Science & Technology

How to Build an Offshore Wind Farm

Let’s talk about building an offshore wind farm. For starters, it’s not your average construction job.

The country’s first major project, Vineyard Wind I, plans to use a longer turbine than the John Hancock Building, Boston’s tallest 790-foot skyscraper. And oops, boys, these things are heavy. Just take the nacelle. This is the elongated part that houses the motor and is just behind the blade. It weighs a whopping 794 tons. This is about the same as the two fully equipped 747s.

Now imagine installing these things in the ocean.

Today, I will explain how to actually install an offshore wind turbine. let’s start.

Choose a foundation

The type of foundation used by developers usually reflects the depth of the surrounding water. The Vineyard Wind Project area, about 15 miles from Martha’s Vineyard Island, ranges in depth from 115 feet to about 200 feet. For these things, it’s relatively shallow, which means that you can use what’s called a monopile for the foundation.

Monopile is a steel pipe that is driven into the seabed. The Vineyard Wind monopile is 34 feet in diameter and 312 feet from end to end. According to the company’s federal environmental permit, about half of the structure will be buried under the seabed.

In the deep sea, developers use what is called a jacket. The jacket is like a tripod. They have three or four legs that are fixed to the seabed. The vineyard permit provides up to 10 jackets.

Choose a turbine

Offshore wind turbines are getting bigger and bigger. Much bigger.

Consider this example. Each of the five turbines used at the Block Island wind farm off Rhode Island can generate 6 megawatts of electricity. They measure about 300 feet from the waterline to the rotor and boast 242 feet long turbine blades.

This is in contrast to the turbines that Vineyard Wind plans to use. They produce 13 MW and can measure about 500 feet from the waterline to the rotor. Its blade extends over 350 feet — it’s about the same length as a soccer field. Only one turbine can generate enough electricity for 16,000 households.

Choose a boat

There are about 50 boats in the world where offshore wind turbines can be installed. according to To the government accountability bureau. These vessels are sometimes referred to as jack-up boats because they are lowered to the seabed when the turbine is installed and have legs that lift the vessel and lift it out of the water.

Jack-up boats have two challenges. First: None of them are American. This is problematic because there are laws in the United States that prohibit foreign vessels from moving between US ports.

Developers have a way around the law. When Deepwater Wind built the Block Island Wind Farm, it used a Maltese flag ship called Brave Tern. Braveturn anchored off Rhode Island and was supplied with parts and equipment by a small fleet of barges and transport vessels.

Vineyard Wind plans to use a similar strategy. The problem is that few jack-up boats have cranes high and strong enough to install the Haliade-X. In fact, there are currently only three boats on which the Haliade-X can be installed. according to To a researcher at Tufts University. Vineyard Wind has signed a contract with one of them, Deme Group, a Belgium-based company that owns a 438-foot vessel named Sea Installer.

Requires some assembly

Paul Murphy is one of the few Americans to have experience building offshore wind farms. He oversees the construction of the Brock Island Wind Farm and is one of the leaders of Ørsted A / S. South Fork, Revolutionary style When Sunrise wind Development off the southern coast of New England. I asked him how to actually assemble one of these projects.

His advice: “The best way to build a project in the middle of the ocean is to spend as little time as possible in the middle of the ocean.”

That means doing a lot of work on land. For Ørsted, the first two projects will be put together at the Staging Ground in New London, Connecticut. VineyardWind uses the Marine Commerce Terminal in New Bedford, Massachusetts.

According to Murphy, the tall part of the turbine, usually called the tower, is divided into three sections that are 100 feet high. They are stacked and welded on land and equipped with all the necessary cables and electrical wiring.

Then they emerged in wind development and are installed using one of their huge jack-up boats. Once the tower is firmly anchored to the seabed, a nacelle containing the motor is placed above it and each of the three turbine blades is mounted.

Of course, this only covers the actual turbine installation. Developers also need to route transmission cables between turbines and offshore substations. It then powers the main transmission cables leading to the mainland.

Everything sounds simple, doesn’t it?

Reprinted from E & E News With permission from POLITICO and LLC. Copyright 2021. E & E News provides essential news for energy and environmental professionals.

How to Build an Offshore Wind Farm How to Build an Offshore Wind Farm

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