Challenges of the green transition in Denmark

05.11.2020

In Denmark, as in Europe in general, the energy transition presents new and challenging tasks for the players in the energy sector. To improve the information basis and to prepare adequately for these challenges, TSCNET customer Energinet, the Danish transmission system operator (TSO), has created two reports on long-term development needs in the Danish energy system. There are two reports, as Energinet is not only the national TSO for electricity, but also for gas.

The forecasts in “Long-term Development Needs in the Power Grid” are similar to those of other European TSOs and allow similar conclusions. Not surprisingly, Denmark, as a world leader in renewable energy, needs to make even greater efforts to integrate these amounts of energy from renewable sources. In concrete terms, the TSO expects that by 2040 the maximum generation of wind turbines and solar cells could increase from 7.4GW today to perhaps 26GW. Such a tripling or quadrupling will cause problems for the current high-voltage grid, which is not designed to transmit such large amounts of energy.

Some challenges may not be due for 10-20 years, but others are already on the doorstep. In some places in Denmark, large-scale local production from wind and solar energy is already putting a considerable strain on the power grid. Hanne Storm Edlefsen, Head of the Strategic Planning division in Energinet Elsystemansvar, the TSO’s electricity system operator branch, emphasises the need for cooperation at all economic, political, and social levels to make the green transition a success and, for example, to ensure that “a doubling of electricity demand does not mean twice as many power pylons and overhead lines”.

The analyses show, among other things, the locations in Denmark where high-voltage grid extensions are required, either as underground cables or overhead lines. However, Edlefsen also points to other solution approaches beyond mere expansion: The proper placement of wind farms or large photovoltaic systems can reduce the need for grid reinforcement. And electrolysis plants of the future, which convert green electricity into hydrogen and other green fuels, could be located close to major green generation units so that electricity need not be transported across the country.

Energinet has presented two reports on the Danish long-term development needs in the power grid and in the gas system (picture: Energinet)

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> See Energinet press release (html)
>Open report on needs in the power grid (pdf, 7.42MB)

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TransnetBW starts modernisation of Daxlanden substation

04.11.2020

The Daxlanden substation near Karlsruhe is an important node in the transmission grid of TransnetBW, the German transmission system operator (TSO) from the federal state of Baden-Württemberg. It is also the central link between two 380kV grid reinforcement projects included in the German National Grid Development Plan for Electricity. To prepare the substation for its future tasks, the TSCNET shareholder began with the upgrade and expansion of Daxlanden at the beginning of November.

The preparatory works will be completed in spring 2021, after which the TSO will start to replace the existing 380kV outdoor switchgear with two new gas insulated switchgears (GIS). For the Daxlanden GIS facilities, the TransnetBW has opted for the so-called Clean Air technology, which exclusively uses processed air as an insulating medium instead of sulfur hexafluoride (SF6). The greenhouse effect of the switchgear is thus radically reduced. Alongside this, the 220kV line between the Daxlanden and Eichstetten substations will be substituted by a 380kV line. The first switchgear is scheduled to be commissioned in 2024 and the second in 2027. The entire installation and grid connections are expected to be completed in 2030.

TransnetBW has commenced the modernisation of the Daxlanden substation (computer simulation of the future Daxlanden substation: TransnetBW)

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> See TransnetBW press release, in German (html)

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Transmission capacity and renewable generation do not match

03.11.2020

The Austrian transmission system operator (TSO) APG has been monitoring the development of the electricity market since the beginning of the corona crisis and regularly publishes charts on topics such as energy exchange, electricity consumption in Austria and Europe, or electricity imports and exports. A look at the September charts of the TSCNET shareholder reveals, on the one hand, the strong role that renewable energies are already playing in Austria and have also continued to play during the pandemic. On the other hand, this particularly good generation from hydropower, wind, and photovoltaic plants could not be fully exploited due to the lack of transmission capacity.

“The streamflow of the Danube accounts for the majority of the run-of-river hydroelectricity generation, which this year has ranged 40 percent above the longtime average on several days. This is the reason why Austria is currently still able to export electricity,” explains Thomas Karall, CFO of APG. However, the insufficient use of renewable energies is also evident from the statistics of APG, especially regarding redispatch. Until the end of September, redispatch measures had to be carried out almost daily. This resulted in costs amounting to around €103m. „This figure shows the importance of the timely realisation of grid expansion and renovation measures – in particular of the Salzburg Line”, concludes Karall. The Salzburg Line (“Salzburgleitung“) is currently APG’s most important infrastructure project and crucial for the integration of renewables.

The September energy charts of APG show solid renewable generation and insufficient transmission capacity (picture showing the Austrian hydroelectric power station Gössendorf in the south of Graz: Eduard Aldrian)

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> See APG press release (html)
> Visit APG infographics site (html)

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Construction progress for Oradea-Békéscsaba line

02.11.2020

In July 2020, the Romanian transmission system operator (TSO) and TSCNET shareholder Transelectrica finally was able to award the construction contract for the missing section of the 400kV Oradea-Békéscsaba power line. For more than ten years, the completion of the overhead line in the far west of Romania has been prevented due to unsettled property issues concerning this section, namely between the Oradea South substation and Nădab. Now that the ownership concerns have been resolved, the investment in the new line will ensure interconnection capacity in the region. Transelectrica expects the construction works to be completed by summer 2021.

Closing this transmission gap is important to Romania’s overall security of supply because the commissioning of the last 72 kilometres between the Romanian town Nădab and the Hungarian border town Békéscsaba not only completes the Oradea-Békéscsaba overhead line, but also contributes to the closure of the “400 kV Ring” in western Romania, a priority energy objective for Romania. The new line will also enable Transelectrica to reduce congestions and thus save considerable intervention costs. As regards European market integration, Romania’s interconnection capacity will be increased by 100MW in export and 300MW in import direction.

The management of Transelectrica represented by the Chairman of the TSO’s Directorate, Cătălin Nițu, and the members of the Directorate, Andreea Miu and Bogdan Marcu, have now informed themselves personally about the progress of the construction work. Mr Nițu emphasised the particular importance of the project for the Romanian energy landscape and the European electricity market

The management of Transelectrica has assessed the construction progress of the last section of the 400kV Oradea-Békéscsaba overhead line (picture: Transelectrica)

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> See Transelectrica press release, in Romanian (pdf, 188.5kb)

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Middle Axis increases capacity sevenfold

27.10.2020

Since the 60s of the 20th century, a 220kV overhead line has been in operation between Hamburg and Denmark, thus crossing Schleswig-Holstein, the northernmost of the German federal states, in its entirety. Schleswig-Holstein is a true “wind power state” in terms of generation, but consumes very little energy in comparison to the southern and western German states. The green electricity produced here therefore has to be transmitted to the centres of consumption. As a result of the energy transition with increasing shares of wind energy, the capacity of the old line has long since been insufficient, resulting in grid bottlenecks. The Dutch-German transmission system operator (TSO) TenneT, whose control area includes the state between the North and the Baltic Sea, thus has replaced the old line with a new 380kV line capable of transmitting seven times as much green electricity.

The new overhead line is called Middle Axis (“Mittelachse”), as it is flanked by two other line projects of the TSCNET shareholder, the East-Coast-Line and the West-Coast-Line. On the Danish side of the border, the Danish TSCNET customer Energinet continues the Middle Axis from Frøslev to the Kassø substation, thereby increasing the electricity trading capacity between Denmark and Germany. On 21 October, TenneT put officially into operation the two northern sections of the Middle Axis between the Audorf substation near Rendsburg and the border with Denmark. With a symbolic push of a button at the substation Handewitt near Flensburg, Thomas Bareiß, Parliamentary State Secretary at the German Federal Ministry for Economic Affairs and Energy, Jan Philipp Albrecht, Minister of Energy, Agriculture, the Environment, Nature and Digitalisation of Schleswig-Holstein, Henrik Riis, CEO of Energinet-Eltransmission, and TenneT COO Tim Meyerjürgens connected the new 82 kilometres long power line to the grid.

The southern section of the Middle Axis from Hamburg/North to Audorf with a length of 70 kilometres was commissioned by TenneT in early 2018. Since 2015, a total of 388 new pylons have been erected along 152 kilometres between Hamburg/North and the border with Denmark, including the required substations Audorf/South, Schuby/West and Handewitt. The extension of the line by Energinet across the border by 30 kilometres into the Danish grid area increases security of supply for both the German and Danish electricity markets and enables the exchange of renewable energy between the two countries.

Tim Meyerjürgens explained: “With the 82 kilometres from Audorf to the Danish border, we are completing the important Middle Axis in the energy transition region of Schleswig-Holstein for the transmission of electricity from renewable sources between the river Elbe and Denmark.” Henrik Riis added: “The Middle Axis is a tremendous success, and it provides a new, continuous electricity highway that runs all the way from Denmark to Hamburg and on to Lower Saxony across the river Elbe. A strong cross-border infrastructure and well-functioning energy markets are essential for all of us – both at national and European level – to shape a future with high security of supply, large amounts of renewable energy and an efficient green energy transition.”

TenneT and Energinet commissioned the northern section of the Middle Axis, a new 380kV line from Denmark to Hamburg (picture showing from right to left Thomas Bareiß, Henrik Riis, Tim Meyerjürgens and Philipp Albrecht at the far left: TenneT)

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> See TenneT press release, in German (html)

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Final court confirmation for Salzburg Line

21.10.2020

From the first submission of the project to the Salzburg state government in September 2012 until the approval of the construction of the second section of the Salzburg Line (“Salzburgleitung”) by the court of last instance, the beautiful Austrian state of Salzburg has certainly seen many sunsets. The Austrian transmission system operator (TSO) APG is now all the more content with the definite legal groundwork for Austria’s most important infrastructure project. Although the legally valid building permit for the Salzburg Line had already been granted by the Austrian Federal Administrative Court in March 2019, there were still final legal details in connection with the project, which the Supreme Administrative Court has now clarified on 20 October 2020, thus confirming the permit.

The new 380kV overhead line will replace the old 220kV line from the 1960s and will be capable of transporting seven times more electricity than the current line. To improve supply security in the city of Salzburg, the first 46-kilometre section of the Salzburg Line from the St. Peter grid node near the German border to the newly constructed Salzburg substation near Elixhausen was already commissioned in January 2011. The second section of the Salzburg Line, from Elixhausen to the Tauern grid node near Kaprun, will now close the western gap in the Austrian “380kV Ring”. This ring-shaped extra-high voltage grid is the backbone of the national electricity supply and crucial for the integration and transmission of renewable energies.

The total length of the new line, which has 449 pylons, is 128 kilometres. However, as old lines will be dismantled when the Salzburg Line is completed and some of them will run jointly on the new line, there will be 229 fewer masts in Salzburg than before. Commissioning of the Salzburg Line is planned for the year 2025, dismantling will be completed by 2026. “With €890m to be invested, the Salzburg Line is by far the most important investment project in the Austrian electricity infrastructure. Of the approx. €350m that APG is investing in the expansion of the electricity grids this year, the Salzburg Line alone has a share of €125m for the domestic economy,” comments Gerhard Christiner, CTO of the Austrian TSCNET shareholder, who also praised the day of the court ruling as a “good day for the energy transition and for the secure supply of electricity in Salzburg and Austria”.

The Austrian Supreme Administrative Court has definitively confirmed the construction permit for the 380kV Salzburg Line of APG (picture: Martin Lugger / APG)

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> See APG press release, in German (html)

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Combined Grid Solution inaugurated

20.10.2020

On 20 October, the world’s first hybrid offshore interconnector was ceremoniously put into operation: the Danish-German Combined Grid Solution (CGS). This interconnector in the Baltic Sea links the transmission grids of two countries via national offshore wind farm grid connections. For this purpose, two submarine cables with a length of merely 25 kilometres and a capacity of approx. 200MW each were laid between the offshore transformer platforms of the German wind farm Baltic 2 and the Kriegers Flak wind farm in the Danish part of the Baltic Sea, which is currently under construction. The CGS – a joint project of TSCNET shareholder 50Hertz, one of the four German transmission system operators (TSOs), and TSCNET customer Energinet, the TSO from Denmark – thus not only connects the platforms with each other but also the existing onshore connections of the wind farms. This allows the transmission of offshore wind power to Denmark or Germany and also cross-border electricity trading.

The official opening ceremony, which took place on site in the German capital of Berlin as well as digitally, was attended by Peter Altmaier, German Federal Minister for Economic Affairs and Energy, Dan Jørgensen, the Danish Minister for Climate, Energy and Utilities, as well as Kadri Simson, EU Commissioner for Energy. With their appearance, these high-ranking political representatives acknowledged the CGS as a technical innovation with model character for future offshore power grids. The hybrid nature of CGS is that it is the first electricity interconnector between two countries, that not only provides capacity for electricity trading, but also transports offshore wind energy onshore – in both directions. The costs of the binational EU-funded project amount to around €300m.

A technical obstacle had to be solved in the realisation of CGS: Because the transmission grids in eastern Denmark and Germany do not operate synchronously, it was necessary to install a back-to-back converter at the 50Hertz substation in Bentwisch near the port city of Rostock in the federal state of Mecklenburg-Western Pomerania. The device converts the incoming AC into DC and immediately back. Only in this way is it possible for electricity to flow smoothly from Denmark to Germany and vice versa. But CGS has not only hardware but also software components. The central digital control unit of the system is the Master Controller for Interconnector Operation (MIO), located in the 50Hertz control centre near Berlin. The MIO balances market requirements with offshore electricity production, which depends on wind conditions in the Baltic Sea. Its main function is to ensure optimum use of the CGS while preventing any overload of the line and the operating facilities in the substation.

Stefan Kapferer, CEO of 50Hertz, commented at the inauguration: “With this project, 50Hertz and Energinet are pioneering the efficient integration of offshore wind farms into the cross-border European electricity market. It offers us several effective options to balance the frequency and voltage of our transmission grids at all times, to deal with the integration of renewable energy sources with more flexibility and to increase the stability of the overall system.” Thomas Egebo, CEO of Energinet, added: “The CGS is not only a very important milestone in reaching Denmark’s ambitious goal of a 100 percent green power system in 2030. The groundbreaking project also delivers an important building block for decarbonising the rest of the society.”

The Danish-German Combined Grid Solution has been ceremoniously put into operation (illustration uses photos of 50Hertz, one of which shows Minister Altmeier)

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> See 50Hertz press release (html)
> See Energinet news release (html)
> Watch CGS inauguration film (YouTube)

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Construction start of Slovenian-Hungarian interconnector

16.10.2020

A glance at the guest list of the official ceremony for the start of construction of the Cirkovce-Pince overhead line reveals that a major project has been launched here. The Slovenian transmission system operator (TSO) ELES had the honour to welcome both the Slovenian Prime Minister Janez Janša and his Hungarian counterpart Viktor Orban to the opening event for the new construction. And indeed, the project is of historic proportions, as the 400kV AC line, a good 80 kilometres long, will be the first interconnector between the Slovenian and Hungarian transmission systems.

The double circuit line with 264 pylons will increase the operational reliability of the Slovenian transmission system and import transmission capacity, facilitate access to energy sources from the North and East, and allow for the integration of larger amounts of renewable energy from the whole region into the grid. The line runs from the Cirkovce substation in the northeastern Slovenian region of Lower Styria to the border settlement of Pince, which is not only on the Hungarian border, but also in the triangle of Slovenia, Croatia, and Hungary. Therefore, in addition to the substation of the Hungarian TSO MAVIR in Hévíz in Zala County, the substation of the Croatian TSO HOPS in Žerjavinec near Zagreb can also be connected to the new line, truly a European Project of Common Interest (PCI). The power line will thus even interconnect three countries. The presence of Gordan Grlić-Radman, Croatian Minister of Foreign and European Affairs, confirmed the trinational dimension of the Cirkovce-Pince line.

At the ceremony with symbolic unveiling of the construction panel, Aleksander Mervar, CEO of ELES, illustrated the supraregional significance of the power line: “This project is of great importance not only for Slovenia but also for the wider region and Europe. That is why this project was included on the list of Projects of Common Interests in 2015, while in 2019 we managed to acquire €50m funds.” Mr Mervar also explained that the project, which includes major upgrades of switchgears in Cirkovce, is the largest investment in transmission infrastructure in the history of ELES, totalling some €150m. Finally, he emphasised the good cooperation of the three TSCNET shareholders ELES, HOPS, and MAVIR: “Without this cooperation, this project would surely not be happening today.”

ELES has started construction of the Cirkovce-Pince 400kV line, which will connect the transmission grids of Slovenia, Hungary, and Croatia (picture: ELES; from right to left: Gordan Grlić-Radman, Viktor Orban, Janez Janša; second from left: Aleksander Mervar)

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> See ELES press release (html)
> Visit project website (html)

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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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> See TenneT press release (html)

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German field report on underground cabling

07.10.2020

The use of underground cables for power transmission in the extra-high voltage three-phase current range is partly still uncharted technical territory for the four German TSCNET shareholders 50Hertz, Amprion, TenneT, and TransnetBW. As most projects are in the planning, approval, or construction phase, no partial earth cabling project is yet in full system operation, let alone a project with exclusive cabling. However, Tennet has commissioned the Wilhelmshaven-Conneforde line as recently as last week: It is the first 380kV line with underground cable sections in three-phase technology connected to the meshed power grid by the Dutch-German transmission system operator (TSO).

To inform politics and public about the current status of underground cabling in the national transmission system, the four German TSOs have, at the request of the German Federal Ministry for Economic Affairs and Energy, jointly prepared a field report on the use of underground cables in the extra high-voltage three-phase current range. The 65-page report examines seven different key issues in respective main chapters, covering technical, administrative, economic, environmental, and social aspects: dialogue and acceptance, approval procedures and the environment, design and construction, operation and operational safety, underground cable technology, systems engineering, and finally economic efficiency. Key findings of 50Hertz, Amprion, TenneT, and TransnetBW can be summarised as follows:

  • Partial underground cabling does not per se lead to a greater acceptance of line construction projects – compared to the construction of overhead power lines, the concern merely shifts from the residents mainly to landowners and farmers.
  • As far as planning, approval, and construction times are concerned, current experience shows that partial underground cabling requires at least one to two years more than overhead lines. More extensive implementation planning, intensive soil investigations, and negotiations with the owners consumed a great deal of time in the pilot projects. The construction itself is also more complex due to the necessary crossing of infrastructures, 40 to 60-metre-wide aisles, and major interventions in the soil ecosystem.
  • Regarding operational and system safety, underground cable installations have a lower availability rate than overhead lines, as repair times are significantly longer in case of damage. Moreover, with an increasing share of partial underground cabling, the complexity of grid operation and thus the risk to system stability also rises.
  • In terms of economic efficiency, the costs of partial underground cabling are significantly higher than those of overhead lines, and this applies to planning, construction, and operation. Depending on the project-related terrain and soil conditions, the investment costs are usually six times higher.

The four German TSOs have published their joint “Field report on the use of underground cables in the extra-high voltage three-phase current range” (picture: TenneT)

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> See TransnetBW news release, in German (html)
> Open Field Report, in German (pdf, 2.9MB)

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