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Apples, Oranges and Btu            
Last Updated: June 2006
Next Update: To Be Determined


Assume that you have been assigned the responsibility of purchasing fuel for a large electric utility company. The 2004 average prices of fuel delivered to electric power plants were $27.42 per short ton of coal, $26.56 per 42-gallon barrel of oil, and $6.11 per thousand cubic feet of natural gas. Tons, barrels, cubic feet--how do you compare apples and oranges?

To make meaningful comparisons of different energy sources, you must convert physical units of measure (such as weight or volume) into a common unit of measurement based on the energy content of each fuel. One practical way to compare different fuels is to convert them into British thermal units (Btu). The Btu is a precise measure of energy--the amount of energy required to raise the temperature of 1 pound of water 1 degree Fahrenheit.

In 2004, a ton of coal used to generate electricity cost about 3 percent more than a barrel of oil and about five times as much as a thousand cubic feet of natural gas. However the thousand cubic feet of gas contained about 1 million Btu and the barrel of oil contained about 6 million Btu, while the ton of coal contained about 20 million Btu, over three times as much energy as the oil and 20 times as much as the gas. On a Btu basis, coal was cheaper. (Of course, cost is not the only consideration in selecting a fuel. Environmental restrictions, equipment costs, and other factors must also be taken into account.).

Approximate Btu Values
of Selected Energy Sources

1 Gallon of Gasoline = 125,000 Btu
1 Gallon of Heating Oil = 139,000 Btu
1 Gallon of Propane = 91,000 Btu

1 Pound of Coal = 10,000 Btu

1 Kilowatthour of Electricity = 3,412 Btu

1 Cubic Foot of Natural Gas = 1,021 Btu

A single Btu is insignificant in terms of the Nation's energy consumption, or even in terms of energy use in a single household. One Btu is approximately equal to the energy released in the burning of a wood match. The average single-family household consumed 92 million Btu of energy in 2001. So on the family level, 1 million Btu is a meaningful quantity. Billions, trillions, and quadrillions of Btu are used to measure quantities of energy larger than those consumed by typical households. (Written out, 1 quadrillion is a 1 and 15 zeros.) To put those quantities in perspective, 1 million Btu equals about 8 gallons of motor gasoline. One billion Btu equals all the electricity that 300 households consume in one month. One trillion Btu is equal to 500 100-ton railroad cars of coal intended for electric power plants. And 1 quadrillion Btu is equal to 172 million barrels of crude oil. In 2004, the Nation used 100 quadrillion Btu of energy: 41 quadrillion Btu of petroleum, 23 quadrillion Btu of natural gas, 22 quadrillion Btu of coal, 8 quadrillion Btu of nuclear energy and 6 quadrillion Btu of renewable energy.

More information on this subject can be found in the following EIA publications: Monthly Energy Review, Annual Energy Review, and Electric Power Annual.