According to the U.S. Energy Information Administration (EIA), Americans consumed 140.43 billion gallons ofgasoline in 2015, or about 384.74 million gallons each day. It’s generally thought that one can produce on average 7.5 metric tons of corn per hectare, and achieve about a 30% yield of ethanol from this corn (i.e., 0.3 kg ethanol/kg corn). The total amount of land in all active farms in the U.S. is 415 million acres. (a) How much farmland would be required to replace the current volume of gasoline with ethanol? (b) How does that compare to the total amount of land now being farmed? (Hint: In working this problem, be careful with units, particularly hectares and acres. Comment: Note that your answer to (a) relates simply to volumes of the two liquids, not replacing the amount of energy in gasoline with energy from ethanol.)
Part a
Volume of gasoline required Vg = 384.74*10^6 gal/day
Volume of ethanol required = Vg = 384.74*10^6 gal/day
Density of ethanol = 6.585 lb/gal
Mass of ethanol required = volume x density
= (384.74*10^6 gal/day) x (6.585 lb/gal)
= 2.533 x 10^9 lb/day x 1kg/2.205lb
= 1.149 x 10^9 kg/day
1 kg corn produces = 0.3 kg ethanol
Mass of corn required
= (1 kg corn/0.3 kg ethanol) x (1.149 x 10^9 kg ethanol/day)
= (3.83 x 10^9 kg corn/day) x (1MT/1000kg)
= 3.83 x 10^6 MT corn/day
Land required
= (1 hectare / 7.5 MT corn) x (3.83 x 10^6 MT corn/day)
= 5.11 x 10^5 hectare
Part b
total amount of land in all active farms in the U.S.
= 415 * 10^6 acre x 1hectare/2.471acre
= 1.679 x 10^8 hectare
Percent of land in corn farming
= 5.11 x 10^5*100/ 1.679 x 10^8
= 0.30%
According to the U.S. Energy Information Administration (EIA), Americans consumed 140.43 billion gallons ofgasoline in 2015,...