Winds of Change: Offshore Wind Farms at the Forefront of Energy Transition
At a time when the importance of turning to sustainable energy sources and reducing our carbon footprint is increasingly recognised, offshore wind farms represent a ray of hope amid growing concerns about the energy crisis. They constitute a significant step forward in the search for long-term solutions in the field of renewable energies and sustainable development. In this article, we take a detailed look at the world of offshore wind farms. We’ll explain the captivating workings of these gigantic wind turbines, exploring everything from rotating blades to energy converters. You’ll understand how they have become a crucial resource for clean, renewable energy. Plus, we’ll look at the distinctions between offshore and onshore wind farms– and much more!
What are offshore wind farms?
Let’s start with the basics. An offshore wind farm is a mega-structure on the seabed that supplies clean, renewable energy. The installation consists of wind turbines, or wind generators, similar to those found on land. The difference is that these turbines are located on platforms or floating structures anchored in deep water.
The turbines in offshore wind farms draw their energy from the sea winds to generate electricity. These winds are considerably more powerful and blow at much higher speeds than on land, due to the absence of natural obstacles to slow them down. What’s more, these marine winds tend to maintain a constant speed.
Offshore wind farms vs Floating offshore wind farms
The distinction between “offshore wind farms” and “floating offshore wind farms” lies in the way the turbines are anchored in the sea.
As we mentioned previously, offshore wind farms traditionally involve turbines fixed to the seabed, using foundations such as monopiles, jackets or tripods that are firmly anchored to the ocean floor. This technology is viable within certain depth limits and under certain seabed conditions, generally in shallow waters, where the turbine foundations can be firmly anchored.
On the other hand, floating offshore wind farms represent an innovative approach, employing turbines mounted on floating structures that are not fixed to the ocean floor. These floating platforms allow turbines to be deployed in deeper waters where fixed foundations are impractical or expensive. They use tension leg platforms, semi-submersible platforms or other innovative floating structures to support the turbines, enabling offshore wind power to be generated in deeper and more remote locations.
The distinction between the two is crucial when considering geographical limitations, as traditional offshore wind farms are confined to areas with shallower waters and suitable seabeds, whereas floating wind farms extend the possibilities to deeper waters previously inaccessible to offshore wind installations.
What’s more, while both types of turbines harness wind power to generate electricity, the engineering and installation processes differ considerably. The development of floating wind technology represents an emerging frontier in offshore renewables, offering opportunities to extend the reach and capacity of offshore wind farms to more diverse locations, with stronger and more consistent winds.
Each approach has its advantages and limitations, and the choice between the two depends on factors such as water depth, proximity to shore and specific seabed conditions, all of which have an impact on the feasibility and cost-effectiveness of deploying offshore wind energy infrastructure.
How an offshore wind farm operates
Offshore wind turbines are installed on separate foundations: fixed concrete bases for conventional wind turbines or floating platforms for more innovative installations. These structures are meticulously designed to withstand harsh marine environments, ensuring stability and reliability in difficult sea conditions.
Once in service, these turbines harness the wind energy and convert it into electricity. The energy produced is transmitted via submerged cables to transformer stations strategically positioned at sea. At these stations, the electricity undergoes a crucial transformation, being converted to high voltage, generally between 33 and 132 kilovolts (kV). This high-voltage electricity is then efficiently transported and distributed through the power grids to reach the end users for whom it is intended.
Offshore wind: How turbines work
The technology used in offshore wind turbines works on the same principles as onshore wind turbines.
- The kinetic energy of the wind sets the blades of the wind turbine in motion.
- These blades are connected to the hub of the wind turbine (also known as the “nose”), and the hub is connected to the wind turbine, enabling the motion to be transmitted.
- The slow shaft rotates at the same rate as the blades, generally at a speed of 7 to 12 rotations per minute.
- The speed is increased considerably by the gearbox, more than 100 times, and transferred to the fast shaft.
- This increased speed is transferred to the wind turbine’s high-speed shaft, which rotates at over 1,500 rpm and transmits it to the wind turbine.
- The wind turbine is responsible for converting the kinetic energy received into electricity.
Location of offshore wind farms
As we’ve seen previously, offshore floating wind farms are located in shallow waters, at an average depth of 27.5 metres, and in areas some 41 km from the coast. They are also located far from shipping lanes, other infrastructure and areas of high ecological value.
This choice was made specifically to avoid the proximity of these features to inhabited areas. This means that the wind farms have no visible or audible impact on humans. It should be noted that offshore wind farms on floating platforms open the door to wind farms even further offshore, in areas of great depth as discussed earlier.
What is the difference between onshore wind farms and offshore wind farms?
Although the operation of the two wind farms may be very similar, there are some notable differences between them.
The main distinction lies in the technical challenge associated with their development, since construction and maintenance in an offshore environment are considerably more complex and require strict compliance with safety measures. In addition, the creation and operation of offshore wind farms require the use of highly specialised logistical resources.
On the other hand, in the offshore environment, electricity generation capacity is considerably higher due to the superiority and regularity of the wind resource compared to the onshore environment. This translates into higher electricity production.
In offshore wind farms, individual turbines can achieve outputs of more than 10 MW, and even up to 15 MW. On land, on the other hand, it is common to find turbines with a unit capacity of around 6 to 7 MW.
It’s important to stress that, because of access constraints during the operational phase, offshore wind farm components need to be more reliable. This is why these components are designed with higher levels of safety than land-based wind farms.
Advantages and disadvantages of offshore wind farms
Offshore wind farms offer multiple benefits for both society and the environment. In what follows, we will look in detail at some of these significant benefits. In addition, we will discuss the associated disadvantages and strategies for mitigating them.
Advantages of Offshore Wind :
- It is an inexhaustible source of renewable energy. It offers a valuable alternative for reducing greenhouse gases, thereby helping to combat climate change.
- It also has the potential to produce a greater quantity of energy than its terrestrial counterparts. The absence of obstacles allows the wind to reach its maximum power at sea.
- Offshore location minimises the visual and acoustic impact and means that very large areas can be used.
- Offshore transport means that wind turbines can reach much larger unit sizes and outputs than on land.
- It reduces the energy dependence of many countries. It allows them to produce enough energy to meet the needs of their own populations on their own territory.
- It creates local jobs and stimulates economic and social growth in the region.
Disadvantages of Offshore Wind :
- Compared with onshore wind farms, offshore wind farms involve significantly higher costs, both for installation and maintenance.
- During the construction phase, the fishing industry may be temporarily affected. This is due to possible restrictions in fishing zones or interference with their activities, resulting in a reduction in their income.
- It is possible for seabirds to collide with the blades of moving wind turbines at offshore wind farms. However, this is less common than in onshore wind farms.
- The construction of foundations and structures can disturb the seabed and the ecosystem, which can affect species living in the area.
- The operation of offshore wind turbines can generate underwater noise. This disturbs marine mammals and can affect their behaviour and migration patterns.
- The underwater structures of offshore wind farms can influence local currents and tides.
As a result of all these factors, setting up an offshore wind farm involves a complex process of applying for permits, obtaining authorisations and carrying out compatibility studies, among other procedures. Let’s take a closer look at these aspects.
What are the requirements for installing an offshore wind farm?
The basic conditions required for the installation of an offshore wind farm include the following:
- A positive environmental assessment.
- Comprehensive studies over several years are required. These studies cover areas such as the impact of the farm on shipping, marine life, migratory birds and other aspects.
- Subsequently, a compatibility study....