I previously posted about how it is simple and complete.
It's also a compact solution. Other hydrokinetic turbines for micro-generation (i.e. less than 100kW) are much less so. Almost all use some kind of raft and place their generator and electronics above the water line. This solves one problem--how to keep the electronics dry--but introduces others:
- Transmission--The rotor under water must somehow connect to the generator above it. Shafts, belts or chains can be used, but all have drawbacks, including efficiency loss, added maintenance burden, additional points of failure, and more mechanism that can entrain debris or become fouled.
- Efficiency--Vertical axis turbines with a lift design, (e.g. a Darrieus turbine) lose efficiency unless they are perfectly vertical, However, extending the shaft to the surface makes maintaining vertical alignment nearly impossible.
- Adaptability--By using a raft, other turbines must be sited close to the surface.
- Cost--Additional materials and a larger design add to the cost to build, to transport, and to deploy.
- Sustainability--The added cost is not just in money, but also in embodied energy and carbon footprint.
Compact is good. Power from Water.