400 watts per hour isn’t a huge amount of power, a space heater consumes about 1,300 watts per hour, but it’s still a pretty decent chunk of electricity. A deep discharge marine battery (common for cheap backup power) could keep a larger blower running for maybe 3 hours tops, assuming an unreasonable 100% discharge and 100% conversion efficiency. So, not a lot, but still something that you’d need some pretty specialized backup gear to run.
As an anecdote, my furnace blower pulls about 11 amps on 120V AC. So I can run it with a little 2000W inverter generator but won't have much spare capacity for anything else.
For backup heat generation nothing beats an EPA certified wood burning stove, especially the free standing ones.
Probably obvious in retrospect, but took a bit of brain rewiring to realize no-power != no-hot-water given I had mostly dealt with areas with electric water heaters with fairly small tanks up till then.
Both a hot water and a forced air furnace work by burning natural gas to heat something up until it's hot enough. In both cases the combustion is separated from whatever its supposed to heat by a chunk of steel, and the gas is simply burned in open air without any extra compression. Ventilation is usually done via convection, which works without power. So far, so good; both cases just need a small amount of power to open a valve and kick off combustion. The similarities largely end there though.
In the case of a hot water heater, the flame is heating a big slab of metal under 40+ gallons of water. It's very hard for this slab to overheat and get damaged, as water is both thermally dense and a great conductor. There's also no need to move the heat around; the flame is literally right underneath the thing that needs to be heated. This proximity also makes the control logic extremely simple; you turn on the flame when the tank is too cold and turn it back off when it isn't. This consumes a tiny amount of power, and you can use the heat generated by the pilot light to keep such a circuit alive.
A furnace on the other hand has an issue. While burning gas in a furnace is easy, getting that heat back up to where you need it isn't. Air is a pretty terrible thermal conductor, and without some cooling that combustion chamber is going to overheat and get damaged. You need to move a lot of air past the combustion chamber to get the heat away before that happens, which means you need a powerful fan to get that air moving. These fans consume a lot more power than you can reasonably generate locally, about 75-400W per hour, with an extra spike needed to get the fan moving in the first place. You also have the issue that it's not possible to measure the outcome of the furnace at the furnace; which means you're going to need relatively complex remote sensing and control devices, which only adds to the system's total power needs.
Most (gas) furnaces are forced air, and how exactly would the fan run without electricity? How do you think the thermostat runs its thermistor (and probably LCD display) without a power?
The Technology Connections YT channel has a recent good overview, "Forced-air Furnaces: The What, Why, and How":
* https://www.youtube.com/watch?v=lBVvnDfW2Xo
As for efficiency, you can get units that are 99% efficient (AFUE):
* https://www.lennox.com/products/heating-cooling/furnaces/slp...
* https://en.wikipedia.org/wiki/Annual_fuel_utilization_effici...
I have no idea if this is common or not, but I know of at least two counterexamples to your statement here in Michigan.
Some do, some don't. Mine has a pilot light and a thermocouple. I used it to keep warm while our power was out for three days this past weekend.
Gas fireplaces are slightly less efficient than high-efficiency furnaces because some heat goes out the exhaust.
If you use a heat pump, you might get a COP of 3 or 4, which is effectively 300-400% efficiency. It's able to do this because it makes the outside colder while it makes the inside warmer.
Overall, the electric/heat pump system can be more efficient, but it has a lot more complex and expensive machinery, both in the home and in the power plant, and it's only been in the past 20 years or so that this has been practical. Many new homes are being built without gas hookups and use heat pumps instead.
My gas costs $0.51 per therm, including distribution. When I consume electricity (more on that in a sec) it costs me $0.085 per kWh. On a straight therm to kWh basis, electricity is ahead.
But a single therm is equivalent to 29.3 kWh, so on an energy equivalent basis we've got $2.49 worth of electricity per therm of gas. So for 100% efficient electric radiant heat, electricity is about 5x more expensive than gas. That's close to the efficiency band of an air source heat pump, which tends to run in the 200-300% efficiency range, and geothermal might just beat out gas per BTU transferred into the house, especially if you include hot water consumption in that.
The extra complication is solar. Roof top solar is getting cheaper every single day, and for some of us the effective cost of electricity is $0. If you've got a rooftop solar system it's kind of silly not to switch over to electric heating if possible, since you can get your electricity cheap. Especially if you have net metering or a backup battery. If I didn't have a really high efficiency furnace in my new house, I'd probably have already done that.
That being said, we know that in the long run rooftop solar reduces electricity cost, because otherwise most people would never buy it. From my numbers above rooftop solar only needs to reduce electricity prices by ~40% to put them within striking distance of a heat pump being cheaper than gas.
A basic gas furnace is 80% efficient, with a nicer condensing unit being 96-98% efficient. Meanwhile most gas turbines hang out in the 32-38% efficiency range, plus transmission losses. Maybe if you’re using a heat pump and your local power plant is a triple pressure high efficiency model (~60% efficient) you might end up ahead, but for most users in most municipalities it’s actually better to burn the gas at home directly rather than at a power plant, at least for heat.
https://www.calculator.net/voltage-drop-calculator.html
I’d call them semi -complementary from a consumer perspective and have different strengths and weaknesses, similar to phone and cable before.
My long term view is gas will go away first as electric costs go down and reliability goes up with local caches such as the PowerWall. Eventually usage will be light enough to cut the cable from long distance generation for close range neighborhood nukes.
https://www.greentechmedia.com/articles/read/a-texas-sized-g...
> According to a paper from Pecan Street, an Austin-based energy research organization, the transition would reduce climate-warming pollution, save Texas households up to $452 annually on their utility bills, and flip the state from a summer-peaking to a winter-peaking system. And that winter peak would be “nothing the grid couldn’t evolve to handle,” according to co-author Joshua Rhodes.
> Our analysis finds that electric heat pumps generally use less energy in warm states and have moderately positive economics in these states if a heat pump can replace both the furnace and a central air conditioner.
> Based on our analysis, we find that electric heat pumps have higher equipment and installation costs than gas furnaces and that electricity is generally more expensive per Btu than natural gas. As a result, in all of the comparisons the gas furnace has a lower life cycle cost for homes without central air-conditioning. However, if a central air conditioner can be replaced with a heat pump, the high-efficiency heat pump has lower life cycle costs in climates from Virginia southward as well as in the Northwest. This is shown by an analysis that credits the avoided cost of a central air conditioner and also includes cooling-energy savings from replacing a central air conditioner meeting federal minimum efficiency standards—a seasonal energy efficiency ratio (SEER) of 13 in the North and a SEER of 14 in the South—with a higher-efficiency heat pump
> As discussed above, our analysis is only for existing homes. The results may be more positive toward heat pumps for new homes, as most new homes have air-conditioning and the cost of supplying gas to the home can be avoided by installing heat pumps.
Note that this is a few years old (2016), and more efficient heat pumps improve the economics.
In that mode less of the energy in the gas becomes heat in the home (good furnaces are really good).
[1] https://www.houstonchronicle.com/business/energy/article/Tex... ("A federal report that summer recommended steps including installing heating elements around pipes and increasing the amount of reserve power available before storms, noting many of those same warnings were issued after similar blackouts 22 years earlier and had gone unheeded.")
Weatherization makes any heating and cooling more efficient too, so everyone should assess for improvements.
* https://www.mitsubishicomfort.com/benefits/hyper-heating
These are designed in Japan, where they often have earthquakes, and so any flammable materials (natural gas) seem not to be used for heating. Things can get quite chilly up north:
* https://en.wikipedia.org/wiki/Rikubetsu,_Hokkaido
* https://en.wikipedia.org/wiki/Hokkaidō#Climate
AFAICT, the units do not have external thermometers, but rather look at the refrigerant temperature. So if the piping from the unit into your wall is short, then the refrigerant isn't exposed to the cold that much, and so may not effected as much by air temperature.
I believe why natural gas heating is not popular is because they are a bit expensive and gas pipes aren't common outside big city. I'm getting curious why gas heating isn't popular even in big city (Sapporo). Your assumption (earthquake) looks reasonable for a part of reason.
Maybe gas heater is hard to install/uninstall and never use except winter. So we don't want to put all year on small house is reasonable.
And then gas does usually need ducting or radiators.
It's not just Texas. There has been extreme cold across Europe, and unseasonable warmth across parts of the Arctic.
Of course it's far too late to fix the primary cause now. But it's still true that extreme weather events caused by climatic instability were being discussed more than twenty years ago.
Adding more of Power Source [X] is a bandaid. The real problem is structural, and it could have been solved more cheaply back then.
You can use it to heat your home, or you can send it to a power plant to convert it into electricity and heat your home at a 3x markup.
But regardless, you are relying heavily on a single resource in a single state.