Embodiments of the invention provide a process in which a gas comprising biomethane having a heating value of less than about 925 BTU/cubic foot is introduced to a pipeline system that is connected to at least one source of natural gas having a heating value of at least about 950 BTU/cubic foot. The gas comprising biomethane combines with natural gas in the pipeline system to produce a mixed gas having a heating value below about 925 BTU/cubic foot. An amount of natural gas at least equal to the amount of gas comprising biomethane is withdrawn from the pipeline system for use as a transportation fuel, a fuel intermediate or as a feedstock for producing a fuel. The process can enable fuel credit generation and/or reductions in life cycle greenhouse gas emissions.