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Old 07-24-12, 12:17 AM   #1
AC_Hacker
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Default Induction Cooking Efficiency...



There is a good write-up in Wikipedia on Induction cooking & efficiency and environmental impact.

To make a fairly succinct write-up even more brief, they differentiate between source energy used and site energy used. For instance, the source energy efficiency of an electric device is much lower, due to generation inefficiencies and transmission losses, than is site energy efficiency, where the generation and transmission losses are disregarded.

Gas Cooking Efficiency -
  • Source energy efficiency: 38%
  • Site energy efficiency: 40%
Electric Non-Induction Cooking Efficiency -
  • Source energy efficiency: 22%
  • Site energy efficiency: 74%
Induction Cooking Efficiency -
  • Source energy efficiency: 25%
  • Site energy efficiency: 84%
Also stated was that induction cooking has a 12% efficiency advantage over non-induction electric cooking.

NOTE: Gas efficiency differences are very small because gas distribution pipe losses are also very small.


Bottom line, single counter top induction cooking units are becoming fairly inexpensive (< $100) but for some reason, full 4 burner induction cook tops are priced between $1000 and $2000. Since cooking consumes a fairly small amount of most home energy (around 4%), payback will be long, especially if a full 4 burner cook top is used (I calculated a breakeven of about 34 years for a $100 table-top unit, and about 340 years for a $1000 4-burner cook top). However, if on-site generated electricity is used for cooking, induction would be a clear winner.

Takaway: For those of us using grid power, the cost of an induction cooking device would be much better spent on home insulation.

Best,

-AC

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Old 07-24-12, 09:38 AM   #2
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Interesting compairison.

Perhaps its a typo, but you have the source for both electric supplies at different efficiencies, or is there an explination behind that?
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Old 07-24-12, 10:04 AM   #3
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Quote:
Originally Posted by Daox View Post
...you have the source for both electric supplies at different efficiencies...
The Source Energy Efficiency is the efficiency measured from the burning of the source fuel (usually coal in the case of electricity) to the heating of food.

Both induction cooking and non-induction will have the same losses from the prime heat source to the cooking device, but different efficiencies when cooking... so Source Energy Efficiency measures the entire chain, in all cases.

Source Energy Efficiency should be of special interest to those of us who understand that there is a link between the energy we use and it's effect on the environment, global warming for instance.

Site Energy Efficiency would be of interest to those of us who think that the chain of effects begins at the kilowatt meter and ends at the electricity bill.

Best,

-AC
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Old 04-04-13, 03:05 PM   #4
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Default AC Takes a Second Look at Induction Cooking...

It is interesting how following one path of action can open up other unforeseen paths of action, and lead on to unexpected conclusions.

I'm still working on my CO2 controlled HRV project. I have my controller working, even controlling fans as I wanted it to. Some problems remain to be solved.

But living with a device that tells me the CO2 concentration of my living space has been very educational.

It has shown me that the gas appliances that I am very fond of are currently in conflict with my goals of achieving very robust insulation and infiltration sealing. I am able to see a surprising difference in CO2 levels whenever I use any of my gas appliances which are a gas dryer, a gas cook stove, a tankless gas water heater, and most recently a gas 'ventless' space heater that is down cellar.

My house is very small, so the differences I'm experiencing are likely greater than most people would experience. So, to a certain extent, I am the canary in the coal mine.

I have a strong belief in the desirability of having multiple sources of fuel as a hedge against the unanticipated lurchings of our industrial society, as cheap energy declines.


But it is my beloved gas cookstove (which is similar to the one above but all black, with no stainless) that has caused me to re-think my previously tepid opinion of induction cooking.

I bought the cheapest induction cooktop I could find locally and started using it for daily cooking to see how it fits and if the advantages I hoped for were true.

The unit I got was this one, from target:


The unit is advertised as 1500 watts and cost $70.

As I have learned, this unit holds the distinction of being the very lowest point in the induction cooking food chain. I measured the wattage of the following heat settings with my Kill-a-Watt:
  • warm = 600w on/off (low duty cycle)
  • P1 = 600w on/off (high duty cycle) ("Low")
  • P2 = 600w 100% duty cycle
  • P3 = 750w 100% duty cycle
  • P4 = 950w 100% duty cycle
  • P5 = 1100w 100% duty cycle
  • P6 = 1275w 100% duty cycle ("High")

Notice that the advertised 1500 watts is not reached, not even close.

I tested my cookware with a magnet and only a surprising few were induction capable.

Since I usually have oatmeal, or something similar for breakfast, and since the pot I would use was non-magnetic, I picked up a suitable Ikea pot from Goodwill. It turned out to be an excellent choice, for the size and most importantly for the construction of the magnetic bottom. I think I paid $9 at Goodwill and new they're about $13. Good price great pot.

As I quickly learned, it's not just that magnetic cookware is required, it's more like the cookware and the induction unit are both part of the cooking system, and that a proper pan needs to be matched with the induction cooking unit (AKA: "hob").

I set it up for oatmeal, turned the hob on high by repeatedly stabbing my finger at the plastic picture of a button on the control panel. I must say, that the experience of controlling a gas stove and the experience of controlling this thing are quite different. I vastly prefer a nice smooth turning gas knob. The water boiled fairly quickly, and the time required was not so terribly different from my commercial gas stove. Considering the power levels of the two (commercial gas burner versus a cheap induction birner), it was a very pleasant surprise.

Once the water got to ab boil, I put in the raisins and oatmeal as is my usual method, let it come back to a boil and turned the power down to low (by repeatedly stabbing my finger at the plastic picture of a button on the control panel until I got to 'Low'). Then I set the timer for 10 minutes, and thought about all the times that I have done exactly this thing, and forgot completely about cooking because of a friend dropping by, or some intense interest in some topic I found on the Internet, or else I drove to the store for some galvanized washers, only to come back to a smoke-filled house, ruined oatmeal and a wrecked cooking pot, with the gas fire happily supplying heat to the catastrophe. In short, typical bachelor behavior.

In fact, I completely forgot that I was even cooking my first meal on the induction cooker for almost 45 minutes. So I rushed into the kitchen in typical bachelor fashion, ripped the top off of the pot, looked in and found perfectly cooked oatmeal, patiently waiting for me, on 'warm'. The oatmeal was warm, and the handles of the pot were cold.

I think I could get used to this.

I did some tests to see how the heating pattern looked, by heating up water and photographing the pattern made by the bubbles.



An oval omlet pan that happened to be magnetic



A 12" induction skilet showing localized heating



A 10" good quality cast iron skillet showing poor heat dispersion



An inexpensive Ikea pot with very even heating

I checked the CO2 readings and they were where they had been before the cooking started.

So, I appreciate the fact that the handles of the pots stay cool, the timer feature is great, heat level change is every bit as rapid as I had hoped, the kitchen stays cool, and no CO2 increase.

More to follow...

-AC
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Old 04-05-13, 07:07 PM   #5
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Strictly from its "ability to cook" induction brings electric cooking up to par with gas(full range heating wise). My brother is a professional chef and wouldn't cook on a non inductive cooktop for anything. I think the full cook top units are still being marketed to the "foodies" who are willing to pay for induction and not the energy conscious where the one/two burner units are aiming. Unless the price comes down a lot or I snag a bargain one I will opt for a smaller counter top model. I cook a lot of one, two pot meals anyway. Less dishes to wash. Energy saved in cooking can come from what and how you cook as much as on what you cook it. My brother can cook for hours and use a dozen pans to just fill one plate(and I won't say its not delicious) but I can cook several meals worth of something in a single stock pot which is fine for me. If it wasn't for a half dozen family meals a year I doubt I would even really need a full range.
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Old 04-05-13, 09:56 PM   #6
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Quote:
Originally Posted by Drake View Post
Strictly from its "ability to cook" induction brings electric cooking up to par with gas...
Good feedback Drake.

Yeah, even in the brief time I have tried induction cooking, I'm pleased with how many of the advantages of gas are available with induction. But I did hit one snag last night, I wanted to include a fresh chili pepper in a meal I was preparing, and I wanted to roast the chili until the outsides were blackened... couldn't figure a way do it on the induction cook top...


...so I fired up a gas burner for that operation. I guess they each have their place. My girlfriend suggested that I could roast the chili peppers with a propane torch. Wow, another use for propane... you can actually use the stuff in torches!

I agree with you that the full size induction ranges are pretty expensive, and for me, they just take up too much space. But these little counter-top units have a lot of advantages per buck and they occupy minimum real estate.

I'd be interested to know, what type of cook top unit you're using? The Aroma model I have pictured above, was good enough to convince me to dive deeper into the technology, but the power increments were a bit too far apart for my liking.

-AC
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Old 04-06-13, 10:36 AM   #7
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Propane torch ws my first thought before your significant other beat me to it(I figured you know how to use one with all the soldiering you do- what about MAPS, lol. May have to scrounge up an old single unit camp burner for those things one can't do without gas). Currently we are still using the natural gas range we bought when we rebuilt our first house 28 yrs ago. Everything I am researching is for the retirement home life change that I will be breaking ground on next spring. We will be going rural from metro so all energy options won't be there. I favor the no combustion advantages of electric. It will be interesting to see if the lower price point of countertop units helps induction to become more popular by breaking that high price ceiling. Cooking with alum cookware may not be a good thing anyway(though I dearly love my revere wear as well). I was talking to a knowledgable appliance seller and he was tell my that some future manufacturers are working to expand useable cookware options.
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Old 04-06-13, 04:56 PM   #8
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Default Induction + Knob

The finger stabbing at a plastic picture of a button thing was so dissatisfying, that I looked around to see what kind of induction unit was available with a more pleasing interface (AKA: "knob").

I discovered that there were an abundance of induction units with a knob, but almost all of them fall into the "commercial" classification, which means that the number of manufacturers is pretty limited, but the price is not limited. $1000 per induction hob seems to be the going rate.

But incessant hunting revealed another classification, which is "disposable commercial". As was explained to me by an on-line salesman, means that this unit is an import (they all are, thank you Uncle Sam) and that I shouldn't expect the unit to be able to stand up to regular use (8 hours per day, 7 days per week) for more than two years... then if it breaks, throw it away. Well, I whipped out my EcoRenovator-style calculator and determined that meant 5,824 hours. To be very generous, in an average week, I might use one for 1 hour per day (they do cook pretty fast), so I might expect one of these units to crap out after 16 years.

I think that 16 years would be enough time to give one of these things a fair test.

So, I went for it and got one of these:


It cost about $130, not including shipping.

An impressive list of features, 1800 watts (really about 1500w), 15 levels of power (from an effective 400w to 1500 watts in steps), 32 levels of heat (140F to 460F in 10 degree increments). A timer from 5 to 120 minutes in 5 min increments. But best of all, a genuine knob that is used for adjustment of power and temperature. Time settings are still adjusted with a plastic picture of a button, but that's a less frequent operation, so not so vexing.

Oh, and did I say it was noisy?

More later...

-AC
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Old 04-08-13, 09:57 AM   #9
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I used the Avantco cooker yesterday to cook up a mess of beans.

When I hit high power to bring the water up to boil quickly, the noise from the cooker was only something a mad scientist could love, and a Chinese mad scientist at that. I had to go in the other room to find peace.

But when the water reached boiling temp, and I turned the power down to an ongoing cooking level, the sound became quite tolerable.

I am hearing how the unit maintains temperature, as there are a series or 'ramping-up' sounds and then a 'click' (relay) and a time interval and repeat, etc. It sounds less like a square wave, and more like a saw-tooth wave.

So, later today, I'll have to look at the cooker's innards to see if there is any way to improve things. I think that for sure, a relay-ectomy will be followed with a Solid State Relay replacement. There may also be ways to reduce the noise.

I did talk to one of my close friends who told me, for the first time, that he had been using induction cooking since 1985 and wouldn't use anything else.

He is not having the problem with noise. He just commented on the sound of cooling fans in his induction range... Hmmmmm... I should be so lucky.

I suppose that in an active commercial kitchen, with all the pandemonium of multiple meals being prepared, and insane expectations going on, or in a war zone, with bullets flying and mortars blasting, the raspy, buzzy humming of my cooker wouldn't be so noticeable. Maybe I should count my blessings.

But back to the beans, I was really busy with other tasks as I was cooking, and decided to try cooking at a temp that was just below a simmer, since now I can do that. The thought was that stirring wouldn't be so critical then. I used quite a few fire-roasted (thank you, natural gas) Poblano, Anaheim and Jalapeño peppers in the preparation as well as a whole head of finely chopped garlic chunks sautéed to a light coffee color. All went into the pot, along with salt and some black pepper. Then sub-simmered for about an hour and a half.

The results were much better than I had expected. Not only was there almost no need of stirring, but many of the subtle flavor harmonics that can be lost from boiling, were still there.

Finally, I added some crushed tomatoes and green peppers and cilantro and lime juice, just after I cut the heat. Then I let it meld for about 10 minutes.

Amazing flavor.

Buzz on, little induction buddy, buzz on...

-AC
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Old 04-08-13, 04:52 PM   #10
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Great, do you have a link to the unit you bought?
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