« Well-Tended Fires Outperform Modern Cooking Stoves | Main | The Revenge of the Circulating Fan »


Feed You can follow this conversation by subscribing to the comment feed for this post.

Jon Freise


Fantastic article! I just discovered fireless cooking using an old Stanley Thermos to cook oat groats for breakfast. It cooks overnight, always works perfectly, never boils over, and even works in a hotel room with an electric kettle. We hardly cook oatmeal any other way.

You bring up Low-E glass coatings for solar box ovens. I wonder if the vacuum insulated glass might be an ideal application. The glass has visual distortions, but that would not be an issue with solar cookers.



Sounds a bit like the cooler sous vide cooking technique. Put some food in a ziploc, put some hot water in a cooler, place ziploc in, and wait.


works very well. Alas, it can be wasteful of water, but you can always re-use it for drinking, cleaning, etc.

Poul-Henning Kamp


Electrical induction deserves a closer look.

Since there are no particular hot parts near the pot, you can in principle wrap your pot in textile insulation while you cook without fire-risk.

Spills will still be a mess though, but we can do better:

Induction pots could have a a radiation shield ("Calorimeter principle") insulation: The exterior wall made from non-magnetic metal, such as aluminum or brass, the interior pot from iron.

Done right, such an "insulated induction pot" would not appear different from most common cooking pots today, and can even be put into dishwashers etc.

Claire Leavey


Lovely article. I've written about these (and fuel efficiency in general) in 'How to run a Thrifty Kitchen'! http://www.retrometro.co/shop/how-to-run-a-thrifty-kitchen.html

Lloyd Alter


The toledo cooker was very popular a hundred years ago in America, and there are still versions being made http://www.treehugger.com/kitchen-design/nissan-thermal-cooker-crockpot-without-cord.html



What about slow cookers or crock pots? Similar to the fireless cooking, but electrical. Not insulated, but if you have a slow cooker, you could build a hot box in which to put it. Once you know how long the crock pot takes to bring the contents up to a boil, you could plug it into a timer.

The crock pot cord goes through a hole punched in the bottom of the hot box, plugs into a timer. The timer turns off the crock pot after 2 hours (or however long it takes for the pot to get up to a boil).



Like this article series! Well done!
Also liking Poul-Henning Kamps comment. Sounds interesting.

A field for further studies is obviously camp stoves where fuel efficiency is a big factor, and the designs reflect that fact.

Insulation for a camping cook pot is commonly called a "pot cozy" and varies from retail neoprene versions to homemade bubble wrap contraptions. Could be something for home use as well.

The pot skirt concept is well utilized in the Trangia type of stoves, where the windshield of the stove goes a way up the sides of the pot. There are others as well.

kris de decker


@ Poul-Henning

Good point. Induction stoves lend themselves perfectly for integration with fireless cookers, in the spirit of the hybrid systems from the early twentieth century. An insulated cooking pot would reduce both heat transfer loss and power conversion losses and thus increase thermal efficiency.

@ Lloyd

Some fireless cookers were indeed equipped with soapstones. But the efficiency of this approach very much depends on how you heat the soapstones. If you do that in an oven, I'm afraid there's no advantage to it because ovens are less efficient than gas or electric hobs. But if you could use some source of waste heat it could be very worthwhile.

@ pond

As you say, a crock pot or slow cooker is not insulated, so that's a clear disadvantage compared to a fireless cooker. But if you put it in an insulated box, I guess you have what you need to cook more efficiently. Only I would feel more at ease leaving the house when the fireless cooker is cooking than when the insulated crock pot is cooking.



Like improved biomass stoves and fireless cookers, solar cookers are mainly promoted in developing countries as an alternative to the use of open fires.

Note that developing coutries have on average more sunshine than developed ones. They are generally closer to the equator.

One thing the article doesn't mention is why insulated cookers fell from favour.

David Wilson


If I understand the fireless cooker, the traditional Hawaiian imu would qualify as an industrial-strength fireless cooker. A wood fire heats rocks, which are then placed in and around the food in a covered pit. My wife's family cooks this way for luaus on the Big Island. I don't know how efficient it is, but the results taste fabulous.

Wikipedia has a good description in an article on kalua cooking: http://en.wikipedia.org/wiki/Kalua

Tim Barker


Hi Chris great article. It was good to see someone make the link between pressure cookers and retained heat cooking , we have used such a system in the past with very good results. Pressure cookers and solar also are a good combination but older pressure cookers with a bobble weight are better as the new ones require quite a head of stem to initially seal. At the Koanga institute where i do some work on Appropriate technology we did some tests with retained heat cookers where we installed the heating element out of an old slow cooker (approx 170 watts) and added a thermostat out of a hot water system which matches the heat range required well. Quite literally our hot box was an old solar oven with an insulated lid substituted for the glass and the heating element was sandwiched to the bottom of the bottom tray with a strip of aluminium. Our testing showed a minimum of 70% reduction in electricity used. Such a system if well built brings up some interesting possabilities as it could be used as a hot box, solar oven, or slow cooker and would cope very well in difficult climates. Worth mentioning also is the cooking pots themselves. Wide bases and good conductivity (tinned copper pots) over smaller footprint heating sources are the go.
Cheers Tim

Mark McClure


I enjoyed the article very much.

I have a 6-liter vacuum thermal cooker. One drawback to this device is that the pot needs to be fairly full in order to provide the thermal mass to see the cooking process to conclusion. I have thought of adding stones or big stainless steel ball bearings to the pot to provide the thermal mass when I am cooking only for two.

Regarding the pot skirt, I have thought of using galvanized steel duct parts to use as a sleeve, but I worry about the zinc oxide fumes that may develop when heating on a gas stove.

greg blonder


An excellent review, and a reminder that the biggest deposit of fossil fuels in the world are energy efficiency improvements under our control.

Sadly, when I was in high school in the 70s I wrote a similar paper in response to the OPEC energy crisis. Even had a chance to cook on a deep-well stove. With the enthusiasm of a teenager, boldly predicted all new stoves would consume 1/3rd the energy in 15 years. Ah well.

Note an electric crock pot with decent insulation and a feedback controller is quite efficient, and bridges the gap between fireless insulated pots and the oven. But most are pieces of junk. Conversion efficiencies do put electricity at a disadvantage, but co-gen and community power can bring it back in line.

Also, WHAT you cook matters, and it is hard to shift cultural tastes. Steaming veggies can take 1/3rd the energy of boiling, if you only steam the minimum amount of water required. But people often grow up the taste and texture of boiled.

David Karger


Here's another innovation: fins on the pot to collect extra heat from the flame: http://www.latimes.com/food/dailydish/la-dd-saucepan-rocket-scientist-heat-efficient-20140710-story.html

Mario Stoltz


Hello Chris,

Really enjoyed this and the previous article on cooking efficiency. Like Greg has commented, I would also think that the cooking style and the ingredients used make a difference. Not every cooking style corresponds well to more efficient methods of cooking / stoves. And here may be the main catch, in fact.

Slow cookers seem to correspond well to Foods that can cook for a longer time unattended, and where you do not have to stir and look all the time. Note that this also applies to steam cookers, for example - you have to be fairly sure about your cooking time in advance.

This may be the very reason why steam cookers are not very successful on a broad scale: not everyone is sufficiently confident in their cooking skills, or even cooks regularly at all. The food industry is trying to convince us that cooking is so difficult that we should rather buy their pre-fab / "semi-finished" foods and only warm them up.
To get this ball rolling seriously, both cooking Hardware and people's mindset about cooking must be changed.

kris de decker


@ Greg & Mario

What you cook indeed matters. It should also be noted that water is a more efficient heat transfer medium than oil, while oil is a more efficient heat transfer medium than air. Therefore, boiling food is always more efficient than frying or baking it.

In fact, when it comes to carbon emissions, the diet is more important than the cooking technology. For instance, boiling meat is more carbon intensive than frying vegetables, because meat production is inefficient.

@ Tim & David

Cooking pot design is important, too. Material, shape, color. I've seen a similar finned pot for use in a solar box cooker.

Etienne Bayenet


Very good article. I used the fireless cooker to sterilise water in Colombia. Works very well.

Etienne Bayenet



I also wrote an article (in French) about saving energy while cooking. The concept in the article is that reducing waste does not reduce our comfort, so I wanted to explain where energy is wasted. I didn't know about the fireless cooker when I wrote it.

You will find it with another about drying clothes on this page.

Since I found this article about insulated cooking pot great, I also added a link to it.

Best regards,

Etienne Bayenet

Pete Sherwood



Have you found any references to using (or not) cast iron in/with fireless cooking?
Although getting the cast iron up to temperature takes longer, it seems to be the perfect match for the retention of heat in the fireless box.
I've seen no mention of this in the several articles I've read.

Mario Stoltz


Hello Kris,
your article made a concrete difference in my camping vacation in Sweden this summer. I used a Trangia cooker (works on alcohol). Already in a past year, I built myself a windscreen in 6 segments from 1mm aluminium plate and hinge ribbons. So far, I have only used this by forming a U-shaped windscreen around the cooker with the opening facing away from the wind.
This year, I have closed the screen around the cooker (a fairly snug fit, though just by accident) and tried to put a partial lid on top if I had any suitable objects at hand. The difference in cooking time was immediately obvious. I have no measurement but would estimate at least 20% shorter time to get water to boiling point, even with such a rudimentary insulation. Thanks a lot!!



I'm rather surprised nobody has made mention of Rice Cooker appliances yet. Any halfway decent one will be insulated. You can touch the outside of it and it will be cooler than the surface of a car on a hot summer day, while rice is boiling inside. They are popular in Asian countries where energy is more expensive (phils for instance). They are also very cheap (I think I paid $20 for mine). Very handy appliance!



As one commenter just mentioned, the ole stanley thermos is my standard in fireless cookery. Metal model only please. Great for anything that will fit the small mouth opening. Done soups, stews, rice, etc this way.



To slow cook beans, lentils etc., I bring a pressure cooker to the boil, take it off the heat and wrap it in an old down jacket for a few hours. Works a treat.

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Your comment could not be posted. Error type:
Your comment has been saved. Comments are moderated and will not appear until approved by the author. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.


Post a comment

Comments are moderated, and will not appear until the author has approved them.

Your Information

(Name is required. Email address will not be displayed with the comment.)

News & Links

The Chinese Wheelbarrow

  • Chinese wheelbarrow
  • How to downsize a transport network: the Chinese wheelbarrow
    For being such a seemingly ordinary vehicle, the wheelbarrow has a surprisingly exciting history. This is especially true in the East, where it became a universal means of transportation for both passengers and goods, even over long distances.

Human Powered Cranes

  • Human powered crane
  • The sky is the limit: human powered cranes and lifting devices
    From the earliest civilisations right up to the start of the Industrial Revolution, humans used sheer muscle power, organisation skills and ingenious mechanics to lift weights that would be impossible to handle by most power cranes in operation today.

Wood Gas Vehicles

  • Wood gas cars 2
  • Firewood in the Fuel Tank: Wood Gas Vehicles
    Wood gas cars are a not-so-elegant but surprisingly efficient and ecological alternative to their petrol (gasoline) cousins, whilst their range is comparable to that of electric cars.

Hand Tools

  • Hand powered dril</a><br /></li>
							<li class=Hand Powered Drilling Tools and Machines
    Hand-powered devices have been used for millennia, but during the last quarter of the 19th century a radically improved generation of tools appeared, taking advantage of modern mass production machinery and processes (like interchangeable parts) and an increased availability in superior material (metal instead of wood).


Open Modular Hardware

  • Open modular hardware2
  • How to make everything ourselves: open modular hardware
    Consumer products based on an open modular system can foster rapid innovation, without the drawback of wasting energy and materials. The parts of an obsolete generation of products can be used to design the next generation, or something completely different.

Power from the Tap

  • Water motors
  • Power from the Tap: Water Motors
    Just before the arrival of electricity at the end of the nineteenth century, water motors were widely used in Europe and America. These miniature water turbines were connected to the tap and could power any machine that is now driven by electricity.

Aerial Ropeways

Other Languages

  • Some articles have been translated into French, German, Spanish, Italian and Dutch. Find them here.