A typical 10,000-square-foot (1000-square-metre) data centre consumes enough juice to turn on more than 8000 60-watt light bulbs.

That amount of electricity is six to 10 times the power needed to operate a typical office building at peak demand, according to scientists at Lawrence Berkeley National Laboratory. Given that most data centres run 24/7, the companies that own them could end up paying millions of dollars this year just to keep their computers turned on.

And it's getting more expensive. The price of oil may fluctuate, but the cost of energy to run the data centre will probably continue to increase, energy experts say. This is because global demand for energy is on the rise, fuelled in part by: the proliferation of more powerful computers. According to Sun Microsystems engineers, a rack of servers installed in data centres just two years ago might have consumed 2 kilowatts and emitted 40 watts of heat per square foot. Newer, "high-density" racks, which cram more servers into the same amount of space, are expected to consume as much as 25 kilowatts and give off as much as 500 watts of heat per square foot by the end of the decade. The dire predictions keep coming. Most recently, a Google engineer warned in a research paper that if the performance per watt of today's computers doesn't improve, the electrical costs of running them could ultimately exceed their initial price tag.

"As the demand for computing grows, the cost of power is a larger and larger concern," says Dewitt Latimer, CTO at University of Notre Dame. Latimer is grappling with finding the space and adequate power to handle a growing demand for cheaper and ever-more powerful high-performance computer clusters at Notre Dame. The problem comes not just from the computers themselves; Latimer is worried that the air-conditioning needed to keep the machines cool will also eat away at his budget.

Like Latimer, every CIO who is responsible for a data centre - even those who outsource data centre management to a hosting company - faces this conundrum: how to keep up with ever-increasing performance requirements while taming runaway power consumption. The problem is most pressing for companies on either coast and in large cities in between, where space is at a premium and companies compensate by putting more servers into their existing buildings. And there is no simple solution. Business demand for more applications results in companies adding more servers. According to market research company IDC, server sales are growing by 10 percent to 15 percent annually.

Nevertheless, some CIOs with huge energy bills are developing strategies for containing power costs by deploying more energy-conscious equipment and by using servers more efficiently.

"There's no question that the issue of power and cooling is a growing concern," says John Humphreys, an IDC analyst. "The assumptions used for building data centres have been blown away."

The Problem: IT Hogs Energy

IT's energy woes have a lot to do with market factors that affect everyone who drives a car or turns on a light switch; at the beginning of the year, the price of a barrel of oil was more than double what it was three years earlier. And anyone who thinks the current energy crunch is going away need only look at global energy markets.

The oil shocks in the 1970s and 80s stemmed from large, sudden cuts in supply. This time, it's different. While it's true that some of today's high prices stem from supply shocks tied to the US invasion of Iraq and hurricanes on the Gulf Coast, the world's thirst for oil over the past 25 years has grown faster than the energy industry has been producing it. And with rapid economic expansion in China and India, those countries are demanding more and more energy, putting further pressure on the world's energy markets.

Servers in corporate data centres may use less energy than manufacturing facilities for heavy industries, but within a company, IT is an energy guzzler. "We're pretty hoggish when it comes to power consumption in the data centre," says Neal Tisdale, VP of software development at NewEnergy Associates, a wholly owned subsidiary of Siemens. NewEnergy's Atlanta data centre performs simulations of the North American electric grid to help power companies with contingency planning. "We turn on the servers, and we just leave them on."

The exact amount of electricity used by data centres is hard to pin down, says Jon Koomey, staff scientist at Lawrence Berkeley National Laboratory. Koomey is working with experts to come up with such an estimate. Nevertheless, most experts agree that electricity consumption by data centres is going up. According to Afcom, an association for data centre professionals, data centre power requirements are increasing an average of 8 percent per year. The power requirements of the top 10 percent of data centres are growing at more than 20 percent per year.

At the same time, business demands for IT are increasing, forcing companies to expand their data centres. According to IDC, at least 12 million additional square feet (1 million square metres) of data centre space will come online by 2009. By comparison, the Mall of America in Minnesota, the world's largest shopping mall, covers 2.5 million square feet (230,000 square metres).