Except, unless you are powering a laser pointed offworld, most of that energy is going to end up in your local environment as heat. Or, you meant just your house's greenhouse problem? Running a heat pump or AC would do that.
Yes, but the energy that gets converted into heat is replacing energy that would have come from some other source (fossil or not) that now doesn't have to be consumed.
I'm not enough of an environmental physicist type to know for sure, but I think warm air (produced by various electronics) is preferable to a hot roof emitting blackbody radiation (which radiates at the wavelength that greenhouse gasses absorb).
