TenneT B.V. is the national electricity transmission system operator of the Netherlands, headquartered in Arnhem. Controlled and owned by the Dutch government, it is responsible for overseeing the operation of the 380 and 220 kV high-voltage grid throughout the Netherlands and its interconnections with neighbouring countries. It is additionally responsible for the 150 kV grid in South Holland. In Germany, it is one of the four transmission system operators operating through its subsidiary TenneT TSO GmbH.
As of 2006, it operates 3,286 km of lines and cables at 150 kV and above, connecting at 51 high-voltage substations. Peak demand for 2006 was 14,846 MW. The sole shareholder is the Dutch Ministry of Finance.
TenneT was formed in 1998 when the Dutch electricity industry was liberalised, and was incorporated as a business in 2001 with the passing of the Electricity Production Sector Transition Act. Its statutory tasks included management of the national transmission grid and maintaining the balance between electrical supply and demand. In 2003, it acquired the regional system operator Transportnet Zuid-Holland.
TenneT moved beyond these regulated businesses in 2004 when it entered the gas market by acquiring EnergieKeuze, an online gas and power contract exchange market. In 2005 TenneT further expanded its operations when, together with the Belgian and French TSOs Elia and RTE and the APX and Powernext power exchanges, it formed the Belgian Power Exchange Belpex. This granted it a right to participate in the Belgian electricity market.
Since 1 January 2010, Tennet owns the German high‑voltage grid operator Transpower Stromübertragungs GmbH, formerly a part of E.ON, now renamed to Tennet TSO GmbH. The agreed value of transaction was €885 million. The company quoted several reasons for the merger, including price equalization, improved grid balancing, greater insight into grid situations, and better possibilities for sustainable development in both countries.
TenneT is a partner in European Market Coupling Company.
In 2006, TenneT entered into construction of the 700 MW NorNed undersea HVDC submarine power cable with the Norwegian transmission operator Statnett. Commercial operation of the link was delayed by poor weather and a break in the cable, but it eventually entered operation on the night of 6 May 2008. Connecting the Norwegian and Dutch grids at Feda and Eemshaven, the ±450 kV bipolar cable is, at 580 kilometres (360 mi), the longest undersea power line in the world. During the first two months of test operations, it generated approximately €50 million in revenue, greatly exceeding estimates, and recovering 12% of its cost of construction.
TenneT has formed a joint venture with the British transmission operator National Grid for a 260-kilometre (160 mi) 1,000 MW BritNed DC link between the Isle of Grain, Kent and Maasvlakte, near Rotterdam. Operation is projected to begin in late 2010. The BritNed interconnection would serve as vital link for the foreseeable European super grid project.
A 700MW submarine power cable called COBRA (like NorNed, also from Eemshaven) to Denmark is planned with Energinet.dk for 2019, signing contracts with Siemens and Prysmian in 2016. Further 3½ GW offshore DC links are intended to provide a sea grid structure, and 6½ GW AC links are planned between Netherlands and Germany.
Its subsidiary Transpower Stromübertragungs together with Statnett plans the 1400MW NORD.LINK cable between Norway and Germany for 2020.
TenneT plans SuedLink, an onshore DC link between Hamburg and south Germany (near Frankfurt), but local opposition means that a timeline is unclear. Both SuedLink and NORD.LINK are on the EU "Projects of Common Interest" list, and SuedLink is supported by EU with €40 million.
TenneT plans onshore AC upgrades in North Germany, connecting new wind power to some of the above DC links.
In 2016, TenneT suggested a 6 km2 artificial island on the Dogger Bank in the middle of the North Sea, connecting several GigaWatts of offshore wind farms with alternating current. Converters on the island would then transmit direct current to the countries around the North Sea in a more economic manner than if each wind farm had its own cable to the country building it. TenneT called for feasibility studies in 2017.