Hello smart cookies!

I am trying to design a device that is attatched toa post in a park that can send a jpeg with text to someone when they walk past, I gathered that bluetooth was the option I would use.

I saw a billboard that used bluecasting to send out an advert, this was wired into 240v mains! My problem is that I dont have any power source to tap off, except the sun! and batteries.

Does a bluetooth radio permenantly search for bluetooth devices? Does the radio have an internal harddrive that saves the deired information and sends it?

Any ideas would really help my project. Can you steer me towards anyone who can help

cheers disenchanted