Overview
Kriegers Flak is an operational offshore wind farm situated in the Baltic Sea, specifically located on the Danish side of the reef that shares its name. The facility has a total installed capacity of 604.8 MW, making it a significant contributor to the regional renewable energy mix. Owned and operated by Vattenfall, the wind farm was commissioned in 2021, marking a key milestone in the expansion of offshore wind infrastructure in Northern Europe. The project is strategically positioned to leverage the strong and consistent wind resources characteristic of the Baltic Sea, providing a stable source of electricity generation for the surrounding grid systems.
Integration with the Denmark-Germany Interconnector
A defining feature of the Kriegers Flak wind farm is its direct integration with a major cross-border energy infrastructure project. The facility forms an integral part of a new 400 MW interconnector linking Denmark and Germany. This interconnection enhances energy security and facilitates the efficient exchange of electricity between the two nations. By connecting the wind farm directly to the transmission line, the project reduces the need for extensive onshore cabling and optimizes the flow of renewable energy from the generation site to key consumption centers in Germany. This setup exemplifies the growing trend of integrating offshore wind generation with high-voltage direct current (HVDC) transmission technologies to maximize efficiency and reduce losses over long distances.
The strategic placement of Kriegers Flak on the reef allows for optimal access to wind resources while minimizing environmental impact on coastal areas. The collaboration between Vattenfall and the broader energy infrastructure network underscores the importance of cross-border cooperation in achieving energy transition goals. The 604.8 MW capacity of the wind farm, combined with the 400 MW interconnector, provides a robust framework for delivering clean energy to both Danish and German consumers, supporting the regional shift towards a more sustainable and resilient power grid.
Site Selection and Location
The Kriegers Flak wind farm is situated in the Baltic Sea, specifically located on the Danish portion of the reef that shares its name. This strategic positioning places the installation within Danish territorial waters, facilitating its integration into the regional energy infrastructure. The site's geographic coordinates and maritime boundaries are defined by the reef's natural formation, which serves as the foundation for the offshore array. The bathymetry of the selected area is characterized by moderate water depths, which are critical for the engineering design of the turbine foundations. The depth at the Kriegers Flak site ranges from 16 m to 25 m. This depth profile is significant for offshore wind development, as it allows for the utilization of specific foundation technologies that balance structural stability with installation costs. The relatively shallow nature of the Baltic Sea in this region contrasts with deeper North Sea installations, influencing the choice of monopile or jacket foundations for the turbines. The wind farm is part of a broader energy corridor in the Baltic Sea, sharing proximity to other major offshore installations. Notably, the site is in close proximity to the EnBW Baltic 2 wind farm. This clustering of renewable energy assets in the region highlights the strategic importance of the Danish-German border area for offshore wind development. The presence of multiple farms in adjacent waters necessitates coordinated grid connection strategies and maritime traffic management. The location was chosen to support the new 400 MW interconnector between Denmark and Germany, which is integrated with the wind farm's output. This interconnector, known as the Kriegers Flak Link, utilizes the wind farm's platform to house the converter stations, thereby optimizing the use of marine space and reducing the overall footprint of the cross-border transmission infrastructure. The synergy between the wind farm and the interconnector represents a key aspect of the site selection rationale, enhancing the economic and operational efficiency of the project.| Parameter | Specification |
|---|---|
| Location | Danish part of the Kriegers Flak reef, Baltic Sea |
| Water Depth Range | 16 m to 25 m |
| Proximate Installation | EnBW Baltic 2 |
| Integrated Infrastructure | 400 MW Denmark-Germany Interconnector |
How does the combined grid solution work?
Kriegers Flak represents a significant engineering shift in offshore wind integration, utilizing a serial connection strategy that links the wind farm directly to the power grids of two distinct countries: Denmark and Germany. This configuration allows the wind farm to function as a hybrid asset, simultaneously generating electricity and facilitating cross-border energy trade. The system relies on a high-voltage direct current (HVDC) link to bridge the geographical gap between the Danish offshore site and the German onshore grid, optimizing transmission efficiency over the Baltic Sea.
Serial Connection and Power Flow
The operational model involves connecting the offshore wind turbines in series with the HVDC interconnector. This setup enables the wind farm to feed power into both the Danish and German grids depending on load demands and market prices. The connection facilitates a bidirectional flow of energy, where the wind farm can export surplus generation to either country or import power to balance local fluctuations. This serial architecture reduces the need for separate subsea cables for generation and transmission, streamlining the offshore infrastructure.
Conversion from DC to AC
Power generated by the wind turbines is initially in alternating current (AC) form. However, for efficient long-distance transmission across the Baltic Sea, the power is converted to direct current (DC). This conversion occurs at offshore converter stations, which transform the AC output from the turbines into HVDC. The DC power is then transmitted via subsea cables to the onshore end of the link. Upon reaching the German coast, the power undergoes a second conversion process, transforming back from DC to AC to integrate seamlessly with the existing German grid infrastructure.
HVDC Converter Substation in Bentwisch
The onshore termination point of the Kriegers Flak interconnector is located in Bentwisch, Germany. Here, a specialized HVDC converter substation manages the final stage of power integration. This facility houses the necessary equipment to convert the incoming HVDC power back into AC, matching the frequency and voltage standards of the German transmission network. The Bentwisch substation plays a critical role in stabilizing the grid connection and ensuring reliable power delivery to German consumers.
| Parameter | Value |
|---|---|
| Interconnector Capacity | 400 MW |
| Wind Farm Capacity | 605 MW |
| Transmission Type | HVDC |
| Onshore Location | Bentwisch, Germany |
Tender Process and Economic Profile
The development of the Kriegers Flak wind farm was formalized through a competitive tender process that concluded in 2016. Vattenfall secured the rights to develop the project, emerging as the preferred bidder for the offshore site located on the reef of the same name in the Baltic Sea. The tender results highlighted the economic viability of the project, with Vattenfall securing the lease at a price of €49.90 per MWh. This pricing structure was a critical factor in the project's financial modeling, influencing the subsequent construction and operational phases that led to its commissioning in 2021.
Tender Pricing and Economic Comparison
The €49.90 per MWh price point achieved by Vattenfall in the 2016 tender placed Kriegers Flak among the more competitively priced offshore wind projects of its era. This economic profile was essential for integrating the 604.8 MW capacity into the broader regional energy market. The project’s economic structure was designed to support not only power generation but also the infrastructure requirements of the associated interconnector. The tender process evaluated various economic indicators, ensuring that the selected operator could deliver the project within the projected cost frameworks.
| Parameter | Value / Detail |
|---|---|
| Winning Bidder | Vattenfall |
| Tender Year | 2016 |
| Price per MWh | €49.90 |
| Installed Capacity | 604.8 MW |
| Commissioning Year | 2021 |
When compared to other major offshore wind developments such as Borssele, Kriegers Flak demonstrated a distinct economic profile driven by its specific location and interconnector synergy. While Borssele represented a larger scale of development in the North Sea, Kriegers Flak’s integration with the 400 MW interconnector between Denmark and Germany added a layer of economic complexity and benefit. The interconnector allows for the export of surplus wind energy, enhancing the revenue streams beyond simple feed-in tariffs. This dual-purpose infrastructure—combining generation and transmission—was a key differentiator in the economic assessment of the project during the tender phase. The successful execution of the tender and subsequent construction underscores the strategic importance of Kriegers Flak in the Danish offshore wind portfolio.
Construction and Commissioning
Construction of the Kriegers Flak offshore wind farm commenced in 2018, marking the beginning of a multi-year development phase in the Baltic Sea. The project involved significant coordination between the primary operator, Vattenfall, and key technology suppliers to establish the 605 MW capacity installation. The site is located on the Danish part of the reef of the same name, serving as a critical component of the broader energy infrastructure linking Denmark and Germany.
Turbine Installation
Siemens Gamesa was responsible for the installation of the wind turbines that make up the farm's generating capacity. The installation process required precise engineering to accommodate the specific conditions of the Baltic Sea environment. The turbines were deployed to achieve the total installed capacity of 605 MW, which is equivalent to 604.8 MW as recorded in operational data. This phase was crucial for establishing the physical generation assets of the project, ensuring that the mechanical and electrical components were correctly positioned and secured on the seabed foundations.
Cable Commissioning and Interconnection
A critical aspect of the Kriegers Flak project was the integration of a new 400 MW interconnector between Denmark and Germany. NKT was tasked with the commissioning of the cables necessary for this interconnection. The cable systems were designed to transmit the generated electricity efficiently from the offshore turbines to the onshore grids of both countries. This infrastructure enhancement facilitated greater energy exchange and grid stability between the two nations. The commissioning of these cables was a complex logistical operation, involving the laying and testing of subsea power lines to ensure reliability and capacity performance.
The construction and commissioning efforts culminated in the official commissioning of the wind farm in 2021. This date marks the point at which the facility became fully operational, delivering power to the grid and fulfilling its role in the regional energy mix. The successful completion of the project in 2021 represented a significant milestone for offshore wind development in the Baltic Sea, demonstrating the viability of large-scale wind farms combined with international interconnectors.
Why it matters
Kriegers Flak represents a pivotal innovation in North European energy infrastructure as the first offshore wind farm integrated with a high-voltage direct current (HVDC) interconnector. This combined grid solution fundamentally alters how renewable energy is captured, transmitted, and utilized across national borders. By co-locating the wind generation assets with the transmission link between Denmark and Germany, the project addresses two critical challenges in the energy transition: the intermittency of wind power and the need for efficient cross-border capacity.
Grid Reliability and Transmission Efficiency
The integration of the 605 MW wind farm with the 400 MW interconnector creates a synergistic effect on grid stability. Traditional offshore wind farms often require separate subsea cables to feed power into the national grid, which can lead to congestion and curtailment when local demand fluctuates. Kriegers Flak’s design allows wind-generated electricity to flow directly into the HVDC link, smoothing out supply variations and enhancing the reliability of power delivery to both Denmark and Germany. This structural approach reduces the dependency on synchronous generators for frequency regulation, a key metric for grid resilience in regions with high shares of variable renewables.
Economic Impact on Electricity Markets
By improving the efficiency of cross-border transmission, Kriegers Flak contributes to reducing electricity prices in both Denmark and Germany. The project facilitates the arbitrage of energy between the two markets, allowing cheaper wind power from Denmark to flow to Germany during peak demand periods, and vice versa. This dynamic helps to flatten price spikes and enhances the overall cost-effectiveness of the regional energy mix. The operational status of the farm since 2021 has provided real-world data on how such integrated solutions can lower the levelized cost of energy for consumers in both nations.
Strategic Role in the Baltic Sea Energy Corridor
Located on the Danish part of the reef of the same name in the Baltic Sea, Kriegers Flak serves as a strategic node in the broader Baltic Sea energy corridor. Its success demonstrates the viability of combining offshore wind generation with interconnectors, setting a precedent for future projects in the region. The project’s operator, Vattenfall, has leveraged this model to optimize asset utilization and maximize the return on investment for both the wind farm and the transmission infrastructure. This approach is increasingly seen as a blueprint for integrating large-scale offshore wind into the European supergrid.
What are the technical specifications of the turbines?
Kriegers Flak is equipped with 72 wind turbines manufactured by Siemens Gamesa, each with a rated capacity of 8.4 MW. This configuration results in a total installed capacity of 604.8 MW, which aligns with the wind farm's overall operational specifications in the Baltic Sea. The selection of the 8.4 MW turbine model reflects the specific wind resource characteristics of the Kriegers Flak reef area, optimizing energy yield for the site's conditions.
Turbine Configuration and Capacity
The 72 Siemens Gamesa units represent a significant deployment of mid-to-large scale offshore wind technology. Each turbine contributes 8.4 MW to the grid, providing a consistent power output profile that supports the stability of the regional energy mix. The total capacity of 604.8 MW is a direct aggregation of these individual unit ratings, ensuring precise alignment with the wind farm's design parameters. This standardized approach to turbine selection facilitates maintenance and operational efficiency across the entire array.
Foundation Systems
The turbines are mounted on monopile foundations, a common structural solution for offshore wind installations in the Baltic Sea. Monopiles consist of large cylindrical steel tubes driven deep into the seabed, providing robust support for the turbine nacelle and rotor assembly. This foundation type is particularly suited to the relatively shallow waters and soil conditions found at Kriegers Flak, offering a balance of structural integrity and cost-effectiveness. The monopile design minimizes the visual impact of the wind farm while ensuring long-term stability against wind and wave loads.
The integration of these 72 turbines and their monopile foundations is a critical component of the Kriegers Flak project's broader infrastructure goals. The wind farm not only generates electricity but also plays a key role in the 400 MW interconnector between Denmark and Germany, enhancing cross-border energy exchange. The technical specifications of the turbines and foundations are thus aligned with the dual objectives of power generation and grid connectivity, reflecting a comprehensive approach to offshore energy infrastructure development.