The horizontal axis marine turbine GEM "the Ocean's Kite" is an hydrokinetic turbine designed to be driven by
slow-moving flows of water, namely river, tidal or water currents in general.
The patented turbine has been developed since 2005 after a research project done in collaboration with Eng. Nicola Morrone, who is the patent holder together with Prof. Domenico Coiro, professor at University of Naples "Federico II" (Department of Aerospace Engineering) and coordinator of the ADAG Reserch Group.
The GEM system can be easily towed to the installation site and thanks to the self-towing winch can be positioned at predetermined depth (standard depth: 13 m). In absence of current, the GEM assumes the position shown in (Fig. 3).
When water current is flowing, it assumes the position as shown in (Fig. 2). For maintenance, the GEM can be easily brought to the surface simply releasing the tension of the mooring line (Fig. 1).
The main characteristic of the GEM, however, is its passive capacity of aligning itself along the current direction (as shown in the Fig.4) and this reminds the typical behavior of a kite from which the name "Ocean's Kite". In case of need, however, it is possible to control this alignment through the aid of a controlled designed system which uses the turbines as propellers.
- Length: 9.2 m
- Height: 5.2 m
- Width: 10.4 m
The GEM is basically made by the following parts:
- a buoyant unit;
- two contra-rotating turbines, with three blades, attached to two electrical generators, symmetrically positioned on the two sides of the frame;
- two diffusers, mounted around the two turbines, shaped to double the power output;
- a barrel-shaped container placed at the foot of the frame, and containing a winch;
- a mooring block, laid on the sea bed to which a mooring line is connected;
- an electric cable to connect the electrical generators to the grid; the electric cable running along the mooring line;
- tailplanes to provide the system stability;
- an automatic control system based on the differential turbine/propeller action to control orientation during current direction reversal.
Detailed numerical analysis and two different scaled models (see figures below) have been tested in the towing tank of the "Federico II" University.
The first full-scale GEM prototype has been built by a consortium of Venetian companies and partially sponsored by Veneto Regional and has been deployed in the Venetian Lagoon. For this prototype, the expected power is ~ 20 kW with lagoon maximum current speed of 1.5 m/s.
