The U.S. Environmental Protection Agency cites an average about 113,500 BTU as t

Question

The U.S. Environmental Protection Agency cites an average about 113,500 BTU as the energy content of 1 gallon of typical gasoline. How many joules is this?

It takes about half a gallon of gasoline for a rancher to produce 500g of beef. About how many joules is this and how does it compare to the amount of food energy in beef.

For comparison, it takes about 3 MJ for fertilizer and farm machinerey fuel to produce 500g of dried soybeans. Which is more energy efficient. beef, or soy production? By how much %?

Explanation / Answer

therefore, 113,500 BTU or 1 gallon of typical gasoline = 113,500 x 1,055.06 = 119,748,839 joules of energy

100g of beef have approximately 1063kj (1063000j)of energy

therefore, 500g of beef will have approximately 5 x 1063kj = 5,315,000j of energy

100g of dried soybeans have approximately 1789kj (1,789,000j)of energy

500g of dried soybeans have approximately 5 x 1789kj (8,945,000j)of energy

59,874,419.5 joules of energy is required in beef to give 5,315,000j of energy

while, 3,000,000 joules of energy is required in dried soybeans to give 8,945,000j of energy.

Hence, dried soybeans is more energy efficient than beef.

1 joules of energy is required in beef to give 5,315,000/ 59,874,419.5 = 0.0887j of energy

1 joules of energy is required in dried soybeans to give 8,945,000/3,000,000= 2.981j of energy.

Percentage = (2.981j/0.0887j) x 100= 3361.5%

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