A question of wind turbine and the blades.?

Question

Why blades that are very long and wind speeds that are high may not generate more wind energy than shorter blades or slower wind speeds? Please explain the reason.

Answer 1

Just an engineers guess...

A wind turbine with long blades would not turn very fast, but one with short blades would turn fast. They'd could both generate the same amount of power as a gear box can match the blade speed to the best speed required for the generator.

Longer blades would have a higher tip speed and would loose efficiency at high speeds. At high speeds, as the air is displaced by one blade, the blade 'following' it would be moving in a vacuum. The next blade going by might be in a partial vacuum. As the vacuum and pressure areas of the atmosphere the blades are 'cutting' through come and go, the blades would be unbalanced and the tower could be damaged from vibrations. It could buckle and even come down.

I would think they would have some sort of mechanism to slow the blades in high winds, but they'd be much better off using shorter blades in high wind areas.