I live in central Florida and some years ago there was a cold for down here winter. The natural gas lines suffered low pressure and the gas company actually shut down portions of the gas system. If i remember correctly the guy from the gas company said it took about three days to get everyones gas turned back on. Part of the reason it took so long was they had to go to all of the places that had shortages and turn off all of the individual gas supplies, turn the mains back on, and then go turn back on all of the individual supplies, and relight all of the pilot lights. So to answer your question, yes your natural gas supply can go out. But it is a rare occurrence.

Thanks to all. I mentioned electric power failure since, apparently, the electricity went out and the gas pressure dropped within hours of each other during a severely cold winter - kinda limits most people's options. Doesn't sound like the two events were connected except by coincidence (probably). Anyhow, I guess I don't have much to worry about in terms of Natural Gas reliability but it's good to know that something could affect the supply.

It might be useful to point out that many gas appliances, furnaces stoves and heaters, use electrical power to run blowers and controls and many of these won't work at all without line power. Check your manual, ask your regular service tech or, a useful way to double check and avoid misconceptions, turn off the power at the mains and see what is still kicking.

Some of those that use line power use such minuscule amounts of power to run timers and controls that some of them can be inexpensively set up with a small battery backup. Others can be bypassed even if it requires that you operate the unit manually. All of which is a lot easier to figure out and adapt before any emergency.

How you adapt any system is going to vary with your system and installation. A sympathetic and highly knowledgeable service technician is your best guide. It has to be noted that such modifications require an exceptional amount of engineering skill, inventiveness and knowledge to operate outside the margins. Your average technician that has to operate out of a standard flow chart won't be much help.

I was going to mention this earlier today, but apparently I didn't hit submit. I just have one question:

Why is there not something for these heating systems that makes them near-perpetual assuming they have enough fuel? Can there not be enough heat to power a steam turbine to generate enough electricity to power the system itself?

It could be done, but normally is not on account of the extra cost and complexity.
Most domestic sized heating systems use either hot water, at less than boiling point, or hot air at similar temperatures.
No steam is produced, therefore cant run a steam turbine (which is a relatively costly device)
Electricity could be produced from peltier chips, heated by the system, but the costs are signifcant. A battery would still be required for starting from cold, and for re-starting without line power after any stoppage.

I would suggest either a generator, or a heat source that needs no electricity such as a wood/coal stove.

I have seen a coal burning heating system that used peltier generators to produce about 60 watts, for a circulating pump and a couple of small lamps, it worked fine but would be too costly for general use.

There are natural gas fireplaces/heaters that don't require line power to operate, but they are slightly more expensive. Two of them helped keep my parents' pipes from freezing after a fire knocked out the power.

All an appliance really needs is enough juice from the thermocouple to operate the control system, shutting off the gas if flame is lost.

A blower is an electric motor, and that takes a lot more juice. But I have one of those self-powered fans on my wood stove and it works rather well. They are available for freestanding natural gas fireplaces as well.

There are some units that use simple mechanical thermostats and either thermal-expansion type or millivolt safety valves. The later converts the heat from the pilot light into a tiny electrical current that holds a gas solenoid open. If the pilot light goes out the pile cools, stops producing power and the gas valve closes.

These units would also lack a blowers to distribute the heat. Many of these units are wall-mount radiant heaters and fairly inexpensive.

These units are not all that common despite their relative low cost because they heat unevenly, only really heat one room, they are not pretty, and their presence places limitations on what you can place along the wall in front of the heater. Drapes or furniture places in front of them can overheat and ignite.

Mostly you see them installed in rural cabins and lodges where their low cost makes them attractive, there are not a lot of furniture that is likely to catch fire, and aesthetics are not an issue.

Well, they don't *have* to be ugly. The natural gas fireplaces my parents have are quite nice, and they have blowers that run off 110VAC. The only difference is that the thermostat and control system don't require line power, so they produce heat during an outage. I assume they have a heavy-duty heat exchanger because of the additional stresses, and that explains why they are a bit more expensive.

Some units are less aesthetically challenged than others. In a rural cabin butt ugly is less an issue than avoiding freezing. I've never made any great effort to review all the units available but as I understand it the fireplace type units are generally more about the romance of a fireplace than warmth.

Yes, as noted, there are some models that have blowers that make them pretty good at heating. Unfortunately if the blower doesn't run, you loose power or the blower fails, many of the blowers are afterthoughts and poor quality, you are back to mostly looking pretty. I wouldn't count on that type unit to keep a room above freezing if the weather turns frosty and the power goes out. Might be worth a shot to experiment on a cold day, with the main furnace off, and see if it can keep up without the blower. Better to know while you have power than be disappointed in a blizzard when there are few other options.

Generally the units that put out the most heat, and will continue to provide heat without electrical power, look more like heaters and less like a traditional fireplace. These are convection or radiant units. Confusing the issue, in a nod to the mystique of a fireplace, some heaters offer a small window that allow you to see the flame. These are generally failures as romantic accessories.

What looks like a decent heater for a power-out situation:
http://www.homedepot.com/webapp/wcs/stor...&marketID=1

Edited to add link.

Times have changed. It used to be that a home with natural gas could have heat, hot water, and both stove top and oven cooking ability without any electricity. Whether you lived in an apartment in a large city or a farm in a rural location, if you had natural gas, you did not need electricity. Piezioelectric cells were added as a safety device to stop gas flow in case the pilot light went out preventing explosions. Piezioelectric cells did not need an outside electrical source to work. It used the flame / heat of the pilot light to function. Early furnaces used gravity to circulate heat within the house, no fan was used. Early stove tops and ovens did not even have pilot lights to work. Later ovens used pilot lights with bimetal thermostats to roughly hold to a given temperature. These appliances worked very well but were not very efficient.

Today things are different. It is all about convenience and efficiency. Pilot lights are generally out due to wasteful gas consumption. Stove tops usually have manual ignitors which again requires no external electricity. Ovens, for many years now, have an externally powered electrical ignitor which saves gas, no pilot light, and eliminates the combination of pilot light piezioelectical cell in the oven. In other words, no external electrical power means the oven no longer functions. High efficiency gas water heaters require a fan to force the flue gases to travel out the flue stack because there is not enough heat loss to move the gases out of the flue. High efficiency gas furnaces also do not have enough heat loss to move flue gases without the addition of an electrical fan. There is also the requirement of the main fan to blow the heat through the houses duct work. These new highly efficient furnaces also do not have a pilot light only externally powered ignitors. These efficient but complex furnaces require electrically powered sensors, relays, circuitry, and multifunction thermostats to operate. New high efficiency gas fire places also require externally powered fans for flue gases and heat distribution and electricity for ignitors and remote control ignition and temperature settings.

So, become familiar with your gas appliances. When you replace an old gas appliance with a new highly efficient one, they will most likely not operate without external electrical power. In fact, most twenty year old gas appliances already require external electrical power to operate.

And as already mentioned, natural gas appliances, if they are so designed, may operate on liquid propane gas only of if the jets are changed, adjusted, or modified.

You may be able to buy older technology gas appliances, which are still available, but your local building codes may not allow you to install them.