Induction Cooktops

mike95490 · December 2007

While preparing for the oil crash, I was wondering about cooking, and how it's best done. I know some gas cooking ovens use a power hungry glow bar igniter, and some use a spark igniter. In the absence of gas, I was wondering about cooking with electricity, and I believe the standard 240V spiral cooktop elements are pretty lame about conducting heat to food, and am wondering about the comparative efficiencies of microwave ovens, and inductive tops. Any stories, suggestions, etc ??? (for days when the solar oven is not working)

System2 · December 2007

Re: Induction Cooktops

As far as smaller amounts of food are concerned, the microwave is the way to go if you are only looking at energy efficiency. There comes a point however as the mass of food is increased, where the break even point is reached and then standard resistance heating is better.
As to the induction, I'm not sure how the energy losses involved would compare, to the standard stove top, but I do know that only certain materials can be used as cookware. Probably the most efficient other than microwave would be dedicated items, such as skillets with the heating elements embedded within the underside of the cooking surface.
A point of possible interest, all the "slow cookers" I've ever owned, I've torn apart and added heat proof insulation. The outside now stays much cooler, and the heat once used to warm the room now goes into the food. With solar, every little bit helps. Yeah I know, the UL / CSA thing, but it was my decision and it worked. When will manufacturers catch on?
Wayne

BB. · December 2007

Re: Induction Cooktops

Grog find stick work good.... Stick hit animal on head, rub sticks together and fire heat meat... hack, cough, hmmm...

Back to the present... Another thread seem to show microwaves were a bit better than 50% efficient... Add that with all of the other inefficiencies:

Sun * Solar panel * charge controller * battery * inverter * microwave =

100%*12%*95%*80%*85%*60% = 4.7% sun to food heating efficiency...

Just for a point of interest, from a UN (or derivative) report (PDF), wood/rice hull/etc. stoves (around the world) seem to run from about 10% to 30% efficient. And for areas that used low efficiency stoves, changing to a better stove can cut fuel use by almost 1/2.

In the end, if there is no oil or natural gas--we probably won't have solar panels, charge controllers, batteries, inverters, microwaves, refrigerators, stores, well pumps, fresh food shipped from around the world, etc... after 5-10 years anyway...

My two cents--various prices will continue to slowly rise and people will adapt. Just like Wayne did, he added insulation to a electric pot. For campers, you can get high efficiency stove kits with wind screens, accordion pleated bands/bottoms (also here for boiling water/cooking cup with insulated sides) to place on pots to better transfer heat from a portable stove to the pot. And there are little metal wood burning stoves that burn much more efficiently than cooking over rocks.

I believe that solar heating/cooking will still be an option--for my climate, that would probably mean that I could get 50% of my energy for cooking/heating from solar--and those times when the sun is not available, then fossil fuel (or hydro, or nuclear electric, etc.) would have to do...

We (in developed countries) today waste tremendous amounts of energy and resources. It will help to waste less--but it will not fix our problems--just postpone them until later (if we cut our use of resources by 50% but continue to grow by 3% per year, we would be back at this point again in ~34 years).

Without oil and electricity, things are not going to be pretty with the present world population (especially in cities and other densely populated areas).

-Bill

niel · December 2007

Re: Induction Cooktops

wayne,
i'd be curious as to the type of insulation you had used that you termed as heat proof. i'm assuming you meant ignition proof, but there aren't many insulations that when exposed to high heat that they will not either become damaged or catch fire. asbestos is one that works, but look out for possible health risks there.
along these lines i've often wondered about window air conditioners as i've added insulation to some i've had. the wall between the cooled air and the hot outside air is often poorly insulated if insulated at all. i've sometimes wondered about how much better the eers would be with some insulation properly placed as i've done. my biggest peeve with air conditioners however is the poor quality fans and motors used in them as i have had most of my ac units fail due to the fans and motors. no coolant leaks. no compressor failures except once. i sit here thinking about how much more life could've been had with these ac units, but that they are going to the garbage man. there's nobody that comes around to even salvage the coolants either so that goes into the air eventually anyway too, be it the old freon or the newer coolants. the last one i bought didn't bother with the metal wall between cold and hot areas of the ac unit, but poorly placed a thin piece of styrofoam insulation there that i can see gaps between hot side and cold side. companies aren't worried about making quality anymore imho as they want you to buy more of them and sooner as cheaply to them as possible. i can imagine what a bit of effort would do for the eer values.

icarus · December 2007

Re: Induction Cooktops

Mineral wool works well for high heat applications. There is a product called (I think) "fire safeing" that is a mineral wool that is used to plug penetrations to comply with fire stopping material in buildings.

On the other hand, fibreglass works quite well in the kind of temps used in things like crock pots.

Icarus

System2 · December 2007

Re: Induction Cooktops

Oh, I just shredded bits of paper and stuffed it between the walls of the cooker.
Just kidding. Yes, I've used both fiberglass and also mineral wool. Mineral wool is often used in metal chimneys and at any temperatures it may be exposed to there, it's both heat, fire and melt proof. Fiberglass is also heat and fire proof, but it you take a blow torch to it, you can get it orange hot and and if you really work at it, you can eventually get it to melt down into little balls of glass. Been there, done that with fiberglass pink. I had to know if it would burn. The glue used to hold the bats together, as well as the pink die may stink when heated, but there is no burning, smoldering, etc. In fact, I turned to mineral wool for the pots, because of the smell from the pink glue.

System2 · December 2007

Re: Induction Cooktops

Re microwave efficiency, yes indeed they are only about 50% efficient - - - BUT, even at that, like I mentioned, they can hardly be beat for smaller items. What other way can one cook a potato in under 4 minutes. Yes,the microwave may draw 1000, or 1500 watts for that 4 minutes, but compare that to the energy required to boil that same potato for 40 minutes. No contest. But if you're looking at cooking 40 potatoes, now that's a whole different story.

lamplight · January 2008

Re: Induction Cooktops

re mircrowaves:

http://forum.solar-electric.com/showthread.php?t=739

Induction Cooktops

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