Gas extractor comprising: - an assembly, referred to as a fan-motor assembly, comprising: ∘ an extraction fan comprising a rotary shaft, referred to as fan shaft, and a number of blades, ∘ a motor coupled with the extraction fan to be able to rotate same, - a wind turbine coupled with the fan-motor assembly to be able to rotate same, the wind turbine comprising a rotary shaft, referred to as wind turbine shaft, wherein: - the fan shaft and the wind turbine shaft are parallel with one another and disposed along the same direction, the wind turbine being a vertical-axis wind turbine, - a first coupling device, inserted between said wind turbine and said motor, said motor being disposed between the extraction fan and the wind turbine, - said first coupling device being suitable for having: ∘ a first status, referred to as coupling status, wherein the wind turbine is coupled with the fan-motor assembly to be able to rotate same, ∘ a second status, referred to as uncoupling status, wherein said fan-motor assembly does not rotate the wind turbine, characterised in that: - the gas extractor further comprises a second coupling device, inserted between the extraction fan and the motor, so as to enable a greater rotational speed of the extraction fan than that of the motor, the motor and the wind turbine then not impeding the free rotation of the blades of the extraction fan. - an assembly, referred to as a fan-motor assembly, comprising: ∘ an extraction fan comprising a rotary shaft, referred to as fan shaft, and a number of blades, ∘ a motor coupled with the extraction fan to be able to rotate same, ∘ an extraction fan comprising a rotary shaft, referred to as fan shaft, and a number of blades, ∘ a motor coupled with the extraction fan to be able to rotate same, - a wind turbine coupled with the fan-motor assembly to be able to rotate same, the wind turbine comprising a rotary shaft, referred to as wind turbine shaft, wherein: - the fan shaft and the wind turbine shaft are parallel with one another and disposed along the same direction, the wind turbine being a vertical-axis wind turbine, - a first coupling device, inserted between said wind turbine and said motor, said motor being disposed between the extraction fan and the wind turbine, - said first coupling device being suitable for having: ∘ a first status, referred to as coupling status, wherein the wind turbine is coupled with the fan-motor assembly to be able to rotate same, ∘ a second status, referred to as uncoupling status, wherein said fan-motor assembly does not rotate the wind turbine, - the fan shaft and the wind turbine shaft are parallel with one another and disposed along the same direction, the wind turbine being a vertical-axis wind turbine, - a first coupling device, inserted between said wind turbine and said motor, said motor being disposed between the extraction fan and the wind turbine, - said first coupling device being suitable for having: ∘ a first status, referred to as coupling status, wherein the wind turbine is coupled with the fan-motor assembly to be able to rotate same, ∘ a second status, referred to as uncoupling status, wherein said fan-motor assembly does not rotate the wind turbine, ∘ a first status, referred to as coupling status, wherein the wind turbine is coupled with the fan-motor assembly to be able to rotate same, ∘ a second status, referred to as uncoupling status, wherein said fan-motor assembly does not rotate the wind turbine, - the gas extractor further comprises a second coupling device, inserted between the extraction fan and the motor, so as to enable a greater rotational speed of the extraction fan than that of the motor, the motor and the wind turbine then not impeding the free rotation of the blades of the extraction fan.