Why new energy sources can't work

Exotic energy sources like what's featured in the movie Thrive will never work, not (just) because they violate the laws of physics (after all, we don't know all of them).  The problem is that we only have one sink to get rid of waste heat, by radiating it out into space.  We can't make space colder or the planet larger, so the only way to radiate more heat is to make the planet hotter.  Not a good solution.