Sweden is undertaking one of the most ambitious electricity grid expansions in its modern history. In its Network Development Plan 2026-2035, the Swedish transmission system operator, Svenska kraftnät, has outlined SEK225 billion (approximately EUR20.7 billion) in grid investments over the next decade. The plan echoes a broader trend across advanced economies: the energy transition requires not only new generation capacity, but a fundamental reconfiguration of transmission infrastructure.
The government’s planning assumption that annual electricity demand will reach at least 300 TWh by 2045, more than double the consumption of around 127 TWh in 2025, emphasises the urgency and scale of the required grid expansion. The most significant drivers are industrial electrification in the north (fossil-free steel, green hydrogen, and battery manufacturing), as well as transport electrification and data centres in urban regions. These shifts are altering power flows, creating new demand centres in regions with limited infrastructure while saturating capacity in others.
Scale and structure of the plan
The scale of the physical expansion is substantial. Svenska kraftnät plans to commission approximately 2,900 km of new transmission lines and around 40 new substations by 2035. It will also reinvest over 1,100 km of existing lines and upgrade roughly half of its nearly 200 substations.
Around 90 per cent of new lines will be built at the 400 kV AC voltage level. A government directive in early 2025 formally designated overhead lines as the default technology for transmission expansion, simplifying permitting. Underground and subsea cables account for a much smaller share, mainly in specific geographic contexts such as island connections.
The SEK225 billion investment is structured in four categories. Reinvestment in ageing infrastructure accounts for the largest share at 45 per cent, reflecting assets built during the mid-twentieth century and approaching the end of their operational life. System reinforcement to increase internal transmission capacity follows at 36 per cent. New connections for generation and consumption represent 14 per cent. The remaining 5 per cent is allocated to market integration, which includes measures to improve trading efficiency domestically and with the neighbouring countries.
This distribution carries an important implication: nearly half of all capital is required simply to maintain existing capacity rather than expand it, a constraint common to mature electricity systems undergoing rapid change.
The financial scale of the plan is matched by the pace at which spending must accelerate. Annual investment is expected to nearly double from approximately SEK9 billion in 2025 to around SEK20 billion per year in 2027 and 2028.
However, sustaining that rate over a decade requires not only capital but consistent access to contractors, equipment and engineering capacity — resources that are under pressure as grid operators scale up their plans simultaneously across Europe.
Regional priorities
Svenska kraftnät’s investment priorities centre on four areas.
Increasing transmission capacity between northern and southern Sweden is one of the four focus areas, aimed at relieving bottlenecks and enabling the connection of new generation and consumption. This objective is being addressed primarily through the NordSyd project and capacity upgrades across all three internal cross-sections.
NordSyd is the single most extensive grid development programme ever undertaken by Svenska kraftnät, involving nine regions in central Sweden. Launched in 2018, it focuses on reinvesting in the six old lines and replacing them with four 400 kV double-circuit lines along the Uppsala, Västerås, Karlstad and Hallsberg transmission corridors. When complete, average transmission capacity along the corridor will increase from today’s 7.3 GW to approximately 10.5 GW. The Uppsala and Västerås legs are each expected to be commissioned in stages during 2030-33, the Karlstad leg in the winter of 2035, and the Hallsberg leg, currently under investigation, is expected to receive a decision to proceed in 2026.
The second priority is strengthening electricity supply in Norrbotten and Västerbotten, where a concentration of energy-intensive industries is driving up the demand for electricity. The northern grid was originally built to carry hydroelectric power southward from the river valleys, meaning there is no existing high-voltage infrastructure near the new inland industrial sites now emerging. Major investments are underway in Norrbotten in particular, centred on fossil-free iron and steel production. A key project is the Norrland Coast Package, which includes three new 400 kV lines, three new 400 kV substations and multiple connecting lines to serve electricity-intensive industries in Boden, Luleå and surrounding coastal municipalities. In the inland Malmfälten area around Gällivare and Kiruna, Svenska kraftnät is extending the main grid into areas with no existing high-voltage infrastructure, with a grid concession application already submitted for a new 400 kV line from Gällivare to Jokkmokk and further lines, and a new substation in Gällivare in preparation.
Hydrogen production is also one of the key drivers for the northern region investment rationale. Much of the hydrogen demand is expected to arise in the regions of Västernorrland, Västerbotten and Norrbotten. Svenska kraftnät and the government are now developing a co-planning framework for electricity and hydrogen infrastructure, recognising that the two networks cannot be expanded independently.
The third priority is reinforcing electricity supply to Stockholm and parts of Västra Götaland, where demand is already growing rapidly. Stockholm accounts for approximately SEK30 billion of planned investment, the largest single regional allocation in the plan. The region faces capacity saturation in a dense urban environment, with demand growth driven by a growing population, reduced local electricity production, electrification of transport and the expansion of digital infrastructure. Electricity consumption is already so high that further increases cannot be accommodated within the current grid.
Two major programmes are underway. Stockholms Ström will restructure the existing 220 kV network around a new 400 kV City Link between Upplands Väsby in the north and Haninge in the south, decommissioning approximately 150 km of overhead lines in the process. The programme comprises around fifty sub-projects and involves Svenska kraftnät, the regional grid owners and 21 municipalities in Stockholm County.
Storstockholm Väst, developed in response to faster-than-anticipated demand growth, will add a new north–south 400 kV connection through the western part of the region, a new 400 kV line from north of Märsta to northwest of Sollentuna, and several new 400 kV substations. The plan notes that a large number of underground cables are required in Stockholm’s dense urban environment.
The fourth priority is connecting Gotland to the national transmission grid for the first time, via two 220 kV submarine alternating current cables, each with a transmission capacity of 220 MW. The cables will run between Västervik and Oskarshamn on the mainland and connect to a point south of Visby on Gotland, with commissioning targeted for the early 2030s. Gotland is projected to face a power deficit within a few years, making a new connection necessary. This will also provide a foundation for future offshore wind development.
Strengthening international interconnections
Sweden’s transmission strategy cannot be understood in isolation from its role within the broader Nordic and European electricity market. The plan’s market integration investment category, representing SEK11 billion, or 5 per cent of the total planned spending, reflects this dimension. A new 400 kV interconnector with Finland was commissioned at the end of 2025, increasing trading capacity, contributing to price equalisation across the Nordic region, and improving security of supply. A possible fourth interconnector with Finland is under investigation. A capacity increase on the connection between northern Sweden and northern Norway is also being studied.
On the southern border, a planned new interconnector to Germany was rejected by the government in 2024 and subsequently terminated. Svenska kraftnät is now investigating the socio-economic case for a potential connection to the Danish island of Bornholm, where Denmark and Germany are separately planning interconnectors.
Power adequacy and flexibility
Grid expansion alone will not be sufficient. Svenska kraftnät’s analysis finds that increased electricity use without significant volumes of flexibility in the power system will become unsustainable as early as 2035, with the problem intensifying through to 2045. In the long-term scenarios modelled in the plan, Sweden may become entirely dependent on large volumes of flexibility during peak hours, as well as on imports from neighbouring countries, to maintain supply adequacy.
Flexibility can be provided through demand response, energy storage or flexible electricity production, and the plan treats all three as necessary complements to physical grid investment rather than substitutes for it. Three pumped storage projects, in Dalarna and Värmland, have been identified and included in the plan to support their eligibility for the European Union (EU) Project of Common Interest (PCI) status and associated funding.
As the share of weather-dependent generation increases, maintaining real-time balance between supply and demand becomes more complex. Strengthening system flexibility must therefore be prioritised alongside physical grid expansion to ensure long-term power adequacy.
Civil and defence preparedness
The plan reflects a dimension not commonly seen in transmission planning documents: national security. Sweden’s changed geopolitical environment, following the North Atlantic Treaty Organization (NATO) accession and against the backdrop of the war in Ukraine, has elevated energy infrastructure to an explicit defence priority. Sweden’s Defence Decision 2025-2030 identifies energy supply as one of the most critical preparedness sectors. In response, Svenska kraftnät adopted a formal preparedness goal in 2024: to ensure electricity supply under all conditions, including crises and conflict.
Within long-term grid development, the stated goal is to integrate preparedness perspectives into routine planning processes and investment criteria. Svenska kraftnät has also incorporated lessons from the ongoing conflict in Ukraine, particularly the vulnerability of energy infrastructure to disruption, into its resilience planning. Together, these measures signal a shift towards a power system designed not only for efficiency and growth, but for robustness under extreme external conditions.
Delivery challenge
An important feature of the plan is the distribution of projects across different development stages. A large share of planned investment remains in early phases. Approximately SEK160 billion is classified as under consideration, while around SEK125 billion is in preparation. This includes activities such as route selection, environmental assessment and permitting.
Only a smaller portion of the total investment is currently in the construction phase. This reflects a key constraint in transmission development. In Sweden, as in many other countries, the time required for permitting and land acquisition can exceed the time needed for physical construction. As a result, the pace of delivery is determined less by engineering capacity and more by regulatory and administrative processes.
The coming decade will therefore be defined by the transition from planning to execution. Moving projects efficiently through the development pipeline will be critical if capacity expansion is to keep pace with demand growth.
Svenska kraftnät is responding by coordinating reinvestments and new build wherever possible, designing projects to serve multiple needs simultaneously and working to streamline permitting processes. As mentioned earlier, the government directive in early 2025 designating overhead lines as the default technology for national grid expansion is one such measure intended to reduce the complexity and duration of permitting processes. Even so, the plan acknowledges that lead times remain a binding constraint, and that halving them is an explicit organisational priority.
Conclusion
Svenska kraftnät has set out an ambitious programme of grid transformation for the coming decade to support the country’s long-term energy transition and industrial expansion. Beyond traditional grid reinforcement, the plan positions transmission infrastructure as a strategic enabler of electrification, renewable integration and regional economic growth. By expanding transmission capacity, strengthening north-south power flows, and improving system resilience, the plan aims to ensure that the rising electricity demand from industry, transport and emerging clean technologies can be met reliably and efficiently.
The plan also highlights a broader shift in power system planning whereby grid development is increasingly central to energy security, competitiveness and decarbonisation. Successful implementation will depend not only on infrastructure investment but also on faster permitting, stronger coordination across stakeholders, and continued advancement in digitalisation and system operations. As Sweden moves towards a more electrified and renewable-based economy, the network development plan is expected to provide the foundation for a more flexible, interconnected, and future-ready power system.