How Much Energy is Consumed by a Google Search?

Times Online a response to this article, Urs Hölzle, Senior Vice President, Operations at Google, has put up a post on the Official Google Blog. Hölzle says:

But as computers become a bigger part of more people's lives, information technology consumes an increasing amount of energy, and Google takes this impact seriously. That's why we have designed and built the most energy efficient data centers in the world, which means the energy used per Google search is minimal. In fact, in the time it takes to do a Google search, your own personal computer will use more energy than Google uses to answer your query...

We've made great strides to reduce the energy used by our data centers, but we still want clean and affordable sources of electricity for the power that we do use. In 2008 our philanthropic arm, Google.org, invested $45 million in breakthrough clean energy technologies. And last summer, as part of our Renewable Energy Cheaper than Coal initiative (RE<C), we created an internal engineering group dedicated to exploring clean energy.

Between those paragraphs, Hölzle explains why the estimates made in the article about Google's energy consumption are too high, which also cites Second Life and Twitter as potential energy problems. I must admit that energy consumption is not something I often think about when using any of these sites, and even if the article is off in it's numbers, the issue discussed is still an interesting one to consider.