If I buy a generator that uses either natural gas or LP gas, I can hook it up to my permanent gas line. So my question is, what happens during a blackout? Does the natural gas stop flowing and if so, how long does it take? Thanks.
Natural gas does not stop flowing during a blackout. Gas transmission is unrelated to electrical transmission, at least physically.
ETA: There are compressors that are needed to keep pressure on gas lines, but they are usually powered by the natural gas itself. An interesting source of alternative energy is what is called recycled energy, where the waste heat from the compressors are used to power turbines that feed into the grid. It hasn’t really caught on yet, but there are some companies pushing it as the new Rocky Express is being expanded.
As Darth Panda said, no, gas won’t stop flowing during a blackout. So, yes, you could run a generator off it. You can also use a gas hot water heater (but don’t if you’re on well water) or a gas stove to cook with during a black out.
My son has a natural gas generator that comes on automatically when the power fails. It takes about ten seconds and then automatically most of the house electricity to the generator. All except the electric oven (and, until he changed to a gas dryer, the dryer). It was quite pricey (I think on the order of $15K, but they have fairly frequent failures. I remember one day it failed on Thanksgiving day just as we were about to cook the turkey. He quickly fired up the gas grill and did it there.