Abstract: A power system comprises structures which capture wind and solar energy to drive turbines for generating power. The structures can assume different forms, some intended to operate only from wind power. All in common, however, have lower air intake means which can accept the wind from any direction, air passageways that conduct the air upward through turbines, and venturi-assisted upper air exhaust vents which discharge the air downwind. Structures intended to operate on solar power in addition to wind have generally transparent sun-facing outer surfaces to admit solar radiation into the air passageways, a heat absorbing and transferring means inside the air passageways, and sufficient height that the solar heated air will rise with adequate velocity to operate the turbines. The invention includes an air inlet louver configuration which permits free entry of normal winds, but restricts entry of winds that have excessive force.