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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 H2OHeat 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).
Eseman
Jonny69
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).