A major cost of this device is the is the installation and location of the Waterotor. The water flow is fastest at the surface of the river. Therefore, the ideal location of the Waterotor is just below the surface. If the water is too deep, then a special construction must be made to support the Waterotor. I doubt if a network of tethers would be adequate. The use of the Waterotor is restricted to nontidal streams unless some method of raising and lowering the device is developed. It is also requires a means of rotating the device at each tidal change.
I think that the optional size of a unit should be 30 to 50 kW. In this way, it is still easily transportable and no special equipment is required for installation. An array of these units will be suitable for a small town.
The cost of having an electrical generator at each unit is considerable and perhaps they can consider a hydraulic system. This will also eliminate electrical cables, underwater. What is the efficiency and cost of an hydraulic system, as opposed to an electrical system?
I know this subject is not strictly HAWE but perhaps we should consider alternate systems since with HAWE we have the seemingly intractable problem of autonomously launching and landing the device.
As I recently mentioned here, Magenn went to Waterotor.
See also Hydro-Gen/taylor made solutions about “paddle wheels turbines”. The same company also manufactures water turbines using a retractable propeller Hydro-Gen current turbine.