The energy demands of modern data centres are huge and growing, according to a new study.

A study by the US Lawrence Berkeley National Laboratory (LBNL), released today and funded by chipmaker AMD, found that servers in the US consumed 45 million kWh in 2005.

That's almost one-third of the world's total, and more than the total for US state of Mississippi or 19 other US states, reckoned LBNL scientist Jonathan Koomey. The global total was 123 million kWh, and the annual energy bill was $2.7 billion in the USA, and $7.2 billion globally.

Koomey, who is also a consulting professor at Stanford University, said that demand was growing fast, having doubled in the five years to 2005. He said he expected this level of energy consumption to increase by 2010 by 40 per cent, a figure he calculated by extrapolating from server sales forecasts provided by research firm IDC. The assumption was based on server power consumption remaining static -- if it rises at the same rate as before, by 2010 demand will have risen by 75 per cent. Most of the growth came from low-end servers, he said.

Koomey said the study included consumption by infrastructure such as air-conditioning and lighting, but not data processing equipment such as storage arrays or network switches, which increases the total about one-third.

"Though we have long known that data centres worldwide consume a significant amount of energy, AMD believes Dr. Koomey's findings are a wake-up call not just for the IT industry, but also for global business, government and policy leaders," said AMD's Randy Allen, vice president for servers and workstations.

"This study demonstrates that unchecked demand for data centre energy use can constrain growth and present real business challenges. New generations of energy-efficient servers are now able to help provide IT departments with a path to reduce their energy consumption while still achieving the performance they require."

Koomey's study was subject to peer review by IT industry, government and energy efficiency policy professionals, said AMD, which plans to share the study's findings at an industry stakeholder workshop in Silicon Valley tomorrow, 16 February. Organized by the US Government's Environmental Protection Agency (EPA), the workshop is designed to explore technical issues relating to a study mandated by the US Congress and requiring the EPA, "to study and promote the use of energy-efficient computer servers in the United States."

AMD didn't say that it expected its processors, which initially led the way towards lower CPU power consumption between 2003 and 2006, to make a significant difference to this level of power consumption -- which might lead one to assume that the company didn't believe it could make that claim with any credibility.