NordBalt

NordBalt: A Baltic Sea Submarine Cable

The NordBalt submarine cable connects Klaipeda in Lithuania to Nybro in Sweden, spanning approximately 400 km across the Baltic Sea. It is owned by Litgrid, the Lithuanian electricity transmission system operator, and Svenska Kraftnät, its Swedish counterpart. Listed as in service since 2016 according to GeoCables records, NordBalt is a key infrastructure for electricity transmission between the two countries, although its design capacity and fiber-optic specifications remain undisclosed in publicly available sources. What makes NordBalt particularly interesting is its dual role as both an electricity interconnector and a telecommunications cable. While its primary purpose is to facilitate energy exchange and grid stability between Lithuania and Sweden, the cable also supports data transmission. However, significant uncertainties remain regarding its technical specifications, including fiber pairs, supplier, and technology, as these details have not been disclosed.

Quick facts

Cable name	NordBalt
Length	400 km
Ready for service	2016 (GeoCables database; other sources not surfaced)
Owners	Litgrid, Svenska Kraftnät
Status	In service
Design capacity	Not disclosed
Fiber pairs	Not disclosed
Supplier	Not disclosed
Technology	Not disclosed
Landing points	Klaipeda (Lithuania), Nybro (Sweden)

Show NordBalt on the interactive cable map

Route

NordBalt runs across the Baltic Sea, connecting Klaipeda, a port city in Lithuania, to Nybro, a locality in the southeastern part of Sweden. The corridor traverses a relatively shallow and geologically stable part of the Baltic Sea, which is advantageous for cable installation and maintenance. The landing points are strategically located to integrate with the electricity grids and telecommunications networks of both countries.

Why it was built and what it carries

NordBalt was primarily built to enhance energy security and electricity market integration between Lithuania and Sweden. The interconnector allows for the exchange of renewable energy, particularly wind and hydroelectric power, between the two nations. This helps Lithuania reduce its reliance on fossil fuels and imported electricity, while Sweden benefits from access to additional energy markets. In addition to electricity transmission, NordBalt supports data transmission, although its telecommunications capacity is not well-documented. This dual-purpose design is relatively uncommon and reflects the growing trend of integrating energy and data infrastructure in submarine cables.

History: what can be established

GeoCables data lists NordBalt as ready for service in 2016, and this date aligns with the cable's operational status as reported by its owners. Publicly available sources do not suggest any conflicting dates for its commissioning. The project was a collaborative effort between Litgrid and Svenska Kraftnät, with funding from the European Union to support regional energy integration.

Capacity and technology

The design capacity of NordBalt is not disclosed in publicly available sources, nor are details about its fiber pairs, supplier, or specific technology. Without operator documentation, it is impossible to provide precise figures or specifications. This lack of transparency is not unusual for cables with a primary focus on electricity transmission, as their telecommunications capabilities are often secondary and less publicized.

Latency: the physics

The theoretical one-way light propagation latency over NordBalt's 400 km wet segment is approximately 2.0 ms, with a round-trip time (RTT) floor of 3.9 ms. However, real-world latency measurements are significantly higher due to additional factors such as land tails, terminal equipment, and network routing. GeoCables live measurements show Klaipeda to Nybro RTTs ranging from 12.6 ms to an average of 21.6 ms, while Nybro to Klaipeda RTTs are higher, with a minimum of 34.1 ms and an average of 34.3 ms. These figures suggest that other network components, possibly including routing inefficiencies or terrestrial links, contribute substantially to the observed latency.

Redundancy: what happens if it breaks

If NordBalt were to experience a fault, redundancy would depend on alternative routes in the Baltic Sea region. Other submarine cables and terrestrial links between Lithuania and Sweden, as well as connections to neighboring countries like Latvia, Estonia, and Finland, could provide backup for telecommunications traffic. However, redundancy for electricity transmission would be more complex and might require rerouting through other interconnectors or increased reliance on local generation. Repairing a submarine cable typically involves deploying specialized cable-laying and repair vessels, which locate the fault, retrieve the damaged segment, and replace or mend it. Given the Baltic Sea's relatively calm conditions, repairs to NordBalt would likely be less challenging than those in deeper or more turbulent waters.

Bottom line

• NordBalt spans 400 km between Klaipeda (Lithuania) and Nybro (Sweden).
• Primarily designed as an electricity interconnector, it also supports data transmission.
• Ready for service in 2016, according to GeoCables records.
• Design capacity, fiber pairs, supplier, and technology are not publicly disclosed.
• Theoretical RTT floor is 3.9 ms over the wet segment; real-world measurements are higher.
• Redundancy relies on regional alternatives, with repairs facilitated by the Baltic Sea's conditions.