Google search's carbon footprint

A Harvard University physicist says a typical search on a desktop computer generates about 7 grams of carbon dioxide. Thus, performing two searches is comparable to bringing a kettle to boil, according to a report Sunday in The Times of London. While that may not sound like a lot, the report notes that Google handles about 200 million searches daily.

"Google operates huge data centers around the world that consume a great deal of power," Alex Wissner-Gross told the newspaper. "A Google search has a definite environmental impact."

The global IT industry generates about 2 percent of global carbon dioxide emissions, or about as much greenhouse gas as the world's airlines, according to a recent Gartner study cited by the newspaper.

Google disputed that report late Sunday evening, saying in a blog that the "time it takes to do a Google search, your own personal computer will use more energy than Google uses to answer your query." The blog also noted:

Queries vary in degree of difficulty, but for the average query, the servers it touches each work on it for just a few thousandths of a second. Together with other work performed before your search even starts (such as building the search index) this amounts to 0.0003 kWh of energy per search, or 1 kJ. For comparison, the average adult needs about 8000 kJ a day of energy from food, so a Google search uses just about the same amount of energy that your body burns in ten seconds.

The search giant has actively campaigned to reduce the amount of energy consumed by the IT industry.

Google is a board member of a new coalition called the Climate Savers Computing Initiative, which aims to reduce computing power-consumption by half by 2010. It will do that largely by encouraging member companies like Google to turn off computers when they're not in use. The coalition says that reaching that goal would be the equivalent of taking 11 million cars off the road.

The search giant's Google.org philanthropy released numbers and policy recommendations in November regarding how the U.S. could wean itself from coal and oil for electricity generation and nearly halve its gasoline consumption by 2030.

Google first introduced its 2030 energy road map in the fall. And CEO Eric Schmidt, an adviser to President-elect Barack Obama, called on the federal government to show more leadership on climate change by fostering clean-technology businesses.

Schmidt told the Corporate EcoForum last year that the company's plan is to reduce global demand for oil and to help generate new white- and blue-collar jobs by investing in solar, wind, and geothermal energy projects.

But As per i think

Harvard has made a major miscalculation here. Harvard says it takes the energy of "bringing a kettle to boil" for 2 searches. This would be a minimum of 178 KJ of energy. (Asssume raising 500 cc of water from 15 degC to 100 degC = 85*500 cal = 42.5 kcal or 178 KJ or 0.05 KWH). Thus Harvard's estimate of energy is about 90 times greater than Google's. (Google says 2 KJ for 2 searches.) Using Harvard's estimate would mean that the electrical cost of 200 million searches would be about $500,000 per day or $182 million per year. (Assume $0.10/KWH, 200 million searches/day, 0.05 KWH/two searches). Using Google's estimate yields $5500/day in electrical usage. I think that Harvard has way over estimated Google's energy usage.