If you aren't really passionate about natural disasters or the genocide then I wouldn't do them if I were you. Your I-search needs to be something that you really care about and that you would be willing to spend several months on. With that in mind, your last topic, Alternative energy and conservation, seems to be something you're really interested in so I would definitely say go for that one.
Also, I know there are several locals around the area that use alternative energy (windmills, biodiesel... that sort of thing) you could interview them for some first-hand information! :]
