Everyday, a transporter delivers clean cotton towels from a laundry facility and hauls away dirty ones. The laundry facility is responsible for washing and drying the cotton towels. The company would like to conduct a life cycle analysis to assess the carbon footprint of using cotton roller towels to dry one pair of hands. The following data has been collected for this analysis.
Distance to laundry where cotton towels are washed and dried: 10 km.
Capacity of van: 200 rolls on forward and return journey.
Diesel consumption of van: 45 miles per gallon
Density of diesel = 840 kg / 1 m3
Emission Factor for diesel consumption in transportation: 3.32 kg CO2Eq/kg
In every trip, the same van delivers the clean towels and transports back the dirty towels. Assume the van runs in full capacity in both ways.
Length of towel per roll: 50m
Length of each pull of the towel: 20cm
Assume that to dry one pair of hands you need only one pull.
Dry weight of towel: 4kg per roll
Required electricity for washing: 0.33 kWh per kg of cotton
Drying requires the evaporation of 1kg of water per kg of dry cotton
The latent heat of evaporation of water[1] : 2.5 MJ/kg
The dryers at the laundry are electrically powered.
Assume the laundry purchases electricity generated by coal with an emission factor of 0.32 kg CO2Eq/Kwh.
Some Conversion Factors
1 mile = 1.6 km
1 kWh = 3.6 MJ
1 litre = 0.2641721 gallon
1 m3 = 1000 liters
1 tonne = 1000 kg
Latent Heat is defined as the heat which flows to or from a material without a change to temperature. The heat will only change the structure or phase of the material, e. g. transferring water from the fluid phase to vapor phase.
Help Smart Inc. calculate the carbon emission of using cotton roller towels to dry one pair of hands. Include and explain your calculation steps.