Chapter 6: Evaluation and ranking of green processes and products

Question 1

What is the last step in a life cycle analysis?

Answer 1

interpretation and
normalization.

Question 2

What should you perform if conducting a consequential LCA or comparing several technologies/products or exploring different pathways/options for improving a process?

Answer 2

A systematic evaluation of all possible
options/pathways/products so that the higher ranked options
can be identified for further evaluation or implementation.

Question 3

What are the key aspects in product/process evaluation?

Answer 3

1. Reduction in environmental and health impacts
2. Economical advantages
3. Technical feasibility
   – Availability
   – Proven performance
   – Ease of implementation.

Question 4

What are ranking indicators of green processes and products?

Answer 4

• Environmental impacts
  – Environmental
  – Health
  – Resource depletion
• Economic impacts
  – Environmental costs or total cost
• Technical feasibility
  – Resource utilization
  – Timeliness of the project
  – Transferability

Question 5

What are environmental impact indicators?

Answer 5

• Global warming (kg CO2 equivalent)
• Ozone depletion (kg CFC-11 equivalent)
• Acid rain formation (kg SO2 equivalent)
• Smog/ozone formation (kg org. mixture, or C2H4)

*Nutrification/Eutrophication (kg PO2 equivalent)

• Ecotoxicity (kg DDT equivalent)

Question 6

What are resource depletion indicators?

Answer 6

• Primary energy consumption (MJ)
• Solids waste generation (kg)
• Water usage (kg)
• Land usage (m2)

Question 7

Health risk indicators for green products and processes

Answer 7

• Non-carcinogenic risks (Toxicity index, TLV, PEL, RfD)
• Carcinogenic risks (CSF and LD50 or LC50)
• Intake fraction (iF)
• DALY

Question 8

What is the procedure for ranking based on weighting factors/scores?

Answer 8

Procedure:

1. Impact scores are first normalized to simple dimensionless scores;
2. Weighting factors are assigned to each criterion based on its
   importance on the overall performance.
3. Overall scores are calculated based on dimensionless scores and
   weighting factors.

Question 9

How are environmental and risk criteria normalized?

Answer 9

By background scores based on regional or international inventories.

Question 10

What does the accuracy and reliability of the simple weighting factor method rely on?

Answer 10

The weighting factors assigned to each criterion.

Question 11

How has the stability of the ranking method for green products and processes been improved?

Answer 11

A hierarchical
ranking system based on weighting factors has been proposed
and used by Amoco for the ranking of oil refinery pollution
prevention options.

Question 12

How can performance metric/indicators be selected for evaluating green products and processes?

Answer 12

It is based on the environmental and social impact concerns, technology maturity, product
performance and economic advantages.

Question 13

How are metrics/indicators normalized?

Answer 13

Using background data or simple
formula to dimensionless scores.

Question 14

Why must a sensitivity analysis be performed?

Answer 14

-To ensure the stability of the proposed ranking system.

-Since there is no single correct set of criteria and weights for ranking.

Question 15

Why are weighting factors assigned to each indicator/metric based on their relative importance?

Answer 15

To derive an overall performance score for the
ranking of all processes/products.

Question 16

What is needed to conduct a systematic evaluation of different processes/products?

Answer 16

Aspects on technical feasibility, environmental impacts and health risks,
and total costs need to be considered.

Question 17

What approach is commonly used to rank different process/product options?

Answer 17

Total scores based on relative weighting factors and
normalization scores have been commonly used in ranking
different process/product options.