Hi, Umbra,

This article brought to mind those home hot-hot water taps, the kind that dispense 190-degree water on command.  Does one sacrifice greeniness for convenience in that case?

Thanks!
Rebekkah

Umbra, I'm usually a fan of your well-informed responses, but your comment that, "in my opinion, microwaved water doesn't hold heat long enough to make decent tea" just doesn't hold water.  The heat capacity of water is unrelated to the method used to heat it; water of a certain temperature doesn't "care" how it got there.

I challenge you to a blindfold taste test of tea made with water heated in the microwave vs. water heated in an electric kettle.

The microwave is clearly the most efficient method to heat water for any purpose.  Not to mention that an electric kettle is an appliance that is only good for one purpose (heating water) while a microwave can serve many functions (heating anything) making it superior from the manufacturing and durable goods waste standpoint as well.

Did the comparison of an electric kettle to a gas range take into consideration the energy loss before the electric kettle heats the water?  Since approximately two-thirds of the energy used to make electricity is lost to waste heat and other losses, the losses could be comparable to the gas heat losses you describe with a gas range.

I performed a scientific test. I have a "Kill-a-watt" watt-hour meter. I plugged the microwave into it and made 500ml of hot water, measuring the temperature before and after. I did the same with a electric kettle, stopping the kettle when it reached the same temperature as the microwaved water. Anyone can repeat this experiment with a $40 "Kill-a-watt" and a thermometer.

I don't have my notes handy, but the microwave was quite a bit more efficient in this simple case.

Another thing in the microwave's favor is that you make exactly as much hot water as you want. In the electric kettle, you either measure and pour, take a chance at not having a full cup, or heat extra water, which ends up getting dissipated.

In the kettle's favor is (as you point out) the "phantom load" of the microwave, which uses energy just to show you a flashing "12:00", since the instructions got thrown away long ago and no one can recall how to set the clock. I search for old, thrift-store microwaves with mechanical timers -- no light show, but no phantom load, either.

Also in the kettle's favor is what I would assume is a higher embodied energy in the microwave. On a mass-basis alone, the microwave consumed more energy in its manufacture. Considering the electronic parts and special materials pushes the embedded energy up even more. Then there's the greater disposal problem, too.

Let me know if you'd like me to dig out my notes for exact kilowatt-hour consumption of both devices.

In addition to looking at the heat loss and inefficiencies in the energy plant and in losses assoiciated with delivering electricity to your home, we should also consider the energy required to stimulate the heating elements in the electric teapot. I learned in installing a solar setup that household appliances with heating elements are some of the biggest energy hogs we own. (hairdryers, toasters, coffee makers, irons, curling irons, electric stoves, etc)

Another seasonal consideration is; if you are drinking tea in the winter and heating your house with natural gas. A little heat loss around your pot of boiling water is only lending a helping hand to your furnace.

Its a complex equation, but I'd be surprised if the electric teapot doesn't come out last on the list in terms of efficiency, and the microwave first.

PS- A Nast-tea tip. A problem with the electric kettle is that it automatically boils the water. This is fine for black and herbal teas, but if you like green tea, you should steep the leaves (use whole leaves, not tea crumbs) between 170-180 degrees F. Boiling the water or oversteeping makes it taste bitter.

Rebekka,

One of the first things I did when I moved into my current house is to unplug the 190 degree F hot water tap that was installed on my kitchen sink.  Such devices are basically mini hot water heaters, sans any insulation, that keep a cup or two of water at a constant sub-boiling temperature.  They consume enormous amounts of electricity.   Even if you are home all day and consume frequent hot beverages, this is like keeping your electric kettle on simmer 24/7. IMHO, the convenience of having such instant hot water is not worth the impact on the planet.

Anyone who thinks they might consume more than one cup of hot beverage in a sitting might want to try making a bigger batch and using a thermos to keep the stuff warm. That or an old-fashioned tea cozy over the teapot.  BTW I once won a "Queen Mum" lookalike contest wearing such a tea cozy as a hat!

Not to mention the landfill issues from disposing burnt-out electric kettles!

I love "Ask Umbra." The English teacher in my soul wants to point out that in the US, all right is always spelled as two words. (It's often spelled as one word in the UK, in case you're wondering.)

loses its heat more quickly than water heated in a kettle or on a stove (and thus is not as good for steeping tea.) I don't know why this is but it's something I have observed for years. I think it is true of foods as well as liquids. I know this because, in addition to my observations in my own kitchen, I worked at a restaurant where foods that were microwaved were always being sent back to the kitchen because they weren't warm enough even if they were taken directly from the microwave to the customer, whereas the foods that came off the stove were never sent back for being thermatically challenged.

You're right, it's all a bit petty in the greater scheme of things, though as a Brit, tea takes on greater significance than is necessarily healthy.
Anyhow, to the point: studies I have done (as in, me asking my family and friends) suggest that electric kettles get popped back on with far greater frequency than kettles on the stove. People turn the electric kettle on, forget to make the cup of tea immediately, then turn it on again to re-boil the water. This would seem to negate the saving made by kettles, and takes me back to my first comment of the petty-ness of it all...

The most Green and best tasting way to make tea is with the SUN.  One gallon glass jar (a fancy one with a spigot near the bottom if you must).  Fill the jar with clean water, drop in the number of tea bags to suit your taste, screw on the lid, and set it in the sun.  The darker it gets, the hotter it gets, the darker it gets....
The UV from the sun also kills bacteria.

Concerning, "You may be interested to learn that microwave oven digital displays are responsible for the lion's share of their power draw -- 80 percent, by one reckoning. (This means unplugging microwaves when they're not in use is a good way to increase their efficiency and decrease your overall energy use. Ditto for other home appliances and electronics.)"

My preference is to use a Microwave Oven with simple mechanical timer and no display (I can't figure out all those darn buttons and menus anyway).  In stand-by, the non-display, non-electronic control type consume no power.  There is less to fail and go wrong.  I lived three years in Zaire,(Congo) Africa.  The simple mechanical dial type Microwave was the only type that would survive the horrible power fluctuations.

Does anyone know if the boiling of water in the plastic kettles leaches anything toxic into the water?

Another vote here against the ickiness of microwaved tea water.

I have a Capresso electric tea kettle, heats up very fast, turns off automatically, with a glass pot. A bit pricey, but worth it.

In the winter, I keep my tea kettle on my wood-burning stove and the water is kept close to boiling by setting it a little off the side. In the summer, I make sun tea. The microwave does make for good backup.

I remember reading that a Microwave will ALWAYS be the most efficient way to heat water.
That's because heating water is how a microwave cooks, or so I read.

Allegedly, the frequency a microwave operates at is the EXACT frequency to add energy to Water.  Thus, the water gets hotter.  Then, the hot water in the food radiates this heat out to the rest of it.  This is why microwaves sometimes don't cook things as well as we'd like.

Also, an electric kettle, by its nature, would be less efficient.  It uses electricity to heat a piece of metal, and then this metal radiates its heat to the water.  
Plus, electric kettles are plastic, crappy plastic at that.
For the life of a microwave (also a multi-tasker), I would have to get several electric kettles.  Plastics always reach a point where they're just too gross to keep using...Espescially those electric kettles...I'll never have one again....

Dear Umbra,
I too disagree with your teapot assessment.  I would argue that the gas stove is by far the best way to make your tea.  The Canadian report you cited did not mention gas, only electric range tops.  My 1000 BTU gas stove boils 2 cups of water in 3.75 minutes.  Given the heat capacity of water, this means (following a few calculations) that my gas burner is rouglhly 30% to 40% efficient at raising the temperature of water.  Power plants are about 30% efficient in generating and transmitting electricity (~33% efficient in generation and ~93% efficient in transmission).  If your electric kettle were 100% efficient, it still would not beat my gas stove.  In addition, 50% of the electricity in the US is generated by burning coal, with far-reaching environmental consequences compared to the relatively clean-burning gas in my stove.  Finally, regarding microwaved tea water.  It might taste the same as stove-top water, but tea is supposed to be savored slowly, not microwaved.

Most UV passing through glass is converted to IR radiation, so don't count on Mr. Sun to disinfect any liquid stored in glass.  UV disinfectant pens are a new water purification technology but must be placed inside the container to work.

At a given atmospheric pressure, water heated to boiling in mug inside a microwave is the same temperature as boiling water heated in a kettle.  However, don't count on easily getting water that hot in your microwave unless you are prepared to see much of it splatter out of the mug.  All the people who think they are observing a scientific phenomenon, i.e. that microwaved substances cool more quickly than those heated by convection or conduction, are making a false comparision. What I think they are actually seeing is that foods heated to lower temperatures in microwaves aren't as warm as foods heated to higher temperatures elsewhere. Add to this the fact that microwaves do not heat ceramics or glass (unless they contain lead) while plates etc. placed under restaurant IR lamps do absorb heat, and you will see why food warmed on plates in a microwave arrives at a table colder than food warmed under IR lamps or placed from a saucepan directly on to a warm plate.

Many of us who make tea in a mug or teapot will put some hot water in the container for a while to warm it up, pour it out, and then pour in the tea-making water.  I don't think anyone makes microwaved tea this way.

I'm guessing the gas stove is the way to go, since it doesn't involve the process of converting coal to electricity to heat (at which point you're probably getting about 1% of the energy in the coal) compared to a higher, if not great, percentage for the gas stove.

Tea is not supposed to boiled anyway. The water shouldn't be boiled in the first place, just below boiling, and this will preserve the integrity of the tea. This alone could save energy, time and the flavor of the tea.

I can understand the purist view of not using the microwave for water for tea, but I watch my grandchildren, both under two ... need I say more?
How many minutes in the mic for water to reach 180 degrees ... for green tea?
jsk