Going Green

Is the growing power consumption of data centres a threat or an opportunity?
Economist StaffMarch 5, 2007

The people, places and things inside Second Life, a thriving online world with millions of residents, may be imaginary — but the power consumption of the computers that maintain the illusion is all too real. Nicholas Carr, a business writer and blogger, recently worked out that each of the 15,000 or so residents logged in at any one time consumes electricity as a result of their activities in the virtual world almost as fast as the average inhabitant of Brazil does in real life. Second Life’s residents, Mr Carr concluded, “don’t have bodies, but they do leave footprints.”

It is just one example of the growing concern over the increasing power consumption and environmental impact of computers, and in particular the warehouses full of corporate machines known as data centres. A study by the Lawrence Berkeley National Laboratory, released last month, found that the power consumption of data centres doubled between 2000 and 2005, and now accounts for 1.2 percent of American electricity consumption, though other estimates put the figure at 4 percent. Companies now spend as much as 10 percent of their technology budgets on energy, says Rakesh Kumar of Gartner, a consultancy. (Only around half of this is used to run computers; much of it goes on cooling.) IDC, a market-research firm, says power consumption is now one of systems managers’ top five concerns.

Power consumption has increased because of the rise of the internet, of course, but also because of way in which computers have historically been designed: to maximise performance at all costs. Between 1996 and 2006, says Jed Scaramella of IDC, the number of servers in use went from 6m to 28m and the average power consumption of each server grew from 150 watts to 400 watts. But things are now starting to change and the computer industry has been seized with enthusiasm for “green computing”.

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Dell, a big PC-maker, recently launched a scheme that allows its customers to plant trees to offset the carbon emissions generated by their computers. DigiPlex, a Scandinavian data-centre firm, boasts that locating servers in its Oslo facility is greener than elsewhere in Europe, since Norway generates 99 percent of its electricity from hydropower. And this week several of the industry’s main firms, including AMD, Dell, HP, IBM, Intel, Microsoft and Sun, launched a “Green Grid” consortium dedicated to reducing data-centre power consumption.

Three technological fixes in particular could help. The first is new “multi-core” processor chips, in which performance is improved not by increasing clock speed, but by building several processing engines, or “cores”, into each chip — a far more energy-efficient approach. AMD, Intel and Sun now boast of their chips’ “performance per watt” (ie, work done for each unit of energy), rather than simply emphasising raw performance. Dual-core chips are commonplace, and quad-core chips are spreading too. The switch from dual-core to quad-core over the past 18 months increased performance per watt by a factor of 4.5, says Stephen Smith of Intel. This ought to mean that average power consumption per server will level off in coming years, says Mr Scaramella.

The second fix comes from using more efficient power supplies. At the moment, data centres perform many conversions between alternating current (AC) and direct current (DC). This wastes energy, which is emitted as heat and increases the need for cooling. It would be far more efficient to power servers directly from a central DC supply. Data393, a data-centre company based in Denver, Colorado, has tried this approach and says it can reduce power consumption by nearly 20 percent. The problem is that there is no single standard for DC power supplies, so such savings cannot easily be achieved in a data centre filled with equipment from different vendors. Developing new power-supply standards is one of the aims of the new consortium.

The third fix is the more careful use of cooling systems. HP, for example, has devised a scheme called Dynamic Smart Cooling, which links temperature sensors installed on servers to air-conditioners so that blasts of cool air can be directed towards particular servers only when needed. Such systems can reduce cooling costs by 25-40 percent, says Paul Perez of HP. Once again, however, standards are needed to ensure that different sensors and cooling systems can talk to each other.

Worldwide server costs

All this will take time. “It’s all talk so far,” says Mr Kumar. Energy costs will continue to rise and will rival annual hardware spending by 2010, Mr Scaramella predicts (see chart). As managers worry about energy costs, they will grow more interested in replacing old servers with new ones based on multi-core chips, installing more efficient power supplies and switching to more sophisticated cooling systems — in other words, buying lots of new gear. For vendors, mushrooming energy bills represent a big opportunity.