Fossil fuels contain energy that are not in the form of heat, so electricity from fossil fuels would heat the planet even ignoring greenhouse effect. If from renewables, however, the energy has been previously extracted from the environment, thus being neutral in terms of heating the planet.

Not that it matters, because the effect would be miniscule in any case.

I did some napkin math and the amount of energy used from burning buried coal and oil since the industrial revolution began would warm the atmosphere about 3 degrees C. The assumption that all of the energy would be dumped into the atmosphere and stay there is obviously deeply flawed, but the overall effect might not be miniscule.

Technically if you power a laser shooting into space with solar panels you are cooling the planet, but you are ofcourse right in practice and on the scale of the universe!

That sounds like a good way to waste tons of energy during negative electricity prices to me! Shoot it into space.