Abstract: The present invention relates to a process for producing biomethane suitable for supplying a natural gas network that incorporates a process for providing heat for heating the biogas production step, the process comprising at least steps of producing biogas by anaerobic fermentation of organic matter, of pretreating and compressing the biogas and also of permeation in order to obtain, after a first separation by permeation, a stream of biomethane and a gaseous permeate having a reduced methane content; the process additionally provides the heat necessary for the anaerobic fermentation step via a boiler using the retentate from a second permeation step fed by the permeate from the first separation.