How energy efficient are induction stoves compared to gas? Your questions answered

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Recently, we wrote about researchers ditching their gas stoves after measuring the high levels of dangerous indoor air pollution they produce.

Some scientists and chefs, concerned about the health and environmental impacts of gas stoves, are switching to electromagnetic induction stoves or even portable induction burners and touting some additional benefits.

These stories prompted some questions from readers. How does the energy efficiency of induction actually compare to gas? Do gas fireplaces or furnaces cause indoor air pollution too? Or propane stoves? Are newer gas stoves less polluting? Are induction stoves safe for those with pacemakers?

Here are the answers to some of those questions.

Donald M. wrote: "What is the actual energy use comparison, when for example bringing a pot of water to a boil between a new natural gas burner and an induction stove top?... Also how does that compare in dollars and cents?"

Energy Star is the energy efficiency certification and labelling program supported jointly by the U.S. Environmental Protection Agency and the U.S. Department of Energy that aims to promote the adoption of energy-efficient products and practices. A similar system exists in Canada in partnership with the federal government.

It says induction cooking tops transfer energy with approximately 85 per cent efficiency, compared to about 32 per cent for gas stoves (which transfer much of their heat to the surrounding room, not the pot and water you're boiling). The per unit efficiency for induction stoves is five to 10 per cent higher than for conventional electric resistance stoves and induction is three times more efficient than gas. EnergyStar says that if all cooking tops sold in the U.S. in 2021 used induction technology, the energy cost savings would exceed $125 million US and the energy savings would exceed 1,000 gigawatt hours. That's roughly equivalent to the amount of electric power consumed annually by 93,000 U.S. households.

Dave R. of Innisfil, Ont., asked if the nitrogen oxides — contaminants linked to negative health impacts such as asthma — are naturally found in small amounts in the gas or come from burning it.

The answer is that they're produced during burning, when nitrogen and oxygen in the air react with each other due to the heat from the burning gas. 

Meanwhile, carbon monoxide is produced by incomplete combustion of the gas.

Eric Lebel, research scientist at PSE Healthy Energy in California and lead author of a recent study on pollution from gas stoves, said his team is starting to look at natural gas composition in different cities, including Toronto and Vancouver.

While it's mostly methane, he said, "there could be other pollutants in the gas as well." Those could include volatile organic compounds and sulphur compounds used to make natural gas — which is normally odourless — smelly and therefore detectable when there are leaks.

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