Life cycle assessment calculations

Environmental Management II

Exam preparation

June 2^nd 2009

 

Life cycle assessment calculations

 

Instructions

Please do the following question for homework. You won't be awarded predicate marks but a similar question has been asked for the exam. It is therefore in your own best interest to complete the homework diligently in order to gain a firm understanding of how to do the calculation for life cycle assessments.

 

The following life cycle assessment is based on the production and use of bar fridges.

Question 1

Use the following information to conduct a simple life cycle impact assessment.

Medium	Substance	Amount
Air	Carbon Dioxide (CO2)	200kg
Air	Nitrogen Dioxide (NO2)	20kg
Air	CFC-11	2kg
Air	HCFC-10	3kg
Air	Methane	40g
Water	Lead (Pb)	50g
Water	Tin (Sb)	30g
Water	Mercury (Hg)	20g
Water	Arsenic (As)	10g
Water	Phosphate (PO43-)	70g
Water	Nitrate (NO3-)	150g
Soil	Lead (Pb)	10kg
Soil	Mercury (Hg)	50g
Product	Bar fridge	20

Table1: Inventory of selected emissions from process.

 

Table one contains the emissions from production 20 bar fridges.

You need to include the following impact categories:

1) Global warming potential

2) Ecotoxicity

3) Eutrophication

4) Ozone depletion potential

 

 

Follow the following steps in order to complete the life cycle impact assessment

1.1) Classify

1.2) Characterize

1.3) Add up impact category score

1.4) Normalize

1.5) Apply weighting

(5 x 5 = 25)

 

 

Substance	Pf (CO2eq)
Carbon Dioxide	1
Methane	23
Nitrogen Dioxide (NO2)	2.4
CFC-11	17
HCFC-10	20

Table 2: Global warming potency factors

 

Substance	LD50	1/LD50	Pf (1/LD50 X 100)
Lead (Pb)	40mg/kg	0.025	2.5
Mercury (Hg)	10mg/kg	Calculate	Calculate
Tin (Sb)	140mg/kg	Calculate	Calculate
Arsenic (As)	5mg/kg	Calculate	Calculate

Table 3: Potency factors for Ecotoxicity

 

 

 

 

 

 

Substance	Pf (NO3- eq)
Phosphate (PO43-)	4.5
Nitrate (NO3-)	1.0
Ammonia (NH3)	0.7
Ammonium (NH4-)	0.8

Table 4: Potency factors for eutrophication

 

Substance	Pf (CFC-11 eq)
CFC-11	1
HCFC-10	0.6

Table 5: Ozone depletion potential

 

Category	Emissions per person
Global warming	180kg CO2eq
Ecotoxicity	2 1/LD50 X 100
Eutrophication	10 NO3- eq
Ozone depletion	5 CFC-11 eq

Table 6: Average emissions per person (for normalization)

 

Impact category	Wf
Global warming	2
Ecotoxicity	2.6
Eutrophication	1.8
Ozone depletion	1.4

Table 7: Weighting factors for different impact categories

 

 

 

 

 

After doing all of the above, also answer the following questions.

1.6.) Before applying weighting, which category had the highest score?

1.7) After applying weighting, which category had the highest score?

1.8) From looking only at the weighting factors, which of the categories do you think has the greatest importance in terms of this study?

1.9) Where do you think the company should focus to reduce it's ecological footprint?

1.10) Why did you add up the water and soil emissions of heavy metals for toxicity? If you were classifying them for aquatic toxicity would you do the same?

(5)

 

Total marks (30)

 

Do and redo this question during exam preparation because you will find something similar in the main and supplementary exam. I will go through all of the answer during the class next week.