Which is more energy efficient - boiling water using an electric kettle, a kettle on a gas hob or a

Which is more energy efficient - boiling water using an electric kettle, a kettle on a gas hob or a microwave oven?

• 'One accurate measurement is worth a thousand expert opinions’ Grace Murray Hopper Using a ‘plug in’ power meter I have measured the efficiency of boiling 1 litre of water in a two types of kettle (stainless steel and plastic) and a microwave. I have also measured the gas used to boil a pan of water on my gas hob. The sums are the sort you learn for GCSE science. Kettles; 65% Microwave: 30% Gas kettle: 25% You have to remember that gas is about a third the cost of electricity per kWh (or Unit or Joule) and also has a third of the CO2 emissions. In this test gas has a small advantage, which may be improved with a lighter more efficient kettle. The electric kettle has the advantage that it turns itself off automatically. While the microwave was inefficient bringing water to the boil, it was more efficient when only warming it to 50 degrees C at 45%.

  Andy Brown, Cambridge UK

• If you take into account the efficiency of getting the power to you from source, which you should, John Ackers has it exactly right - as gas is a primary energy source it is definitely the most efficient.

  Klina Jordan, Oxford UK

• In my test at home, the microwave required 1650W input for 120 seconds, but the electric kettle required 2000W for 145 seconds to produce boiling water for a cup of tea. In my case the electric kettle is less efficient for making a single cup (which is my primary use). This is because the kettle requires a minimum fill of 500ml of water and I only need around 350ml.

  Richard Hertz, Upton USA

• Kettle on top of wood burner if burner on anyway. Another tip with electrics, don't keep re boiling the kettle if it goes off the boil. You won't have to let your tea cool, you won't burn the tea/coffee, it'll still brew and taste lush and be at perfect temp. Peace. X

  Neal, Hereford, England