Most natural gas or propane gas fireplaces will run and operate without the electricity although the electronic ignition and blower motor will not work.
Still you can usually use a match to light the propane or natural gas fireplace and have some radiant heat provided to your home with the natural gas fireplace.
That's one benefit of a natural gas or propane gas fireplace since when the power goes out your regular furnace will usually not work because it requires electricity to operate the blower and ignition portion of the furnace.
But with a fireplace you don't need the electricity to light and operate the natural gas or propane fireplace.
My natural gas fireplace works just fine without electricity although I have to use a match to light it.