>>how much coal, gas, or oil must be burned

No idea the KWh required, but you understand we're moving away (slowly, I'd admit) from burning stuff to make electricity? As it is, here in the Boston area, I can opt for electricity from fully-renewable sources and it's maybe two cents per KWh more. Some of my neighbors have enough rooftop PV power to heat their homes and charge their cars (grid works like a big battery). That still doesn't address where the generated power is coming from then they recharge cross country, but the issue there seems to be more building out the grid for this kind of usage rather than providing power input.