But now what am I going to do with all this plutonium I bought from the Libyans?

What are you doing buying plutonium from the Libyans in the first place? I hope you're wearing a bullet proof vest when they come back for their plutonium later. Didn't you learn anything from Back to the Future?

Wormholes are bad enough, but you want to play with plutonium to make it happen? You don't know how to use your brain, do you? Look at all of the bad things that happen with plutonium:

• The radiation from plutonium can cause cancer and death. Look at Madam Curie. (Sure she was working with primarily with polonium and radium, but it's close enough.)
• Plutonium is one of the key components of a nuclear bomb. That's why the Libyans gave it to Doc Brown after all. Do you want to be responsible for that?
• Sure power plants are great, but what about all of the negative side effects of nuclear power? You've seen the Simpsons and that three-eyed fish.
• Do you want to become Mr. Burns? I don't think I need to say any more on that count.
• If you're just walking around with plutonium, the government is going to think that you are a terrorist. I'm pretty sure you don't want them thinking that.
• Maybe you can manage to create that 1.21 gigawatts of energy to travel through time, but flux capacitor or not, it's just another wormhole and I've already talked about the problems with that. (Look at all the trouble Marty caused by a simple trip back in time.)

So if you're smart, you'll get rid of that plutonium and stop playing around with wormholes.