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A Case for Induction Heating

If you have been following the last couple of articles. You would know a thing or two about an Induction cook-stove. If you haven’t, check them out here to know about how it has revolutionized cooking to be more sustainable.

Cooking is science. Where ingredients mix and match to create a great fusion. Although recipes might look similar, they are different since everyone has their own tweaks that make it unique from one another.

A typical off the shelf induction heater with the right pan can easily impart heat twice as better as a conventional burner stove. Then why hasn’t the modern cook-top overtaken the conventional setup in our kitchens? But first, let’s take a quick look at the history.

Looking back:

Induction cook-tops haven’t been around for long but induction heating has.

Industrial induction heating made its debut right after its discovery and stayed well into the 18th century. They have always been around in forging and making iron tough and strong. Because they were easy to implement as larger metal blocks the IH system had to run at a lower frequency. This enabled some pretty neat use cases of Induction heating by using power right off the 50/60Hz mains.

Only recently (as recent as the early 1950s) have semiconductors developed to the extent that they can aid the switching speeds that are appropriate for a household vessel.

Back in 1985 bipolar transistors were being hypothesized to be used as a switch in high voltage Quasi Res. Induction heaters. In fact, in this paper, the authors lament for a more robust switch to withstand commercial use. 35 years later today, things are so much different.

Induction heaters were initially a premium product but only recently the demand and high volumes for the product have brought down the price for an average consumer. In every way, Induction heaters are the way to go for a sustainable electric future. Their higher efficiency (2X than that of a burner) and ability to impart energy without prejudice to the size of the pan (unlike electric stovetops whose efficiency “discriminates” based on the pan to coil coverage) make Induction heaters a viable option for the future.

What makes induction cook-tops a must-have?

Induction heaters are more efficient and higher efficiency means more power is transferred to the food you want to cook. This also cuts down the time you wait for your water/contents to heat up considerably which means your dinner is served faster. Sauteing on such cook-tops are astronomical time savers.

Induction heaters are also great in places with space constraints, either at home or in a commercial setup. At a commercial space, Induction heaters not only save you space in the house but also where the storage of large quantities of fuels outside (not to forget they always pose a hazard).

Induction heaters are a must-have in homes with individuals who run a high risk of asthma attacks or have other breathing difficulties. According to a Stanford Medicine study, the air due to an average meal cooked in medium-sized homes with average ventilation had a considerably higher concentration of pollutants such as nitrogen dioxide — exceeding the standards for air outdoors. They also contained fine particles and organic compounds as by-products.

Another larger problem that we are currently trying to tackle is climate change.

Countries such as The USA are already underway to reduce emissions by half to sustain life for the generations to come. Even with coal-based power plants retiring at a record pace, burning gas is a major source of pollution when compared to burning coal because nearly a third of the gas is burned in homes and commercial buildings. The USA predicts that the energy usage of CO2 emissions will remain near the current level even throughout 2050 if not for an increase.

This means that cutting down on household emission can have a positive effect on emissions that aid global warming.

With all these benefits why haven’t we moved completely to the electric future?

Why not the induction stove?

An induction heater is one appliance that has become affordable with the increase in demand over the last couple of decades. But if we consider most of the common over-the-counter induction heaters today, 90% of the time they contain the same hardware that was patented or invented in the 1990s. Which brings us to the not-so-good side of using induction heaters.

Cooking with induction heaters comes with cons as much as while using any other cook-top.

Searing can be a quick nightmare for users struggling to find the right heat setting for the contents in the pan. If the power is too low, it will take too long and if the heat is a bit too high then food sticks to the pan.

Induction heaters currently available in the markets allow only step increments of a few hundred watts each. And unlike cooking with a traditional cook-top where you can visually understand the heat applied, increments of power might not be intuitive enough.

One well-known pain point with going all-electric induction heating is you have to redo your entire cookware range. Making all the pans and utensils induction compatible is bound to take a toll on your pocket.

In addition, cooking your favourite dish on an induction heater also calls for you to understand where the hot-spots lie on the pan. Some parts of the pan get hotter and faster than the rest of the pan (usually the centre of the pan absorbs more power than the rest). This is especially of concern when you use a stainless steel reinforced pan where the steel element is mostly on the bottom and does not cover the entire base area of the pan.

For a better cooking experience, using multi-ply clad pans is the way to go. All-Clad Pans are made up of alternating Stainless Steel and Al/Cu Sheets. The SS helps absorb energy effectively and the Al/Cu sheets spread it around faster. This reduces temperature hot-spots and spreads heat evenly across the entire pan. They are a great addition if you like to sear or stir fry on your cook-top more often.

But Induction heaters are great investments in the long run and think of it like buying an electric car. The initial investments are huge, but they pay off big time eventually to you, the planet, and the generations to come.

What does the future hold?

Most of today’s over the shelf Induction heaters give a sour experience because manufacturers are trying to cut costs. This makes transitioning into sustainable cooking on Induction heating slower and unattractive. Some predictions for potential innovations in induction heating follow:

  1. A major upgrade to the modern-day induction heater would be the ability to precisely control power. Mimicking the precision that traditional burners provide would be a game-changer especially when you sear or stir fry. It also means that you have the upper hand in determining the heat that goes into the pan based on the contents of the pan and not the other way around.
  2. Safety and temperature controls could be improved to define the temperature profile of the food rather than the pan’s base to which it is stuck. This is also crucial with pans that have a PTFE (Teflon) coating. The coating cannot handle more than 260 Deg C/500F in cookware.
  3. A majority of power loss in induction cooktops is due to these 3 elements — switching device, coil and the pan.
    Around 10–15% of the heating capacity of an induction heater is lost on the switches. Most commercially available Induction Heaters use IGBT’s as switches, which are low-cost but lossy in nature due to their shared characteristics with BJT’s; hence leading to heat loss and bad efficiency.
    Current advancements in the Electronics industry have already paved the way for better switching solutions. GAN and SiC FET’s (Add a suitable link here) are one of the most efficient high-speed switches present today. They would make an ideal candidate for use in household Inductions as they can switch at very high speeds and leverage skin effects on Pans to make the system more efficient. We anticipate seeing these switches being used in commercial induction heaters in the coming decades as the demand for these switches drives the cost down and makes them more affordable.
  4. The other frontier of improvement would be the pans and the coil. A common misconception about induction heaters is that they can only heat pans made with ferromagnetic material (i.e. something that a magnet sticks to). Although this sounds and feels true for the current commercial Induction cook-tops today, technically, an Induction Heater can heat any metal if a suitable coil is used in the cook-top. Non-ferromagnetic metals have lower resistances, which in turn will require coils with lower resistances to heat them effectively. Just the improvements on the coil front — which can be the coil material, thickness, density etc — can result in the efficiency of such a set up to reach as high as 70% with an Aluminum pan. This is close to the efficiency which we see in commercial induction stoves today with stainless steel pans. We touch on this point in our previous articles as well here.
  5. Some other good additional features to have are, coils that change shape to conform to the curvature of different pans, electronics that estimate the amount of heat that actually goes into a pan and compensate for the losses in an open environment through real-time calculation.

Looking forward to innovations in consumer electronics and household appliances is an exciting part of living in the 21st century. It won’t be too long before all of us have smart devices at home capable of cooking your favourite dishes just the way we like them.

Here at Nymble, we are building a kitchen robot to whip up nutritious and fresh meals for everyone and help you put your cooking on autopilot.

To cook or not to cook is your choice. But with Julia eat healthy, always.

If you’d like to take Julia for a trial run and join our early access wait-list, sign up here.

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