Offshore renewable energy structures are the physical installations deployed in marine environments to capture energy from natural resources like wind, waves, tides, and thermal gradients.
According to the reference, there are four main types of offshore renewable energy: wind, wave, tidal, and thermal. Each of these requires distinct structures adapted to the specific energy source and the harsh conditions of the ocean.
Types of Offshore Renewable Energy Structures
Harnessing the power of the ocean and offshore winds involves various types of structures, each designed to convert natural energy into usable electricity.
Offshore Wind Energy Structures
As the reference mentions, wind power is generated via turbines which use blades to collect kinetic energy from the wind as it blows. Offshore wind structures primarily consist of the wind turbine itself and its supporting foundation.
- Wind Turbines: These are large machines with rotor blades connected to a nacelle atop a tower. The blades capture the wind's kinetic energy, spinning a generator to produce electricity. Modern turbines are specifically designed to withstand corrosive saltwater environments and strong winds.
- Foundations: These anchor the turbine structure to the seabed. Types include:
- Fixed-Bottom: Structures like monopiles, jackets, and gravity-based foundations are used in shallower waters to securely fix the turbine tower to the seabed.
- Floating: For deeper waters, turbines are mounted on floating platforms tethered to the seabed by mooring lines and anchors. These platforms can be semi-submersible, spar-buoy, or tension-leg types.
Offshore Wave Energy Structures
Wave energy converters (WECs) are designed to capture the energy from the motion of ocean surface waves. There are numerous designs, often categorized by their location and method of energy capture:
- Point Absorbers: These are floating structures that absorb energy from all directions through their bobbing motion.
- Attenuators: These structures align parallel to the wave direction and capture energy from the bending motion as waves pass along their length.
- Oscillating Water Columns (OWCs): These are chambers with an opening to the sea below the waterline. As waves enter, the water level rises and falls, compressing and decompressing trapped air, which drives a turbine.
- Overtopping Devices: These structures capture water from incoming waves in a reservoir elevated above sea level, which is then released through turbines (similar to hydropower dams).
Offshore Tidal Energy Structures
Tidal energy harnesses the energy from the movement of tides. Structures include turbines and barrage systems:
- Tidal Turbines: Similar in concept to wind turbines but designed to operate underwater, capturing energy from tidal currents. They can be installed on the seabed or within floating structures.
- Tidal Barrages: Large structures built across a tidal estuary or bay, creating a reservoir. Sluice gates allow water to fill the reservoir during high tide, and it is then released through turbines during low tide.
- Tidal Lagoons: Similar to barrages but enclosed areas separate from the natural coastline, offering more control over water flow and potentially less environmental impact on existing estuaries.
Offshore Thermal Energy Structures
Ocean Thermal Energy Conversion (OTEC) harnesses the temperature difference between warm surface water and cold deep water.
- OTEC Plants: These facilities, often built on floating platforms or located on shore with extensive pipelines reaching into deep water, use the temperature difference to drive a heat engine and produce electricity. They require long pipes to bring cold water from depths of several hundred meters.
These structures represent the infrastructure required offshore to convert the vast potential of marine renewable resources into sustainable energy.
| Energy Type | Primary Structure(s) |
|---|---|
| Wind | Turbines, Foundations (fixed-bottom, floating) |
| Wave | Wave Energy Converters (various types) |
| Tidal | Tidal Turbines, Barrages, Lagoons |
| Thermal | OTEC Plants (platforms, pipelines) |
