[toecutter]

The existence of fundamentally non-effective wind capturing technologies, such as rooftop windmills, vawts, and kites, does not preclude existance of effective designs aka multi-megawatt 3 bladed wind turbines.

By analogy, just because early attempts to build a concept does not work, can you prove future attempts won't work? As far as I know, the energy potential in the ocean is not disputed, just the initial attempts to build the machines have not been successful. Many attempts at flying machines were unsuccessful before the wright brothers.

[jacquesm]

Windmills have been making usable power for millennia. They are well understood.

Tidal energy has been tried time and again and nobody has managed to make anything that would work at scale.

[toecutter]

Well the comment you replied to that you agree with "100%" also said wave energy + tidal energy.

Your method of analysis is assuming we exist in the best of all possible worlds. "Flying machines have been tried time and again" is valid right until wright brothers. "Electric cars have been tried time and again" right before Tesla enters the market.

It's one thing to say "roof top wind" and you can look at the loads an average roof can support, realize it will be a small swept area at a low elevation and conclude that roof top wind couldn't power the building its mounted on. There is no way to write off tidal with the same sort of first principles analysis, the power is there, its a matter of design whether or not it can be captured efficiently.

[jacquesm]

Electric cars were proven to be viable in the early 1900's. We've had electric vehicles in one form or another in all that time since then.