Offshore wind farms forge ahead with underwater help

Off the coast of Portugal, a team of underwater robots scan the base of a wind farm’s turbines and look for signs of damage while drones inspect the blades. This activity is part of a project to reduce inspection costs, keep wind turbines running longer and ultimately lower electricity prices.

Wind energy accounts for more than a third of electricity generated from renewable source in the EU in 2020 and offshore wind energy is expected to make an increasing contribution in the coming years. Denmark became home to the world’s first offshore wind farm in 1991, and Europe is a global leader in the field.

However, running wind farms in the seas and oceans is expensive and adds to the overall cost of such clean energy. Furthermore, Asian companies in this sector are gaining ground, increasing the need for European industry to maintain a competitive edge.

Cheap

“Up to 30% of total operating costs are related to inspection and maintenance,” says João Marques of the research association INESC TEC in Portugal.

Much of this comes from sending maintenance crews to sail to inspect and repair offshore wind infrastructure.

The ATLANTIS The project is exploring how robots can help on this front. The ultimate goal is to cut wind energy costs.

Underwater machines, surface vehicles and drones are just some of the robots being tested. They use a combination of technologies—such as visual and non-visual—and sonar to inspect the infrastructure. For example, infrared imaging can identify cracks in turbine blades.

Research conducted by the project shows that robot-based technologies can increase the amount of time maintenance ships can spend on wind farms by around 35%.

Greater safety

Cost is not the only consideration.

“We also have some safety concerns,” said Marques, a senior researcher on the ATLANTIS project.

It is very dangerous to let people move from boats to turbine platforms, dive under the waves to check anchor points and expand turbine towers.

People can only switch from the boat to the turbine platform when the waves are less than 1.5 meters high. In contrast, robotic inspection and maintenance systems can be deployed from ships in waters with waves up to 2 meters high.

In addition, easier and safer maintenance will increase the time that wind farms can be fully operational. In winter, it is often not possible to conduct offshore inspections and maintenance, but to wait for better weather in spring or summer.

“If you have a problem with a wind farm or a particular turbine for a month where you can’t reach it, it needs to be stopped until someone can reach it,” says Marques.

The ability to operate in higher wave conditions means wind farm outages can be remedied more quickly.

first of its kind

The project’s test site is based on a real offshore wind farm in the Atlantic Ocean, 20 kilometers from the northern Portuguese city of Viana do Castelo. This is the first of its kind in Europe.

“We needed somewhere to really test these things—somewhere where people could actually develop their own robots,” says Marques.

In addition to its own robotic technologies, ATLANTIS aims to help other research groups and companies develop such systems of their own.

European researchers and businesses working in this cutting-edge field can book time to use the facilities starting as early as this year.

damage prevention

Another way to cut maintenance costs is to reduce damage and the need for repairs in the first place. Recent Conclusion FarmConners The project sought to do just that through extensive use of a technology called wind farm control, or WFC.

When impacted by the wind, a turbine draws energy from the airflow. As a result, the flow behind the turbine is reduced in energy, a phenomenon known as ghosting. Due to this uneven distribution of energy loads across the rotors and towers, some turbines suffer more damage than others.

According to project coordinator Tuhfe Göçmen of Technical University of Denmark, WFC aims to balance the distribution of wind energy throughout the farm.

There are several ways to minimize the impact of shadows. One is the wrong tuning of the turbine. Instead of pointing directly into the wind, the turbine can be rotated slightly so that the shadow effect is driven away from the turbine behind.

The pitch and rotational speed of the three turbine blades can also be changed. While this cuts down on the amount of power the turbines produce, it leaves more power for the turbines behind to harvest.

grid-friendly

Along with reducing wear and tear and maintenance costs, WFC can make wind farms more efficient and help them generate electricity in a way that is easier for the grid to handle.

Renewable energy includes wind energy usually created at the tops and bottoms. Sometimes peaks, or power spikes, can overload the grid.

According to Göçmen, with turbines working together, electricity production can be balanced to provide a more consistent and stable input to the grid.

“If we control the turbines together, it is simply more efficient,” he said.

Research has shown that such wind farm control can increase the electricity production of all wind farms in the EU by 1%.

That equates to twice the output of a 400 megawatt wind farm, which will cost about 1.2 billion euros to build, according to Gregor Giebel, coordinator of FarmConners also at the Technical University of Denmark.

The technology is also easy to implement because most wind turbines can be controlled and tuned to work in ways that WFC needs. The wind farms just update their driver software.

According to Göçmen, there is a lot of commercial interest in WFC technology, making it a promising way for Europe to expand its use of wind energy.

It’s “low cost and potentially profitable,” he said.