TGS | Powered by 4C Offshore

4C is now TGS

We are excited to announce a significant milestone in 4C Offshore's journey. Our integration into the TGS family marks the beginning of a new era in offshore wind market intelligence.

Learn what this means for you!

Offshore Wind Transmission System Intelligence Database

Search The Database

TGS | 4C Offshore has developed a Wind Transmission System Database to help navigate the complex landscape of offshore wind farm export. This database provides comprehensive information and insights on converters, substations, transmission cables and export cables involved in offshore wind transmission systems, and can be accessed with the company's marine intelligence software 4C Offshore. Developers, investors, and consultants in the offshore wind industry can use the Offshore Wind Transmission System Intelligence Database to access the necessary information for success. HVAC and HVDC systems are commonly used, with the latter increasing as distances and capacities grow. This tool can make offshore wind transmission easier to understand, helping to facilitate smoother operations and more efficient development.

The 4C Offshore software is a comprehensive suite of reports, databases and online tools for the offshore wind sector and adjacent industries. 4C Offshore allows us to create our sector-specific subscriptions to help people gather intelligence to inform decisions, for example, our offshore wind farm database subscription. Sector subscriptions are fuelled by wide-reaching data and insights to help organisations make informed decisions.

Subscriptions include:

  • Sector-specific on- and offline databases
  • Reports
  • Newsletters
  • Online Tools

This enables:

  • Competitor analysis
  • Industry analysis
  • Offshore wind project pipeline opportunity discovery
  • Resource assessment

  • Offshore wind cable database.
  • Interconnector cable database.
  • Project details, supply chain and contracts awarded are all listed.
  • Graphs and charts - market shares for installers and manufacturers.
  • Charts detailing company activities for global interconnector projects.

4C Offshore marine intelligence software provides you with exclusive access to a range of specialised services, including the Global Offshore Wind Export Cables Database.

Transmission Systems Overview

Transmission System Country Owner(s) Wind Farm(s)

An Introduction To Offshore Energy Transmission

Offshore wind transmission is becoming an increasingly important technology for renewable energy.

Offshore wind farms are typically located in shallow waters, where they can generate energy from the wind. The turbines on the wind farm are connected to each other through an electrical network, and the power generated by the turbines is collected and sent to a substation located on the wind farm.

From the substation, the energy is transmitted to the onshore grid through a subsea cable. The onshore grid then distributes the energy to consumers.

While the basic process of offshore wind energy transmissions may seem straightforward, several challenges are associated.

Export Cables

Transmission of Offshore Wind Energy

Offshore wind energy must be transmitted from offshore turbines to the onshore grid. Two primary types of offshore transmissions exist: alternating current (AC) and direct current (DC). AC transmission systems are the traditional method for transmitting electricity, but DC systems are becoming increasingly popular due to their efficiency over long distances. DC transmission systems can also transmit large amounts of electricity over a single cable, reducing the number of cables needed for offshore transmissions.

The technical specifications of an average offshore wind energy transmission system can vary depending on factors such as the distance from the wind farm to the onshore grid and the amount of energy to be transmitted. However, some general characteristics are common to most offshore transmissions types.

Subsea Cables

Offshore wind energy is typically transmitted through subsea cables designed to withstand harsh environmental conditions such as strong currents and rough seas. These cables are made of high-quality materials such as copper or aluminium and are typically coated with layers of insulation to prevent damage and energy loss. The cable size will depend on the amount of energy transmitted and the distance between the wind farm and the onshore grid.


At the wind farm, the energy generated by the turbines is collected and sent to a substation, which converts the energy from AC to DC. This conversion is necessary for efficient transmission over long distances. The substation is also responsible for controlling the voltage and frequency of the energy before it is transmitted to the onshore grid.

High-Voltage Direct Current (HVDC) Technology

Many offshore transmissions systems use HVDC technology to overcome the energy loss associated with long-distance transmission. HVDC cables can transmit energy over longer distances with less energy loss than traditional AC cables. HVDC technology is also more efficient at transmitting power between different voltage levels, making it ideal for offshore wind energy transmission.

Grid Connection

Once the energy is transmitted to the onshore grid, it is typically connected to a high-voltage substation, which steps up the voltage of the power before it is distributed to consumers. The grid connection will depend on the location of the wind farm and the existing electrical infrastructure in the area.

Challenges in Offshore Wind Energy Transmission

There are some key challenges when it comes to offshore wind energy transmission and the infrastructure associated with it. However, there are also solutions to these challenges, and organisations continue to innovate and collaborate to develop new and better ways to traverse these obstacles.



Offshore wind farms are located far from the shore, and the distance presents a challenge for transmitting energy to the grid. The longer the distance, the greater the energy loss during transmission.


One solution to the distance challenge is to use high-voltage direct current (HVDC) technology. HVDC cables can transmit energy over longer distances with less energy loss than traditional alternating current (AC) cables.



The subsea cables used for offshore wind energy transmission are subjected to harsh environmental conditions, including strong currents and rough seas. These conditions can cause damage to the cables, leading to power outages and expensive repairs.


Cables can be protected using various methods, including armour, coatings, and flexible joints. These measures can help prevent damage to the cables and reduce the need for costly repairs.



The installation and maintenance of subsea cables for offshore wind energy transmission can be expensive, which adds to the overall cost of offshore wind energy.


Collaboration between wind farm developers, cable manufacturers, and grid operators is crucial. By working together, these parties can optimise the design and installation of subsea cables, leading to cost savings for all involved.

Planning and Building Offshore Wind Transmission Networks

The planning and building of offshore wind transmission networks must consider regulatory requirements, such as permits and environmental impact assessments.

Offshore wind energy is a rapidly growing sector in the renewable energy industry, and as such, there is a great demand for the planning and construction of offshore wind transmission networks. The following article outlines the critical steps in planning and building offshore wind transmission networks for an expert audience.

The first step in planning an offshore wind transmission network is to select a suitable site for the wind farm. The site selection process will consider factors such as water depth, wind speed, and distance from shore. Once a site has been selected, feasibility studies will be conducted to assess the site's potential for wind energy generation and to identify any potential obstacles or challenges that may arise during construction and operation.

After the site has been selected and feasibility studies have been completed, the wind farm can be designed. This includes choosing the type of wind turbine to be used, determining the layout of the turbines, and designing the electrical infrastructure for the wind farm. The electrical infrastructure will include subsea cables to transport the energy generated by the turbines to shore and an onshore substation to connect the wind farm to the grid.

Before construction can begin, environmental impact assessments (EIAs) must be conducted to identify and assess any potential environmental impacts that may result from the construction and operation of the wind farm and associated transmission infrastructure. These assessments will also identify any mitigation measures that may be necessary to minimise the impact on the environment.

Once the EIAs have been completed and any necessary mitigation measures have been identified, permits and approvals must be obtained from regulatory bodies to ensure compliance with local, state, and federal regulations. This may include licences for constructing, operating and decommissioning the wind farm and transmission infrastructure.

Once all necessary permits and approvals have been obtained, construction of the wind farm and associated transmission infrastructure can begin. The construction process will involve the installation of the turbines, the subsea cables to transport energy to shore, and the onshore substation to connect the wind farm to the grid.

After construction, the wind farm and transmission infrastructure will undergo commissioning, which involves testing and verifying the system's functionality. Once the wind farm is operational, ongoing maintenance and monitoring will be required to ensure efficient and reliable operation of the transmission network.

Economics of Offshore Wind Transmission

The economics of offshore wind transmission must be considered when evaluating the feasibility of offshore wind energy production. While the cost of constructing offshore wind turbines is higher than that of onshore turbines, offshore wind transmission costs are comparable to that of other energy transmission methods, such as natural gas pipelines. According to a report by the International Renewable Energy Agency, the cost of transmitting electricity from offshore wind turbines has decreased by more than 50% since 2012.

Environmental Impact

The impact of offshore wind transmission on the environment must also be considered. While offshore wind energy production is generally considered environmentally friendly, constructing and maintaining offshore wind transmission systems can harm the marine environment. For instance, the installation of cables can disturb the seabed and harm aquatic life.

However, the impact of offshore wind transmission on the environment can be minimised through careful planning and mitigation measures.

Safety and Maintenance of Offshore Wind Transmission Networks

The safety and maintenance of offshore wind transmission networks are critical to their success. Offshore wind transmission systems must be designed to withstand the harsh marine environment and prevent hazards such as cable failures and fires. Maintenance of offshore wind transmission systems is also critical, and regular inspections and repairs must be conducted to ensure the systems function correctly.

A worker climbing a turbine

Advancements in Offshore Wind Transmission Technology

Advancements in offshore wind transmission technology are occurring rapidly. Offshore wind turbines are becoming more extensive and efficient, increasing their electricity generation capacity. Additionally, advances in cable technology are increasing the efficiency of offshore wind transmission systems. For example, cable systems are being developed to transmit electricity over longer distances with less energy loss.

Here are some of the most recent innovations and new technologies in offshore wind energy transmission:

HVDC transmission

High Voltage Direct Current (HVDC) transmission systems are being used to transfer large amounts of power over long distances with minimal losses. HVDC is more efficient than traditional AC transmission, making it ideal for transmitting power from offshore wind farms.

Subsea cables

New subsea cables that are more durable, reliable, and efficient in transmitting power over long distances are being developed. These cables are also being designed to withstand harsh weather conditions and resist damage from fishing and shipping activities.

Floating substations

Offshore wind farms require substations to convert the power generated by the turbines into a form that can be transmitted to the grid. Floating substations that can be positioned closer to the turbines are being developed, reducing the length of the subsea cables required and increasing efficiency.


The use of digital technologies such as sensors, data analytics, and machine learning is helping to optimise offshore wind energy transmission. These technologies enable real-time monitoring and control of wind turbines and transmission systems, improving their efficiency and reducing maintenance costs.

Hybrid solutions

Hybrid solutions that combine offshore wind energy with other renewable energy sources, such as solar or wave power, are being explored. These solutions can provide a more stable and consistent supply of energy, making it easier to integrate offshore wind power into the grid.

Future of Offshore Wind Transmission

The future of offshore wind transmission is promising. The International Energy Agency predicts that offshore wind energy production will grow 15-fold by 2040, generating more than 1,000 gigawatts of electricity. Additionally, advancements in offshore wind technology and transmission systems will continue to drive down costs and increase efficiency, making offshore wind energy more competitive with traditional energy sources.

Offshore wind transmission is a critical technology for the future of renewable energy. While there are challenges associated with building and maintaining offshore wind transmission networks, the benefits of offshore wind energy production are significant.