Life Cycle Analysis of Hand-dryers for NDSU

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Life Cycle Analysis of Hand-dryers for NDSU
La Toya KissoonDavid MushetXiana Santos
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Introduction

• Obj Replacement of 100 folded-paper towel
  dispensers with either motion-sensing paper towel
  dispensers or warm air hand dryers
• Purpose to determine which hand drying method
  used at (NDSU) bathroom facilities produces least
  impacts on the environment.

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Life Cycle Inventory

• Inputs (material and resource) and outputs
  (emission and product) from unit processes in the
  life cycle of each hand dryer type was identified
  and quantified.
• Data was collected from both primary and
  secondary sources.
• Secondary data was collected from existing
  databases associated with GaBi software.

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Data Type and Quality
Life-cycle Stage Data type Relative Quality
Upstream (material extraction and processing) Secondary Moderate
Dispenser manufacturing and shipping Secondary Moderate
Paper manufacturing and shipping Secondary Moderate
Use Primary Moderate
Final disposition of dispenser Primary and secondary Moderate
Final disposition of paper towels Primary Moderate
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Calculating the Number of Uses / Dispenser
We used information on towel dispenser use at
NDSUs Stevens Hall to estimate uses / dispenser.
We obtained an estimate of the number of boxes of
towels used / year at Stevens Hall from Chad,
NDSU Maintenance Staff.
We observed use habits to estimate the number of
towels used during the hand drying process.
Finally, we tallied the total number of towel
dispensers in Stevens Hall.
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Calculating the Number of Uses / Dispenser
(cont.)
(40 boxes/yr) (4000 towels/box)

(3 towels/use) (10 dispensers)
5,333 uses/dispenser/year
Thus, we estimated that the 100 dispensers at
NDSU would receive approximately 533,300 uses /
year
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Calculating Paper Usage
Folded Paper Towel Dispensers
(533,300 uses/yr) (6.63 g/use) 3536 kg/yr
Motion-Sensing Towel Dispensers
(533,300 uses/yr) (3.51 g/use) 1872 kg/yr
Warm-air Hand Driers
(533,300 uses/yr) (0 g/use) 0 kg/yr
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Calculating Power Usage
Folded Paper Towel Dispensers
0 MJ/yr
Motion-Sensing Towel Dispensers
(533,300 uses/yr) X (1 sec/use) X (hr/3600 sec)
X (1.2 kWh/hr) X (3.6 MJ/kWh) 640 MJ/yr
Warm-air Hand Driers
(533,300 uses/yr) X (55 sec/use) X (hr/3600 sec)
X (2.4 kWh/hr) X (3.6 MJ/kWh) 70,396 MJ/yr
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GaBi 4 Inputs
Folded Paper Towel Dispensers
3536 kg/yr paper 0 MJ/yr power
Motion-Sensing Towel Dispensers
1872 kg/yr paper 640 MJ/yr power
Warm-air Hand Driers
0 kg/yr paper 70,396 MJ/yr power
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GaBi 4 Inputs
  FOLDED TOWEL MOTION SENSING WARM-AIR
INPUTS      
Production residues in life cycle      
Waste for recovery 576.37 305.14  
Resources      
Energy resources 4210.7 2302.3 8035.4
Material resources 149.69 79.245  
Valuable substances      
Energy carrier      
Materials 1088.5 576.24  
Total Input Flows 6025.2 3262.9 8035.4

• Table 1 Material and resource inputs associated
  with folded-towel dispensers, motion
• sensing dispenser, and warm-air hand dryers. All
  values are in kilograms (kg).

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GaBi 4 Outputs
  FOLDED TOWEL MOTION SENSING WARM-AIR
Emissions to air      
Heavy metals to air 0.0026253 0.0015942 0.022478
Inorganic emissions to air 1560.8 947.71 13356
Organic emissions to air 5.9352 3.16617 57.147
Particles to air 2.6308 1.407 1.5641

• All values are in kilograms (kg).

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GaBi Outputs
  FOLDED TOWEL MOTION SENSING WARM-AIR
Emissions to water      
Analytical measures to water 45.712 24.205 0.46942
Heavy metals to water 0.48309 0.29205 3.9916
Inorganic emissions to water 58.806 33.04 209.85
Organic emissions to water 0.35138 0.1929 0.7563
Particles to water 10.99 5.8505 3.576
Solid wastes      
Wastes to landfill 3536 1872 0
Total Output Flows 5221.7 2888.35 13634
All values are in kilograms (kg)
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Interpretation of results

• Environmental Impacts
• motion sensing dispensers lt Folded-paper towel
  dispensers lt warm-air hand-dryers
• Folded-paper towel dispensers - 6.63 g per usage
  (no control over usage uneconomical dispensing
  method)
• Motion-sensing dispensers - 3.51 g per
  usage/little energy usage (controls usage ? saves
  paper ? cuts down on waste ? environmental
  advantage)
• Warm Air Dryers significant environmental
  damage very high inorganic emissions to air
  water

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Conclusions

• Our LCA rated the motion-sensing towel dispensers
  as having the smallest environmental impact
  (Recommend its use due to smaller environmental
  impact)
• Greater efficiency of dispensing method accounted
  for less environmental impact
• Impacts associated with production, shipment and
  paper-waste disposal of the two paper dispensers
  could not compare with the energy expenditure and
  emissions of the warm-air dryers

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References

• American Dryer Corp. 2006. Protect the global
  environment with American Hand Dryer. American
  Dryer, Inc., Livonia MI. http//www.americandryer.
  com/environment.html
• IKP. 2006. GaBi 4 Software. University of
  Stuttgart, Institute for Polymer Testing and
  Polymer Science, Leinfelden-Echterdingen,
  Germany. www.gabi-software.de
• Acknowledgements
• Chad from Stevens Hall