<p>In association with a fan, a secondary fan which is mounted coaxial with the fan and with the blades relatively close to the blades of the fan and generator means associated with the secondary fan whereby power can be generated by the rotation of the secondary fan due to the movement of the air being passed through the fan. The secondary fan may have the same or a lesser number of blades as the fan and the pitch of these blade can be such as to provide the required output.</p>
