If you are going to do your own presentation, you should use Richard Heinberg's 'The Party's Over' as the 'plain and simple' guide to explaining peak oil, especially the section about alternatives and their limitations. Even with all of my peak oil books, I keep coming back to that book as the friendliest, most accessible work available. Richard's skill as a presenter, lecturer, and writer really show in that book. As formidable as Matt Simmons' presentations are, they are not very good for the general public as they are tailored to oil industry professionals, investors, and other folks that are 'in the know'.
Why don't you upload the slides you come up with once you're done? I think it would be challenging to be able to do a 30-minute talk on peak oil and have your audience 'get it' in a really mobilizing way. I mean, Chris Martenson's Crash Course is 3 1/2 hours long! Mike Rupert used to talk for 3-4 hours at his public engagements! Great material, but you have to be really interested to stay with it.
Think in terms of 30 minutes as the maximum attention span of the average person, based on the length of the TV episode...or perhaps 22 minutes?
Best of luck!
Kevin