Modern data centres have become insatiable consumers of power. Server racks traditionally operating at two kilowatts of power have been forced to accommodate more tightly-packed, power-hungry servers, eating up to 25 kilowatts.

These servers are also generating tremendous amounts of heat, which needs to be moved away from the equipment if it is to operate smoothly. The cooling adds further costs and draws more energy. According to Hewlett-Packard, for every kilowatt of energy consumed in processing, a further kilowatt is used for cooling.

The impact of this is heightened by rocketing energy prices. Furthermore, the ability of high-density racks to suck up power actually threatens to outstrip the ability to draw the power from the local electricity grid in some cases.