Searching, Energy and Greenhouse Gases
Times of London has reported that Harvard physicist Alex Wissner-Gross has estimated that a Google search generates 7g of carbon dioxide. It's not clear what the assumptions are or how accurate the estimate is given Google's unwillingness to share details of their infrastructure but that's ok - the question may be more important than the answer.
CORRECTION: It turns out those questions about where the researcher got his data raised concerns with others as well. TechCrunch and others looked into it found Wissner-Gross hadn't been so specific in his estimates. The rest of this post is still relevant since it didn't focus on the quantified aspects of the Times of London report.
This research is going to force us to consider the total costs of information technology. This is what economists call an negative externality, a cost that is paid by the community at large but not captured in the cost. Searching is "free" or so we thought. Same goes for other "free" services. The London Times points out:
Nicholas Carr, author of The Big Switch, Rewiring the World, has calculated that maintaining a character (known as an avatar) in the Second Life virtual reality game, requires 1,752 kilowatt hours of electricity per year. That is almost as much used by the average Brazilian.
It's hard to think that my industry is in many ways a lot like manufacturers with smoke stacks and sewage pipes but it's time to start facing that reality.
UPDATE: Google responded with it's own estimates of much smaller impact:
Recently, though, others have used much higher estimates, claiming that a typical search uses "half the energy as boiling a kettle of water" and produces 7 grams of CO2. We thought it would be helpful to explain why this number is *many* times too high. Google is fast -- a typical search returns results in less than 0.2 seconds. 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.In terms of greenhouse gases, one Google search is equivalent to about 0.2 grams of CO2. The current EU standard for tailpipe emissions calls for 140 grams of CO2 per kilometer driven, but most cars don't reach that level yet. Thus, the average car driven for one kilometer (0.6 miles for those in the U.S.) produces as many greenhouse gases as a thousand Google searches.
Again, I'd argue we need to think of the environmental impact of IT services. Even minutely small impacts, multiplied billions of times, can have a material impact.
Email This!
Digg it!
Sphere it!
Del.icio.us
Reddit!
Newsvine
