Wind is merely air in motion. Wind turbines convert kinetic energy from the wind that passes over the rotors into electricity.

Wind turbines consist of four main components—the rotor, transmission system, generator, and yaw and control systems—each of which is designed to work together to reliably convert the motion of the wind into electricity. These components are fixed onto or inside the nacelle, which is mounted on the tower. The nacelle rotates (or yaws) according to the wind direction.

Rotor:	The rotor consists of the hub, three blades and a pitch regulation system, all of which are located upwind of the tower. The blades are airfoils, which depend on aerodynamic lift to move the blades and cause rotation. (Air moving over the blades creates a negative pressure on the upper side of the airfoil and a positive pressure on the lower side; this causes the rotor to rotate.) The design speed of the rotor is 16 rpm.
Transmission system:	The mechanical power generated by the rotor blades is transmitted to the generator by the transmission system. This consists of a gearbox and a braking system plus the auxiliary lubricating and cooling systems. The gearbox is needed to increase the rotor’s speed (16 rpm) to the 1800-rpm speed of the generator. The braking system is designed to lock the rotor when shut down.
Generator:	The generator converts the mechanical energy to electrical energy in an asynchronous (induction) generator.
Yaw and control systems:	The yaw system turns the nacelle into the actual wind direction using a rotary actuator and a gear mechanism at the top of the tower. A fully automatic microprocessor-based control and monitoring system is a part of the wind turbine. The control system is designed for remote operation from the shore-based operations center via a fiber optic communications system.

The Cape Wind project will utilize tubular steel towers that result in an overall hub height of 246 feet above mean sea level and which are secured onto a single (monopile) foundation. Each tower allows internal access via ladders and platforms. The tower and foundation system are designed to withstand high winds, earthquakes, high waves, ice and other damaging elements that may be encountered.

Once the electricity is produced in each turbine’s generator, a transformer located in the nacelle increases the voltage to 34.5kV. Then it is tied into a grid, which has between 10 and 15 turbines connected on it. The 34.5kV grid cable is buried six feet below the bottom surface and is connected to the electronic service platform (ESP). On the ESP, the voltage is increased to 115kV and transmitted to shore in two cables, which also will be buried six feet below the bottom surface. The ESP is fitted with circuit breakers and electric relays to protect the electrical system, as well as the control systems.