Methanation system for the conversion of carbonaceous material into methane, comprising: - a gasifier for gasifying carbonaceous material into syngas, said gasifier being at least partially steam fed and comprising: - an internal volume comprising an upper section, a middle section and a lower section, and optionally a first connecting section, connecting said upper section and said middle section and optionally a second connecting section, connecting said middle section and said lower section, wherein said upper section, middle section and lower section are arranged along the longitudinal direction of said gasifier, with the upper section placed on top of the middle section which is placed on top of the lower section; - one or more carbonaceous material inlets configured to receive a carbonaceous material feed and fluidly connected to the internal volume; - a bed material comprising catalytic particles, inside the middle section and/or lower section and connected to at least one gas inlet to fluidize the bed material; - a gas outlet, fluidly connected to the upper section of the internal volume; and - at least one plasma system configured inside the upper section so that gas that leaves the gasifier via the gas outlet passes through a zone heated by said at least one plasma system; - a first cooling unit (18, 29), comprising a hot gas inlet and a cold gas outlet, wherein said hot gas inlet is fluidly connected to the gas outlet of said gasifier; - a methanation unit, suitable to produce crude methane from syngas, comprising a syngas inlet and a crude methane outlet, wherein said syngas inlet is fluidly connected to said cold gas outlet of the first cooling unit; - a second cooling unit (24,28), comprising a hot methane inlet and a cold methane outlet, wherein said hot methane inlet is fluidly connected to said crude methane outlet of the methanation unit; wherein said first cooling unit and said second cooling unit independently comprise an economizer, an evaporator and/or a super-heater for steam production for the gasifier. - a gasifier for gasifying carbonaceous material into syngas, said gasifier being at least partially steam fed and comprising: - an internal volume comprising an upper section, a middle section and a lower section, and optionally a first connecting section, connecting said upper section and said middle section and optionally a second connecting section, connecting said middle section and said lower section, wherein said upper section, middle section and lower section are arranged along the longitudinal direction of said gasifier, with the upper section placed on top of the middle section which is placed on top of the lower section; - one or more carbonaceous material inlets configured to receive a carbonaceous material feed and fluidly connected to the internal volume; - a bed material comprising catalytic particles, inside the middle section and/or lower section and connected to at least one gas inlet to fluidize the bed material; - a gas outlet, fluidly connected to the upper section of the internal volume; and - at least one plasma system configured inside the upper section so that gas that leaves the gasifier via the gas outlet passes through a zone heated by said at least one plasma system; - an internal volume comprising an upper section, a middle section and a lower section, and optionally a first connecting section, connecting said upper section and said middle section and optionally a second connecting section, connecting said middle section and said lower section, wherein said upper section, middle section and lower section are arranged along the longitudinal direction of said gasifier, with the upper section placed on top of the middle section which is placed on top of the lower section; - one or more carbonaceous material inlets configured to receive a carbonaceous material feed and fluidly connected to the internal volume; - a bed material comprising catalytic particles, inside the middle section and/or lower section and connected to at least one gas inlet to fluidize the bed material; - a gas outlet, fluidly connected to the upper section of the internal volume; and - at least one plasma system configured inside the upper section so that gas that leaves the gasifier via the gas outlet passes through a zone heated by said at least one plasma system; - a first cooling unit (18, 29), comprising a hot gas inlet and a cold gas outlet, wherein said hot gas inlet is fluidly connected to the gas outlet of said gasifier; - a methanation unit, suitable to produce crude methane from syngas, comprising a syngas inlet and a crude methane outlet, wherein said syngas inlet is fluidly connected to said cold gas outlet of the first cooling unit; - a second cooling unit (24,28), comprising a hot methane inlet and a cold methane outlet, wherein said hot methane inlet is fluidly connected to said crude methane outlet of the methanation unit;