Tidalenergy generator#
As a result, the design of a flooded generator has to be different from the airgap generator. In a flooded generator, instead of an airgap the stator-rotor gap is filled with the seawater. One possible way of minimizing the O&M expenses and improving the capacity factor is to use a flooded (or wetgap) generator rather than the sealed airgap generator. Likely reduction in per unit LCoE for 20 and 50% reduction in cost component (Source: ). Consequently, the focus of this chapter will be also on HATTs. As is evident, most of them prefer horizontal axis tidal turbines. Some of the main tidal energy developers are listed in Table 1. This is primarily because of their higher technology readiness level (TRL), and similarity to commercial wind turbines. Although vertical axis tidal turbines and other topologies such as oscillating hydrofoil, enclosed tip turbine and tidal kites are also used to harness tidal energy, most of the research and development efforts are focused on HATTs see Figure 3.
Ī typical tidal stream turbine is shown in Figure 2, which is an example of a horizontal axis tidal turbine (HATT). Furthermore, the potential for tidal stream turbines is expected to be more than the tidal range technology. The commercial success of wind turbines is to a large extent responsible for this shift in harnessing tidal energy. Recently tidal stream turbines have become a preferable mode of harvesting tidal energy over tidal range (or dams) technology. The focus of the chapter is, however, to give a basic insight into the design aspects of the flooded generators, and compares it with the currently used sealed airgap generators in tidal turbine systems. The chapter begins with a brief description of the generator systems used in current tidal stream turbines.
This architecture has the potential to improve cooling and reduce reliance on ancillary systems (e.g., bilge system), thereby improving reliability. Inside flooded generators, the gap between the stator and rotor is filled with the seawater. A possible way of minimizing the LCoE and improving the availability is to use a flooded (or a wetgap) generator rather than a conventional airgap generator. A major reason for this is the high operation and maintenance costs for submerged installations. The main issue for low utilization of tidal energy is the high levelized cost of energy (LCoE) from tidal stream turbines. There is also a discussion as to what degree there is an effect due to noise and vibration of turbines on maritime environment.Recently, tidal stream turbines have become a preferable mode of harvesting tidal energy. The tidal power plants, though environmentally sound, are known to affect the normal flow of water and disrupt the natural structure of the environment (e.g.
The difference in levels between low and high tides must be 6 meters or more to create a feasible amount of energy.Įxamples of tidal energy production can be found in the Bay of Fundy (Canada) and in Russia (Kislaya Guba near the Port Vladimir, Barents Sea). Illustration of one type of tidal energy (Photo: GettyImages)The turbine blades are then reversed so that the outgoing tide also produces electricity.
The incoming tide generates electricity as it flows through turbines constructed in the dam. It is exploited by building a dam across the mouth of a bay or inlet. Tidal barrage is possibly the most used type in the circumpolar North up to now. There is one prototype installation in Kvalsund, south of Hammerfest, Norway and another demonstration plant near Race Rocks (Vancouver Island) in Canada. Tidal stream generators (TSGs) are similar to wind turbines but being under water and utilizing the kinetic energy of flowing water. There are three types of tidal power generators. The tides are predictable due to their linkage to the lunar cycle, making it possible to calculate them and their related production of energy with astronomical precision for years in advance. Illustration of one type of tidal energy (Photo: GettyImages)The shift of height in water level due to the tides represents another potential, renewable source of energy.
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