Question

According to a recent study1, it takes between 5.6 and 10.2 million joules of

energy to produce a 1 L of bottled water (for simplicity, let’s assume the value is 7.9

million joules for 1 L). To produce 1 L of tap water takes about 0.005 million joules per L

for treatment and distribution

a.) Americans consume approximately 33 billion L of bottled water per year. Assuming

gasoline has an energy density of energy density of 125,000 BTU/gallon, calculate the

equivalent number of gallons of gasoline that would be saved if everyone switched to

tap water.

b.) In 2015, America consumed an estimated 97.7 quadrillion BTUs of energy. What

percentage of that energy went to making bottled water?

Answer 1

a) 125000BTU= 131.8 million joules of energy

energy neede for bottled water = 33* 10⁹ *7.9*10⁶

energy neede for bottled water = 33* 10⁹ *0.005*10⁶

1L of gasoline= 35.62 million joules of energy

gasoline needed for bottled water= (33* 10⁹ *7.9*10⁶)/35.62*10⁶= 7.318 billion l of gasoline

gasoline needed for tap water= (33* 10⁹ *0.005*10⁶)/35.62*10⁶= 0.004 billion l of gasoline

gasoline saved=7.318-0.005=7.313 billion l of gasoline=1.931 billion gallons of gasoline