I'm doing a perswasive speech

I need to organize my speech into 3 points with at least 2 subpionts each

the 3 big points are
problem, cause, solution

my speech topic is something like why we should switch to green reknewable energy like windmills and solar pannels


for problem I said something about
limited resources and pollution
???

for cause i said
expensive to switch
????
???

for solution I have
get solar panels and stuff


if you can suggest any other points to make it better, ples do, even put in comments if no answer space