Discover the different types of wave energy devices. From floating buoys to underwater systems, learn how each machine captures ocean power.
There are many different wave energy devices. Engineers have invented dozens of designs. Each one takes a different approach to capturing power from the sea. Here is the short version:
A point absorber is a floating device that rides on the ocean surface. It looks like a large buoy. As waves pass, the device moves up and down. This motion drives a generator inside.
The device connects to a base on the seafloor. Some use a tether. Others use a rigid rod. The base keeps the device in place while allowing it to move with the waves.
Point absorbers capture energy from waves coming from any direction. This makes them flexible. They work well in many locations. But each device produces only a small amount of power. Wave farms need many point absorbers to generate significant electricity.
An attenuator is a long floating device made of connected sections. It sits parallel to the direction the waves are traveling. As waves pass under the device, the sections move up and down at different times. This creates a flexing motion at the joints.
The flexing motion drives hydraulic pumps or generators inside the joints. The more sections a device has, the more energy it can capture.
Attenuators work best in regular swell waves. They are less effective in choppy waves. They must be aligned with the wave direction. Some designs use computer controls to turn the device to face the waves.
The Pelamis was the most famous attenuator design. It had four sections and measured 180 meters long. It could generate up to 750 kilowatts of power.
An oscillating water column is a partially submerged hollow chamber. The bottom is open to the sea. The top has a narrow opening where air can flow in and out.
As a wave enters the chamber, water rises inside. This pushes the air above it out through the top opening. The moving air spins a turbine. When the wave recedes, water drops and air rushes back in. The turbine spins again.
The turbine in an OWC is special. It spins the same direction no matter which way the air flows. This means the device generates electricity on both the upstroke and the downstroke.
OWCs are often built into coastal structures. The Mutriku plant in Spain is built into a breakwater. This saves money by sharing the structure with coastal protection.
An overtopping device uses a different approach. It does not capture wave motion directly. Instead, it collects water in a raised reservoir.
The device has a ramp that faces the incoming waves. Waves flow up the ramp and spill over into the reservoir. The reservoir holds the water above sea level. When the water flows back out, it passes through a turbine and generates electricity.
Overtopping devices work like a small hydroelectric dam. They need consistent waves to keep filling the reservoir. The Wave Dragon in Denmark is a floating overtopping device. It uses two curved arms to funnel waves toward the ramp.
Submerged pressure differential devices sit on the seafloor. They have no parts on the surface. As waves pass overhead, the water pressure changes. High pressure under a wave crest pushes water through the device. Low pressure under a wave trough pulls water back.
The device uses this pressure change to drive a turbine or pump. Because the device is underwater, it is protected from storms. It does not interfere with surface navigation.
The main challenge is maintaining the equipment underwater. Repairs require divers or remotely operated vehicles. This adds to the maintenance cost.
A bulge wave device is a long rubber tube filled with water. It is anchored to the seafloor. One end is open to the sea. The other end has a turbine.
When a wave passes overhead, it squeezes the tube. This creates a bulge of water that travels through the tube. The bulge gains energy as it moves. By the time it reaches the far end, it has enough force to spin the turbine.
The tube is flexible and can handle a wide range of wave conditions. The Anaconda device was a well-known bulge wave design.
A rotating mass device uses a different principle. It contains a heavy weight inside a sealed housing. As the device rocks with the waves, the weight moves inside. This motion drives a generator.
The device does not need to be aligned with the waves. It captures energy from any direction. It is completely sealed, so no parts touch seawater. This reduces corrosion problems.
The main challenge is that rotating mass devices are less efficient than other types. They generate less power for their size.
Think of wave energy devices like different playground equipment.
A point absorber is like a seesaw. It goes up and down with the waves.
An attenuator is like a bendy straw. It flexes as waves pass.
An oscillating water column is like blowing bubbles through a straw into a drink. The air moves in and out.
An overtopping device is like filling a bucket with water and then pouring it out to spin a toy wheel.
Each device does the same job in a different way.
Device design involves trade-offs between cost, efficiency, and survivability.
Size matters. Larger devices capture more energy but cost more to build. Smaller devices are cheaper but produce less power. Engineers must find the right balance.
Depth matters. Offshore devices in deep water capture more energy. But installation and grid connection cost more. Nearshore devices capture less energy but are cheaper to install and maintain.
Control systems can improve performance. Some devices adjust their damping to match wave conditions. This can increase energy capture by 50 percent or more.
Array effects matter when multiple devices are grouped. Devices can shadow each other or create wave patterns that affect neighboring devices. Proper spacing is important.
Pelamis. The sea snake attenuator tested in Portugal and Scotland. 180 meters long, 750 kilowatts per device.
CETO. Submerged point absorber from Australia. No visible surface parts. Pumps water to shore.
Wave Dragon. Floating overtopping device from Denmark. Uses curved arms to funnel waves.
Mutriku. OWC built into a breakwater in Spain. Operating since 2011.
Ocean Energy OE Buoy. Large OWC tested in Scotland. One of the most advanced designs.
Draw each type of wave energy device. Label how it captures wave energy. Then research one real device and present a short report on how it works.
Last updated: June 15, 2026
Which wave energy device floats on the surface and flexes like a snake?
What type of device sits completely underwater and has no visible parts?
What does an overtopping device use to generate electricity?
Where are shoreline wave energy devices usually built?
What is a bulge wave device made of?
Answers: B: Attenuator, D: Submerged pressure differential, B: A reservoir of water that flows through a turbine, B: Into breakwaters or cliff walls, B: A long rubber tube filled with water
How many types of wave energy devices are there?
There are many types, but they fall into a few main categories. The most common are point absorbers, attenuators, oscillating water columns, and overtopping devices. Each uses a different method to capture wave energy.
What is the simplest wave energy device?
A point absorber is probably the simplest. It is a floating buoy that bobs up and down with the waves. The up-and-down motion drives a generator inside. Its simple design makes it easy to build and maintain.
Can wave energy devices be seen from the shore?
Some can and some cannot. Surface devices like point absorbers and attenuators can be seen from shore if they are close enough. Submerged devices sit underwater and are not visible at all. Shoreline devices are built into coastal structures.
What materials are wave energy devices made from?
Most devices use steel, concrete, and special composites. Steel provides strength. Concrete is used for large structures. Composites resist corrosion and are lighter. All materials must survive saltwater, sun, and storms.
How long do wave energy devices last?
The target design life for most wave energy devices is 20 to 25 years. In practice, many devices need repairs sooner. The ocean is hard on equipment. As the technology improves, devices are expected to last longer.
