Induction vs gas cooking calculator

Data sources and assumptions

The energy usage for a gas range is based on the average amount of natural gas used for cooking in each U.S. state as reported in the Residential Energy Consumption Survey (RECS) by the U.S. Energy Information Administration.

According to the RECS, most households use about 20 ccf of natural gas per year for cooking, which translates to 2,076,000 British thermal units (Btu) of energy.

To generate an equivalent amount of Btus, an induction cooktop with an efficiency of about 70% will consume about 2,965,714 Btus of electrical energy. One kWh of electricity translates to 3,412 Btus of heat energy, which means that an induction cooktop will consume about 869 kWh to generate the same amount of cooking heat as our gas stove.

Different studies list different energy efficiencies for gas, conventional electric, and induction cooktops, with some showing that induction cooktops can be better than 80% efficient.

What does energy efficiency mean exactly? A cooktop that is 100% efficient will transfer all the heat energy from the fuel used into the cooking vessel. Of course, no cooktop is 100% efficient. If you have a gas cooktop, you’ll know that a lot of heat is lost to the air. Much of the energy from the gas flame flows around the cooking vessel and never has a chance to heat the cooking vessel.

This is also true with a conventional electric cooktop, which uses electric resistance to heat a coil that in turns heats your cooking pot. While generally more efficient than a gas cooktop - the study I cite below shows an average efficiency of 39% - electric coils still have the problem that some of the heat goes into the air.

However, an important point is that cooking efficiency depends greatly on the cooking vessel itself. With a gas cooktop or electric coil, a narrow pot paired with a large flame will result in a lot of heat lost to the air. However, if your pot is more compatible with the heating surface, energy efficiency will improve significantly. In the study, the maximum efficiency for a gas cooktop improved to 35.5% with a compatible pot.

Induction cooking is more efficient because the cooktop uses a magnetic field to heat the pot directly, avoiding the type of losses that coil and gas cooktops have. Efficiency loss happens in the induction coil, and is also affected by a property of the cooking vessel called magnetic permeability. In general, induction cooktops experience a small amount of efficiency loss due to poorly compatible cookware than gas and electric coil cooktops do.

For further details, refer to the article “Heat transfer characteristics and cooking efficiency of different sauce pans on various cooktops” by Karunanithy and Shafer (University of Wisconsin-Stout) ¹.

Why switch from gas to induction cooking?

One big reason to switch from a gas to an induction cooktop is that induction provides a better cooking experience: it has instant response like gas, but is more powerful and doesn’t have an open flame, making it safer. A typical home induction cooktop will boil a pot of water in about half the amount of time as a gas cooktop ².

While cooking performance and features like built-in sensors and WiFi connectivity are probably the top considerations for most consumers, lower operating costs and environmental impact are often factors too.

Better indoor air quality is also a clear advantage of induction cooking. Numerous studies have now show that gas cooktops release a wide range of pollutants, including formaldehyde, nitrogen dioxide (NO_₂), fine particulates (PM2.5) and carbon monoxide into the air. Even if the pollution levels are not high enough to cause acute problems, long term low level exposure to these pollutants have been linked with chronic health conditions, including childhood asthma.

How energy usage and operating cost are calculated

In its Residential Consumption Survey, the U.S. Energy Information Administration reports on the average amount of natural gas used by households by end-use, including cooking. The calculator uses this estimate as the starting point for the energy usage of a gas range, but you can modify this input in the calculator if you know how much you actually use.

According to data from the EPA Greenhouse Gases Equivalencies Calculator ³, one CCF of natural gas produces 11.27 pounds of CO_₂ when burned. That figure is used here to calculate the carbon footprint of a gas range. Note that this carbon footprint calculation doesn’t include leaks in the gas distribution system or in the appliance itself. The leaks from just five big U.S. cities could be close to a million metric tons per year ⁴, so the impact is massive. Given that the global warming potential of methane is about 28 times worse than CO_₂ over a 100 year period, the climate change impact of gas leaks related to residential supply systems could be higher than the impact attributed to the gas burned by the gas range itself.

To calculate the energy usage, operating cost, and carbon footprint of an induction stove, we start by determining the heat energy of the fuel used by the gas range. One CCF of natural gas produces 103,600 Btus of energy when burned. Meanwhile, 1 kilowatt-hour of electricity is equivalent to 3,412 Btus of heat. An induction cooktop is 70% efficient on average, so 1 kWh of electricity used in induction cooking will generate about 2,388 Btus of useful heat.

So as an example, if a home uses 20 CCF of natural gas per year for cooking, that translates to 2,072,000 Btus of heat. To figure out how much electricity an induction cooktop would consume to generate that same amount of heat, we divide that figure by 2,388 Btus/kWh, which works out to about 869 kWh of electricity.

The national average cost of electricity in the U.S. is about $0.18 per kWh, but this varies significantly by state. The EIA reports on the average cost of electricity by state, which is the figure used in this calculator. However, electricity costs can vary by utility and also time of day if you have a time-of-use plan with your utility. If you know what your actual costs are, you can plug that into the calculator to get a more accurate estimate.

Finally, the carbon footprint of electricity also varies by state according to the mix of generating sources. This is also reported by the EIA and is used by the calculator to provide an estimate of the approximate amount of CO_₂, nitrogen oxides, and sulfur dioxide released by power plants in your state to generate the electricity used by your induction range.

It’s worth emphasizing again that leaks related to residential natural gas distribution can have a big climate impact and is not included in this estimate, so switching to an electric appliance will likely be even better for the environment than the figures estimated by this calculator.

References