Thursday, October 27, 2011

The Energy and Emergy of the Internet

(To find out what "emergy" is, you have to read the rest of this post).

Google and other operators of huge data centers spend a lot of money on power, which leads them to locate server farms near sources of cheap, renewable energy, frequently near rivers in rural areas.

Two recent news items, one on Facebook's planned data center near the arctic circle and a study of the energy and emergy of the Internet remind us that the Internet consumes a lot of energy.

Facebook announced plans to build a server farm in LuleƄ Sweden, about 100 kilometers from the Arctic Circle. They will benefit from low cost electricity generated by dams on the LuleƄ river and from savings in cooling. The average temperature is around 2 degrees centigrate, which will enable them air cool the datacenter, which will consume enough power to run about 50,000 houses.

Powering data centers and the computers and devices that use them is only about half the story according to a recent study by Barath Raghavan and Justin Ma. We must also consider embodied energy (emergy) — the energy used in making the devices and infrastructure that make up the Internet. They remind us that we can save energy by extending the life of our computers and smart phones as well as by reducing operating power.

Taking both energy and emergy into account, Raghavan and Ma estimate that the Interent consumes between 1.1 and 1.9% of the 16 TW used by humanity. That is a lot less than we devote to transportation, so we will still be ahead if we can subsitute communication for transportation.