How do you like to do it: Horizontal or Vertical?

Tidal stream has a similar behaviour to wind as it is a fluid as well. So it has been relatively easy for engineering to transfer the concept of 3-bladed horizontal axis design to this new environment. Engineers argue that if it works with onshore and offshore air streams, being even the icon of clean energy and sustainability, why shouldn't it work with water streams?

It's pretty sure it will work. No doubt about engineering abilities on horizontal axis wind turbines. Yet we are talking about hydrodynamics and not aerodynamics,  the question should be: is this the best design we can achieve?

Recently I have read an interesting paper from Stephen Salter called "Are Nearly all Tidal Stream Turbines Designs Wrong?" which was presented during the Oxford Tidal Energy Workshop, held in Oxford during 29-30th March.

The aim of this paper is, in words of the author,  "to show that, despite its widespread popularity, the transfer from wind technology is wrong and that a cross-flow design with rotation about a vertical axis is better. "

3-bladed horizontal axis wind turbines are "universal" as everybody, including industry, investors, public, mass media and politicians assume it as the best choice in this area.

But if a company achieves a better design in terms of efficiency, cost reduction, installation and O&M in tidal/ocean streams using a vertical axis design [don'tforget it is a completely different environment] there will be a major question to answer:

* Will this company achieve a leadership position in the industry and get the confidence of the investors?

I guess this issue can be one of the main topics for the next as the technology is developing faster than expected and I hope to get a further understanding of the different possibilities of the designs.

Photo from Marine Current Resource and Technology Methodology