BT’s green credentials are well established. It is the largest commercial buyer of renewable electricity in the UK, emphasises the importance of carbon reduction across the organisation, and pushes voice and video conferencing at an unconvinced customer base. In any international ranking, BT’s sustainability measures get high marks.
But BT has the same problem as many other organisations: its server farms are growing in number and size. The increased power consumption in its data centres explains why the organisation’s electricity demand is growing. Eventually, its brand image will suffer as critics suggest that its public stance on green issues is not matched by its internal behaviour.
BT’s electricity use is about half a percent of the UK’s total, and its server farms represent over 10% of its energy consumption. BT says that data centre use is rising at 40% a year, and the company’s emphasis on growing video businesses, such as BT Vision, is likely to increase data storage and transmission demands into the foreseeable future.
BT’s response has been to attack the power use of the server with radical measures that set best practice elsewhere in the world. Its new data centres use fresh air cooling, not air conditioning, and the company runs its machines at much higher temperatures than used to be considered possible. Since cooling servers uses at least as much power as running them, this is an important step. The second major innovation is to run the farms on DC power, cutting the very significant losses in the multiple AC to DC conversions in a conventional centre. Better ‘loading’ of the computers helps as well. A well-utilised machine uses only a little more power than an intermittently under-employed server. BT claims that these measures can reduce the typical power consumption of a server farm by 60%.
Across the world, data centre energy consumption is becoming a bigger issue. The world has about 26m servers pumping out data day and night. Estimates suggest that they use about 2% of all electricity produced and global growth is probably around 15% a year. BT’s innovations may be a useful model for others to follow. But the unfortunate fact is that at current growth rates the maximum efficiency gains will be wiped out in less than four years.
In an intriguing trend, some companies are dealing with apparently unquenchable growth in data traffic by beginning to move away from thousands of servers based on PC technology towards huge single computers with lower total energy costs. Who said the mainframe was dead?
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In Denmark and Germany, large numbers of individuals own shares in local wind farms. If the government encouraged this in the UK, a large part of the local opposition would disappear. Onshore wind farms in windy locations are good investments which could form an effective part of many people’s pension plans.
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