Google this week dumped a massive amount of data about how much energy it uses (a lot), and how efficiently the company uses it (quite).

As per usual with Google, the news came out via a blog post, this one from Urs Hoelzle, Google’s Senior Vice President of Technical Infrastructure, who writes in part that, “For the last decade, energy use has been an obsession.”

Hoelzle’s post, lifting the curtain on a broad new Google Green site, followed an earlier report this week that spelled out how using Gmail is 80 times less carbon-intensive than using other email services, because of how efficiently Google runs its data centers.

To follow on that peek inside its data centers, Google published a comprehensive and downright pretty (especially from a company that has been criticized as letting its visual design live or die “strictly by the sword of data”) website that digs into the company’s overall footprint, and breaks it down by each of the company’s main areas of activity: Search, services (YouTube & Gmail) and the corporate campus.

In short: Google uses 2.6 million megawatt-hours of electricity, or enough to power 200,000 homes.

That’s about 1 percent of all the energy used by all data centers in the world, or .01 percent of all the world’s energy use. A small number, but that’s still a lot of energy for one company to be responsible for.

And Google defends its massive carbon footprint — 1.46 million metric tons of carbon dioxide emissions in 2010 — by saying that 1) its data centers use half as much energy as competitors, because of Google’s singleminded focus on energy efficiency; and 2) it’s making all of its users (i.e. everyone) greener, again by way of that focus on efficiency, as well as replacing other carbon-intensive needs.

For example, watching 72 hours of YouTube has the same carbon footprint as the entire lifecycle of a DVD — which, unless you’re watching one of the Lord of the Rings DVDs one time, or watching any other video many, many times, means streaming video is a net positive.

Similarly, a year’s worth of Gmail usage has a smaller carbon footprint than the entire lifecycle of a bottle of wine — from growing the grapes to drinking the wine to, as Bill Wiehl, Google’s Energy Czar, explained in an interview today, sending off a message in the now-empty bottle.

I asked Wiehl if there were any surprises that he and his team found in creating the new site, and he said that the act of making those kinds of data visualizations together was one of the big surprises.

“I’ve believed for a long time that taking activities that we have typically done in the past phyiscally, like mail or shopping, doing those online can save an enormous amount of energy,” Wiehl said, “but actually quantifying it was very eye-opening.”

Next page: Is a Google CSR report the next step?

Beyond quantifying the data, Wiehl said there weren’t a lot of surprises in putting the page together, partly because Google has been so maniacally focused on energy efficiency for so long.

But in the historically tight-lipped IT industry, the fact that Google is opening up on so many aspects of its green operations — not the least of which is a new white paper on data center energy effciency — is news in and of itself.

I asked Wiehl what prompted this outpouring of data, and whether it signaled a new era of glasnost for Google.

“The simple answer is that we’ve been concerned for a long time about competitive advantage in certain areas and providing details on our energy consumption might compromise us in some ways,” Wiehl said. “We’ve always wanted to balance our concern with our desire to be transparent. And we’ve matured a lot over the last 13-plus years — and the industry has too — and now it’s more important to share information about it to encourage dialogue and action about corporate sustainability.

“This is one step in a series of increasingly more transparent discussions we’ve been having,” he added.

For many companies, gathering the data to present in a CSR report shines a light on areas that need more improvement. For Google, they’ve long known their energy use and where their hot spots are, and are simply continuing to focus on where they can get more efficiency and lower impacts out of their operations.

(To be clear: This is not a “Google CSR report,” and when I asked Wiehl if the new Google Green site marked a step toward comprehensive reporting, he said that it is not, and the company has no plans to publish a CSR report soon.)

On the data center side, Google has already made so much progress on energy efficiency that they’re facing stiff challenges to further improvement. Although the data center hardware — from servers to HVAC — is running at industry-leading levels, Wiehl said there may be more room for improvement at the software level, to get more efficiency out of their billions of search queries and data storage operations.

Renewable energy, though, is an area where Wiehl said Google needs to double down. Despite making big commitments to green power through power purchasing agreements, there’s room for improvement.

“We’ve really just started on procuring renewable energy,” Wiehl said. “Ultimately, we’d like to be 100 percent clean power, but there’s a lot left to do.”

While Google will no doubt continue plugging away on sustainability — and we may be hearing more about what they’re doing, more often — there’s plenty of information and how-to’s to dig into at Google Green.