New Wave Media

 

According to the designer, the SIT design purposely avoids complex subsystems: SIT features passive-adaptive composite blades with no need for any active pitch mechanism. Its drive train is standardized with a two-stage planetary gearbox and an induction generator. The ambient water ensures a steady operating temperature of the generator, thus no additional cooling mechanism is needed. An optional multi-disc brake is available for very harsh environments or in case it is required by a regulator.

 

“The simple turbine layout results in a robust and lightweight device,” explained Niels Lange, Managing Director of Schottel Hydro, “In contrast to other instream energy converters with nacelle weights of 130 t to more than 200 t, a single SIT only weighs about 1 t.”

 

SIT turbines are scalable in terms of quantity, depending on the required output. For example, 1 MW of installed power requires about twenty SIT turbines. The multi turbine principle therefore leads to an optimum ratio of power and material use. Each of the turbines is connected to a frequency converter feeding into a common DC bus installed on the tidal platform. The system thus includes redundancy and ensures a high availability of the power plant. SIT turbines are compatible with various support structures: fixed land-based, floating, semi-submerged or full submerged platforms are suitable.

 

Schottel Hydro identifies three flow speed standard classes for SIT applications. These classes result in three SIT rotor diameters of five, four or three meters optimized to the respective flow speed and application. Depending on the diameter and the current velocity, one SIT produces between 54 and 70 kW rated, grid-ready electric power.