June 16, 2010 - a look into historic energy usage

The United States Energy Information Administration tells us that in 2008, Americans consumed 99.304 quadrillion Btu of "primary energy" resources.

How much is that? One quadrillion Btu, or "quad", is one thousand million million Btu, or 10^15 Btu. One quad is roughly the amount of energy contained in:
* 8,007,000,000 Gallons (US) of gasoline
* 293,071,000,000 Kilowatt-hours (kWh)
* 36,000,000 tons of coal
* 970,434,000,000 Cubic feet of natural gas
* 5,996,000,000 gallons of diesel oil
* 25,200,000 tons of oil

Dividing the 99.304 quads by the U.S. population, each American is responsible for 327 million Btu annually. Energy intensity, or the annual per capita consumption, peaked for America in 1978-1979 at 359 million Btu, but we've been moving back and forth above 311 million Btu since 1968.

How do these numbers compare to historic figures? US EIA has an interesting table showing estimated primary energy consumption for the U.S. for 1635-1945. The table shows 0.001 quad consumption in 1645, the first year for which data is provided. By 1835, the figure has broken above one quad (1.305 quad). Energy consumption grows fairly linearly through 1900 (9.587 quad), after which the figure shoots up sharply.

In 1835, the official U.S. population was 14.7 million. This gives an 1835 intensity of 88 million Btu -- about one quarter of today's per capita consumption.

Interestingly, I suspect these figures don't take into account the literal horsepower provided by livestock in 1835. How much more energy do we really consume today?