Sun is expanding its Network.com utility computing service from the US to 23 countries in Europe and Asia, the company anounced.

Utility computing, in which customers pay an hourly rate for access to a Sun data center, began as a US only pilot in March but is now ready for a large geographic expansion, said Rohit Valia, group product manager for the Sun Grid Compute Utility.

Sun charges $1 (50.3 pence) per central processing unit (CPU), per hour to access a network of Sun x64 hardware running the Solaris 10 operating system.

End users can now access the utility from the UK, Australia, Austria, Belgium, Canada, China, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, India, Ireland, Italy, Japan, New Zealand, Poland, Portugal, Singapore, Spain and Sweden.

IBM, HP and other computer vendors provide similar utility services, also called on-demand computing. The services are for companies or other enterprises that have a short-term need for extra computing capacity but don't want to incur the expense of adding onto their own data centres. They only have to build out their own capacity for an average level of usage, not the occasional peak usage, said Valia.

"Our business model is around charging for CPU cycles, not idle CPUs. We only charge when your CPU is actually processing data," he said.

Sun is also adding a feature called Network.com Internet Access so that Sun customers can interact, through Sun's utility data centre with other companies that have resources the customer might want to use for a particular project. And Sun is also offering a limited beta program for developers called Job Management Application Programming Interfaces, which allows users to perform production scale tests to build software applications using Network.com.