Same Taste With Less Energy: Optimizing The Way We Cook Food

Ceramic stove (credit: Felix Reimann)

Preparing food is the fourth most energy-intensive activity in a household. While there has been a lot of effort on the first three — space heating, water heating, and electrical appliances — most houses still use stoves and ovens that are not too dissimilar to those from half a century ago.

More recent technologies that make cooking more efficient and pleasant have been developed, such as induction heating. Other well-known and common appliances are secretly power savers: microwaves and electric kettles. In addition, pressure cookers enable the shortening of cooking times, and for those who like dishes that take hours to simmer, vacuum-insulated pans can be a real energy-saver.

Not Just About Energy

One aspect that is often neglected in discussions about saving energy is that many more power-efficient methods are simply more convenient and require less cleaning. Speaking as someone who has had to do things like heating milk on a gas stove, using a microwave saves one from having to scrub the pan clean afterwards. Similarly, an electric kettle beats a stovetop tea kettle any day of the week for its speed and convenience.

Not having to keep an eye on whatever will be boiling soon, and never coming upon a boiled over pan of milk is convenient, and an induction stove is very easy to clean as it’s only ever indirectly heated. Heating something up in a microwave directly on the plate is much more convenient than having to clean a dirty a frying pan afterwards.

All of which is to say that not only are many of these approaches energy-efficient, they’re also excellent for lazy people and everyone else who doesn’t want to spend more time on cooking, boiling, and cleaning each day than strictly necessary.

Running The Numbers

In an article by the BBC on why you should stop using your oven, they cite a study by Frankowska et al. (2020), in which the energy consumption of a few different heating methods are compared. Of these two the boiling of water and reheating of a casserole are good examples:

Boiling water (1 cup of tea)

  • 0.05 kWh, 4 minutes in a microwave
  • 0.07 kWh, 2 minutes in an electric kettle
  • 0.14 kWh, 2 minutes in covered pan or kettle on induction stove
  • 0.18 kWh, 5 minutes on standard electric stove

Reheating casserole

  • 0.11 kWh, 8 minutes in microwave
  • 0.35 kWh, 5 minutes on induction stove
  • 0.43 kWh, 12 minutes on standard electric stove
  • 2.27 kWh, 45 minutes in the oven

Porridge

  • 0.07 kWh, 5 minutes in microwave
  • 0.35 kWh, 5 minutes on induction stove
  • 0.36 kWh, 10 minutes on standard electric stove

Of note here is of course that when an electric kettle is mentioned, it refers to a European-style electric kettle. These tend to be rated for 2 kW – 3 kW, which enables them to boil water very quickly. So it’s no surprise that they’re boiling water twice as fast as a microwave with a 1,000 W setting. Depending on the use case, more energy input can make things boil and cook significantly faster, while saving energy and one’s time as well in the process. Which leads us to the other options, such as optimized heat transfers and lids.

Putting A Lid On It

A general idea behind efficient cooking is to get as much of the energy into the item that is being heated, without having it be converted to waste heat and escape into the environment. This is an obvious issue with gas stoves: a significant part of the heat produced by the combustion flows out the side and never heats up the cookware.

With an electric stove where the pan is placed directly on the surface that is being heated by the heating element, there is significantly less heat escaping into the environment, though here we still have the inefficiencies of heating the stove surface, transferring that heat into the pan’s material and from there into the contents of the pan.

This is where the idea behind induction stoves is so very attractive and simple: rather than putting the cookware on something hot, with induction an induction coil induces inductive coupling in the ferromagnetic material of the cookware, which causes it to heat up. This way the cookware itself becomes the hot surface that heats the food, which skips all of the previously mentioned intermediate steps, and thus losses.

This then leaves the other loss of heat: from the pan contents itself, which is where lids come in. By turning the pan into a closed vessel, the only effective way for heat to escape from the pan is through heating up the pan and lid and radiating into the environment that way. As a simple comparison can show here, the use of a pan lid can significantly shorten the amount of time needed to boil water, and the power needed to keep the contents on temperature.

From this we can thus deduce that an even more efficient way to cook on a stove would be if we could prevent the heat from radiating through the pan’s material. This is where double-walled cookware comes into play, with some level of vacuum between both walls much like in a thermos, which are great at keeping drinks hot or cold for long periods. In these pans, food stays warm for hours even without externally applied heat.

Putting On Pressure

The only major disadvantage of double-walled cookware (like Kuhn Rikon) is that they are very pricey, with a simple pan often costing upwards of a few hundred dollars. Outside of finding a used one for cheap, this is probably the kind of expense that’d be hard to justify. So on the other end of the budget scale, consider pressure cookers, which are somewhat like the extreme version of pan lids.

The basic idea behind a pressure cooker is that the high pressure inhibits boiling, so the cooking temperature can be increased above 100 °C. This significantly shortens the time it takes to cook the food, although it obviously is limited to damp cooking because of the steam that enables the increased pressure levels.

Unlike vacuum-insulated cookware, pressure cookers can be found for relatively cheap, and provide energy and time savings. Perhaps the biggest disadvantages are not being able to look inside the pan while cooking – requiring cooking times to be determined beforehand – and them being unsuitable for cooking noodles, pasta and similar foods which would expand too much.

Keeping It Fun

As noted earlier, the best part of saving energy is when it also makes life easier at the same time. The good news is thus that using the microwave to (re)heat food is both easy and efficient, and an easy to clean induction stove more efficient than a gas or electric stove. This was fortunately also my finding when switching from a ceramic stove to an induction one. While the former required some scrubbing and scraping after ‘accidents’, the latter just takes a simple wipe-down with a moist kitchen towel.

I’m also fortunate enough to living in a country where I’m able to plug my 3 kW electric kettle into a kitchen outlet and efficiently boil water that way, and was able to get a 3.5 kW induction stove that I could plug into an outlet next to the kettle’s. With it being obviously so much more efficient to use electricity to cook and heat food, perhaps having a kitchen fully wired for 240 VAC is the winning move for fun, efficient cooking?

With how much of a personal topic cooking is, please feel free to sound off in the comments about your own experiences and approaches when it comes to making cooking more fun and efficient.

153 thoughts on “Same Taste With Less Energy: Optimizing The Way We Cook Food

  1. I was initially typing up a rant about gas stoves being far superior for actual cooking, but it looks like they do a better job at thermal transfer, and you don’t have to have special cookware. Really this article should have been about gas vs induction – anyone who cares about cooking knows that electric radiant stoves are horrible. Fine for an oven, but otherwise terrible – unresponsive, low maximum heat.

    I think the choice for induction vs gas boils down to: how much do you trust your power company? I’ve lived many places where an electric stove just wasn’t an option, and I think there are significant infrastructure questions around what happens when we switch a bunch of stoves from gas to induction.

      1. I picked up a single “burner” induction cooktop at a thrift store, so it might not be top shelf quality. I find that it will sort of work with (old – probably 50+ years old) stainless steel conventional cookware. But the placement has to be exact for whatever sensor inside there to see the cookware.

        It works great with cast iron.

        1. Stainless may or may not be magnetic, which is why it sometimes works.

          It’s all about the skin depth effect, which for pure iron is really small – all the induced current is concentrated in a shallow surface layer which limits the amount of current by resistance and generates the heat. In effect, the impedance of the load is much larger than the impedance of the source, which ensures efficient energy transfer.

          For aluminum, copper, and some stainless steels which aren’t magnetic, the impedance matching is close to 1:1 which means the induction coil heats about as much as the pan does, if not more, and that’s why the cooktop refuses to work with these materials.

          1. >> In effect, the impedance of the load is much larger than the impedance of the source,
            >> which ensures efficient energy transfer.

            I’m not sure if I buy this. Power is voltage times current, P = V * I. You cannot dump power into an open circuit with infinite impedance, because the current will be zero. You also cannot dump power into a short circuit (zero impedance) because the voltage will be zero. Hence, the optimal impedance must be somewhere between those extremes.

            >> For aluminum, copper, and some stainless steels which aren’t magnetic, the
            >> impedance matching is close to 1:1 which means the induction coil heats about as
            >> much as the pan does, if not more, and that’s why the cooktop refuses to work with
            >> these materials.

            Usually, in electromagnetic energy transfer systems, you want the source impedance matching the load impedance. Think about antennas, you use a 50 Ohms Transmitter, 50 Ohms cabling and a 50 Ohms antenna (or all 75 Ohms, 150 Ohms, the number does not matter as long as all components are impedance matched). If one components does not meet the system impedance, you get energy reflected back to the source and power transfer is not optimal.

          2. >Usually, in electromagnetic energy transfer systems, you want the source impedance matching the load impedance.

            For reactive loads and sources in radio technology etc. where the reactive properties of the system are dominant, impedance matching is done.

            For systems that are dominated by the real part of the math, impedance matching is often not done for the simple reason that you have your R-source and R-load in series and you want the power to be dissipated in the load. If they were matched, your efficiency would be just 50%.

            For example, an audio amplifier pushing power to an 8 Ohm speaker does not have an output impedance of 8 Ohms, but more like 0.8 Ohms because that way 90% of the power ends up in the voice coil instead of heating up the amplifier. At audio frequencies, we’re not concerned with signal reflections of the cables etc. because those effects are very very small, so we want the source impedance to be as small as physically possible.

            Of course the audio amp too could deliver more power to an equal impedance, but we’re not maximizing the power throughput of the system – we’re maximizing efficiency for a given load.

          3. > you use a 50 Ohms Transmitter, 50 Ohms cabling and a 50 Ohms antenna

            Here you’re talking about characteristic impedance, which is not quite the same thing.

            If you take 1 ft of antenna cable and measure it end to end, your multimeter won’t read 50 Ohms. The characteristic impedance is the input impedance of a transmission line when its length is infinite, and the point of impedance matching is to keep this apparent impedance of the transmission line the same from end to end, because any step change in impedance causes reflections.

          4. >> Of course the audio amp too could deliver more power to an equal impedance, but
            >> we’re not maximizing the power throughput of the system – we’re maximizing
            >> efficiency for a given load.

            Thanks, that make sense. Of course you are right, maximum power transfer and maximum efficiency are not the same thing here.

          5. It’s not about the magnetic properties of the materials at all.

            Think of an induction stove as a one side of a transformer, and the pan as the other side but as a shorted turn. You drive a current in the ‘primary’ side, which is induced as a current in the pan. This current only turns into heat when it flows through a resistance. For aluminum and copper pans this resistance is low – they are good electrical conductors. But the cast iron and stainless pans have a higher resistance and heat up nicely

          6. >It’s not about the magnetic properties of the materials at all.

            The reason why we don’t use simple steel wire to run power cables is because the skin effect in ferromagnetic materials is 10,000 times stronger than with copper, which in practice means only about 200 micrometers of the surface of the steel wire actually conducts any current at 60 Hz.

            Even a thick iron bar as thick as your thumb appears to a high frequency AC source as if it were a hair thin filament with high resistance, and it’s all about the magnetic permeability of the metal.

      1. So are burning candles, making popcorn, photocopying, 3D printing, using talcum powder, having windows open, and a whole host of other things. And just like cooking, I don’t do these all day every day either, so I’m not worried about them.

          1. Even short-term asbestos exposure can cause mesothelioma. This is not true of most things, so this is a bad argument. A major part of the harm from cigarettes comes from the way people become addicted to them and smoke them many times a day. So this also isn’t a great argument, though it could perhaps be applied to burning candles or someone with a bad microwave popcorn addiction.

      2. This is one reason why we have exhaust fans above stoves. It’s not only about heat. Properly utilized kitchen tools mitigate risks. I’ll take a functional gas stove over an unreliable or stove that only works with certain materials any day. Not everyone lives in cities where outages are usually brief

    1. As someone living in an apartment with a gas stove, I can attest that the journey towards energy efficient cooking can lead past all the stations mentioned in the article.
      Dried chickpeas, beans, whole grain rice, lentils and other foods with long cooking times* got me into cooking with pressure cookers. I then came across a vacuum insulated pan. it’s hard to describe how tangible the difference is between the latter and regular cookware which sheds a lot of head through convection. It does for energy efficiency what is otherwise reserved to a pressure cooker, with the added feature that one can look inside.

      What has been left out in the article seems to be the historical approach of cooking food to near-completion and then putting the pot into a hay box (German: Kochkiste, a purpose-built insulated box with lid and a pot-shaped cavity inside). Some recipes call for wrapping the pot or pan in multiple towels and blankets so the food can passively finish cooking.
      They now also sell foam boxes and flexible insulation sleeves for that purpose, which is a low-cost option to complement existing cookware.

      After buying a simple induction stove to play around with, I’m enjoying using it for the more “fashionable” dishes that require frying, blanching or constant supervision / stirring.

      In essence, efficiency improvements both at the stove and the cookware level have a combined effect without any real disadvantages or inconveniences. You can make of the insulation what you will – passive cooking comes with a learning curve, but I prefer the texture and level of hydration I get with the vacuum insulated pan + passive cooking over that achieved with pressure-cooked legumes.

      (*) adding soda to beans for cooking can cut the cooking time in half. Another factor is soaking time. Not all recipes call for 24h soaking and pH adjustment. More on that: “Effect of Soaking and Cooking on Nutritional and Quality Properties of Faba Bean”, https://juniperpublishers.com/nfsij/pdf/NFSIJ.MS.ID.555765.pdf

      1. >then putting the pot into a hay box (…) now also sell foam boxes and flexible insulation sleeves for that

        It made a popular resurgence in the mid 90’s after the soviet collapse and banking crises around eastern Europe, when people had to mind paying pennies for electricity to save money any way possible. Example:

        https://fi.wikipedia.org/wiki/Aromipes%C3%A4

        The point was that you’d take the cheapest foods, such as split pea soup, and then save money on the long cooking time by putting it in a Styrofoam box. In the developed countries, we normally pay something like 4-5% of the GDP for energy – to be so poor that you struggle to afford the electricity for cooking your meal was sad indeed.

      2. When making rice, we bring the pot to boiling point and then put tje pot to the sofa, cover it up with som cushions and let is sit for a while. Perfect rice every time

    2. as an absolute cheapskate inbetween measure to reduce gas consumption : consider heating your water to boiling point in an electric kettle, then use the boiling water normally on your gas stove. saves the gas needed to get the water to boiling point. Since I have solar panels, I can choose to use a bit more electricity to reduce gas consumption. In order to use solar electricity, and not electricity-made-by-gas-turbines, consider eating your main dish at noon instead of in the evening (just like in the old days, I’m told).

      1. The electricity is often many times more expensive than gas.

        That’s including the power from your solar panels if you count the investment and maintenance cost over the lifetime output, but with the solar panels you kinda have to use it or lose it anyways.

    3. I agree that gas stoves are superior for actual cooking!! This vilification of gas cooking has really come out of left field. According to the linked article, all cooking accounts for 6.1% of residential energy usage. And “In 2020, households represented 27% of final energy consumption, or 19% of gross inland energy consumption, in the EU.” Also, “Around 40% of households are connected to the gas network”, and a smaller fraction of them even have gas cook tops. So, we are talking about changing/reducing something that is a fraction of ~1.5% of all energy usage here. I’m not saying that we should ignore all the small stuff to only focus on the biggest things, but man, sure seems like there are bigger fish to fry than trying to get rid of gas cook tops.

      1. Between the pandemic, mass shootings, the economy, and just life in the 21st century, I don’t need yet another problem for the sake of utility companies hoping to sell the more expensive product (here in the US usually it’s the same company selling electricity and gas), or “activists” hoping to get that next grant, or “influencers” getting PR monies.

  2. The lid thing is so easy it blows my mind that not everybody does it. If you’re boiling something like pasta or potatoes it takes 50% power on my stove to keep it boiling. If you put a lid on it, it takes like 20% tops.

    Some people worry food boils differently with the cover on, but I’ve been doing it for years and Im certain it does not.

    1. *maintains eye contact while filling a mug from the hot spigot of a water cooler and stirring in powdered tea, finishing with a slow grin*

      I’m auditioning for Bond Villain next week.

        1. I’d say so, the floorsweepings of the tea packing plants you get in most lower end teabags are bad enough, but powdered tea, that is pure heresy!

          I mean I don’t mind the idea of the microwave for boiling the water – heat is heat and how water gets there makes so much less difference than where you sourced the water from, but you have to let the magic of infusion do its thing with tea, where instant coffee’s can at least be passably facsimiles of coffee…

          1. If you boil water in a microwave the cup or whatnot will get limed up and hold stains and not be washable. This the unfortunately meant the end of a British friend’s kettle many years ago. He introduced me to a chrome dome that was faster than any other way. At work I used to boil water in the micro but in a glass jar which got thrown out when it got bad. Adding powder to water is messy and of course needs a spoon. Adding some water and condiment to the powder lets the everything stay in the bottom of the cup. Swish to mix then fill up the rest of the way. No spoon!

          2. Just wipe the cup with strong vinegar or lemon juice once in a while and the lime scale will dissolve off of the glazing. Good as new.

            The descaling powders and liquids for coffee makers and kettles are basically citric acid or phosphoric acid – both of which you drink in your soda.

      1. Why don’t you just drink dirty mop water you animal! (Joke)

        I don’t think I’ve ever seen instant tea. I had to look it up to check you weren’t joking :)

        1. It takes a trivial amount of effort to drop a spoon into the mug before grabbing it—and that’s only necessary if you don’t observe the water bubbling in the mug while it’s being heated. At worst, you’ll have a little water to wipe out of the microwave.

          1. You can actually put the spoon in the cup in advance, so you don’t get the potential splash of boiling water as you’re dropping it in.

            You’d think the spoon comes out glowing hot and you’d burn your fingers on it, but no. It has to do with the poor thermal conductivity of the steel, and the fact that the spoon reflects microwaves rather than absorbing them. My microwave oven from the 90’s actually has a small infographic on it with a cross over pots and pans, but a thumbs up on a cup of water with a spoon in it.

          2. That has not, in fact, been the worst outcome of superheating water in a microwave.

            You want a scratch on the bottom inside of the Brazil press (Brazil press = microwave safe Frog press). Assuming you drink coffee like a civilized person.

  3. i agree with the article but i have a hard time getting too worried about it. some things make sense in the microwave, and some things don’t. i actually like my traditional resistive electric stovetop. i’d be curious to know the actual number but a rough estimate is that it uses less than 20% of my household electricity usage, and probably closer to 10%.

    i have been impressed with how much electricity i can save from looking further down the consumption ladder…incandescent to LED lightbulbs and switching from forced air to water for distributing natural gas heat around the house both made my electric bill go down even as the rates i was being charged went up. but just today, i got my second highest electric bill of all time (since 17 years) simply because i have been running my dehumidifier!

    there is of course room for a newer / more efficient dehu but that single appliance apparently draws as much as the whole rest of the house combined…just makes it hard to get excited about a little savings from using a microwave to boil water

  4. Microwave ovens are actually terribly inefficient. The typical cheap model on the market puts out about 700 Watt of heat and demands 1500 Watts out of the wall – less than 50% efficient. That’s why they have the loud fan at the back, and you’re supposed to leave air space around them because it’s like a hair dryer in there.

    The reason why boiling a cup of tea in a microwave versus a kettle is more efficient is because kettles have minimum water level that’s usually around half a liter, so you end up boiling more water than you need to make sure the automatic cutoff works and the kettle can’t boil dry.

    I quit using microwave ovens entirely because it heats food unevenly and ruins the texture. It’s basically steam cooking the food in its own liquids in a shallow surface layer because the microwaves don’t go through very deep. They’re kinda the bad middle ground between grilling the surface and slow-cooking at mild heat, which makes the texture of food turn out like school cafeteria that was all done in a big industrial steam oven: bouncy rubber ball potatoes, soggy slimy chicken, half-cooked rice… it’s almost impossible to actually cook anything decent with a microwave oven, and re-heating stuff tends to turn it nasty. It’s only good for pre-packed pies and mud-flap pizzas, which you really shouldn’t eat.

    1. Microwaves are pretty good when used properly, and way more efficient than some other methods, like ovens.
      Though obviously, they require to be used properly, a tool is only as good as how you use it.
      Need to reheat a liquid? Need to steam something? Need a quickly reheat anything containing water mole ules without either steaming it or drying it? Microwave’s your guy, when you know how to use it.
      Also hands down vest method to cook potatoes evenly. You loose no nutrient and on top of that it’s the fastest

      1. I used to use the microwave for thawing frozen veg, but then I realized that putting the whole lot in a colander and running water over it accomplishes the same effect faster without some pieces remaining frozen as others are already boiling away.

        To avoid the fire and ice situation you have to turn the power way down, but then it takes 5-10 minutes to do anything and it’s no longer quick.

      1. For pure water at 25 C the absorption depth of microwaves is 14 mm or about half an inch. Coincidentally, ice does not absorb microwaves well, so microwaving something that is frozen will easily cause some of the water to boil while there’s a chunk of ice right next to it.

        For 2.45 GHz frequencies, the wavelength is about 12 cm which means you get standing waves and nodes about 6 cm or 2-3 inches apart, which explains why sometimes your hot pocket is bubbling away and turning into rubber at one end while the middle part is still frozen. That’s why the plate is rotating.

        Larger industrial microwave ovens use lower frequency around 300-500 MHz which does go through quite well and doesn’t develop such hot spots as typical consumer microwaves. However, since the operating frequency of the oven is linked to the size of the cavity, you can’t make a regular microwave oven work at those frequencies – it needs to be big.

  5. Isn’t induction generally speaking somewhat lower efficiency? “Make the pan hot” OK, lets do that: run some RICH CHUNKY AMPS right through the bottom of the pan. Contact rings and Big sparks when swirling stuff on the stovetop.

      1. This happens in any stage of the pipeline. If you’re cooking dinner, at a traditional dinner time, anywhere in the US, chances are overwhelmingly high that your power is coming from a peaking power plant, and it’s generating the electricity from fossil fuels, with less than a 50% thermal efficiency. In this case, a gas stove is the clear winner, but for electric stoves, the resistive ones are clear losers, unless the element is integrated into the pan. An induction cooktop will get more of its energy into the pan than a resistive element, simply because at those temperatures the radiant and conductive losses are significant, before the heat even transfers from the heating element to the pan.

    1. It should be better efficiency than a resistive electric or gas cooktop. Inductive has switching losses and some losses in the coil and surrounding objects, but the bulk of the power in is ending up in the bottom of the pan.

      With a resistive cooktop, the element is heating the pan with a poor thermal contact, and some of the heat escapes the element through air convection.

      With a gas cooktop, convection of the hot gas of the flame takes a lot of the combustion energy upwards and away from the pan bottom and heats your room instead.

      Also an induction cooktop shouldn’t spark.

      1. Resistive can end up the most efficient from what I’ve seen – but only when cooking for very long periods, as that very long, slow, (and poorly controllable) high energy heatup kills it, but at the steady state for cooking it can at least need less continued supply of energy.

        Induction really is good though, for exactly the reason you state, and its knock on effect of being quicker to heat – which added with extra control-ability means using a big resistor isn’t to be encouraged IMO…

    2. They like to put the cheapest IGBTs in those drivers, then blow cooling air in betwen the coil and the Ceran top plate. Since I took mine apart, I find this design choice extremely annoying. I’m pretty sure one could have cut the conductive heat loss on the bottom and only fan air across the glass ceramic plate when in shutdown mode.
      I’m looking forward to future generations that are less crappy and actually put something nice in there, like a beefy SiC MOSFET.
      With SiC or GaN power semiconductors you might perhaps even be able to operate at frequencies where non-ferromagnetic cookware would also work.

      Also don’t underestimate resonant topologies where conduction losses dominate.

        1. I’m mostly interested in higher switching frequencies as far as the coil allows that. Cost-optimized solutions will probably keep the efficiency the same but allow for lower cooling and operating noise levels, as well as a wider power range.
          The induction stove I bought used (and basically new) was sold because the precious owner wasn’t willing to put up with the noise. It’s a matter of comfort and experience, too.
          I myself am bothered enough by it to consider upgrading my unit with a SiC MOSFET, but I haven’t bothered to reverse engineer the board and re-do the gate driver section to make that happen.
          On top of that, the “litz wire” the coil is made of looked rather coarse and will probably suffer from higher skin effect losses were I to increase the switching frequency.

          1. I have cooked with induction at friends places, the cooking experience is better than the gas I’m used to, but the reason I will not switch at the moment is that the high-frequency noise absolutely kills me.
            That, and I want one with knobs, not a stupid panel next to a hot pan that you have to touch 17 times to change a setting.

          2. @IIVQ I agree, those are rather striking shortcomings. It’s time to popularize higher switching frequency devices, though that might not fully eliminate the noise (ultrasonic cleaners also create subharmonics and broadband hissing despite having a 40 kHz resonant frequency)

      1. >operate at frequencies where non-ferromagnetic cookware would also work
        That actually already exist in high end models from Panasonic. Not efficient though.

        1. Another interesting aspect is that thin aluminum pans may try to levitate on an induction stove. There’s youtube videos of floating aluminum dishes in air with eggs cooking inside over a big induction coil.

  6. Vacuum sided cookware is an almost total waste of money. Almost all heat is lost through the top of the pan so adding a lid is a great idea, especially if boiling water to add stuff to. The losses through the side are pretty minimal so spending loads to insulate them is just a waste.

    Now my main rant is on cooking appliances in the US. I just moved the the UK and had a nice double oven and induction hob combination. Moving the a gas oven with no fan and a gas hob is just horrid. The oven takes ages to heat up, is massive, yet doesn’t actually have much space to cook in. The temperature is very different in different places and heat doesn’t travel well if you put a few dishes in it. Then the gas hob takes ages longer to cook things, isn’t as powerful at heating the food and is a real pain to clean.

    Oh to move from a rented apartment and be able to have a decent oven and hob again. Don’t get me started on how slow the damn kettles are!

    Next weeks rant will be on US electrical plugs. God I hate them.

    1. >Vacuum sided cookware is an almost total waste of money. Almost all heat is lost through the top of the pan so adding a lid is a great idea

      Got one where the lid is also double-walled and vacuum insulated. They’re wild. At the price they’re being sold though, I cannot disagree on the “waste of money” part. It would seem that a “towel with a hole in the middle” would at least get us half of the way to that.

    2. Taller plastic jug type of kettle are the least annoying this side of the pond, at least you can put just a mug worth in at once to lower boil time.

      For tea, you can find Tetley and Yorkshire Tea often in the “foreign food” aisle at Walmart and perhaps some large grocery chains. Irish breakfast is usually passable if nothing else is around. Avoid the Red Rose and Lipton yellow box, it takes 3 bags just to make the water look dirty. Up in Canada here we find Tata brand from India appearing once in a while, reminds me of PG Tips, so not bad, not sure if it’s selling in US.

    3. I have a great electric double wall oven. Both are big inside and have convection fans. Of course, it’s European – made by Electrolux. The challenge here is that it needs a 50A service line and breaker so isn’t a trivial install in a kitchen that isn’t already built for it. I also have a good gas stovetop. (“hob” isn’t used here). GE Monogram, heats faster than any gas hob my parents ever owned. You’re unlikely to find either in a typical rented apartment though.

      I have an electrician friend here of Irish birth. Twenty five years ago, electric kettles were just about unheard of here. He installed a 240V UK socket in his kitchen and brought a kettle over from Ireland. That’s not necessary any more as there is a good variety of electric kettles now. Some of them are quite good with features on a par with the rest of the World, albeit still slower. Once you get used to that though you soon adapt.

    4. Wow. Sounds more like some one dumped the cheapest things they could get in your kitchen without regard to use. No wonder you’d have issues. There is a very good reason pro kitchens use gas cook tops. When a kitchen is properly designed and used it can’t be beat for ease of use and all around reliability …. Especially if your electricity is from fossil fuels anyway.

      1. While this is exactly correct as per the video presentation, one must add that what is compared here are “(some of the) practically available options” to heat a given amount of water, not “(all of the) theoretically possible options with ideal conditions”. Chances are you have a gas range and an electrical kettle, so which one should you use? That gas might be the better option if only you had a contraption to capture all that convective hot air is immaterial as long as there’s no practical solution around that does that.

        1. Confined heating is maybe the most used method historically. Its various forms are cooking pit, rocket stove, etc. Even a three-stone could count as one. Among the merits of these devices (if low tech), beyond efficiency and low initial investment, is the ability to use different fuels, locally available at maybe no price.
          A well documented article on their efficiency, compared to electric or gas-fired, can be found here: https://www.lowtechmagazine.com/2014/06/thermal-efficiency-cooking-stoves.html This does not include direct-solar, which also uses confined heating and seems to have the lowest running cost of all, provided you are cooking at noon.

  7. As a self declared home chef and foodie I am not fond at all of microwaves. I have read several scientific articles that purport that molecular changes occur in microwaved food. I will not post links as this is an exercise to open the mind. I have used both gas and electric appliances throughout my life. Some notes on this: electric takes longer to warm up and cool down e.g. if you want to simmer you have to either overshoot and boil then reduce to simmer or wait an extended period of time to come to a simmer. Gas appliance you can put on rip roaring to simmer and reduce to maintain simmer, simply much easier and faster. The big burner on my range is 35,000 btu or 10.26 KWh. It will bring 2 gallons or about 8L of water to boil in under 10 minutes. My range is also dual fuel meaning it has an electric oven and a gas stove top. The electric oven is superior to gas in that the gas oven is basically wide open to the world and the electric oven is a sealed box. If you look inside a gas oven with a flashlight you will see openings to the burner below and it vents through the top into the room it is in. The electric oven uses a pid to maintain temperature. I have never used an induction cooktop and therefore cannot comment on it. I do use a very large pressure cooker to can my veggies from the garden. Almost all my other cookware is 18-8 3 ply stainless. There is absolutely nothing wrong with the electric kettle and i’m a big fan. Carry on and enjoy the chicken piccata.

    1. Molecular changes are what cooking is all about. Even if you’re a raw food nut, molecular changes are happening from the day you pick something, ripening, enzymatic activity and so on. So if you find a cooking method that didn’t cause molecular changes… try plugging the appliance in.

      1. Microwave ovens are basically steam cookers. They heat the water, which then heats the food. It results in the same sort of changes in texture of the food as actual steam cookers, especially the industrial varieties we encountered in primary school: bouncy rubber potatoes, slimy chicken, half-cooked rice… etc.

        It just makes food terrible. It’s only good for melting frozen stuff quickly, and boiling water. Everything that is actually suitable for cooking in a microwave is pretty bad for you, like hot pockets and frozen pies etc.

        1. Yes in particular it doesn’t do the Maillard reaction thing, regarded as a pleasant molecular change, even though it can result in larger amount of cancer promoting free radicals.

          1. The cancer promoting stuff is chiefly HCA/PAHs that are formed mostly by partial combustion because of excess temperatures or actually burning the stuff by dripping over hot coals etc. and then getting the smoke deposited on the food.

            However, the cancer risk from HCA/PAH compounds is somewhat exaggerated, because the link between cooking and cancer was established in animal models (rats) using exposure levels about 1000x greater than you’d encounter in typical human diets.

          2. You don’t really get nitrosamines without particular food preservatives in meat (nitrites), so it’s got less to do with cooking and more to do with what you cook.

    2. I grew up cooking with gas. I find the rapid control of induction to be similar to gas. But, if you use a pan with low thermal mass, you’ll find the on-off cycles of induction to be annoying.

      With the cheap unit I have, the power appears to be fully on or fully off on a really slow PWM sort of behavior. Shallow water will boil then not boil with rapid transitions.

      I’ve often wondered if a better unit might modulate the “heat” in a more sophisticated way. However, if I were using “real” induction cookware I figure more heat would be stored in the base, thus buffering the the wide swing, with respect to visual perception anyway.

        1. Maybe, but I don’t think so. I can hear the same cycling pattern (high frequency current in the induction coil) when using cast iron, but the container holds enough heat to keep the food bubbling until the next cycle. The effect really comes through when making a sauce (gravy) in a fairly shallow layer.

          To be fair to the apples and the oranges, I’ve never actually boiled water in cast iron…because it just seems wrong somehow. And the only “real” inductive-friendly vessel I have is a skillet and I don’t tend to boil water for pasta in one of those either.

          1. Some people find that you should only boil water in cast iron pots, because it lends a particular flavor to the water. Of course it doesn’t apply to pans that have been seasoned – that’d be just gross.

      1. I’m having the same issue with induction cooking. In principle it should be possible to regulate the power level all the way down, but there may be practical limitations in how the control loop is set up, or what minimum pulse width is achievable with the IGBTs used. I’ve looked at NXP AN5030 (“Designing an Induction Cooker Using the S08PT Family”) briefly, but they’re not clear about it.

        Essentially, with better components, it should be rather doable.

    3. I almost never “cook” in a microwave, but I usually cook for 2 days then reheat 2 days later, which I do in a microwave for almost everything.
      There are a few exceptions: Pies I reheat in an oven, the crust will burn far earlier than it heats the innards in a microwave. And for Risotto, I set aside what I’m not going to eat on the day of cooking about 10mn before it’s done. Otherwise I end up with rice porridge.

  8. My wife got one of those air fryers, I thought it was a gimmick but the cooking times are astonishing. The food is cooked and ready to eat while the oven is still preheating. The air is recirculated so it’s efficient and it doesn’t stink up the place.

    1. Here it works out something like, if you’ve got natural gas or heat pump, in heating season only 2/3 of electricity is “wasted” (Cost wise) if you’ve got electric radiant heat, nearly none of it is.

      Heat pump though may have least CO2 emission however your energy normally gets made, natural gas may or may not cause more than equivalent heat from electricity, but I am ambivalent towards constraining my natural gas use until it is no longer burned off as surplus at well heads.

      1. Yeah, if we measure efficiency in CO2 and methane emission, (which we should) clean electric beats gas. I used to think gas was more efficient because of losses in electricity generation and transmission, but huge amounts of greenhouse gasses are released and generated before the gas reaches your stove.

    2. Never underestimate the usefulness of a gas stovetop during a 5 day power outage in New England during January. Even though our heating is oil and gas (older and newer parts of house), neither will run without electric controls.

      Fortunately that’s only happened once in the past twenty years. An early October storm once took out several trees, one of which took out our power line, and that took 3 days to get fixed. That wasn’t such a problem as it was still fairly warm. Still useful to be able to cook though.

      One of these years I’m going to get a generator.

      1. You have to remeber the world is different depending on where you are. In the usa our outlets are typically 120v 15 amp or 1800W or 1.8KW. On your side it may be 240v 50HZ. I do not live in your part of the world but assuming it is 240v 15 amp then it will go 3600W or 3.6KW. in my best yankee accent “you ain’t gettin that outta our outlets!”

        1. I’m happy I’ve got 20A to the outlets above my counter, at least means I can use a toaster/coffee maker at same time as crockpot or something without blowing breakers and smoking wires.

        2. Most UK plugs for the single device max out at 13A at 240V nominally, so why wouldn’t you get a kettle that can use it! Tea is important, and it takes time to infuse properly don’t want to be wasting our precious time just getting the water warm..

          RW, I think you may be a little off though, after all the UK census lists ‘everyone’ but most households will have only one kettle in use (and maybe a backup), add in the office kitchens etc and you still only get a fraction of the population…

          1. Well yes, but unless it’s very much changed since I last looked at one, it lists everyone by household, which I thought was sufficiently obvious not to require further elucidation among a population of smartasses following a blog about practical smartassery.

          2. Ah, but those of us on Thames water will have at least two dead kettles from the limescale waiting to go to the tip… I mean, recycling facility.

          3. @Dan there is this magical family of stuff with a PH that makes it rather good at wrecking limescale deposits, shouldn’t need to toss a kettle for hard water, though eventually they do all die. I like what I call ant juice myself*, never found it hard to get a new bottle and the stuff goes quite a long way, something around a shotglass full in warm water does our kettle rather well .

            @RW it really should be readable as you say well enough, though I think really you are after the number of currently inhabitable structures with a grid hookup or real generator in existence in the UK (and EU really – voltages and power ratings are pretty much the same, so close enough) not the number occupied according to the census. As you don’t take your kettle with you to the caravan/holiday home etc, and lots of families have at least one of those to bump up the number of kettles beyond the number of registered households, but not by near enough to assume everyone over the age of 15 has their own I would think…

            *Formic acid (or whatever other name you care to give it) the stuff ants produce when you annoy them.

    1. Nobody really.

      Kettles (microwaves, vacuum cleaners, etc.) are generally built around the generic room socket circuit in the EU, which is usually fused for 8 – 10 Amps slow fuse, which can handle about 1700 – 2200 Watts non-continuously.

      1. Uh? Most sockets in European countries where I’ve done electrical work are 16A. My current kettle is 2300W and I think my previous one was 2500. I never see the full 3680W being sold though.

        1. The sockets may be the same all over, but the wiring and the fuse/breaker isn’t. There MAY be 16 Amp breakers on the circuit IF the wiring is up to the code, but that’s not a given. The standard “Schuko” socket itself is actually rated for 22 Amps over 1 hour when new.

          Older worn out sockets may only deliver 8 amps safely regardless of the breaker size. 1800 Watts was/is the common size for appliances like vacuum cleaners etc. because the manufacturers don’t want to be known as the company whose products cause your breakers to trip or your house to burn down. Kitchens however do tend to have higher amperage sockets because of the stove being there as well.

          >I never see the full 3680W being sold though.

          That’s exactly because even a 16 Amp circuit is not actually meant to be used at 16 Amps – that’s just the nominal breaker limit. If you tried to use such a device out of a regular wall socket in an average house, you’d trip the breakers a lot.

          1. All breakers in all houses that I’ve seen in .NL, .FR, .BE were 16A (or more for special applocations) save for smaller breakers for special applications – My uncles house has a few 6A breakers in lighting cirquits (with a minuiterie) and a 2A one for the equipment inside the electricity cupboard (apparently, because that room could overheat if more than 480W of heat is generated in it). I have never seen anything other than 16A breakers in cirquits that had schuko sockets.

          2. Mine are 2x 10A and 2x 16A.

            The 10 Amp circuits originally had those old round CEE 7/1 (Type C) sockets without grounding pins, but the previous tenant had burned out one socket and almost caused a fire, so the electrician swapped in a Schuko Type F socket in its place – ground to neutral which is technically not permitted anymore but legal for repairs.

    2. Not that many. The most common high power kettles i see are 2,5kW. I’d say 1,8 or 2kW is average.
      I have one of those 2,5kW things. It’s awesome. It has a flat bottom so it’ll work even with only one mug of water in it, so it’s super fast.

  9. I prefer the authentic and traditional heat source of burning Egyptian mummies (it’s true, look it up).

    As a close second, the heat from whale oil is very consistent. Really everyone should use whale oil. And of course coal is a most efficient heat source, it can cook the lungs of a whole city. There is just something special and magic about these heat sources.

    1. Vermin Supreme has promised to put us back onto whale oil, right after establishing a pony based economy.

      Don’t get your panties in a bunch Welsh people (home of whales).
      The whales will be fed McKrill burgers, hang out on LazyWhale lounge chairs and the oil will be liposuctioned off regularly.

    2. Clearly you don’t love the planet (not the people silly, just the planet; you know, magma and stuff) enough for you to put up with the very minimum personal cost of using eco friendly cooking methods. Like cooking individual food items by rubbing them between your hands and your butt cheeks.

      Oh why, why won’t these peasants move towards the modern, enlightened, beautiful utopia of the revolution.

  10. Another easy thing to do is get a good toaster oven. While some things really are better roasted in an oven, a toaster oven (especially a convection toaster oven) is great: With the smaller volume it tends to heat up more quickly, and you end up using less energy just heating air. A good one can not only make toast, but reheat food, roast vegetables, or bake cookies in small batches. And you don’t have to re-do your whole kitchen to get one.

    1. One caveat though is they are poorly insulated, so don’t retain heat very long, so for short cooking times they are great, but over longer periods, half hour or so, they tend towards using the same as a regular oven.

      However, the sample for regular ovens has been pissed in a bit with I think the Energy star ratings failing to take into account that you have to have the damn thing turned on 15 minutes longer to warm up than previously, therefore all cooking operations take averagely 10-50% more “on” time. i.e. an 1800W element gets you nothing over a 2200W element, because you’re up to temp inside 10 mins with the powerful one, and “are we there yet, are we there yet” waiting for the 1800, which even switches on and off before target temp reached, so add time to usage, even if such tomfoolery brings down the kwH consumption per use hour…. ‘coz now use hours are forced upwards to get the same job done.

  11. An interesting observation about gas ovens. Ours was taking longer and longer to warm up. Eventually the “glowie thingie” gas igniter burned out. After I replaced it the stove would warm up more than twice as fast! The igniter is wired in series with the gas valve (so the gas valve won’t turn on when the igniter is burned out) so as the igniter was dying it’s resistance went up, causing the gas valve to not operate properly.

  12. I have been into “molecular gastronomy” for a number of years. This sometimes requires more precise control of the cooking temperatures. Modern cooking appliances are not good enough to for this, and cooking sous vide is problematic because I refuse to cook in plastic, while glass takes extra time and energy.

    Enter the book “Building Scientific Apparatus”: https://www.amazon.com/Building-Scientific-Apparatus-John-Moore/dp/0521878586 Radiant heat, fuzzy logic (Pi), high-quality sensors… My best oven came from plans I found in Mother Earth News for an outdoor pizza oven. I just modified it to heating elements instead of wood-burning, and twiddled some thermostats. Worked very well for cooking any one item for a given time at a specific temperature.

    The stovetop presented a different problem: I twiddled a laser/infrared temperature gauge to focus on the pans, and used the same fuzzy algorithms to control the current going to the induction coil. The coil is not particularly responsive (I wanted to control +/- 1 degree C) but the output of the gauge only reads out to 0.0C, and that is too coarse. I need to tweak it to read out to 0.00C and then need to calibrate the electric current measurement and responsiveness within pretty small limits. I get very acceptable results using really high-tech cookware (https://www.heritagesteel.us/pages/new-era-cookware), but cast iron is useless for precision cooking. I like to heat the pan first, then add oils (if needed) and heat that, then add food to be cooked. I am presuming, at this stage, that if I control the outside temperature of the utensil, then the inside will be the same temperature. This will have to do until I figure out an acceptable way to gauge the temperature of the food without opening the pan.

    I doubt that my experiments lead to improved energy use, but I cook for the taste.

    1. The aspect of heat distribution reminds me a lot of Alex’s “mother sauces” series where he explores heat distribution and ends up in a copper / silver cookware workshop: https://www.youtube.com/watch?v=33ddRK_jG6E

      One field I haven’t really explored is deliberately cooking with temperature gradients. My intuition is that there are practical limits to perfection there, as the cross-sections, thermal conductivities and contact to the pan will vary.

      Do you have some of your builds up on youtube or hackaday.io?

      1. I’m not satisfied enough with my experiments to post them at this time. I love doing the experiments, but I’m sure if I had more time and more money I could get better results.

      1. Wow! Thanks for pointing this out! It’s a little small, but it sure beats assembling fire bricks, radiant heaters, etc., for my homebrew experience. Probably about the same cost, too.

        Electrolux (Swedish company) used to make some really fine induction stovetop ovens, and the console had plenty of room for me to add in my own instrumentation. They are hard to find now, but the oven part was pretty good and one model used to have an upper convection oven. (Convection cooking has been relabeled “air-frying” for those of you who don’t remember “convection oven”.) I found a few on eBay, but I haven’t looked lately.

  13. Anybody claiming that too much heat escapes off the side of a gas burner just isn’t doing it right under the mistaken impression that the bigger the flame the hotter the burner. Sorry, folks, but when the top edge of the flame touches every part of the pot, you’re not losing heat off the sides. That happens only when you turn the burner up TOO high. Only the top of the gas flame is hottest–below that it gets increasingly cooler.

  14. They want to take away our gas in the U.K. and move us to air source heat pumps and induction hobs.

    But I quite like having two independent energy sources, and somewhat skeptical about the efficiency of burning gas to turn it into heat to turn it into electricity to send it to me to turn it into heat, when I could just skip the middle man and turn it into heat here. If all our electricity came from renewables/nuclear I’d see some value.

    Also, remember it’s not gas or petrol, it’s a carbon monofilament hydrogen storage solution.

    1. Oh but you are standing in the way of progress peasant. What’s that? You like some char on your food? You want to cook in a wok? Toast some bread on the flame? All these things run the risk of introducing joy in your life and as you are well aware that is no longer allowed. Report immediately to camp 14 for supplementary training to help you shed any remaining hopes of happiness.

  15. A lot of American gas burning ovens, while having a 5kW/hr or 10kW/hr gas burner in the oven, also need 600 watts or so for their electric ignition element.

    These “gas” ovens arguably use more kWHrs of electricity than a microwave or air fryer would need for the same meal…..

      1. They detect the heat from the igniter element to open the main gas valve. If the ignitor goes cold, the gas turns off.

        It really is a terrible design.
        My stove is on it’s third ignitor, granted it’s old, I’m cheap. Chinesium ignitors cost about $15.

  16. I have a solar oven that gets to around 350F on a cloudless day. And if away from home and a fire is acceptable a Kelly Kettle (generically a storm kettle) is an amazingly efficient water boiler for tea.

  17. At 100 ° C you’re killing all the flavours of most of the teas, some Japanese green teas need no more than 60 ° C to infuse, the average is 70 ° C… It’s possible to control the temperature of the water on the kettle in my home.
    At work, I must drink a lot because of the ventilation system that dries the air, and my Japanese sencha and Uruguayan Mate mix is slowly infused in 20 ° C tap water, delightful and a good drain.
    An gaz is a very various thing : in Paris, the delivered gaz is very diluted, it doesn’t burn very well, so I heat water for pasta with the kettle, but in an off town house, the gaz burns incredibly hotter and it’s nearly impossible to have something quietly mijoter (simmer), the delivered gas in town is of course not the same : butane in town and propane out, but I’m sure the town thing has a lot of air in it….
    Since about ten years, we always cook (dried, not fresh) pasta in a pressure cooker : first have the water boil, with the help of the kettle in town, closing the lid between every loading (it needs four 1,5 L kettles) then add salt, and the pasta, close the lid, then turn off the heat… the pasta are perfectly al dente cooked at around the time wrote on the packaging, sometimes one or two more minutes are necessary, but pasta cook at 80 ° C, so it doesn’t need to be boiling all the time ! and it’s a big saving for us as we eat pasta very often…
    A good tip if you want to cook meat with the good réaction de Maillard browning : the steel pan must be heated very slowly, for a long time, so the heat is evenly distributed by conduction on all the surface of the pan, not a circle of the shape of the burner under the pan (or whatever is heating the pan), when it’s really hot, you can put some fat (clarified butter) if necessary (some meat is fat enough not to need any more in the pan, duck for instance) and turn up the heat, and before the fat burns (smoke is no good), put the meat, and don’t touch it until it naturally unstick the pan (you can check this by moving the pan after a time), then turn it.

    1. Different teas, different temperatures.

      Matcha doesn’t require you to have to extract much at all since you’re going to drink the leaves anyway.

      Green Tea needs to be around 70-75°C because otherwise somes components just won’t be extracted, lower and it’s bleh (or oxidized and therefore bleh-er), higher and it’s burnt.

      Black Tea needs between 90-100°c because most of the fragiles components have been destroyed/transformed already, and you want the ones that are extracted at higher temps.
      Though multiple hours at low temperatures might work for Black Tea

    2. There are indeed differences between types of gas. The Netherlands has ‘low caloric value’ gas. Ethane and methane.
      Imported LNG needs to have extra nitrogen added, so the heating devices in peoples’ houses don’t get way hotter than they are supposed to get.

      Gas in tanks is usually butane and propane, and has a much higher ‘caloric value’, and doesn’t contain added nitrogen. So it’ll burn a lot hotter.

      As a lovely side note, i work at a high school and the previous science tech guy at the school made a Rubens Tube. A flame tube with which you can standing waves in a pipe. He tried a lot of things to get it working, but never got the proper resonance and standing wave effect with natural gas from the gas tap in the room.

      Eventually he tried some Campingaz. It worked flawlessly! Because of the higher density of the butane/propane gas compared to ethane/methane/nitrogen, the pressure waves from the loudspeaker propagated better along the pipe, showing the nodes and valleys much better.

  18. Cooking devices are related to specific cooking methods. Different cooking methods increase or decrease the overall efficiency. For example, preferring sliced or small chunks food, having more surface for heat exchange, increases the energy efficiency. Therefore devices that are targeted to chunks rather than large pieces can be predicted to be more efficient.

  19. I’ve been using induction for about 25 years, it is way better than gas for everything bar wok cooking – which I use an fairly industrial gas burner for :-)

    Of course, if I was in the USA with it’s shitty power I might not have been so happy with induction.. My induction cooktop is about 10Kw, which isn’t a prob in Aus..

    1. American range outlets aren’t 120V.
      Most modern developments have 100 or 150 Amp 220 V two phase service at the meter. Older houses will have 50A service.
      Don’t let the fact you don’t know what your talking about stop you though.

      Gas’s biggest advantage is you can (and should) look at the flame while adjusting the burner. Most precise control of heat available. Why virtually all commercial kitchens use gas.

  20. My my my how the discussion has grown since my last visit! Chiming in to address the comment about low-tech cooking re: fire pit; also air fryers; also certain delicacies that defy microwave ovens and other modern tech gizmos–there will never be a substitute for a double boiler with regard to that last point.

    Often overlooked in consideration of the fire pit is the type of fuel you’re using–if charcoal, you have to pre-process wood to produce charcoal and if you’re using wood for your firepit, the anaerobic nature of a covered fire pit will turn wood into charcoal which will give you double bang for your buck compared to using commercial charcoal (pre-burnt wood). Before getting to the air fryer, transition needs to be made to the principle of a smelter’s blast furnace which melts metal with nothing more than hot air. Again, fuel used makes the difference.

    By the same token that charcoal is pre-burnt wood for the purpose of delivering more BTUs than regular wood would, the blast furnace requires pre-burnt coal. It’s called coke. Superheated air is just as possible as superheated steam but in order to superheat steam, it needs to be under pressure…and putting a lid on your cookware increases the preasure inside the pot–and voila.

    1. > charcoal is pre-burnt wood for the purpose of delivering more BTUs than regular wood would

      When you carbonize wood, about 30% of the fuel value is lost, which is the amount of resins and volatiles that are removed from the wood. You also use about 10x the energy to cook the wood into charcoal than what you get out of burning the coals.

      Charcoal also has less energy per volume, so you’re not getting more BTUs out of it either. The point is just that charcoal burns cleaner without the flame and smoke.

  21. Frontier Energy made a paper titled “Residential Cooktop Performance and Energy Comparison Study”, in which they experimentally come to conclusion “Induction technology offers precise control, focused heat, quick response and greater energy efficiency over the more traditional cooktop technologies.”

    Complete with numbers and methodology.

    Also, gas is responsive, but very inefficient.

    https://www.sanjoseca.gov/home/showpublisheddocument/39054/637038749934400000

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