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. <EOS>