eWeek.com has an article titled How to Be Green in Your Data Center: Four Suggestions, but I would have title How to Green your Data Backup.
There are a lot of ways to save energy in your data center, including virtualization of both your servers and your backup. Andrew Madejczyk, vice president of Global Technology Operations at Sterling Testing Systems, explains this in more detail. Sterling had found itself with a backup solution that was too slow for its virtual environment. Madejczyk shows how that challenge can be made into both a performance and energy-saving opportunity.
Suggestion No. 1: Leverage the Value of a Backup Assessment
Suggestion No. 2: Virtualize Your Backup
Suggestion No. 3: Compress and Deduplicate Data
Suggestion No. 4: Use Thin Provisioning in Your Backup Environment