Improving biodiversity for submarine cabling

15.10.2020

Looking at the big picture – the energy transition and the achievement of the European climate targets – there is no alternative to expanding offshore capacity for the generation and transmission of North Sea wind power. For that reason, both the Dutch and German governments have set ambitious targets for offshore expansion, which the Dutch-German transmission system operator (TSO) TenneT is gradually implementing and has even exceeded for its German North Sea control area. In the individual case, however, each offshore construction and operational measure obviously has an impact on the valuable North Sea and Wadden Sea ecosystems. As TenneT strives to apply and monitor nature-friendly solutions in all of its offshore grid projects, the TSO is now conducting pilot tests with stone coverings of submarine cable intersections.

When the TSCNET shareholder lays submarine cables, e.g. currently for the high-voltage connection of the Hollandse Kust (zuid) wind region, the cables sometimes cross with existing oil and gas pipelines. In such cases, the cables protrude above the seabed and are usually covered with a layer of granite to protect them. To replace granite with alternative solutions that promote biodiversity, TenneT has launched a pilot project in collaboration with the offshore specialist company Van Oord. In this project, different types of stones are deposited at cable crossings to investigate which of these stimulates biodiversity best. In total, the pilot involves twelve locations in the North Sea. In the case of the first six, recently laid submarine cables already cross existing oil and gas pipelines. Another six intersections will follow during the construction of the Hollandse Kust (Zuid) connection in 2021.

On 14 October, the different stones were loaded onto Van Oord’s special vessel to be placed at the cable intersections in the coming weeks. Among them are small calciferous stones from a marble quarry, which are placed at three of the six cable intersections. Comparison with the other three intersections without calciferous stones will allow to assess the difference in the type of marine life developing at these intersections. “Our expectation is that the calciferous stones will ensure that various benthic species will find it easier to nest here and that a different habitat will emerge at these sites. Over the years, ‛artificial reefs’ can emerge at these sites in the North Sea, where plants and small creatures can settle,” explains Saskia Jaarsma, Head Offshore Developments and Large Projects Offshore at TenneT.

TenneT has launched a pilot project to promote biodiversity at submarine cable intersections (picture: Van Oord)

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Deep Dig-It starts work for Hollandse Kust (zuid) grid

24.09.2020

Hollandse Kust (zuid), an offshore wind area in the Dutch North Sea, is located a good 20 kilometres off the coast of the Dutch province of Zuid-Holland. The Dutch-German transmission system operator (TSO) TenneT is installing the related offshore grid to connect the new offshore wind farms in the area via two offshore platforms and submarine cables to the onshore high-voltage substation that is being built in the Maasvlakte industrial and port area. The jacket for the first of these two offshore platforms has recently been installed and the offshore connection project is now making further progress with the start of the laying of the submarine cables on 22 September.

Four 220kV AC cables with a total length of 42 kilometres each are to be installed in the seabed, of which the first two to the Alpha platform will be laid this year. The other two to the Beta platform will follow in 2021. First, the two cables were brought ashore to the planned Maasvlakte substation via direct drilling. Thereupon the TSCNET shareholder started the marine installation, with the first ten kilometres of the route from the coast at Maasvlakte being extremely challenging. Over this distance, the cables cross the entrance to the port of Rotterdam – Europe’s busiest cargo port – and thus need to be buried more than 5.5 metres deep. For this purpose, the contracted specialist company Van Oord uses its Deep Dig-It trencher, an enormous remote-controlled trencher.

The Deep Dig-It is one of the largest and most powerful devices in its class. The trencher weighs 125 tonnes, is more than 17 metres long, well over 8 metres high, and 11 metres wide. With its enormous power it can bury cables deeply even in very hard ground. The trencher is controlled from an offshore installation vessel equipped with a crane to lower and lift out the high-performance machine. The Deep Dig-It moves unmanned over the seabed and creates a deep trench for the cables by liquefying the seabed. Simultaneously, the Deep Dig-It inserts the cables into the trench and seals the seabed afterwards. With work progressing well, Tennet expects the 1,400MW Hollandse Kust (zuid) grid connection to be completed in 2022.

TenneT has started the laying of submarine cables for the Hollandse Kust (zuid) grid connection (picture: Van Oord)

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Jacket for Hollandse Kust (zuid) Alpha platform installed

08.09.2020

The offshore wind area Hollandse Kust (zuid) is located 22 kilometres off the coast of the Dutch province of Zuid-Holland. The Dutch-German transmission system operator (TSO) TenneT will connect the wind farms in this area to the onshore substation in the industrial and port area of Maasvlakte via two offshore platforms – Alpha and Beta – and submarine cables. The jacket for the Hollandse Kust (zuid) Alpha platform was transported to the operation site by a heavy-duty vessel on 5 September and successfully installed on the seabed. The Alpha jacket is 29 meters long, 20 meters wide, 46 meters high and weighs 3200 tonnes. It will be further installed in the coming days.

The two 220kv submarine cables will be connected to the jacket over the next few months. In 2021, the platform top side will be placed on the jacket. The Hollandse Kust (zuid) Alpha platform is expected to be operational by the end of 2021. The projects in this new wind area are part of the large-scale offshore expansion programme of TenneT. By the end of 2023, the TSCNET shareholder will have installed 3.5GW of offshore grid connections in the Netherlands, of which the first 1.4GW have already been achieved with Borssele Alpha and Beta. The connection to follow Hollandse Kust (south) will be Hollandse Kust (nord). For all the wind farms in these two areas, TenneT will deploy five identical 700MW transformer platforms and identical 220kV cable connections. “Such standardisation enables TenneT to complete these projects more efficiently, more quickly, and more economically,” explains TenneT COO Tim Meyerjürgens.

The Dutch national roadmap for offshore development provides for an additional 6.1GW of offshore wind farms in the wind energy areas Hollandse Kust (West), Ten Noorden van de Waddeneilanden, and IJmuiden Ver from 2024 to the end of 2030. For the first two areas, TenneT will again use standardised 700MW offshore platforms. The efficient connection of IJmuiden Ver, which is located further out in the North Sea, partly requires other technologies based on DC instead of AC. IJmuiden Ver will have two offshore transformer platforms with a capacity of 2GW each, which is unique in the offshore wind industry.

TenneT has installed the jacket for the Hollandse Kust (zuid) Alpha platform (picture: TenneT)

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TenneT commisions “green” substation

04.09.2020

In recent years, the seaport of Eemshaven in the province of Groningen in the north of the Netherlands has become more and more important for the Dutch energy transition. Eemshaven has taken on the role of an energy port: with power plants, sustainable generation, connections to offshore wind farms, and submarine cable interconnectors to Norway and Denmark. The Dutch-German transmission system operator (TSO) TenneT – together with regional distribution system operator (DSO) Enexis Netbeheer – now has commissioned the new high-voltage substation Eemshaven as the first substation entirely built for the suply of wind and solar energy.

The station was built as part of the grid reinforcement for the growing amount of sustainably generated energy in the north of the Netherlands which requires an increase in transmission capacity. Other measures of the TSCNET shareholder include a 380kV connection between the Eemshaven (Oudeschip) high-voltage substation and Vierverlaten near Groningen as well as the extension of the Vierverlaten substation. This new 380kV “power highway” will replace the existing 220kV line. Until it is put into operation – scheduled for 2023 – TenneT will commission a provisional 380kV substation in Eemshaven (Oostpolder) in October 2020.

TenneT has put into operation the new substation Eemshaven for the supply of green electricity (picture: TenneT)

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TenneT to invest up to €5bn p.a. for the energy transition

31.07.2020

The Dutch-German transmission system operator (TSO) TenneT has just published its first-half 2020 report. Needless to say, the second quarter of 2020 was characterised by the corona pandemic and the extensive measures taken to ensure a safe and healthy working environment, but despite this, the TSO has made significant progress in developing the transmission grid onshore and offshore and in integrating growing amounts of renewable electricity. At the same time, TenneT has maintained a high level of supply security of 99.99% for 42m end consumers in Germany and the Netherlands.

As Europe’s first cross-border TSO, TenneT promotes the European market integration. The TSCNET shareholder increasingly benefits from its binational integrated approach to grid planning, management, and operation. Manon van Beek, TenneT’s CEO, comments: “Sharing best practices and lessons learned between our German and Dutch operations is paying off more and more in terms of an integrated approach to offshore and onshore grid expansion, better grid utilisation due to European innovations and cross-border energy system planning.”

TenneT currently operates 14 offshore grid connections, twelve in the German and two in the Dutch North Sea. The twelfth offshore grid connection in Germany, BorWin 3, was handed over to TenneT in the first half of 2020. In Dutch waters, the Borssele Alpha grid connection recently transmitted offshore wind power for the first time and the Borssele Beta grid connection has now been commissioned well ahead of schedule. While in the offshore sector experience from the German market is used for the Dutch, the situation is the other way round when it comes to underground cabling. Here, expertise from the Dutch Randstadt project is applied for the DC connections SuedLink and SuedOstLink. These two largest projects of TenneT, which are being entirely installed underground, will be essential for the transmission of wind energy from northern to southern Germany.

Such efforts require huge investments – facilitated by solid financial results: The underlying operating result (EBIT) increased to €414m in the first half of 2020. During the same period, investments in the German and Dutch high and extra-high voltage grids also increased by approximately 30% compared to the first half of 2019, but will do so much more in the future. TenneT expects a further rise in the annual investment volume to €4 to 5bn in the next years. Otto Jager, CFO of TenneT, explains: “We are going to connect growing amounts of renewable electricity to the grid while facilitating the development of a borderless European electricity market. In light of future equity funding needs, the ongoing talks with the German government about a possible equity participation, next to the Dutch State, are welcomed by TenneT.”

TenneT presents Half-year Report 2020 (picture: TenneT)

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Borssele Beta is ready for the grid

31.07.2020

Borssele Beta is the second high-voltage grid connection for offshore wind farms in Dutch territorial waters of the Dutch-German transmission system operator (TSO) TenneT. Like Borssele Alpha, the first Dutch offshore connection, it transmits green electricity generated in the Borssele wind farm area ashore, in this case from the Borssele III, IV and V wind farms. The operators of these three farms can hook up their wind turbines to the high-voltage grid one month earlier than scheduled, as TenneT has just received the “Grid Readiness” certification from the internationally accredited registrar and classification society DNV GL. This means that Borssele Beta fully complies with the criteria of the “Ontwikkelkader windenergie op zee”, the Offshore Wind Energy Development Framework of the Dutch Government.

The Borssele III, IV and V wind farms will have a total capacity of 700MW. The electricity generated here is collected by the offshore transformer platform, which converts the voltage from 66kV to 220kV for transmission via submarine cables to the onshore substation in Borssele. For feeding into the high-voltage grid, the voltage is then converted to 380kV. Marco Kuijpers, Director Offshore Projects at TenneT, comments on the rapid realisation: “We are proud of the fact that the second part of the Borssele high voltage connection is already complete and was realised within budget. Despite all the Covid-19 challenges, we were successful in continuing with the works; a huge achievement from all the contract parties involved.”

By the end of 2023, TenneT will have installed 3.5GW of offshore grid connections in the Netherlands, of which the first 1.4GW have already been achieved with Borssele Alpha and Beta. The next projects are Hollandse Kust (zuid) Alpha and Beta, followed by Hollandse Kust (noord). For these wind farms, TenneT will deploy five identical 700MW transformer platforms and identical 220kV cable connections. This standardisation allows TenneT to realise these projects faster, more efficiently, and more economically. The governmental Dutch follow-up roadmap for offshore development provides for an additional 6.1GW of offshore wind farms from 2024 to the end of 2030, located in the wind energy areas Hollandse Kust (west), Ten Noorden van de Waddeneilanden and IJmuiden Ver. Only for the first two, TenneT will again use standardised 700MW platforms. The efficient connection of IJmuiden Ver, located further out in the North Sea, partly requires other technologies based on DC instead of AC. IJmuiden Ver will have two offshore transformer platforms with a capacity of 2GW each, which is unique in the offshore wind industry.

The Borssele Beta offshore grid connection of TenneT is ready for transmission (picture: TenneT)

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TenneT records 21% increase in offshore transmission

28.07.2020

In the first half of 2020, the wind energy transmitted from the North Sea ashore by the Dutch-German transmission system operator (TSO) TenneT rose to 11.51TWh. This represents an increase of 21.1% compared with the 9.51TWh in the first half of 2019, bringing the North Sea’s share of total wind power generation in Germany to 15.6%. The maximum feed-in volume from offshore wind farms in the German North Sea was 6,035MW on 2 January 2020. By 30 June, the generation capacity of the German North Sea wind farms reached 6,679MW, a volume which is exceeded by TenneT’s offshore transmission capacity of 7,132MW. This amount, which is higher than the German government’s 2020 target (6.5GW for the North and Baltic Seas combined), is currently being achieved with twelve German offshore grid connections.

Tim Meyerjürgens, COO of the TSCNET shareholder, comments on the impressive figures: „The expansion and integration of offshore wind energy is of central importance for the European energy transition.” And offshore development is also keeping pace in the Dutch market: “With Borssele alpha and – from mid-August – Borssele beta, we have now also successfully completed the first two offshore connections in the Dutch North Sea.” TenneT promotes capacity expansion with technical innovations and, according to Meyerjürgens, wants to remain a driving force in the offshore sector: “Ever since TenneT set the standard for plastic-insulated DC cables at 320kV in the offshore sector around ten years ago, we have been defining a new global benchmark for the future with our 525kV DC subsea cable system and its transmission capacity of two GW.”

The 525kV development programme should lead to a standardised cable system that the TSO can employ by 2030 for the three German North Sea projects BalWin1, BalWin2, BalWin3 and the two Dutch projects IJmuiden Ver alpha and beta as well as in potential further projects of equal power and voltage. TenneT is expecting lower costs, greater security of supply and less impact on the environment. These efforts require considerable investment: “We have an investment programme of around €20bn earmarked for connecting offshore wind energy in the Netherlands and Germany by 2030,” explains Meyerjürgens. Important in this context are also hydrogen and hybrid initiatives. The North Sea Wind Power Hubs proposed by TenneT explicitly include power to gas concepts. Furthermore, in June, TenneT proposed to the EU and the Dutch and German governments an integrated energy system approach for the international offshore development.

TenneT increased its transmission of offshore wind energy by 21% in the first half of 2020 (picture: TenneT)

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Launch of the Equigy balancing platform

25.04.2020

To ensure the stability of the grid frequency, transmission system operators (TSOs) all over Europe respond to the increasingly volatile generation of energy from renewable sources and to the loss of reactive power from large power plants. The challenge of keeping production and consumption in balance does not stop at national borders, for which reason the TSCNET shareholders Swissgrid, the TSO from Switzerland, and TenneT, the Dutch-German TSO, are cooperating with the Italian TSO Terna in the crowd balancing platform Equigy. The platform is based on blockchain technology and the internet of things. It is conceived as digital link between the so-called TSO ancillary service markets and the market players that deliver balancing services. TSCNET customer Energinet, the Danish TSO, has formally expressed its intention to join the consortium, which would extend Equigy’s roll-out to Denmark.

With their cross-border cooperation, the consortium of Swissgrid, TenneT, and Terna wants to set a new electricity-balancing standard, improve the integration of renewables, and provide more flexibility to reduce the renewables’ random impact on the grid. As with previous, regionally limited balancing projects, Equigy aims to unlock flexibility by actively involving small and distributed consumer-based generation and consumption units in grid stabilisation. This involvement enables owners of small-scale assets to play a key role in the transformation of the energy sector by optimising their interaction with the grid. Since Equigy processes multiple small transactions, it requires a secure and scalable solution that ensures trust and transparency between all parties involved. The common vision of the participating TSOs is clear: Millions of households will stabilise the electricity grid in the future.

Open and free of charge
Equigy is based on block chain technology to execute transactions from millions of individual systems securely, cost-effectively, and transparently. This creates a single, immutable, and secure data source from which all parties can benefit. Precise rules and regulations allow consumers, businesses, and manufacturers to easily market the flexible capacity of electric vehicles, household batteries, and heat pumps in all participating countries, regardless of location, thereby simplifying access to the electricity market. At the same time, all local or regional flexibility platforms can be connected to the Equigy platform so that as much flexibility as possible can be bundled. This means: Equigy is not exclusive and can be integrated into existing grid stabilisation processes. The technology and software are open-source and provided free of charge to promote the development of secondary applications in the energy value chain. Equigy has now been successfully launched, and the pilot project to test the technology will run until the end of 2020.

In Switzerland, the project has attracted a lot of interest. Numerous partners have expressed an interest in participating. Yves Zumwald, CEO of Swissgrid, comments: “We are proud to be a founding partner of Equigy. It’s only natural that this ambitious initiative is being driven by TSOs. We are not subject to commercial constraints and are able to operate the new platform adopting a neutral position.” Manon van Beek, CEO of TenneT, can also be pleased to have various Equigy partners in Germany and the Netherlands. She emphasises the European dimension of the project: “Equigy originated from European cooperation. In a common European market, we will have to develop solutions together. We already have the same sockets. It would be a shame and unnecessarily expensive to develop different systems.”

Expansion to the north
The Danish TSO Energinet recognises the potential of Equigy and is highly interested in participating. The consortium behind Equigy appreciates this interest. Swissgrid, TenneT, Terna, and Energinet have thus signed a Letter of Intent in which the parties confirm their common interest in including Energinet in Equigy. Energinet will now examine the possibilities of becoming part of the cooperation. All partners aim to take a decision on Energinet’s accession before the end of this year. Søren Dupont Kristensen, CEO of Energinet Electricity System Operator, explains: “We are now investigating the potential of this platform in the context of the Danish energy system. Based on our findings, we will decide on joining the collaboration regarding the platform.”

The blockchain based crowd balancing platform Equigy has been launched by Swissgrid, TenneT, and Terna

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TenneT develops 525kV HVDC offshore cable system

20.04.2020

In just 10 years, 40% of the Dutch electricity demand will be covered by offshore wind power. Furthermore, the Dutch-German transmission system operator (TSO) TenneT will increase the German offshore grid connection capacity to 17GW by 2030. To meet these high ambitions, the TSCNET shareholder expands its current connection plans and additionally intends to implement a total of five 2GW offshore connections in the Dutch IJmuiden Ver wind energy area and in the German LanWin and BalWin areas. However, since such 2GW offshore grid connections do not yet exist, innovative project development is necessary.

The integration of 2GW offshore grid connections into the onshore grid requires a suitable certified cable system that operates at a voltage level of 525kV DC using extruded insulation types. TenneT has contracted a total of eight cable suppliers to develop these “next-level” submarine cables for the intended high-performance offshore connections. An extruded 525kV high voltage direct current (HVDC) cable system with a 2GW output is currently not implemented in any project worldwide and would thus set a new standard for the connection of offshore wind farms.

The new cable system is expected to reduce manufacturing and installation costs for the entire connection concept, including the HVDC offshore and onshore transformer stations. A reduction in dredging costs is also anticipated, as all cables can be laid in a single trench. Moreover, fewer offshore platforms and shore stations are required, resulting in lower emissions and environmental impact. The adoption of a 525kV 2GW grid concept is a logical step for TenneT after the installation of eight standard AC connections in the Netherlands. The TSO can already draw on extensive experience with DC projects in Germany.

TenneT has contracted eight cable suppliers to develop a 525kV HVDC offshore cable system with a 2GW capacity (exemplary picture of Riffgat cables: TenneT)

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Borssele Beta platform topside ready for sail out

20.03.2020

In the Borssele offshore wind farm area in the south-western part of the Dutch North Sea, Borssele Alpha, the first and largest connection system for wind farms from the Dutch-German transmission system operator (TSO) TenneT in Dutch territorial waters, is already in operation. Now the TSCNET shareholder is in the process of installing Borssele Beta to connect further wind farms, in this case Borssele III and IV that are still under construction. The topside of the offshore transformer platform for Borssele Beta is now ready for shipping. It was built at the construction yard of the offshore platform specialist HSM Offshore in Schiedam in the Rotterdam-The Hague metropolitan area and will be put to sea on 22 March 2020.

When the pontoon carrying the 3,650-tonne superstructure arrives at its destination, a crane vessel will place the top side on the platform substructure (jacket). The top side comprises three interior levels and an outer deck. It is 25 metres high, 58 metres long and 32 metres wide. The Borssele Beta grid connection will have a capacity of 700MW and is scheduled to be commissioned on 1 September 2020. The Borssele III, IV, and V wind farms, which are located about 22km from the coast, will be connected to this transmission system. Borssele V by the Two Towers consortium has been designated as an innovation site within the wind farm zone and will be connected to Borssele Beta. The electricity generated by these offshore wind farms will then be transported ashore via two 67-kilometre-long cables to the high-voltage transformer station near the town of Borssele in the Dutch province of Zeeland.

Marco Kuijpers, Director Offshore Projects a TenneT, comments on the TSO’s progress in offshore expansion: “With this platform, the offshore grid that TenneT is building in the Dutch North Sea is definitively taking shape. Borssele Beta is the second offshore grid connection built by TenneT. Over the coming eight years we will build a new offshore connection every year. I am proud that we are able to make such a significant contribution to the energy transition in which offshore wind energy plays a crucial role.”

TenneT also assumes a marine ecological responsibility and makes its offshore platforms available for other uses. The TSO cooperates in this respect with the Dutch Directorate-General for Public Works and Water Management (Rijkswaterstaat). The Borssele Beta offshore platform therefore also features a Maritime Information Provision Service Point (MIVSP). This is a monitoring station with various monitoring systems, such as nautical radars, meteorological systems and ecological monitoring systems. Similar stations are being installed on every TenneT offshore transformer platform.

The topside of the offshore transformer platform Borssele Beta of TenneT is constructed and ready for shipping (picture: HSM Offshore)

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