Assume that the water for your shower is heated by natural gas combustion, and that the efficiency of the water heater is 1.0, that is that the transfer of energy in the form of heat from the natural gas combustion process to the water is complete, without any losses. How much natural gas did your shower require? How much CO2 was generated as a consequence of your shower?

(Reference: I took 18 gallons of water in 7.20 minutes and the temperature was 30 degrees Celsius, which is also an estimation of a daily shower i take a day).