Question: how much energy does it take to make a cup of tea?
Answer: So, the total energy required to heat this cup of tea/coffee is: 4.184 * 250 * 79 = 82,634 joules. In other words, it takes more than 82 kJ to heat a cup of water to boiling point!! We usually only need between 1 and 10 joules to heat blood/hair sufficiently to destroy their proteins.