How much does it cost to make a tankful of hot water?

Question

Electricity costs about $0.10 per kilowatt-hour (which means, 1000 W for 1 hour: 3,600,000 Joules!). How much does it cost to make a tankful of hot water?

Answer 1

Do you want the answer in money or human lives?

Answer 2

How large is the tank/how much water is there and what is the starting temperature of the water?

Answer 3

It takes one BTU to raise 1 cc of water 1 degree.  Do the math.

Answer 4

Good question

specific heat 4.186 kJ/kgC

"40 gallon water heater contains 160 Kg of water. The water coming from the water company is at 10 C"

Assuming you are heating it to 80C

4.2 kJ/kgC x 160 kg x 70C = 47040 kJ or 47 MJ

47 MJ  is 47 MW-sec

47 MW-sec x 1hr/3600s = 13 kW-hr

13 kw-hr x $0.10/kw-hr = $1.30

plus losses due to poor thermal insulation.

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