Learn about wave energy converters, the main device types, and what wave energy costs. A practical guide for students, teachers, and curious minds.
Ever wonder how you turn a wave into electricity? It takes clever machines. Over the last few decades, engineers have invented many ways to do it. Here’s the short version:
A wave energy converter (WEC) is any device that takes the motion of ocean waves and turns it into electricity. The tricky part? Waves are slow, strong, and unpredictable. A good WEC has to handle all of that — while surviving storms and saltwater corrosion.
WECs fall into three main categories. They differ in how they sit in the water and how they capture energy.
A point absorber is a floating buoy that bobs up and down as waves pass by. Inside, the up-and-down motion drives a generator or hydraulic pump. It’s called a point absorber because it captures energy from all directions at a single point. Think of it as the jack of all trades.
How it works: The buoy rides on the surface. A tether connects it to a base on the seafloor. As the buoy rises and falls, the tether pulls and releases, spinning a generator below.
Pros: Simple design. Works in many wave conditions. Easy to install. Cons: Limited power output per device. Can be damaged in very large waves.
An oscillating water column (OWC) uses a partially submerged chamber open at the bottom. Waves push water up into the chamber. That rising water forces the air above it out through a narrow opening, spinning a turbine. When the wave pulls back, air rushes in and spins the turbine again. It makes power on the way up and the way down.
How it works: Think of it like a bottle held underwater with the opening facing down. As water enters the bottle, air gets pushed out. As water leaves, air gets sucked in. The moving air spins a turbine that sits in the opening.
Pros: Few moving parts in the water. The turbine stays above the surface. Works on both the up and down stroke. Cons: Needs a certain wave height to work well. Larger structures can be expensive to build.
An attenuator is a long, floating device that sits parallel to the wave direction. It flexes as waves travel along its length. The flexing motion drives hydraulic pumps or generators at the joints. Imagine a giant floating snake doing the wave.
How it works: Imagine a giant floating snake made of connected segments. As a wave lifts one segment and drops another, the hinge between them bends. That bending motion is captured and turned into power.
Pros: Very efficient in certain wave conditions. Can be very long and capture energy from many waves at once. Cons: Needs to be aligned with the waves. Large and complex. Mooring can be challenging.
There are many more designs being tested. Engineers are getting creative:
Wave energy costs more than solar or wind right now. Let’s look at why.
The cost of wave energy varies by location and technology. Recent estimates put it between 4 and 10 cents per kilowatt-hour. For comparison, onshore wind often costs 2 to 4 cents. Utility-scale solar costs 3 to 5 cents. So wave energy is catching up.
Experts predict that wave energy could become competitive with wind and solar within 10 to 15 years if investment and testing continue.
Think of wave energy devices like different kinds of playground equipment. Here’s the breakdown:
A point absorber is like a seesaw. One person goes up, the other goes down. That up-and-down motion is energy. The point absorber does the same thing with waves.
An oscillating water column is like a straw in a drink. When you blow into the straw, bubbles come out the bottom. When you stop, water rises back up. The OWC uses that same push-and-pull of air to spin a tiny fan inside.
An attenuator is like a bendy straw. When you bend it, the joint flexes. The attenuator flexes the same way when a wave passes under it, and that flexing makes power.
As for cost — imagine building a sandcastle that can survive high tide. You’d need stronger walls and more time. That’s what building a wave energy device is like. It costs more because it has to be tough enough to live in the ocean.
Let’s take a closer look at the engineering and economics.
The theoretical maximum energy a WEC can capture is called the capture width ratio. Most devices capture 20 to 40% of the wave’s energy in real conditions. Researchers are working to push that higher. Better control systems can adjust to changing wave patterns in real time.
LCOE is the standard way to compare costs across energy sources. It includes construction, fuel, maintenance, and operation over the plant’s lifetime — divided by the total electricity it produces. Wave energy’s LCOE is higher today. But the gap is shrinking as technology improves.
The part of a WEC that actually generates electricity is called the power take-off (PTO). Here are the common types:
Each has trade-offs in efficiency, complexity, and durability.
Build a simple model of an oscillating water column. Use a plastic bottle with the bottom cut off. Hold it underwater in a tub and watch the air blow out the top. Place a pinwheel or lightweight fan in the airflow to see how a turbine works.
If you found wave energy technology interesting, you might also like:
Each of these turns moving water or air into electricity using different but related technology.
Last updated: June 15, 2026
Which wave energy device type floats on the surface and flexes with the waves?
What does a turbine do in an oscillating water column?
Why is wave energy currently more expensive than solar power?
What is a major cost factor for wave energy devices?
Which of these is NOT a wave energy converter type?
Answers: C: Attenuator, B: It spins when air is pushed through it by wave motion, B: The technology is newer and less developed, B: Building devices tough enough to survive storms and saltwater, C: Photovoltaic cell
What is a wave energy converter?
A wave energy converter (WEC) is a machine that captures the motion of ocean waves and turns it into electricity. Different WECs use different methods - some float, some sit on the seafloor, and some are built into the shore.
How many types of wave energy converters are there?
There are three main categories - point absorbers, oscillating water columns, and attenuators. Each works differently. Point absorbers bob up and down. Oscillating water columns use wave motion to push air through a turbine. Attenuators sit parallel to the waves and flex like a snake.
How much does wave energy cost?
Wave energy currently costs more than wind or solar power. Estimates range from 4 to 10 cents per kilowatt-hour, depending on the location and technology. Costs are expected to fall as the technology improves and more wave farms are built.
Why is wave energy more expensive than other renewables?
Wave energy devices must survive storms, salty water, and constant motion. That makes them expensive to build and maintain. The technology is also newer than wind and solar, so fewer devices have been built, and manufacturing isn't yet at large scale.
What is a point absorber?
A point absorber is a floating device that bobs up and down with the waves. The up-and-down motion drives a generator inside the device. It's called a point absorber because it absorbs energy from all directions at a single point.
What is an oscillating water column?
An oscillating water column (OWC) is a partially submerged chamber. Waves push water up into the chamber, which forces air out through a turbine. When the wave recedes, air is sucked back in, spinning the turbine again. It makes electricity on both the upstroke and the downstroke.
What is the most common wave energy device?
There's no single most common device yet. Many different designs are being tested. Point absorbers and oscillating water columns are among the most studied types. The industry hasn't settled on a winner like the three-blade design for wind turbines.
