Dear PF Forum, First of all, I'd like to thanks PF Forum for giving me invaluable answers all this time. Now, I have a "situation" here. My church wants to conserve environment by changing cooking oil into biodiesel from its parishioners I'd like to know how effective this effort is. I have many, many questions regarding biodiesel, car gasoline, hydrocarbon, etc... But in this post, I'd like to know these simple facts first. 1. How much energy is released by reactiing 2 moles CH4 + 5 moles O2 -> 2 moles CO2 + 8 moles H2O. How many joules (or calories equivalent) are released in this process? 2. How many joules/calories are released by this reaction? 2C8H18 + 25O2 -> 16CO2 + 18H2O. All are in moles unit and given the ideal condition where carbon monoxyde are not produced. 3. Is it true that CH4 is considered "cleaner" than C8H18? 4. If that so, why? Is it because for ... 4A. 1824 gr CH4 produces 5016 gr CO2 and 1824 gr C8H18 produces 5632 gr CO2? 4B. Given that I don't know the answers of question 1 and 2. That for 1824 gr CH4 produces more (is it true more?) energies than 1824gr C8H18? 4C. Still that I don't know the answers of question 1 and 2: That for every kg CO2 produced, CH4 releases more (is it true, more?) energies than C8H18? These questions might not have anything to do with biodiesel. But I'd like to study some basic chemistry first. Thanks for any help.