Last year Penn State recycled 77 tons of aluminum cans and prevented them from g
ID: 977763 • Letter: L
Question
Last year Penn State recycled 77 tons of aluminum cans and prevented them from going to the landfill. Diesel fuel has an average chemical formula of C_12H_23 and a density of 6.45 lb/gal. Calculate how many lbs of CO_2 are produced per gallon of diesel burned (assume complete combustion). The landfill is 70 miles away while the recycling centre is 7 miles away. Assume that a 10 ton diesel garbage truck gets 2.8 mpg when full and 4 mpg when empty. How many lbs of CO2 are saved in transportation alone by recycling the cans? Assume the recycling truck and the garbage truck get the same mpg and that both trucks return empty. The production of aluminum (for cans) requires 13 kWh/kg of aluminum while producing aluminum from recycled cans requires 0.65 kWhr/kg. How many lbs of CO2 are saved per year in manufacturing from PSU recycling? Assume that 80% of the energy comes from coal (2.1 lb CO_2/kWhr) and 20% from natural gas (1.3 lb CO_2/kWhr). (1 metric ton = 1000 kg).Explanation / Answer
a) burning one gallon of diesel fuel will produce around 22.38 lbs of CO2 .
b) garbage truck :
When full utilizes = 70/2.38 = 29.41 gallons of diesel fuel
When returning empty comsumes = 70/4 = 15 gallons of diesdi
Total diesel for one up and down trip = 29.41+15 = 44.41 gallons
Amount of CO2 produced = 44.41 × 22.38 = 993.8 lbs
For recycling truck :
When full utilizes = 7/ 2.38 = 2.941 gallons
When returning empty consumes = 7/4 = 1.5 gallons
CO2 produced = 2.941 + 1.5 = 4.441 ×22.38 = 99.38 lbs
Amont of CO2 difference = 993.8 - 99.38 = 894.42 lbs
c) For Al production:
Energy required = 13 KWh/Kg
80% is from coal = 13×0.8 = 10.4 KWh/Kg
CO2 produced = 10.4 × 2.1 = 21.84 lb/Kg of Al produced
20% is from natural gas = 13×0.2 = 2.6 KWh/Kg
CO2 produced = 2.6×1.3 = 3.38 lb/Kg
Total CO2 per Kg of aluminium produced = 21.84 +3.38 = 25.22 lb
Fro Al from recycling:
Energy reauired is 0.65 KWh/Kg
80% from Coal = 0.65×0.8 = 0.520KWh/Kg
20% from natural gas = 0.65×0.2 = 0.13 KWh/ Kg
CO2 produced = (0.52)(2.1) + (0.13)(1.3) = 1.261 lb per kg of Al recycled
On a year basis :
If 77 tons of aluminium is produced , Co2 produced = 77000 × 25.22 = 1941940 lbs
If 77 tons is produced by recycling , Co2 produced = 77000 × 1.261 = 97097 lbs
So by recycling penn state prevented (1941940-97097) 1844843 lbs of CO2 from production alone. That's a great job.
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