Measurement and quantification of methane emissions from residential gas stoves and tankless water heaters in China

Methane is a short-lived and potent greenhouse gas with a rapid warming effect. Gas stoves and water heaters, which are the most widely used domestic gas appliances (over 250 million in China), emit methane because of incomplete combustion and leakage. This study quantified the methane emissions of these two gas appliances at different ages through field measurements and laboratory tests to assess their impact on the climate. Their methane concentrations typically spiked quickly and decayed rapidly during ignition and extinguishment, but were low and stable during the steady-on state. Tankless water heaters emitted 1.69‰ (95% confidence interval: 1.44‰, 2.01‰) of the natural gas consumed, primarily during the on-pulse phase. More than four-fifths of the methane emissions from gas stoves occurred in the steady-on state, and the emission rates were positively correlated with the age of the gas stoves (r2 = 0.79, p