I have been researching and publishing on Cloud Computing for quite some time here. Specifically, I’ve been highlighting how it is not possible to know if Cloud computing is truly sustainable because none of the significant Cloud providers are publishing sufficient data about their energy consumption, carbon emissions and water use. It is not enough to simply state total power consumed, because different power sources can be more, or less sustainable – a data center run primarily on renewables is far less carbon intensive than one that relies on power from an energy supplier relying on coal burning power stations.

At Greenmonk we believe it’s important to get behind the headline numbers to work out what’s really going on. We feel it’s unacceptable to simply state that Cloud is green and leave it at that, which is why we’ve been somewhat disappointed by recent work in the field by the Carbon Disclosure Project. We would like to see more rigour applied by CDP in its carbon analytics.

Carbon intensity should be a key measure, and we need to start buying power from the right source, not just the cheapest source.

I was pleasantly surprised then yesterday when I heard that Google had published a case study ostensibly proving that Cloud had reduced the carbon footprint of at least one major account.

However, it is never that straightforward, is it?

The Google announcement came in the form of a blog post titled Energy Efficiency in the Cloud, written by Google’s SVP for Technical Infrastructure, Urs Hölzle. I know Urs, I’ve met him a couple of times, he’s a good guy.

Unfortunately, in his posting he heavily references the Carbon Disclosure Project’s flawed report on Cloud Computing, somewhat lessening the impact of his argument.

Urs claims that in a rollout of Google Apps for Government for the US General Services Administration,

the GSA was able to reduce server energy consumption by nearly 90% and carbon emissions by 85%.

An 85% reduction in carbon emissions sounds very impressive – but how does Google calculate that figure?