Stanford scientists measured methane released from gas cooking stoves in 53 California homes. They examined how much methane is leaked each time you turn the knob in that second before the gas lights on fire. They also measured how much unburned methane is released during cooking. And unlike most previous studies, they measured how much methane is released when the stove is off.
In fact, it turned out that's when about 80% of methane emissions from stoves happen, from loose couplings and fittings between the stove and gas pipes."Simply owning a natural gas stove and having natural gas pipes and fittings in your home leads to more emissions over 24 hours than the amount emitted while the burners are on," says Stanford professor of earth sciences Rob Jackson, one of the study's authors.
Lebel's research shows it didn't matter if the stove was old or new or what brand it was — the presence of leaks was consistent. There were 18 brands of stoves and cooktops in the study, and they ranged from three to 30 years old. Stoves using a pilot light instead of an electronic sparker leaked more.
There is probably also some gas leakage past the valves on each burner. I have noticed that if I use the top burners on my 1 year old GE gas range every day, they will light up in less than one second. If I don't use the range for a week or longer, lighting up a top burner takes 2-4 seconds. I don't smell natural gas in the vicinity of the range.