • Acidification
  • Eutrophication
  • Photochemical ozone formation
  • Fine dust formation
  • Radiation
  • Odour
  • Noise
• Physical stress:
  
  • Ecosystem/ landscape
  • Victims

Question 8

What to do if there are too many impact categories and products may be better according to one indicator, worse according to another?

Answer 8

• Normalization & Weigthing
  
  • Express impact relative to reference (e.g. average EU citizen)
  • Give weights to the categories (similar to MCA)
• Endpoint indicators
  
  • Choose a few endpoints you think are particularly important e.g. damage to human health; damage to ecosystem quality; damage to resources.

Question 9

What are the advantages and disadvantages of using endpoint indicators?

Answer 9

• Advantages
  
  • Easy to communicate (limited number of categories)
  • Represents what we ultimately care about
• Disadvantages
  
  • Highly uncertain due to all the modelling of (future) damage
  • Because of this uncertainty, reluctance to use these endpoint models