Lesson 3 of 7

Wind Power

Wind power does have a spinning generator, unlike solar — but modern wind turbines connect to the grid in a way that's much closer to solar's power-electronics approach than to a traditional synchronous power plant, for reasons this lesson explains.

From moving air to electricity

Wind turns the turbine's blades, which spin a shaft connected — usually through a gearbox, though some designs skip it — to a generator. The power available in the wind scales with the cube of wind speed (P = ½ρAv³), and no turbine can extract more than 59.3% of it (the Betz limit), which is why turbine siting and blade design are so sensitive to even small differences in average wind speed at a location.

The power curve: three key speeds

Cut-in speed

The minimum wind speed at which the turbine starts generating any usable power — below it, the turbine simply stays idle.

Rated speed

The wind speed at which the turbine reaches its full rated (nameplate) power output.

Cut-out speed

The wind speed above which the turbine deliberately shuts down and feathers its blades to avoid mechanical damage — meaning, somewhat counterintuitively, that a wind farm can produce zero power during a very high-wind storm.

Between cut-in and rated speed, output rises steeply (following that cube relationship); between rated and cut-out speed, control systems deliberately limit output to the rated value rather than let it keep climbing — this combination is what defines a turbine's overall power curve.

Fixed-speed vs. variable-speed turbines

Early wind turbines used generators connected directly to the grid, forcing the turbine to spin at a fixed speed tied to grid frequency — simple, but unable to capture wind energy efficiently across the full range of wind speeds. Nearly all modern turbines instead use variable-speed designs, most commonly a Doubly-Fed Induction Generator (DFIG) or a full-power-converter generator, both of which let the turbine's rotor spin at whatever speed best captures energy from the current wind, while power electronics handle converting that variable-frequency output into grid-synchronized AC.

Onshore vs. offshore wind

Offshore wind benefits from stronger, steadier wind and fewer siting/visual-impact objections, generally giving it a higher capacity factor than onshore wind — but construction, foundations (or floating platforms in deep water) and subsea cabling make it substantially more expensive to build and maintain than an equivalent onshore project.