methanol and propanol

Combustion of Methanol :

CH3-OH + 3/2 O2 => CO2 + 2 H2O

Combustion of Propanol :

C3H7-OH + 9/2 O2 => 3 CO2 + 4 H2O

Since 1 mole of propanol can systhesis 3 mole of carbon dioxide and 4 mole of water , in which the systhesis of CO2 and H2O is an exothermic reaction , combustion of propanol can release more energy than methanol per mole .
Ofcourse , you will need to calculate the " Born Harbor Cycle " in order to find out the acute enthalpy changed per mole during combustion of propanol and methanol .

Finally , it is not always true that more energy released = more efficient . It is , because of the "effcient" is based on at least two critiria :
I) Is it the fuel easy enough to be combusted ?
II) The enthalpy change per unit mass of fuel

In (I) , many long chain-organic compound can release even more energy during combustion than propanol , but they're not so easy to be burnt , so they're not effcient .
In (II) , you will need to calculate [energy released/mass] of the fuel , since every compound have different Molar mass , 1 mole of each compound has different mass than the others .