Biofuel is a renewable energy source and has been proven to be a suitable and useful alternative to traditional fossil fuels. Different processes can produce different types of biofuel. Furthermore, different comparison strategies have been implemented for the various criteria. The current article compares two different processes for producing bio-SNG and investigates the comparison criteria to find a method for comparing the biofuel processes. The processes used in the comparison are gasification and anaerobic digestion. Rice straw is used as a feedstock in each process, to evaluate the applied processes, and to compare the performance of those processes applied on the same feedstock. The Aspen-plus software is used to simulate the processes and the input data were obtained from the literature. Two cases are studied and for each case, energy and exergy balances are calculated to evaluate the processes. The energy efficiency is then calculated based on the Lower heat value (LHV) and the Higher heat value (HHV). The results show that the energy efficiency based on HHV and exergy efficiency are approved methods to evaluate the process when the processes produce bio-methane.