Electricity Saving Tips For Homes And Offices

Cooktop Comparison: Gas, Electric and Induction

By on January 25, 2014

Recently while interacting with a Bijli Bachao reader, we came across a question: which cooktop should I buy Gas or Induction? And this made us realize: Hey! We didn’t think about it! Cooking typically is a small component of the whole energy requirement in a house (especially in most middle and upper class urban homes), which some people typically ignore. Although rising LPG/PNG costs does cause a furore but rarely do we compare it with other form of energy: electricity. But with increasing popularity of Induction cook-top one has to really compare how different types of cook-top stack up against each other. Truly speaking, we did not find glaring benefit of one over other, so we just present facts in this article.

Gas Burner

Types of cooktops available in market

There are 3 types of cook-tops available in market: Gas, Electric and Induction. This is how they are different:

  1. Gas: This type of cooktop has a burner on top and uses gas (LPG or PNG) to burn a flame that is used to cook food.


  2. Electric: This type of cook-top has a coil that heats up due to resistance when current passes through it. As its name, it uses electricity to generate heat and cook food.


  3. Induction: Although this type of cook-top uses electricity but it uses magnetic property of steel to directly heat the cooking vessel. Unlike other cooking methods it does not use flames or red-hot element to cook. Thus it is considered more energy efficient. Also it only heats the vessel in contact thus reduces possibility of injury.

Efficiencies of various cooktops

US Department of energy did some boiling water tests to come up with efficiency of various cook-tops (Source: US DOE) and below was the results of the same:

Gas

Electric

Induction

Efficiency

40%

74%

84%

The efficiency mentioned above is based on the heat transferred to the pan kept on top of it. Please note that the efficiency also depends on the size of pan used compared to the size of flame/heating surface. The numbers above are based on ideal setup.

Comparing costs of sources

Looking at the numbers above one cannot decide which is better economically as one has to also factor in the costs of various sources. So we decided to compare apples to apples. There are 3 types of sources that we commonly get: LPG Cylinders, Piped Natural Gas and Electricity. Now how do these 3 compare:

Let’s take an example that we want to boil 10 ltrs of water (at 25 degrees). So the energy required for the same is:

10000 x 4.2 x 75 = 3150000 Joules.

Now this is how various sources compare:

LPG Stove

PNG Stove

Induction Cooktop

Electric Coil Cooktop

Unit Definition

1 Cylinder (14.2 kgs LPG)

1 SCM

1 kWH

1 kWH

Energy (in Joules) per unit

654620000

41868000

3600000

3600000

Energy (in Joules) per unit factoring efficiency

261848000

16747200

3024000

2664000

Units Required to heat 10 lts of water.

0.012

0.188

1.042

1.182

Cost per Unit (in Rs)

Rs 423 (Subsidized),

Rs 900 (Un-Subsidized)

Rs 23

Rs 5

Rs 5

Cost of heating 10 lts water (in Rs)

Rs 5.09 (Subsidized),

Rs 10.8 (Un-Subsidized)

Rs 4.33

Rs 5.21

Rs 5.91

The above table shows that though efficiency of an induction cook-top is double than that of a gas cook stove, the cost of using it may not be proportional. The final values may vary based on the cost of various sources available to you as price of LPG, PNG or electricity may differ.

Assumptions and Inputs for the data above:

  1. Joules per unit of LPG is taken from Wikipedia source: link.
  2. Joules per unit of PNG is taken from Wikipedia source: link.
  3. Joules per unit of electricity is taken from Wikipedia source: link.
  4. Rate of LPG cylinder is assumed to be the rate of a subsidized LPG cylinder available in Mumbai. It can vary for different cities.
  5. Rate of PNG per unit is taken at average rate of PNG unit in Mumbai. Please note PNG tariffs are slab based. If your consumption is more, rate will be higher.
  6. Electricity rate per unit is approximate average last slab rate across the country. You can check your average rate per unit using our calculator: Online Electricity Bill Calculator – For all states in India.
  7. The efficiencies may vary a little based on the usage.

Pros and Cons of various cook-tops

For Gas Stoves:

  • Pros:
  1. Gas stoves provide better cooking control. One does not have to worry too much about position and size of the utensil kept on it. Though it can impact efficiency.
  2. One does not have to depend on power cuts for cooking.
  3. Good for cooking most Indian food like chapatti, etc.
  4. No specific requirement for utensil type.
  • Cons:
  1. Inflammable and thus dangerous. Can cause burns.
  2. Heats up the surroundings as well. Can increase the cooling bills if the environment is air conditioned.
  3. Ceiling Fans cannot be used along with it.
  4. Flames do produce CO2.

For Electric Coil Cook-tops:

  • Pros:
  1. Not inflammable thus creates a little safer environment.
  2. More energy efficient than gas stoves and can be economical than gas stoves if gas is not available at subsidized rates.
  3. Not as good as a gas stove for cooking food like chapatti but still can be used.
  4. Releases less heat to the surrounding and ceiling fans can be used along with it.
  • Cons:
  1. Can cause burns when touched.
  2. Takes time to heat up.
  3. Can only be used with flat surface utensils.
  4. Inadequate power supply can stop cooking.

 

For Induction Cook-tops: 

  • Pros:
  1. Induction cook-tops heat faster and distribute heat more evenly.
  2. They are completely safe as they heat only when a steel or iron element comes in contact.
  3. They are easier to clean.
  4. Efficient in terms of energy use.
  5. Come with programmable temperature controls.
  6. No heat wasted as it cools quickly as one shuts it down.
  • Cons:
  1. Can only be used with steel or iron utensils. Thus the kitchen has to be adjusted accordingly.
  2. They are generally expensive than regular cook-tops.
  3. Can be used only with flat surface utensils.
  4. Inadequate power supply can stop cooking.
  5. Will not work at all for some Indian food like chapatti.
  6. Some people observe that the heating is localized and mostly happens at the center of the utensil. This makes it important to put the right sized utensil on a induction cook-top and over sized ones should not be used.

Primary and Secondary Sources of Energy

On a side note we would also like to add that Gas is a primary source of energy i.e. it is directly used in the form it is available from environment. Whereas Electricity is a secondary source of energy i.e. either coal or gas is used to generate electricity. There are transmission losses and generation losses of energy with electricity. So by the time electricity reaches your home, a lot of energy is already lost. So if we factor these losses along with efficiency, both sources work out the same and it is a personal preference or economic value that should drive the decision.

References

http://www.aceee.org/consumer/cooking

http://www.nytimes.com/2008/01/02/dining/02curi.html?_r=0

http://www1.eere.energy.gov/buildings/appliance_standards/residential/pdfs/cookgtsd.pdf

Have question, doubt or comment? Leave a message (please submit once as the comments take time to appear online)

There Are 21 Comments

  1. Niraj says:

    Nice article..
    According to me, In country like India the electricity is not reliable option. So for food we cannot depend on that. However, we have option like Gas stove burner. As limitation on fuel, Gas also has to be conserved. Its savings must be our motto.
    I have 2 queries :
    1. As per manufacturing end they are claiming 68% efficiency for Gas Stove burner.(http://indane.co.in/stove.php) Why 40% considered??
    2. What are the loss in this heating process?? so that we can resolve that increase efficiency.Like one can use Cu bottom utensils to capture more heat they are more popular in these days…likewise any solution we can found

    • Abhishek Jain says:

      Hello Mr Niraj,

      Here is my response:

      1) Efficiency of a standard stove is considered. Technologies are improving to increase efficiency (and will improve further). However even with 40% efficiency gas comes out to be cheaper.

      2) In a standard gas stove, there is heat loss to the environment when the fire burns. A flat bottom container put on top of the stove can improve efficiency. Other utensils that are round bottom will have lower efficiency. In case of induction, there is much less energy loss as most of the energy is transferred to the utensil only. Neither the rest of the induction surface, nor the air around it gets heated up.

      • Niraj says:

        Absolutely right…
        Do you have more article/research on this topic?? (Reduce loss or improve efficiency of Gas stove burner).

        • Abhishek Jain says:

          You can check http://www.bijlibachao.com/general-tips/save-lpg-png-used-by-cook-stoves-gas-burner.html , although we still have to cover a lot on Gas. However PCRA website has some good tips.

  2. Arend Wolbers says:

    Thank you for recalculating the expense for heating 10 lts water, so its still cheaper to use gas.

  3. Arend Wolbers says:

    Gould you please recalculate with calorific value of the gas 35,17 MJ for me

  4. Arend Wolbers says:

    At the end you give a story about “Primary and Secondary Sources of Energy” Ok, but without that and the cost price of the induction cooker or gas cooker, if you just count the energy used by cooking 10 lts of water and compare gas to induction use by a electricity price of € 0,0767 Kwh and a Gas price of € 0,3418 Cubic meter what kind of money thus it cost to use gas or induction, or witch is cheaper gas or induction.
    I try to reduce my gas and electricity bill and will buy a induction cooker + cookery ware, the money I spend on a induction cooker + cookery ware is not important for me, but the gas or electricity use is.

    • Abhishek Jain says:

      Hi Arend,

      A lot depends on the calorific value of the gas delivered in your house. The calculation about is assuming calorific value of 41.86 MJ/m3. Typically the range is between 37.5 and 43. Assuming the calorific value taken above is correct, you would spend about € 0,0643 for boiling 10 lts water using gas. Whereas if you use induction, then for the same job, you would spend about € 0,0799. So induction will be costlier than gas. Even with calorific value as low as 37.5, the cost of induction will be more than using gas. So it is more economical for you to use gas.

      Hope this helps

      Regards,
      Abhishek

  5. srinath says:

    the time used by using induction oven is far less than other conventional method will this not effect consumption of source

    • Abhishek Jain says:

      Well time is of lesser relevance. If you need “x” amount of energy to cook some food, induction will take x/0.84 amount of energy, whereas gas will take x/0.4 amount of energy. But that is total energy. Time will depend on the rate at which the energy is provided. If you have a 4 kW induction then x/0.84 will be given faster, but if you take 2 kW induction, time taken will be more. But in both the cases, energy used will be x/0.84 which is required to do the job.

  6. Anna Philip says:

    I am daily using induction cooktop for making chappathi using an induction friendly flat Prestige thava. One has to continuously adjust temperature while cooking. I make dosa also on the same thava.

    • Vishwas says:

      I second that. Majority of the daily Indian cooking can be done on Induction stove. I think your study doesn’t reveal full picture. You have compared boiling 10 liters of water. How about everyday cooking only? Like boiling milk, tea, sambar,using tava to make chapati, dosa, bread toast, etc etc.Since the efficiency of induction top is high, time required is less for heating up the vessel and hence the food.So induction top should cost less money compared to gas stove.

  7. Arch says:

    Hi Abhishek,
    Do you have a comparison/recommendation among the currently available induction stoves? Thank you!

  8. Victor Larco says:

    Good morning dear Abhishek, thank you very much for your help.

    Best Regards.

  9. Victor Larco says:

    Good morning dear Abhishek, I am from Ecuador and I am interested about the effciency comparative chart, you put this link about the source of 84% efficiency in the induction cooktops; http://www1.eere.energy.gov/buildings/appliance_standards/residential/pdfs/cookgtsd.pdf
    The problem is that I cannot get the file from that page, could you please send me the cookgtsd.pdf file to my email please?

    Thanks.

    Best Regards

    • Abhishek Jain says:

      Hi Victor,

      You can look at these links as they might be helpful:

      http://fire.nist.gov/bfrlpubs/build99/PDF/b99015.pdf

      http://www.epa.gov/Region09/islands/conf09/Kelly-Cutchin.pdf

      Hope this helps.

      Regards,
      Abhishek

  10. chandni says:

    Can induction cook tops be used on an inverter when there is power cut off?

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