Although we're all obsessed with the latest ultralight laptops and cool phones, we shouldn't forget that many large organisations still use big mainframe computers made by companies like IBM.

These mainframes compete with the server farms preferred  by Google and Sun, rooms packed with thousands of separate computers networked together and used to store and process vast amounts of data.

One of the things that mainframes have always done very well is self-monitoring. It's not quite the self-awareness of the HAL 9000 series in '2001: A Space Odyssey', but a mainframe will have a lot of information about its internal state, including temperature and energy use. 

This is already used to improve efficiency, but now IBM has taken it a lot further with a real-time energy monitoring system they are calling a 'mainframe gas gauge' (that's a petrol gauge to those of us in Europe), launched as part of their $11bn 'Project Big Green'

They will soon start  publishing typical energy consumption data  from their Z9 mainframe derived  from actual measurements of approximately 1,000 customer machines. According to the press release it will show "average watts/hour consumed which can be used to calculate watts per unit - similar to automobile miles per gallon estimates and appliance kilowatt per year ratings".  Not only will it help customers manage their electricity consumption, it should give the rest of us an insight into just how much power these systems need.

This is all part of the PR campaign around energy use that has seen AMD and Intel fighting over whose chips use less power, but I can't help seeing it as a positive sign. If large companies begin to see competitive advantage in pushing for more energy efficient technologies then we should hope they are rewarded for their efforts, and that customers are serious about the issue.  

And if the numbers do show, as IBM claim, that  "a single mainframe running Linux may be able to perform the same amount of work as approximately 250 Intel or AMD processors while using as little as two to 10 percent of the amount of energy" then we should be looking again at the behemoths of the computing world for one part of the approach to reducing overall energy consumption on IT.