wi fi - Which consumes less battery: Wi-Fi or 2G data?

I just want to know what consumes less battery Wi-Fi or 2G Data.

My battery last long for 12- 16 hours only. I know there are lots of application which continually running and fetching data from internet.

I have both options available, in my office i have Wi-Fi and i also has 2G plan in my sim account, both give me desire speed.

Answer

I already posted this in another answer. As it where different details that time (more a general "what consumes most"), here some details from a reference Motorola Droid. Data taken from a German article named Energiesparplan (Heise is a very famous technology publisher in Germany; Google Translate Version here):

┌────────────┬──────────┬────────────┬──────────┐
|  Standard  |  Upload  |  Download  | Standby  |

├────────────┼──────────┼────────────┼──────────┤
|  3G        |  1410 mW |   1349 mW  | 18,3 mW  |
├────────────┼──────────┼────────────┼──────────┤
|  2G        |  1179 mW |    853 mW  | 11,6 mW  |
├────────────┼──────────┼────────────┼──────────┤
|  Wifi      |   479 mW |   1158 mW  |  7,8 mW  |
└────────────┴──────────┴────────────┴──────────┘

Guess this definitly answers the question. Though the values may vary between devices, relations should roughly match.