Learn how wave energy converters work. Discover the different types of converters and how they turn ocean waves into electricity. Simple guide.
Wave energy converters are the machines that turn ocean waves into electricity. They come in many shapes and sizes. Here is the short version:
A wave energy converter is any device that takes the kinetic energy in ocean waves and turns it into electrical energy. Waves are full of motion. That motion can push, pull, spin, or pressurize parts inside a machine. The machine converts that mechanical energy into electricity.
Think of a wind turbine. Wind blows the blades, the blades spin a generator, and electricity comes out. A wave energy converter does the same thing, but it uses wave motion instead of wind.
The challenge is that waves are not steady. They come in different sizes, speeds, and directions. A good converter has to work well in many different wave conditions.
A point absorber is a floating device that bobs up and down as waves pass by. It is called a point absorber because it captures energy from waves coming from any direction. It absorbs energy at a single point.
How it works. The device floats on the surface. A tether or rod connects it to a base on the seafloor. When a wave lifts the buoy, the tether pulls on the base. When the wave drops, the tether relaxes. This motion drives a generator or hydraulic pump inside the device.
Pros and cons. Point absorbers have a simple design. They work in many wave conditions. They are easy to install. But each device produces only a small amount of power. Large waves can damage them.
Example. The CETO system in Australia is a submerged point absorber. It sits underwater and pumps high-pressure water to shore.
An oscillating water column or OWC uses a hollow chamber. The chamber is open at the bottom and has a narrow opening at the top. Waves push water into the chamber, which forces air out through the top. The moving air spins a turbine.
How it works. Imagine holding an empty bottle upside down in water. As you push it down, air bubbles come out. As you lift it up, water rushes in. An OWC does the same thing. The wave pushes water in and out of the chamber. The air moves through a turbine that spins in both directions.
Pros and cons. Few moving parts are in the water. The turbine stays above the surface. It works on both the upstroke and the downstroke. But it needs a certain wave height. The structure can be expensive to build.
Example. The Mutriku plant in Spain is an OWC built into a breakwater. It has been running since 2011.
An attenuator is a long floating device that sits parallel to the wave direction. It has multiple connected sections. As waves pass, the sections flex at the joints. That flexing motion drives hydraulic pumps or generators.
How it works. Picture a giant floating snake made of metal sections. When a wave lifts one section and drops another, the hinge between them bends. That bending motion is captured and turned into electricity.
Pros and cons. Attenuators are very efficient in certain wave conditions. They can be very long and capture energy from many waves. But they need to be aligned with the waves. They are large and complex.
Example. The Pelamis device was the most famous attenuator. It was 180 meters long and had four cylindrical sections.
The part of a converter that actually generates electricity is called the power take-off or PTO system. Different converters use different PTO types.
Hydraulic PTO. Wave motion pressurizes hydraulic fluid. The fluid spins a generator. This system handles large forces well. It is durable but can leak.
Direct drive PTO. A linear generator is driven directly by the wave motion. There is no hydraulic system. This is simpler but needs careful design to handle slow wave motion.
Air turbine PTO. Used in oscillating water columns. A turbine spins as air flows through it. Special turbines like the Wells turbine spin the same direction no matter which way the air flows.
Hydroelectric PTO. Used in overtopping devices. Water collects in a reservoir and flows back down through a turbine, like a hydroelectric dam.
Engineers have invented many other converter designs.
Overtopping devices. Waves spill over a ramp into a reservoir. The stored water flows back through a turbine. The Wave Dragon in Denmark is an example.
Submerged pressure differential. These sit on the seafloor. The changing pressure of passing waves pushes water through a turbine. They have no visible parts on the surface.
Bulge wave devices. A long rubber tube filled with water. Waves squeeze the tube, creating a bulge that travels through the tube and spins a turbine at the end.
Think about different ways to catch energy from a moving swing.
You could stand under the swing and push up each time it comes down. That is like a point absorber catching up-and-down motion.
You could put a fan in front of the swing and let the moving air spin it. That is like an oscillating water column.
You could hold a long bendy ruler next to the swing and let it flex back and forth. That is like an attenuator.
Each method catches the same swing. But each does it in a different way. That is how wave energy converters work. They all catch wave motion, but they do it differently.
Let us look at the engineering in more detail.
Capture width ratio measures how much of the wave’s energy a converter captures. Most devices achieve 20 to 40 percent in real conditions. Research aims to push this higher.
Reactive control is an advanced technique. The device adjusts its resistance to match the incoming wave. This can double the energy capture. It requires sensors and computer control.
Mooring systems hold devices in place. They must be strong enough for storms but flexible enough for normal waves. Different mooring designs affect how the device moves and performs.
Survivability is the biggest engineering challenge. Devices must survive 100-year storm waves while still being affordable. This tension between strength and cost drives many design choices.
Pelamis. The first commercial wave energy converter. It was an attenuator tested in Scotland and Portugal. It proved the technology could work at sea.
Ocean Energy OE Buoy. A large oscillating water column. It has been tested at the European Marine Energy Centre in Scotland.
CETO. A submerged point absorber from Australia. It sits underwater and pumps water to shore. It has no visible parts on the surface.
Wave Dragon. An overtopping device from Denmark. It uses two curved arms to funnel waves up a ramp.
Build a simple model of two converter types. For a point absorber, attach a cork to a spring and watch it bob in water. For an OWC, use a plastic bottle with the bottom cut off and hold it underwater. Compare how each one captures motion.
Last updated: June 15, 2026
What does WEC stand for?
Which type of converter uses a floating buoy that bobs up and down?
What does an oscillating water column use to spin a turbine?
What is the power take-off system in a WEC?
What percentage of wave energy do most converters capture?
Answers: B: Wave Energy Converter, B: Point absorber, B: Moving air pushed by wave motion, B: The part that turns wave motion into electricity, B: 20 to 40 percent
What is a wave energy converter?
A wave energy converter or WEC is a machine that captures the energy in ocean waves and turns it into electricity. Different converters use different methods, but they all do the same basic job of changing wave motion into power.
How many types of wave energy converters exist?
There are many types. The main categories are point absorbers, oscillating water columns, and attenuators. Other types include overtopping devices, submerged pressure differential devices, and bulge wave devices. No single type has become the standard yet.
What is the most efficient wave energy converter?
Efficiency depends on wave conditions. Attenuators can be very efficient in regular swell. Point absorbers work well in many conditions. The highest theoretical efficiency is over 90 percent, but real devices capture 20 to 40 percent of the wave's energy.
How does a wave energy converter turn motion into electricity?
The converter captures wave motion and uses it to drive a generator. Some use hydraulic pumps to pressurize fluid. Others use a direct drive linear generator. Oscillating water columns use moving air to spin a turbine. The generator then produces electricity.
Where are wave energy converters placed?
Converters can be placed offshore in deep water, nearshore in shallower water, or on the shoreline. Offshore devices capture more energy but are harder to maintain. Shoreline devices are easier to access but capture less energy.
