Wind turbines with horizontal axis more popular than those designs with vertical axis. This choice is done for a reason. The horizontal axis design is more structurally and seismically ragged
The cycloidal propeller StECon works as well horizontal as vertical, because it truns completly under water. The first project StEwaKorad concludes a vertical construction with a gaer outside the water. Now we discuss for a gear filled with water for grease.
The StECon will run also in the wind, but we are looking first for an application in water.
In comparison to an Darrieus-Propeller the blades of the StECon turn arround their own axis and therefore the gear is necessary.
If you are interested have look at www.stecon.xyz and let me know more questions.