Although there is little evidence to suggest that cloud computing is intrinsically 'greener' than delivering IT services efficiently in-house, the UK's carbon trading scheme is likely to push organisations down this route anyway.
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While the marketing momentum around the environmental benefits of cloud is undoubtedly starting to mount, one of the key challenges in validating such claims is that it is currently impossible to compare like with like in any meaningful way.
For example, many a cloud provider will attest that their power usage effectiveness (PUE) ratio is between 1.2 and 1.5 compared with an industry average of 2.5. This means that relatively high amounts of energy go towards powering the individual servers they are meant to power, as opposed to supporting secondary equipment such as cooling systems.
But not only are such metrics partial, they can also be misleading. PUE, which was never intended to be employed as a means of comparing data centre performance, is unable to indicate how much energy any given facility is using overall, for instance.
It also does not show whether an on-site low carbon power source is being employed or not, how much energy is being used to power each application or part of an application, how much server time an individual application is taking up, etc.
But all of these measurements - and more - would be necessary to obtain a rounded view of the situation, and such metrics simply do not exist today. Another important consideration in this context, however, is that much data centre power consumption is dependent on how individual facilities are used.
Tier three or four data centres that are based on widely available IT infrastructure to deliver mission-critical services such as financial trading or e-commerce systems by their very nature consume high levels of energy. Tier one or two facilities require much less power, however, and cloud providers tend to offer commodity services that do not require the same levels of resilience.
Andy Lawrence, research director of eco-efficient IT at researchers the 451 Group, says: "Cloud doesn't save power but displaces it. Ultimately, roughly the same power is drawn from the grid, just by different companies. So it's no greener. Cloud is more about dealing with company-specific issues than planetary ones."
While adopting a virtualised cloud model enables third-party suppliers to operate in a more energy-efficient manner by increasing system use, "if enterprise data centres have high utilisation rates and are well run, there's no reason why they couldn't be as green or greener than any cloud provider", Lawrence adds.
Liam Newcombe, secretary of the British Computing Centre's data centre specialist group, agrees. He indicates that being able to boost energy efficiency by moving to the cloud will inevitably depend "on your own specific situation, which cloud provider you chose, which service you procure and by how much you could improve your own data centre".
Nonetheless, he believes that the UK's Carbon Reduction Commitment (CRC) scheme will push organisations down this - and the more traditional outsourcing route - whether they actually provide greener services or not. CRC legislation comes into effect in April this year and will apply to about 5,000 large UK organisations that consume more than 6,000 MWh of electricity per year.
One of the flaws in the legislation centres on the fact that participants only purchase carbon credits based on their own levels of in-house carbon emissions, not those generated by third-party suppliers on their behalf.
This situation results in a "perverse" incentive for organisations to outsource the issue or at the very least to use third-party facilities to run any new IT services so that their carbon emissions do not appear to rise year-on-year. This latter situation would affect their position in proposed league tables, which would not only be damaging to their reputation, but could also make them eligible for penalties.
As Newcombe explains: "We effectively offshored embodied carbon in manufacturing by moving it to China, India and the like and now, under this short-sighted legislation, people will choose to outsource in-shore carbon too."
Another challenge is that efficient and successful cloud providers that grow customer numbers are likely to end up being penalised under the initiative. The problem is that the more customers they take on, the more IT equipment they require and the higher their energy consumption/carbon emission rates become, which is again damaging in league table terms.
"So the good providers could end up subsidising the bad ones, which is a very good perverse incentive," says Newcombe.
The situation could also lead to more offshoring into developing world countries that routinely have higher grid electricity carbon intensities than the UK. This scenario would not only lead to an overall global increase in carbon emissions, but could also threaten UK jobs, Newcombe adds.
Despite such concerns, charity WWF UK believes that moving to the cloud will, in certain circumstances, help it to reduce energy consumption and cut its carbon footprint. The organisation plans to roll out cloud-based staff appraisal applications in February and has already migrated its website to service provider Carrenza's virtualised infrastructure.
The rationale for moving its formerly paper-based programme development review system to the cloud primarily related to reducing the administration burden on an IT staff of just 12 that caters to 330 staff. But there was also an environmental aspect to the decision, which included cutting paper consumption.
Ian Exton, network manager at the charity, explains: "The cloud is handy because this is a system that's rarely used for substantial chunks of the year. We have two rounds of appraisals every 12 months and, in between, the system is doing nothing. But this way it can be used by someone else in the meantime and we only use it when we need it."
A similar rationale applies to its website. While WWF does not have enough in-house IT staff to support it on a full-time basis, the organisation does experience peaks and troughs in activity.
One such peak is the 'Earth Hour' awareness and fundraising event when famous landmarks and members of the public are asked to turn off their lights for an hour in order to encourage them to think about energy usage.
"A lot of people access our site around that hour so usage peaks dramatically, but we can now add extra processing power or move the service to different hardware to cope with demand," Exton said.
Power consumption has fallen by about 50% as a result of the move, although Exton acknowledged that much of this saving had come from consolidating four machines down to one and virtualising it.