1. In 2021, worldwide combustion of methane (CH4), (natural gas), provided about 40,375 TWh of energy, while petroleum provided 51,170 TWh (ourworlddata.org). Methane has an energy content of 39X103 kJ/m3 (at STP) and the one from petroleum is about 43x103 kJ/kg. b. What was the ratio of kg of CO2 emitted per unit of energy (kJ) for petroleum vs. for methane? a. Find the carbon intensity of methane (gC/kJ) based on its higher heating value (HHV) and based on the lower heating value (LHV). b. Explain the difference between these two values and the calculated kg of CO2 emitted per unit of energy from methane in problem 1b (for this you need to standarise units)..