Energy Use by Computers and Data Centers

Where possible, this discussion will use MKS power units - watts, gigawatts, terawatts. Units such as kilowatt-hours per year and quads per year are confusing, and inherently "resource-depletion" oriented. I won't touch such units with an 87.66 kilofoot-hour per year pole.

Global Energy Use

World energy use averaged 15 Terawatts in 2008 according to Wikipedia . The US Energy Information Administration estimates world usage in 2010 at 509.7 Quads per year. A Quad per year equals 33.4 gigawatts, so that is 17.0 Terawatts.

88% of electricity is generated by fossil fuel, leaving 12% generation by nuclear and hydro, and a small fraction by wind, solar, and other alternatives. Generation is mostly oil and coal, which averages about 33% efficient. So, we can estimate that the multiplication factor from electricity to primary energy is approximately 2.7, that is, every gigawatt consumed by computers requires 2.7 gigawatts of primary energy.

The 2010 CIA World Fact Book estimates global electricity usage for 2010 at 18.8 TKWH per year, or 2.15 Terawatts. This increased from 1.63 Terawatts in 2005, a 5.7% per year increase.

China is increasing energy and computer usage much more rapidly. Electricity use has more than doubled in 5 years, from 186GW in 2005 to 392GW in 2010, an increase of 16% per year. China, India, and other rapidly emerging nations will soon dominate world usage.

Global Computer Energy Use

David Sarokin estimated 2007 computer energy use at 868 billion kilowatt hours per year, or 99 gigawatts. 5.3% of global electricity consumption. Forrester estimates a doubling of PCs in 7 years ( 10% per year). The DOE estimates US data center power usage as a fraction of total US usage (increasing 1.4% per year) will double every 5 years (15% per year), for a total power increase of approximately 16% per year. The average power usage increase might be 13 percent.

In 2010, we can estimate the computer power use to increase by 44% (1.13^3), so the power in 2010 is approximately 140 GW of electrical energy, corresponding to 380 GW of primary energy in 2010.

Aviation

For comparison, Schafer estimates that aviation used 2.5% of the world's primary energy in 2005, and that this will increase to 9% by 2050. If this is accurate, the fraction increases by a factor of 1.0289 a year, and extrapolates to 2.88% of world energy usage in 2010. Times 17.0 TW, that is 490 GW of primary energy for aviation in 2010.

If aviation power increases 1.0289 a year, and computer power increases 1.13 a year, computers are overtaking aviation by 10% per year. In 2013, computers will use 550GW of primary energy, and aviation will use 530GW. By 2020, computers may be using 1860GW, compared to aviation's 710GW.