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  • Energy used heating or boiling water in a kettle. Assuming no losses. There actually isn't really anywhere for the energy to go in a kettle other than into the water, it's quite efficient.

    Specific heat capacity of water: 4200 J/kg/K

    Lets's say tap water comes out at 15°C. 1 litre water in kettle = 1kg water.

    Heat to 92°C = 323.4 kJ = 0.0898 kWh = 1.52p @16.9p / kWh
    Heat to 100°C = 357 kJ = 0.0992 kWh = 1.68p @16.9p / kWh

    Really not much in it. More of your waste is in the water you heat up and don't use.

    I don't know how much you boil off in the few seconds before it shuts off when it's boiling, but it's not going to be much. Latent heat of evaporation of water: 2250 kJ/kg if you want to weigh it. Or 3 kW kettle for however many seconds (best guess).

  • Heat to 92°C = 323.4 kJ = 0.0898 kWh = 1.52p @16.9p / kWh

    Heat to 100°C = 357 kJ = 0.0992 kWh = 1.68p @16.9p / kWh

    From UK Tea Assoc. https://www.tea.co.uk/tea-faqs

    HOW MANY OF CUPS OF TEA DO THE BRITISH DRINK EACH DAY? A: Approximately 100 million cups daily, which is almost 36 billion per year [Source: ITC].

    1 cup = 0.24 L
    100 million cups = 24 million L = 24 mill kg H2O

    Heat 24 million Kg to 92°C = 24 mill * 323.4 kJ = 7,761,600,000 kJ per day

    Heat 24 million Kg to 100°C = 24 mill * 357 kJ = 8,568,000,000 kJ per day

    Difference would be 806,400,000 kJ = 806.4 GJ saved every day by making tea slightly differently while minimally/not affecting the end product. (Someone review my working pls).

  • Fantastic, thanks for all the research!
    Hard Anodized Aluminum and Titanium were neck and neck due to their quick heating abilities due to ultra thin materials, last night though, I ended up ordering a stainless kettle… partly aesthetic, partly durability.

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