It has moving parts, just not moving parts in contact with one another. From what I understand the outer segment is flexible and oscillates because of vortex shedding, and a magnetic coupling between the flexible outer segment and the fixed inner one generates power. So the outer segment is mobile, but it never touches the inner segment.

It uses a similar effect to this: https://www.youtube.com/watch?v=ptYrbQGk6DQ

ie vortex shedding. There are moving parts, but the movement is much smaller and more confined.

It does have moving parts, the article says 'no moving parts that come into contact with each other'.

The tower waggles and is made of piezoelectric materials, so the electricity comes from the deformation of the tower.

Edit - I got sideswiped by marketing. The current one is electromagnetic, the future ones are proposed to use piezoelectrics, but they do not have the materials available to do this.

Sounds like a magnetic coupling to the motor rather than gears, not no moving parts at all. Imagine it saves wear-and-tear and is easier to disengage on winds that are too strong.