Comments on Home Efficiency Blog: Best Way to Boil Water

I am not a scientist, but I know that liquids that...

2012-01-24T16:59:50.577-05:00

I am not a scientist, but I know that liquids that are more substantial (and/or contain fat content) heat up faster in the microwave than water does. That being said, I would think that the microwave would be much more efficient in heating other liquids, like soup, than an elective kettle would. And a question. I know there are products to "brown" food in the microwave. Is there any

The real advantage with the kettle is on the first...

2012-01-22T14:47:05.403-05:00

The real advantage with the kettle is on the first cup. It boils in half the time as the first cup boiled in either the microwave or the stove. Since (at 1450 Watts) it uses about the same amount of power as the others, halving the time halves the energy. Thereafter, the energy requirement for boiling larger volumes of water is nicely predicted by a linear function. Each additional cup requires

The electric hob is easily the worst option, costi...

2011-12-07T01:11:31.791-05:00

The electric hob is easily the worst option, costing three times as much energy and CO2 as the kettle. Although the gas hob still results in almost three times as much energy (heat) being delivered to the home, this comes at very little extra CO2 cost. If that warmth is useful to you, then why not? On the other hand, because the hob takes longer you're more likely to forget about it and/or

Nice to read this indeed. I didnt experiment direc...

2011-10-26T07:07:33.643-04:00

Nice to read this indeed. I didnt experiment directly i just calculated on papers as i found some info.

According to chemical guys A litre of water takes around 2400 Kilo Joules to boil. This is a more or less linear function. Depends on startig temperature of course which is in this case somewhere between 20 and 25 degrees.

i found 2300kj for heating 1L water from 20-100C

These are the concluding remarks for the results I...

2011-09-01T18:09:08.910-04:00

These are the concluding remarks for the results I posted in the two previous anomymous posts.

To put all of this in perspective the theoretical amount of energy needed to boil one cup of water under the conditions of my tests, that is raise the temperature of one cup of water 75 degrees C, is just a shade under 20 watt-hours. Pushing water through the phase change from water at the

As is immediately apparent I was not able to repli...

2011-09-01T18:05:52.936-04:00

As is immediately apparent I was not able to replicate the results in the PlotWatt blog. In fact for the first two cups of water the microwave is at least as efficient as the stovetop. After that there appears to be a small increase in power consumed per cup but given the variability between the two runs for each volume it is probably not statistically significant. (I did not do significance

Before I start I’d like to explain a few things I’...

2011-09-01T17:58:24.990-04:00

Before I start I’d like to explain a few things I’ve learned during my 30+ years of testing ideas using “science”: 1) The first rule of experimentation is that one needs to be able to replicate the results. 2) As many variables as possible need to be controlled to insure that you are actually measuring what you are trying to measure. 3) If your results are “surprising” you should check them. You

energyhawaii, thanks for the comment. we've ...

2011-08-01T09:52:50.632-04:00

energyhawaii, thanks for the comment. we've received lots of induction top questions (see comments above). it ought to be the best electric performer by ~20% but we haven't yet run the test.

you didn't plot energy use via an induction co...

2011-07-31T15:19:36.949-04:00

you didn't plot energy use via an induction cooktop

Always used a kettle..from 1958 to present..Some w...

2011-06-18T02:30:22.860-04:00

Always used a kettle..from 1958 to present..Some were so slow to boil you could walk to macdonalds and back with a hot coffee before it boiled..This pre microwave.. Todays kettles set on a small pedestal and boil water so fast that before you get all the ingredience into cup...its ready for pouring

Very interested to discover this discussion! I al...

2011-05-01T14:57:41.397-04:00

Very interested to discover this discussion!

I always use an electric kettle to boil water for tea. Around here, in green circles, it is like a mantra to "only boil water for what you will immediately use" - in practice this means pouring your water into your mug, then pouring it into the kettle to heat.

However, I've had a longstanding argument with my

Tea kettles offer their users the convenience of s...

2011-04-23T02:09:42.610-04:00

Tea kettles offer their users the convenience of saving them time. A large majority of the electric kettles today have an automatic shutoff on them so that once the water reaches boiling point it will turn itself off automatically.

Hi Luke, Just wondering if you had a lid on the po...

2011-04-17T04:21:24.545-04:00

Hi Luke,
Just wondering if you had a lid on the pot you heated on the stove.
Thanks
Leona

informative post! i have a few questions: -do you ...

2011-02-28T14:55:43.542-05:00

informative post!
i have a few questions:
-do you think superheating played any role in the microwave's relative lack of efficiency (as measured)?
-if an object was placed in the container of water to facilitate bubble nucleation before being placed in the microwave, might it have boiled in less time than without a nucleation aid?
-if the measure of performance was

These are great ways to save money. Great blog i l...

2011-02-21T07:35:01.071-05:00

These are great ways to save money. Great blog i like it!

Anne, Great question! No, we didn't do the im...

2011-02-20T08:11:41.971-05:00

Anne,
Great question! No, we didn't do the immersion heater test. My suspicion is that since an immersion heater allows you to completely surround your heating element with water, the efficiency could be great.
If you have one, it would be awesome if you could run a test or two and post the results. The most helpful info would be:
- Wattage: If you don't have an energy

Wow -- great thread! And it cleared up an initial ...

2011-02-20T01:15:08.511-05:00

Wow -- great thread! And it cleared up an initial assumption I had -- I figured that since there was all that heat in the stove top the microwave *must* be more efficient. I will be looking into an induction kettle. Did you ever do the immersion heater test?

Mark, This is a great point that we have occasion...

2011-02-16T10:21:29.782-05:00

Mark,
This is a great point that we have occasionally touched on but failed to dive into deeply. Accurate life cycle analysis proves to be a real challenge for most of our manufactured products. I do think it is worth noting though that very few manufacturers are going to sell these goods at a loss. Yes, the factory probably has cheap energy and this might be doubly true overseas, but it

Another factor is the energy consumed during the m...

2011-02-16T09:48:00.551-05:00

Another factor is the energy consumed during the manufacturing and shipping process.

I suspect if you already own a stove and microwave, the "return on investment" in energy savings of using a tea kettle would take quite a long time to payback the energy that went into manufacturing and shipping the tea kettle.

@ Tom: The microwave only heats the surrounding o...

2011-02-10T10:05:27.689-05:00

@ Tom:

The microwave only heats the surrounding only very little, though. After all it is still an electrical device that uses some energy.

However, the rays only have an effect on the meal inside. And as you know only certain materials / consistencies are effected.

I assume both the kettle and the microwave heat th...

2011-01-23T01:36:57.784-05:00

I assume both the kettle and the microwave heat the surrounding area also.
-Regards

I have one problem though Luke-do I don't own ...

2010-10-21T04:44:37.686-04:00

Always used a kettle..from 1958 to present..Some w...

2010-10-20T00:03:14.602-04:00

Always used a kettle..from 1958 to present..Some were so slow to boil you could walk to macdonalds and

Always used a kettle..from 1958 to present..Some w...

2010-10-15T23:44:34.264-04:00

I have one problem though Luke-do I don't own ...

2010-10-07T02:21:24.677-04:00

I have one problem though Luke-do I don't own a kettle of any kind. Would someone really boil soup in a kettle? ... then have to clean it afterwards? (see post above on 4 conveniences of the microwave)- In other words as someone born in the 80s I am not sure what else a kettle is good for-but the microwave is so useful-that's an aside...