Which burner should you use to boil water?

My gas stove

During one year I have recorded following values

• Weight of water boiled on kitchen scales
• Amount of gas used on gas meter
• Time until the kettle whistle goes off

Relationship between amount of water and gas usage

Usage of gas and time to boil water

Gas usage	Time spent

Released energy

For simplicity I consider in this example that natural gas is 100% methane (which is usually only around 85% methane).

In this example I consider following values:

• 1.6 kg of water (~1.6L)
• 0.045 m3 of gas used
• Molar enthalpy of combustion of methane : 890.307 kJ / mol

Calculations:

• Amount of substance of gas : n = (V * ρ) / M = (0.045 * 0.8 * 1000) / 16.043 = 2.243 mols
• Energy released : Q = ∆H * n = 890.307 * 2.243 = 1997.82 kJ
• Energy released per liter : Q / V = 1997.821604 / 1.6 = 1230.185 kJ / dm3

Energy released compared to electric kettle