Used to house computers and IT components, data centers are major energy guzzlers. Yet, in efforts to increase environmental efficiency, cut back expenses, and get some positive PR, many financial firms have started to operate "green" data centers. As FierceFinanceIT has noted, green data centers have been especially popular among banks.

Citigroup has gone from 52 data centers in 2006 to 24 at the end of 2010, with three being LEED (Leadership in Energy and Environmental Design) certified, according to the company site.

The key to "green-ing" data centers rests on virtualization (virtualization news). Wells Fargo's Environmental Forum defines virtualization as "going from using multiple computers at partial capacity to using fewer at fuller capacity."

After major virtualization initiatives in 2009, the average server in Wells Fargo data centers uses 150 watts of power, compared with 300 watts just one year ago, reports ZDNET.

Deutsche Bank also touts the benefits of virtualized data centers. "With fewer physical cables and ports, we are finding that we are able to increase network energy-efficiency in our facilities, whilst also simplifying the physical topology and improving the resilience," Chief Infrastructure Architect Andrew Stokes told News@Cisco.

But instead of building new green data centers, firms should focus on modifying old centers, Stokes advised. "This is probably the biggest opportunity: Taking new concepts and applying them back into existing buildings."

Green infrastructure does not stop at data centers. Some banks have even opened energy-efficient branches, such as TD Bank's Queens Village, N.Y. branch. And as of 2010, Citigroup operates more than 100 LEED certified branches. In the wake of BP's environmentally-destructive fiasco, it would seem likely that other banks and financial firms will jump on the data center green band wagon.