Once you get into it, I'm sure you'll enjoy it!
As a start, you might choose a theme...say, exponential growth and energy. Here's a movie of a lecture (Colorado State University?) that might give you an idea for one of your lectures:
http://peakoil.com/images/dr_albert_bartlett.mov
Kuntsler's book, "The Long Emergency" might give you some ideas as well.
Overshoot, by William R Catton, is nice.
The "End of Suburbia" DVD might be worth showing.
I'd suggest that you start out with a semi-catchy title...say, "Energy and Population: over the cliff?" Or, less provocatively, "Energy shortages on the highway to the future."
Next, set up a weekly road-map of what you'll discuss. Choose a theme for each week, and, if possible, a reading.
The first session really ought to be planned to engage the students...so you might want to ask them what they use oil for. Perhaps you could write items on the board...you'll soon run out of space! If they want start off, pick one student and ask him (or her) for one thing they use oil for. Then go to the next one.
Next, segue into a discussion of how oil is used for everything, and how prices will ripple through the economy....
Give them an assignment - perhaps to find how far their breakfast traveled to get to them. Or how far their shirt traveled to get to them.
Anyway, once you have a semester outlined on a weekly basis, with a topic for each week, the curriculum should practically write itself.
Don't worry about not having enough material; instead, present some interesting facts and encourage discussion.
Hope that helps!