The longest blades on current wind turbines are 300+ feet. Engineers are working on prototypes for ginormous turbines with amazing new technology. The blades would be 656 feet long, more than two football fields, with towers taller than the Empire State Building. Each turbine could output a prodigious 50 MW. There will be two blades, not three, and they will face downwind. Blades will expand when wind speed is low and contract when high, allowing more energy to be generated at low-speed and protects the system during high winds.
At dangerous wind speeds, the blades are stowed and aligned with the wind direction, reducing the risk of damage. At lower wind speeds, the blades spread out more to maximize energy production.
Sandia’s previous work on 13-MW systems uses 100-meter blades (328 feet) on which the initial SUMR designs are based. While a 50-MW horizontal wind turbine is well beyond the size of any current design, studies show that load alignment can dramatically reduce peak stresses and fatigue on the rotor blades. This reduces costs and allows construction of blades big enough for a 50-MW system.
The blades are sectional, rather than one huge piece, and would be assembled on site. The segments are 130-160 feet long, making them relatively easy to transport.
The plan is to site them far out at sea away from grumpy NIMBYs and migratory paths of birds. Prototypes are being funded by the Department of Energy through its Advanced Research Projects Agency working with universities.