How can any electric heating system be more "efficient" than an inefficient appliance? Inefficiency in an electrical appliance is nothing more than a measure of how good that appliance is at turning electricity into heat.
I had this same thought at one point and eventually learned of heat pumps. Heat pumps move heat from one spot to another, ie from outside your house to inside your house, or the other way. The point is, they move more energy than they consume. So that 1kwh of energy turned into heat by an inefficient electrical appliance could have instead been used to move 5kwh worth of heat into your home by a heat pump.
Heat pumps are more efficient than they used to be (at some point the outside air is too cold for them to work efficiently), so the cold climate where I'm from is just now starting to see them included in new homes.
Yes, I've considered getting a heat pump; for one reason and another, I can't.
It doesn't feel right to talk about the "efficiency" of a heat pump system; talk of "1W in gets you 3W out" isn't right, because you didn't magic those 3W out of thin air. It's more like "4W in gets you 4W out". It seems wrong to say that a heat pump system is "400% efficient".
I thought efficiency was a measure of how much of the work[0] going into a machine is transformed into the intended output work. I suppose you could say that this heat delivery machine is inefficient if a lot of the input work is expended on producing torque, or raising heavy stuff. But even that eventually turns into heat; just in the wrong place.
[0] I hope I'm using "work" and "machine" in the technical sense, so that "work" means displacement against a force, and a "machine" is any device for converting work from one form to another. Effiency is well-defined for that kind of machine: it's just the ratio of work in to work out, the output being what you want; so "efficiency" intrinsically depends on what your intentions are for your machine. .
> It doesn't feel right to talk about the "efficiency" of a heat pump system; talk of "1W in gets you 3W out" isn't right, because you didn't magic those 3W out of thin air. It's more like "4W in gets you 4W out". It seems wrong to say that a heat pump system is "400% efficient".
Those 3W didn't come out of thin air, it came from outside air.
1W of energy going into the heat pump causes 4W of heat energy to get moved from outside your house to the inside of your house.
That's the key thing to take note of. Traditional resistive heating works by turning electrical energy into heat energy directly. Heat pumps move heat energy the same way an A/C unit does, it just moves it the other way.
Essentially, a heat pump is just an A/C unit with the evaporator and the condenser flipped.
All heaters are 100% efficient in a closed system. However, your house is not a closed system. It’s a spatial region of an open system. In this context it makes sense to talk about efficiency as being lower or greater than 100%.
The efficiency is higher than input because the electricity is only used to transfer heat from one spot to another.
This is when the gas gets compressed, to get to the condensing stage at the high pressure. (+after burn for optimal efficiency)
Another one of my "came across this in YouTube" things (started with the design of a hurricane lantern) Why Heat Pumps are Immensely Important Right Now - https://youtu.be/MFEHFsO-XSI
If your electricity comes from natural gas, it would be more efficient to burn the gas on-site for heat than to burn it to generate electricity, distribute the electricity, and then turn it back to heat.
It'd be far simpler and more efficient to use a reciprocating engine to drive a heatpump via a rotating shaft. As a bonus, you could capture the exhaust from the engine with a heat exchanger and use that to heat the house as well.
However, consider the greater performance scales with generators combined with the amount of useful heat that one gets out of a heat pump can be better than converting the natural gas to heat locally - even with losses on the grid.
The key is that a heat pump doesn't convert electricity to heat (as a resistive heater) but rather moves heat from one spot (outside) to inside with great efficiency.
In addition to what other people are saying, there's also district heating: https://en.wikipedia.org/wiki/District_heating Heat can be generated efficiently in some centralized location (from geothermal heat, power plant waste heat, solar, or whatever) and then distributed to nearby homes.
There's lots of ways to heat homes in ways which use way less than 1 joule of electricity for 1 joule of heat.
Besides the matter of heat pumps which others have covered, there is also the matter of how good your heating system is at getting heat to where you actually need it.
A PC under your desk will keep your toes warm, and maybe with warm toes you don't really mind the rest of the house being at 10 C / 50 F. With such space heater, you can turn down the thermostat for the entire house and only heat the parts you care about most. Furthermore there are radiative space heaters which direct infrared energy to a specific part of the room using a reflective dish, instead of heating the entire room using convection. In large rooms, radiative space heater can keep you feeling warm while using much less energy than a heatpump would require to heat the whole room.
