Problem is thermodynamics. We cannot sustain projected population 9 billion + at current energy levels of consumption even if we have zero point energy because of the waste heat that would really cause extreme global warming - there may be one loop hole however to eliminate the waste heat. In any case planet is too crowded for quality of life for all. Only happy solution short of mass extinction is star gates to parallel unpopulated Earth type planets on similar solar systems.
If we have a Haisch-Moddell zero point energy generator operating between a cold positive temperature and a hot negative quantum spin temperature then all the waste heat Qcold is converted to useful work.
W/Qhot= 1 + |Tcold/Thot| > 100%
This might prevent global warming from waste heat, but we would still be overcrowded and quality of life would diminish severely.