It is possible that Google, because of its 500,000+ servers and massive ranks of disk drive arrays, spread across 40 to 60 datacentres around the globe, is the largest IT producer of carbon emissions on Earth, through emissions from utility companies supplying its energy requirements; ruling out chip foundry companies such as Intel, of course.

On the other hand, Google exec Urs Holzle, has said earlier this month: "Our carbon footprint is actually not that big. We have 10,000 employees. Even at this scale, we care and want to be a model citizen. But we’re not quite ready to tell you what we’re doing."

Google has committed to carbon neutrality by the end of 2007, which is a typically audacious Google target. However it has not disclosed its carbon footprint to the Carbon Disclosure Trust.

The size of Google's carbon footprint will depend upon the number of its datacentres and the numbers of servers and storage arrays within them.

Google datacentres

Google does not say how many datacentres it has. Search engine optimising organisations try to understand just how many it does have based on search request answer IP addresses. They take into account, they say, that individual datacentres will have multiple IP addresses and say such IP address groups are known as C-blocks.

According to Search Engine Genie Google has 72 datacentres. According to it has 41.

According to a November, 2005, note by Microsoft's Business Development Director, Don Dodge: "Two years ago Google had one data center. Today they are reported to have 64. Two years from now, they will have 300-plus. The advantage to having so many data centers goes beyond simple redundancy and fault tolerance. They get Google closer to users, reducing latency. They offer inter-datacenter communication and load-balancing using that no-longer-dark fiber Google owns. But most especially, they offer super-high bandwidth connections at all peering ISPs at little or no incremental cost to Google."

Some of Google's datacentres are located in Mountain View (its headquarters), Santa Clara and Palo Alto in California, Herndon and Sterling in Virginia, Washington DC and Dublin in Ireland.

No-one but Google knows exactly how many datacentres it has. The total would seem to be somewhere between 40 and 60.

New datacentres

The rate of Google datacentre growth in the USA is astonishing:-

Google is building a new datacentre in The Dalles, Oregon. That is going to 34,000 square feet spread across two buildings. The company owns 20 acres of land at The Dalles and has options to buy more.

Another new datacentre is being built at Council Bluffs in western Iowa. Google has purchased a staggering 1,185 acres of land at the site.

A third new datacentre is being built in Berkeley County, South Carolina. It is on a 520-acre site.

A fourth new datacentre is being built at Lenoir in North Carolina.

A fifth one is being built in Pryor, Oklahoma.

That is five new datacentres which Google is building in the USA in just one year.

Google's servers

The number of servers used by Google and the rate at which they grow almost beggars belief.

In March 2001, Google had around 8,000 servers.

In a January, 2005, CBS 60 Minutes TV programme, Google said it had over 100,000 servers on which it stores a cached version of every page it knows about on the Internet.

The New York Times article reckoned the total had grown to 100,000 servers in 2003 and 450,000 spread across 25 global datacentres in June 2006.

Now it is one year later and we can reasonably suppose that the total has passed half a million and that they are spread across 40 to 60 datacentres, meaning an average of over 8,000 servers per datacentre. Once the five new US datacentres are built that would mean an additional 40,000 servers taking the server total to 550,000, unless older datacentres are retired.

As for storage Google has over 100,000 drives. We might expect it to be well over that figure.

Carbon Disclosure Project numbers

From the Carbon Disclosure Project we find out that, in 2005, Intel emitted directly and indirectly 4.073 million tonnes of carbon dioxide. Chip foundry operations are hugely energy-intensive.

IBM disclosed it indirectly emitted 2.451 million metric tonnes of carbon from the energy requirements of 49 IBM operations around the globe. HP declared a total for 2005 of 1,547,000 tonnes of carbon dioxide emissions. Microsoft said it caused the emission of 425,005 tonnes of carbon through energy requirements and business travel, etc. (That seems a low total.)

Dell declared it had produced about 350,000 tonnes of carbon in fiscal year 2006. Cisco was about the same level with 356,178 tonnes of carbon emissions in 2005.

Like Google, Yahoo declined to reply to the Carbon Disclosure Project's questionnaire. Sun Microsystems did not reply either to the 2005 request but has revealed emissions for March this year in its eight major US facilities which, it says, represent about half its worldwide total.

The March figure was 10,515 tonnes of carbon dioxide. Calculating a yearly total from this and doubling it gives a worldwide figure of 252,360 tonnes. Dave Douglas, Sun's VP for Eco Responsibility says Sun has now given data to the Carbon Disclosure Project and it will be revealed in September.

It's possible that companies did not reply because they did not know their carbon footprint, or, conceivably, they did know but did not want it known. It's also not reasonable to directly compare companies on their carbon emissions, because they operate in different sectors of the IT business.

What does this mean for Google's carbon footprint?

If all the Google datacentres used energy from coal, oil and gas-fired power stations then Google should be the world's biggest non-chip foundry IT emitter of carbon because it runs more servers and disk drives in more datacentres than anybody else. However, it is locating at least some of its datacentres by hydro-electric and nuclear power stations. Its Mountain View headquarters represents a serious attempt at using solar power and Google says it will be carbon neutral by 2008.

No doubt it has a serious amount of money to spend on carbon offsetting but there is a delay built into carbon offsetting before the built or grown facilities take the desired amount of carbon out of the atmosphere. It is may be possible therefore that Google is, at present, the IT world's largest indirect contributor to global warming.

A guesstimate would suggest that Google's carbon footprint is larger than IBM's and heading toward 3 million tonnes of CO2 emitted annually by itself and its energy suppliers in delivering electricity to it.

Asked to comment, a Google spokesperson said: "You are certainly right to have noted that Google has committed to carbon neutrality by 2008...we made the announcement with the support of external experts like the Climate Group, and we have been working with the Environmental Resources Trust to calculate our footprint correctly. We will not be disclosing it as it would effectively mean telling our competitors the size of our operational information. With this in mind, I don't think that I will be able to help you further with your query."

A subsequent interview with Bill Weihl, Google's Director of Energy Strategy, expanded on this comment and confirmed Google's green credentials.