Marine Current Turbines: Technology and Deployment Insights

Marine Current Turbines - Marine current turbines capture kinetic energy from tidal flows, generating consistent, low-carbon power for grid integration.

Marine Current Turbines (MCTs), often synonymous with Tidal Stream Generators (TSGs), are devices that operate much like submerged wind turbines, harnessing the kinetic energy of flowing water, primarily from tidal currents. Due to the high density of water, a smaller rotor diameter can yield the same power output as a significantly larger wind turbine, a key advantage.

MCT technology is classified primarily by its rotor axis orientation: Horizontal Axis Turbines (HATs), which are the most common and structurally similar to offshore wind turbines, and Vertical Axis Turbines (VATs). Key design considerations include:

Rotor Design: Often two or three-bladed, with fixed or variable pitch mechanisms to generate power during both ebb and flood tides (bi-directional generation).

Foundations: Systems are typically bottom-fixed (monopile, gravity base) in shallower waters or mounted on floating platforms in deeper, higher-flow sites, offering tow-out maintenance access.

Survivability: The turbines must be engineered for extreme forces, corrosion resistance, and simplified maintenance.

MCTs are considered the most technologically mature form of wave and tidal power, with several multi-megawatt (MW) arrays successfully feeding power into national grids (e.g., in Scotland, Canada). Their high predictability makes them a valuable asset for grid management, and ongoing R&D is focused on reducing the cost of installation vessels and developing advanced, lower-cost moorings for floating systems.

FAQs on Marine Current Turbines

1Why are Marine Current Turbines smaller than wind turbines for a similar power output?The density of seawater is over 800 times that of air. Because kinetic power is proportional to the density of the fluid, a much smaller rotor swept area in water can capture the same amount of power as a much larger rotor in air.2What does "bi-directional generation" mean for MCTs?Bi-directional generation means the turbine blades are designed (often with pitch control) or the entire nacelle is able to rotate so that the turbine can effectively capture energy from the tidal current when it flows in both directions (the flood and the ebb tide).3How is the potential for collision with marine life managed?The risk is mitigated by the slow rotation speed of the turbines (typically less than 15 rpm) compared to the typical swimming speeds of most marine mammals. Extensive environmental monitoring programs at demonstration sites are confirming a low impact.