I am having a hard time finding an answer on this.
I get that heating a liter of water takes a very well defined amount of energy and that does not change regardless of the method used to heat it.
That said is an induction stove more efficient than a standard coil burner stove?
Induction heats the water much more quickly but presumably that means it is drawing more power so I would guess they balance out but I know that is not necessarily the case.
You need to factor in the nearly zero radiative loss of these induction top. Then you see the difference.
I’ve done demos where I put a paper napkin under the pan and heated up chocolate with nothing affecting the paper.
This piece references DOE experiments showing induction tops use less energy.
As MikeG points out, the induction top puts a much large proportion of the energy straight into the pan, where a regular electric stove top has to heat up the stove top itself first and keep that hot while energy leaks not only into the pot but the rest of the environment.
That said, heat is going to leak into the pot a lot more easily than it will into anything else, so you’re not going to have a very high proportion wasted. The induction stove probably is more efficient, but is it enough more efficient to be worth worrying about?
The burner coils also glow red hot, wasting heat through radiation. When I bought mine 15 years ago, they were advertising that coil burners were less efficient than the cite at 74%, but the 84% for induction sounds right.
About a 10% increase in efficiency isn’t nothing. Especially when the waste heat is not just dissipated to the environment, but is added to the heat in the kitchen.
I’m not as impressed with the efficiency though, as I am with the ease of use. It makes a flat glass stove top. One where it never actually gets that hot. Even under a pan on high for some time, you can still wipe a towel across the top without it being singed or damaged, as it would with a regular stove. Boil overs make far less of a mess, too.
There’s also heat lost* when the pan is not perfectly flat, and sitting flat atop the electric coil. And that’s fairly common on frequently-used pans. You can see that in practice – forcefully press a pot of water down on the burner coil, and it’ll start boiling sooner.
*But as k9bfriender said, that heat isn’t really wasted – it goes into the kitchen, thus slightly reducing the work the furnace has to do. Except in summer, when it’s a disadvantage – it makes the air conditioner work harder. (But here in Minnesota, we have a lot more winter than summer!)
I like that mine switches off and beeps four letter words at me if I remove the pot without switching it off.
You must have stayed below Fahrenheit 451.
Except straight up electric resistance heat is terribly inefficient and expensive compared to the gas furnace or heat pump you’re normally using to heat the house.
Also, as far as power consumption, if the induction cooktop uses more power but for a shorter time, then it’s a wash. 2kW for 10 minutes or 1kW for 20 minutes are both 0.33kWh. The induction cooktop still wins because it eliminates the heat loss to the surroundings, but the peak power consumption doesn’t matter.*
*The only time it would is if you had demand metering. That’s usually limited to commercial properties though, where you get an extra fee on your bill based on your peak power consumption in kW (not kWh). That’s usually only affected by large air conditioners, pumps, machinery, and things like that. It’s not that you’re using more energy in total, but it stresses the electric grid more so the power company charges extra for those high-draw customers.
And it also uses less power for less time, IME. I think that the 7% of normal cooktops is an ideal. It is likely that it is ot achieved once the elements have warped a bit, or the pan is not flat, while with an induction stove, it’s always at the ideal. Also, when I take the pan off the stove, it immediatly stops heating, rather than on a resistance element, which stays on until you turn it off, and still glows red for quite a while after. All the heat that was used in heating up that element is lost.
My business is on demand metering, it kinda sucks, but it is only an issue if you are using 15+ kWs peak. You’d have to have a pretty power hungry household to ever hit that.