Work it out. The element is entirely surrounded by the water you want to
heat.
Only foil coil immersion types. Our "kettles" over here have enclosed
heating elements under the kettle, so it would lose a bunch.
So all the energy, apart from that conducted bak into the cable,
passes into the water.
Immersion heating elements are about as efficient as one can get.
We used to place a few coiled rubber bands between two spoons, and hook
'em up, and that would boil water pretty quick too.
Gives "Direct Current" a new meaning.
Most electric kettles these days are plastic, so
not much gets throgh the sides.
Most "plastics" that can handle those temperatures also conduct heat
pretty well.
Rather more escapes through the top,
especially while the kettle is actually boiling-
Stick a lid on it. Once the water is boiling, one can reduce heat and
retain boil, another good reason for gas.
I use this energy to
preheat the teapot. So efficiency is pretty good.
I love finding uses for wafting, otherwise wasted heat.
A more powerful kettle
is better because there is less heat lost through the top and sides when
you are heating it.
A smaller "vat" has less exposed surface area, and is quite valid to
consider as a spoiler to your claim. It all comes down to using the right
heated pot for any given volume considered.
Why do you think solder pots are short and squat, and not some eight or
ten inch diameter device? It isn't just the handling issues. It has a
lot to do with conservation.
As for gas, most of the energy simply wafts round the outside of the
kettle,
When I put water on to boil, I start with *very* low heat, and most of
it hits the mark, and that which wafts, heats those same sides. The
flame barely leaves the burner head, and the gas meter barely moves, and
I boil water much better with a long slow process than a "stick a torch
to it and GO" method, so not much "spills" up the sides.
I am very lean on consumption. My carbon footprint barely exists at
all. Been riding a bike to and from work for the last twelve years.
and never heats the water at all- it just heats the universe.
Which isn't to say that it's not generally the best way to cook.
Gas is definitely the best, most controlled application of heat,
therefore is the best way to cook.
I wish microwave ovens were wattage controlled, instead of duty cycle
controlled. I would have many more uses for it then. Still, it is my
second choice. Electric burner stoves, and cooking accessories are the
most wasteful use of juice there is. The only proper electric stove
would have skillets, pots, and pans with integrated elements in them.
Otherwise there is a lot of loss with electrics as well. I'll take gas
any day.