GE Energy


GE's 4.1-113 offshore wind turbine uses longer, more aerodynamic blades than current turbines, to produce a low-maintenance machine that harnesses five percent more of the wind's energy-generating potential than typical models. Now in production, the first turbine will be installed in Gothenburg, Sweden, later this year. Here's the new spin on turbine tech.


Most generators have a gearbox to speed up the eight to 20rpm rotations of the blades to thousands of rpm, but this turbine has a ring of magnets that turn at the same rpm as the blades. Due to the longer blades, the radius -- and thus the torque -- of each rotation is increased.


Each blade is automatically rotated on its own axis to maximise lift and efficiency, as dictated by the pitch controller. In high winds, the blades turn inwards to limit damage. At wind speeds above 90kph, the turbine shuts down completely.


Converters steady the varying frequencies in current produced from variable wind speeds. Transformers step up the voltage from 690V to 22,000V for transfer to the grid. The capacity of each turbine unit is 4.1MW, enough to power 1,000 average homes.


The 7m-long steel rotor-shaft transfers mechanical energy to the generator, spinning the neodymium magnets to induce current in the surrounding copper coils. This is then transferred to the converters and transformers at the top of the tower.


The nacelle is the streamlined, sealed base unit at the top of the tower, holding the blades. Wind-direction and speed sensors provide data to the yaw drive motor, based at the top of the tower, automatically rotating the nacelle to face directly into the wind.


The three 54-metre fibreglass and carbonfibre blades have flat rather than tapered edges to increase lift. The blades twist as they bend in towards the tower under high winds, allowing the turbine to capture energy and keeping the blades protected from strong gusts.


Detecting wind direction, the turbine automatically positions itself to face in to the wind, and simultaneously adjusts each blade to the angle appropriate for the wind speed. The blades rotate around the rotor shaft, transferring the rotations' mechanical energy to the generator. Its direct-drive design -- the generator's magnets spin at the same rate as the blades -- means fewer moving parts. As a result, the turbine requires maintenance only once a year.


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