Pony keg(30liter) with hot plate heat source?

[theJesusHorse]

I'm considering using a Pony keg(30liters/7.75gal) as a boiler and was wondering if a 1500w hot plate would give me enough heat. The bottom of the keg has a flat surface that is about 5 or 6" in diameter.
From what I have read on here, most people using full size kegs go with gas, but that really isn't an option for me right now. I'd like to use the Pony keg because I can get one for free, but if it won't work with a hot plate then I will have to pay $150+ for a boiler that will. Thanks ahead of time for any info you can give me!