A vertical axis wind turbine has blades that spin around an upright shaft, like a merry-go-round. Its big advantages: it can capture wind from any direction, and its heaviest parts can sit near the ground. The catch is that it typically makes less electricity than a propeller turbine.
It isn't the best wind catcher. Compared with a horizontal axis turbine in steady, strong wind, it loses on efficiency. But efficiency isn't everything, and in a few environments the egg-beater design really does come out on top.
How A Vertical Axis Wind Turbine Works
The blades of a vertical axis turbine are attached to the top and the bottom of a vertical rotor. The wind pushes the blades, the rotor starts rotating, and that turning shaft spins a generator. It's the same job a bike dynamo does when your wheel spins.
The most common design is the Darrieus, named after a French engineer who patented it in 1931. It looks like a giant two-bladed egg beater.
Advantage 1: Wind From Any Direction
A regular propeller turbine has to face the wind. When the wind shifts, a part called the yaw drive turns the whole top box into the wind, and yaw motors power it. That's extra machinery, up high, that can wear out.
Vertical axis wind turbines (VAWTs) skip all of that. Their blades sit on every side of the shaft, so whichever way the wind blows, some blades catch it. No turning, just rotating. That's why they're tempting in turbulent conditions, like the swirly air between buildings in urban areas.
Advantage 2: The Heavy Parts Stay Low
On a propeller turbine, the gearbox, generator and brake all sit in a box at the top of the tower. Scientists call that box the "nacelle". To fix anything inside, someone has to climb up there.
On a VAWT, the drivetrain (the gears and generator) can sit at the base of the tower. Engineers at Sandia National Laboratories point out two wins from that. The weight sits much lower, like a school bus that's harder to tip over than a tall truck. And the parts are simpler to reach, which helps reduce the cost of installation, operation and maintenance. Easy maintenance is one of the biggest advantages of the design.
That's also why Sandia now studies this technology for floating wind farms far out at sea, where a low, steady turbine is a big deal.
Advantage 3: Made For Tight Spaces
Vertical axis wind turbines are the most popular choice for home and town turbines. They fit on poles, roofs and towers where space is short, and the upright design can look more like a sculpture than a machine.
The Eiffel Tower is the famous example of these applications for vertical turbines. In 2015 two vertical turbines went up above its second level, a design that catches wind from any direction.
Are Vertical Axis Wind Turbines Quieter?
Sometimes, but it depends on the design. Many makers sell them as quiet, and slower blades often do make less whoosh. Research on a small vertical turbine found that when the blades turn too slowly, the air tears off them in bursts (scientists call it "dynamic stall"), and that makes its own noise.
So don't buy on the word "silent". Ask for measured noise numbers and check your local wind turbine noise rules.
Why Don't We Use Vertical Wind Turbines More?
Because they don't perform as well. The US Energy Information Administration says very few vertical turbines are in use today for exactly that reason. Propeller turbines get more power out of the same breeze, which is why almost every big wind farm uses them.
They were once more popular. Sandia has studied vertical turbines since the 1970s, and its 17 metre design, built by the FloWind company, was one of the most commercially successful wind turbines of its time.
Is A Vertical Or Horizontal Wind Turbine Better?
For most homes with an open, windy spot, a horizontal axis wind turbine makes more power. A vertical one only makes sense where its advantages matter more than raw production, and where maintenance on the ground counts.
| Vertical axis turbine | Horizontal axis turbine | |
|---|---|---|
| Wind direction | Catches wind from any direction | Has to turn to face the wind |
| Turning into the wind | Not needed | Needs a yaw drive and yaw motors |
| Generator | Can sit at the base | Sits in the nacelle at the top |
| Power from the same wind | Generally less | Generally more |
| How common | Very few in use | Almost every wind farm |
One warning for urban roofs: in a big UK field trial by the Energy Saving Trust, most building-mounted turbines made very little power, while free-standing turbines on open, windy sites did much better. Location beats design. See where vertical turbines work best and what to check before installing one.
The Short Version
- Its generator can sit low, so repairs are simpler and the turbine is steadier.
- It usually makes less electricity than a propeller turbine, so the site matters more than the shape.
Sources
- U.S. Energy Information Administration, Types of wind turbines
- U.S. Department of Energy, How a wind turbine works (text version)
- U.S. Department of Energy, Sandia National Laboratories work to reduce cost of deep-water offshore wind
- Sandia National Laboratories, Vertical-axis wind turbines for offshore wind energy (fact sheet)
- U.S. Energy Information Administration, Wind energy and the environment
- ASME, The Eiffel Tower goes green
- Energy Saving Trust, Location, location, location: small-scale wind field trial (2009)
- Development of a linear acoustic array for aero-acoustic quantification of camber-bladed vertical axis wind turbine (Sensors, 2020)
Hard Words
| Term | What it means |
|---|---|
| VAWT | Vertical Axis Wind Turbine. The egg-beater kind. Spins around an upright shaft, with blades that go around like a carousel. |
| HAWT | Horizontal Axis Wind Turbine. The classic propeller-on-a-pole kind. Spins around a flat shaft. |
| Yaw drive | The part that turns the top of a propeller turbine to face the wind. A VAWT does not need one. |
| Darrieus | The most common VAWT design, with curved blades that look like a giant egg beater. |
| Nacelle | The box at the top of a HAWT tower that holds the generator and brake. |
| Drivetrain | The parts that turn spinning into electricity, with the generator at the end. |
| Dynamic stall | When blades turn too slowly and the air tears off them in bursts. It costs power and makes noise. |
Common Questions
What are the pros of wind turbines?
Wind is a renewable energy source, and wind turbines do not release emissions that pollute the air or water while they turn. A vertical one adds its own bonus: it works with wind from any direction.
Why does a VAWT not need to face the wind?
The blades sit on every side of the shaft, so whichever way the wind blows, some of them catch it.
What are the main advantages of a vertical axis wind turbine?
It catches wind from any direction, it needs no parts to turn it into the wind, and the generator can sit at the base, which makes repairs simpler and the turbine steadier.
Are VAWTs really quieter?
Not always. Blades turning too slowly stall and make their own noise, so ask for measured noise numbers.
Will VAWTs replace HAWTs?
Not on land. Propeller turbines still make more power from steady wind, so very few VAWTs are in use. Sandia is studying them for floating wind farms at sea, where the low drivetrain helps.