This is ANNOYING the hell out of me.
There's this movie that I want to know the title of. So if anyone can tell me that, I will be FOREVER grateful. Seriously.
It's about this boy who uses a time machine to look for his father in the future. When he does get to the future he finds out that humans have evolved into two entirely different species. One type live above ground where they're always carefree and happy and have telekinetic powers(which they use to start a food fight =P). The other type live underground and only come up at night.
The ones above ground have to sacrifice some of themselves every month to those underground in exchange for food and clothes. Turns out the underground people use them as power sources. Boy finds his father trapped underground and manages to save him. Oh, and the boy sort of falls in love with an above ground girl.
That's about it. Should be enough to trigger off your memory if you've watched it.
The reason I suddenly thought of this is I'm reading H.G Well's The Time Machine. And it seems that this cartoon movie is directly inspired by the book. In my opinion at least.