very bright lights

Hello everybody!
In searching for strong lamps to buy, I ended up on this forum, so I subscribed and now I'm posting this message, because I have a few problems with the thing I'm working on.
which is:
a projector for beaming pictures on walls at night.
it will have to be 'lightweight' (I will have to be able to carry it)and powered by accu (battery in English? powersource cars use, I alightned two of them serially so I now have 24 volts)

now, the biggest problem is this:
how do I get enough light? is it even possible with so little power (24v and the lamp I now have is 250 W, 11 A) to create an image over a distance of 50 or maybe even 100 meters (I want to climb buildings with it:) dadadadadadadada batmaaan, batmaaaan)

should I maybe use LEDs or do other strong lamps exist that do not require too much voltage???
LEDs are of course much lighter (to carry), because I would only need one car-battery, but do they give more light? I am hesitate to try, because they are so incredibly expensive.

If anyone could help me with this, I would be very grateful.
thanks apogee

thanks for the guidance, I will start looking right away.
in the meanwhile i've had some good looks at my installation and i made some adjustments
now i'll return to my study, only to return when i'm desparate or when everything's ready , in which case i'll start a webpage with the results

goodbye, etzl