Re the answer above, obviously, it's 80,000 calories, not 60,000 and it makes no difference about the starting temperature - it can only be between 0 and 20 degrees, dummy! As for dividing 60,000 calories by 4,200 to get about 15kw, that makes no sense since the answer has to be in Kw hours!
The answer depends on the efficiency and insulation of the 'kettle' but will be around 0.15Kwh in practice. The theory is 80,000 calories times 0.0000013 equals 0.104 Kwh
