The installation of foundations for all 100 wind turbines, as well as the support structures for two offshore substations belonging to the Bałtyk 2 and Bałtyk 3 projects, with a combined capacity of 1.44 GW, has been completed in the Baltic Sea. This marks the culmination of a months-long installation campaign, itself the result of several years of technical, design and logistical preparations carried out by Equinor and the Polenergia Group.

At the peak of the works, around 35 vessels were operating simultaneously across the construction area, with hundreds of specialists involved both offshore and onshore. Among them was Thialf, one of the world's largest installation vessels, measuring more than 200 by 88 metres and owned by Heerema, which was responsible for installing the turbine foundations and the support structures for the offshore substations.

The scale of the activities carried out in parallel shows that completion of the foundation installation is one of the most visible signs of progress on the energy projects currently being developed in Poland. For the first time, the full layout of the future turbine locations and electrical infrastructure can now be seen across both wind farms, which in the coming years will enable electricity to be generated from the Baltic Sea. The works were carried out while meeting environmental requirements and conducting environmental monitoring at sea. The campaign was completed in accordance with the highest safety standards, demonstrating the expertise and organisational efficiency of the team required to deliver some of the world's most complex offshore projects.

Foundation installation was just one element of a much larger undertaking. At the same time, export cables were being laid offshore and brought into the onshore infrastructure, preparations were under way for the installation of the array cable network connecting the turbines, work was being carried out to protect infrastructure on the seabed, and preparations were being made for the next stages of offshore construction. Meanwhile, further components were being manufactured at production facilities, while onshore infrastructure needed to transmit the electricity to the national power system was being developed. The Port of Łeba and the operations and maintenance base being established there also made an important contribution to the installation campaign – facilities that are already supporting vessels working on the construction of Equinor and Polenergia's wind farms.

"The completion of foundation installation demonstrates the scale of the progress achieved offshore. Behind each of these structures are years of preparation, hundreds of specialists and close cooperation between teams at sea and on land. This stage was completed thanks to offshore expertise and a consistent approach to safety and quality" – said Michał Jerzy Kołodziejczyk, CEO of Equinor Poland.

“The construction of offshore wind farms is an undertaking in which every element depends on the others. Foundations, cables, offshore substations, onshore infrastructure and logistics all have to be developed in parallel and according to schedule. Delivering such a project requires close cooperation between numerous teams, as well as the consistent development of the capabilities of Poland's entire offshore wind sector. Thanks to Poland's first offshore investments, including Bałtyk 2 and Bałtyk 3, it is therefore not only new energy infrastructure that is being developed, but also specialist expertise, local content and industrial capacity for decades to come” – commented Adam Purwin, CEO of Polenergia.

What You Don't See During the Construction of an Offshore Wind Farm

For most observers, the installation of foundations means seeing a large vessel and steel structures appear at sea. In reality, however, it is one of the most demanding stages in the construction of an offshore wind farm.

Each turbine foundation consists of a monopile driven into the seabed and a transition piece installed on top of it. It is on these structures that the towers and turbines of the wind farms will be installed in 2027. For the Bałtyk 2 and Bałtyk 3 projects, the monopiles are up to approximately 70 metres long. The transition pieces installed on them are approximately 17 metres high and weigh around 400 tonnes. Importantly, the transition pieces were delivered and installed together with most of the permanent equipment mounted on them, including work platforms, access systems and crew transfer points. The transition piece is installed immediately after the monopile has been driven, significantly reducing the scope of subsequent offshore works.

Each of the 100 modern turbines will have an installed capacity of 14.4 MW and stand 260 metres tall. One rotation of the blades of such a turbine has the capacity to generate enough electricity to meet a household's four-day power consumption.

Alongside the installation of the turbine foundations, support structures, known as jackets, were also installed for the two offshore substations (OSS), which will eventually receive and transmit electricity generated by the wind farms to shore. The jackets are lattice structures measuring approximately 30 by 30 metres and standing 50 metres high, designed specifically to operate in extreme conditions. Each of the support structures, weighing 3,500 tonnes, is anchored to the seabed using eight piles. The next step will be to install the main parts of the substations, known as the topsides, on these platforms. Once completed, the offshore substations serving Equinor and Polenergia's wind farms will stand approximately 100 metres high and weigh 7,000 tonnes. This is equivalent to the weight of 280 fully loaded lorries, which, if lined up one behind another, would stretch for more than four kilometres.

A significant proportion of the work at the Bałtyk 2 and Bałtyk 3 construction site takes place beyond the range of human vision. Remotely operated underwater vehicles (ROVs) play an important role here, being used to inspect the seabed, monitor infrastructure and check completed works. For offshore teams, they are their “eyes and ears” beneath the surface, enabling them to monitor infrastructure located several dozen metres underwater.

The foundations have to be installed with exceptional precision. Despite working in open sea conditions, amid waves, wind and currents, permissible deviations from vertical are measured in fractions of a degree.

Once operational, Bałtyk 2 and Bałtyk 3 will be capable of generating enough electricity to meet the annual demand of more than two million households. The first electricity from the projects is scheduled to be generated in 2027, with the wind farms expected to become fully operational in 2028.

Photos: Polenergia press release