How do offshore wind turbines work?

Learn how a simple scientific principle combines with cutting-edge technology to capture the natural energy of the ocean breeze and power our homes and businesses.

Electromagnetism: the basics

Electrical energy can be generated by rotating magnets inside a coil of conductive wire. The big question is how to achieve that rotation.

In conventional power stations, fossil fuels like coal, gas and oil are burnt to heat water, producing high pressure steam that can drive a turbine and, in turn, an electrical generator.

Unfortunately, this also produces carbon dioxide and other harmful emissions, as well as relying on finite resources that need to be constantly extracted from underground and transported to the power station.

In a wind turbine, the rotation is achieved through the clean, natural, and ultimately unlimited power of the wind.

Inside the wind turbine

To capture wind energy, the top part of the turbine is turned to face the wind, the three blades are set at exactly the right angle, and the movement of the air past them causes them to rotate.

Within the nacelle – the non-rotating part on top of the turbine – the blades’ rotation is passed through a drive shaft, often via gear box, to turn magnets inside a coil of wire. This generates an alternating current of electricity.

The wind farm as a power plant

One single wind turbine can generate a few megawatts (MW) of power. That’s a lot compared to the power needed to light a home, for example. But it’s still much less than the steam turbine in a conventional power station.

That’s why wind turbines are grouped together to form a wind farm. This can be thought of as one big power station – but one that doesn’t create any emissions when it generates electricity.

An offshore wind farm is made up of many turbines spread out over a wide area of ocean. Each one is firmly fixed to a foundation piece on the seafloor, with a tower that extends up into the air where the blades can make use of higher wind speeds.

Did you know?

One rotation of a single turbine will generate enough electricity to power a typical New Jersey home for more than 19 hours.

Sending the power ashore

Each turbine sends its power through cables down the tower and under the seabed to an offshore substation. Here the energy is stepped up to a higher voltage ready to send ashore via high voltage cables. Higher voltage means less energy is lost in transmission.

On land, another substation adjusts the voltage again so that the electricity can be fed into the grid and distributed via power lines to the homes and business that need it.

Learn more about what happens when the power reaches land

Keeping the blades turning for a quarter century

A wind farm is expected to be in commercial operation for at least 25 years. During this time, it needs to be serviced and maintained to keep working things optimally, prevent faults, and fix anything that goes wrong.

This work is done by a team of highly skilled wind turbine technicians. These technicians use their knowhow, along with the latest technological innovations, to keep everything working as it should be, troubleshooting technical problems as they arise, and carrying out inspections.

Because offshore wind farms are usually located far from the shore, crews of technicians often live on a service and operations vessel – a floating staff hotel – for two weeks at a time. This means they can easily access the turbines that need attention – and take two weeks’ well-deserved leave in between shifts.

Did you know?

As well as creating jobs for turbine technicians, offshore wind generates work, opportunities and economic benefits throughout the local communities where it is built.

What do we do with old wind farms?

When a wind farm eventually reaches the end of its lifespan, it is either decommissioned, life-extended, or repowered.

While life extension involves repairing and maintaining the existing turbines for further years of service, both decommissioning and repowering mean removing the old turbines.

Repowering involves replacing the old turbines with the latest larger and more efficient models, while decommissioning means completely dismantling the wind farm.

In either case, the old turbines need to be removed. At present, up to 95% of a turbine can be recycled, with the lightweight blades proving more challenging. In 2021, Ørsted committed to send no more blades to landfill, but instead to explore options for reuse and recycling.

Recycling wind turbines

Today, 85-95% of the material from a decommissioned turbine can be recycled.

Learn more

Frequently asked questions about offshore wind

How do wind turbines turn wind into electricity?

When the wind blows on the blades of the turbine, it causes them to rotate. This rotation is turned into electricity using the principle of electromagnetism, where magnets are rotated inside a coil of conductive wire. The electrical energy is then sent ashore through cables where it can be used by homes and businesses.
What is wind energy used for?

Wind energy can be used for anything that needs electricity, from supplying homes and businesses to lighting streetlights, powering mass transit or charging electric cars. It can also be used to produce carbon-neutral synthetic fuels and green hydrogen that can be burnt for processes that can’t be electrified. Learn more about green hydrogen on Ørsted’s global website.
How does wind energy power my home?

Power from wind turbines feeds into the regional or national electricity grid, along with power from other sources, like solar farms and conventional power plants. When you use electricity in your home, the energy comes through the grid from this mix of sources. One rotation of an offshore wind turbine of the type installed for Ocean Wind 1 generates enough electricity to cover the power consumption of a typical home for about 20 hours.
How reliable is wind energy?

Offshore wind power is more reliable than you might think. The wind blows much more consistently out at sea, and the turbines are designed to generate power even from a very light breeze. In the rare case that there really isn’t enough wind, other sources of power that contribute to the grid can compensate for this. Even in a future world that runs entirely on green energy, offshore wind won’t be the only energy source.
How clean is wind energy?

Offshore wind is very clean because it provides an emissions-free alternative to fossil fuel-based energy generation. Some one-off emissions are produced in the manufacture and installation of offshore wind turbines. But over its lifetime, an offshore wind farm emits 99 % less carbon dioxide than fossil-based power stations for the equivalent amount of power production.
How much energy does offshore wind produce?

Offshore wind technology has been around for about 30 years now. In that time, the capacity of the turbines has increased significantly. So too has the number of turbines we’re able to install in one wind farm. As a consequence, a large new offshore wind farm today can produce at least as much energy as a conventional power station.