referance :

http://greencomputingisgood.blogspot.com/2011/03/benefits-of-green-computing.html
http://www.beloit.edu/isr/it/campuscomputing/greencomputing/

For more information about green computing, check out these sites:

http://en.wikipedia.org/wiki/Green_computing
http://www.energymanagement.umich.edu/utilities/energy_management/computing/
http://www.uwf.edu/helpdesk/eco/