It’s a deary, rainy Sunday here and I’m in the mood for hot cocoa. Wanting to at least appear “green,” which is more efficient and uses less electricity - zapping the two mugs of water in the micro or heating the water with my electric kettle?
Both mugs are getting dosed with a healthy dollop of Mount Gay, rest assured. 
I don’t know, but let me share my awesome recipe for hot cocoa with little clean up:
Put a spoonful of sugar in the bottom of a mug. Add a spoonful of cocoa powder. Not hot cocoa mix, just plain ground-up cacao. I like some stuff my husband buys on-line, but Droste or Hersheys work fine. I add more cocoa than sugar, but I like a less sweet drink. Adjust to whatever taste you like.
Stir the powders together to reduce the likelihood of having clumps of unwettable cocoa powder. then add a tablespoon or two of milk. Stir until you have a slurry and all the powder has been wetted. Lick the spoon.
Fill the mug with milk. Fresh whole milk. Delicious dairy goodness. You can add a splash of cream or half&half if you have it around.
Put in microwave. Heat on “high” for one minute. Remove and give it a stir. This is also a good time to add a dash of vanilla extract or a larger dash of an alcoholic beverage of your choice.
Return to the microwave for another minute. Stir again. Enjoy.
Someone who compared electric kettle, stove and microwave found:
Energy efficiency
Electric Kettle: 81%
Microwave: 47%
Stove: 30.5%
So the electric kettle is the winner. [while this is from 2009 I don’t believe there have been significant energy efficiency advances since then]
Bear in mind that if you’re heating your home any waste goes into reducing the heat load to whatever you’re using so that has to be taken into account. All of the energy “lost” turns to heat. Of course, if it’s cooling season any lost energy will have to be pumped to the outside, so it has to be transferred twice.
I think I love you
It’s not just a question of energy efficiency, imho. You get better tea by pouring hot water over the tea leaves, whether loose or bagged.
But does this take into account how long you have to use each appliance to heat the liquid to the same temperature?
Sure. And if your kettle used 3000 W instead of the 1200W model they tested, it would be even more efficient, because the water would boil much faster.
I like this answer. It’s pretty much perfect.
I was going to post the following guess: Since an electric kettle at least has the possibility of being well insulated and putting all its energy into the water, whereas a microwave has a fan to blow away the wasted excess heat, the kettle could be made much more efficient than the microwave could. Moreover, since microwaves cost much more than kettles, I could imagine that getting an x% improvement in efficiency would also cost more for a microwave than for a kettle.
It’s no longer a guess, but perhaps offers clues as to the explanation.
Another factor that needs consideration is the amount of water you need to boil. Most modern electric kettles I’ve seen have a “minimum fill” line at around 500 ml. If you’re just making a drink for yourself, that’s probably twice as much water as you need, so the efficiency of the kettle is effectively halved.
My MIL and I did an informal experiment a few months ago testing what heated water to boiling faster, a mug in the microwave, a kettle on the stove, or the electric kettle. The electric kettle won easily.
What kind of stove? We have an induction stove and it it heats water even faster than our electric kettle (which I believe is also based on induction). I think the efficiency of a stove is going to vary greatly according to whether it’s gas, electric, induction, etc., and also the material and thickness of the pot.
Depends on what side of the pond one is making one’s tea, doesn’t it?
Here in the US, kettles average about 1000W. Back in my homeland where 240V rules, your average kettle checks in at around 3kw. Those will boil a cup in about a minute.
I suppose three mins at 1kw is equivalent to one minute at 3kw but when one is waiting for a nice cuppa, time is of the essence.
We have a gas range. The electric kettle was so fast, when it boiled, the water in the stovetop kettle and microwave was still cold. Not just “not hot,” but cold.
I think you have just answered the niggling question of why Americans don’t use electric kettles.
The fastest thing I have ever used was an immersion heater. That thing could boil a cup of water in seconds. The trouble was if you plugged it in while any part of it wasn’t in water it would short out. This was surprisingly difficult to avoid doing. After going through 5 or 6 of them in a year I gave up. They were cheap, but I felt bad continually wasting them.
The electric kettles I’ve seen from Japan are insulated, the idea being that you maintain a pot of water at high temperature for very low energy cost. Want a cup of tea? The water is already hot: just push the button to dispense, get hot water immediately. Example here.
An average kettle (we call them jugs in these here parts) is insulated enough to keep water reasonably hot, so when you come back for your second cup an hour later you will need only a smaller heating time to get it back to the boil.
They are also sensibly energy efficient in having auto power cut-off when they reach the boil. A pot of water on a stove can boil itself dry if you get distracted. Apparently.
This is a factor, but kettles with a one-cup minimum, such as the one I own, are available. I believe it’s due to the element design (there is no visible heating element in the kettle, just a flat base) but I don’t know if that also affects the efficiency.
It boils in well under a minute, too- it takes roughly the same time to boil as it takes me to choose a mug, measure in cocoa powder and sugar and get the milk out the fridge, in fact.
But reboiling water is something you should never do if you care at all about how your tea tastes. People seem to disagree whether this is due to the loss of dissolved gases or the concentration of dissolved solids, but either way, the tea ends up not tasting as good.
I just googled to see if there was a technical difference between electric kettles and electric jugs. Well, bugger me, there actually is!
A kettle has an insulated electrical heating element, so the body of the container can be made of metal, whereas a jug has the heating element directly immersed into the water, so the body of the container has to be ceramic so you don’t kill yourself. I think the jugs have all gone now and the term just lingers.
Still confused? Check out theseor these beauties!.