NOVELTY - The driveline has a controller (12) electrically connected to an auxiliary electrical machine e.g. motor (6). A sensor (11) provides rotational speed information about a power source e.g. turbine blade (1). The controller governs a supply of power to the motor according to the rotational speed information. The motor provides power to a power splitting device (4) via a shaft (5) connected to the motor to maintain a rotational speed of another shaft (10) rotationally connected to a primary electrical machine e.g. generator (9), within a selected controllable speed range.    USE - Electromechanical driveline for electrical power generation from a power source e.g. blade, of a wind or water turbine (claimed) e.g. offshore or inland turbine. Can also be used for a power station, an industrial drive, and an electric vehicle.    ADVANTAGE - The motor/generator allows alternate power transfer paths between the power splitting device and the motor/generator, and allows control of the output speed ranges experienced on the output shafts while cutting down on the associated requirements put on the power electronics to condition the electricity for supply to a grid. The driveline achieves speed control of the primary generator through supplying power to the differential running in motor mode, or taking power from the differential running in generator mode, thus allowing use of a smaller electrical machine to control the speed, which reduces power supply from the motor, and hence reducing/removing the need for expensive power electronics associated with using variable speed auxiliary generator to supply energy to the grid. The driveline is housed in a nacelle, so that the driveline is protected from environmental damage caused by rain or snow.    DESCRIPTION OF DRAWING(S) - The drawing shows a generic schematic view of an electromechanical driveline comprising a fixed speed gearbox, a power splitting device, two motor/generators, a sensor and a controller allowing speed control of the motor/generators.    Turbine blade (1)    Power splitting device (4)    Shafts (5, 10)    Motor (6)    Generator (9)    Sensor (11)    Controller (12)