The development of the fourth Estonia-Latvia electricity interconnection will significantly increase the reliability and stability of the region’s power systems and facilitate the integration of larger amounts of renewable energy sources into the transmission networks, stated in the study prepared by the Italian energy consultant CESI S.p.A.. The Latvian and Estonian transmission system operators (TSOs), AS Augstsprieguma tīkls (AST) and Elering AS, plan to develop the interconnection project as offshore solution in the Baltic Sea between Saaremaa Island in Estonia and the Kurzeme coast in Latvia.

“As the share of renewable energy continues to grow, high-capacity interconnections are becoming increasingly important for maintaining the reliability and stability of the power system. The Baltic power systems are already well interconnected, but request for transmission capacity is expected to continue increase in the coming years. The fourth Estonia-Latvia interconnection will increase the reliability of the regional power system, contribute to a more efficient functioning of the electricity market and allows to integrate of larger amounts of renewable energy sources into the transmission networks. In addition, it will create new opportunities for industrial consumption development, based on renewable electricity, thereby contributing to the climate-neutrality goals of both Latvia and Estonia,” says Arnis Daugulis, Member of the Management Board of AST.

The study proposes a 275 kV alternating current (AC) double circuit interconnection solution, having a length of approximately 100 kilometres, including a relatively short onshore fully undergrounded route. The enhancement of the power transfer capacity between Estonia and Latvia is estimated around 700 MW.

As part of the study, consultant, based on publicly available information, evaluated several preliminary routing options at the sea and onshore till the nearest onshore substation in each country. The study included analyses of transmission system reliability and stability, as well as the interconnection impact to the transmission systems of both countries, taking into account development plans of the power systems of Latvia and Estonia and the increasing share of renewable energy sources. The study also identified and proposed the most environmentally friendly route option for the offshore section of the interconnection, considering environmental protected areas and maritime spatial planning recommendations. The executive summary of the study results is available here: https://www.ast.lv/sites/default/files/editor/Executive_summary_4EELV.pdf

AST and Elering have already launched Environmental Impact Assessment (EIA) activities for the project in both countries. EIA studies in offshore and onshore areas are expected to be started soon in order to identify the route option, acceptable by environment and society. Project implementation is planned to start after 2030, after EIA process completion, interconnection expected to be commissioned in 2035.

Consultant underlines, that project is technically feasible and will provide a significant contribution to the long-term development of the Baltic power system including integration of renewable energy sources across the region. However, successful implementation will depend on further reinforcement of the internal transmission network, voltage control solutions and the timely development of infrastructure necessary for the increasing integration of renewable energy sources.

In parallel of potential interconnection feasibility studies, both TSOs are actively developing internal transmission network reinforcement projects that are essential for the secure and stable operation of the interconnection. In Latvia, AST is currently finalising the EIA process for the 330 kV Ventspils-Brocēni-Varduva transmission line, according to the EIA programme issued by the Energy and Environment Agency (since 1 October 2025 is State Environmental Service). Meanwhile, in Estonia, Elering is carrying out spatial planning activities, including an EIA for a new 330 kV transmission line on Saaremaa Island connecting to Estonia’s existing 330 kV transmission network.

The TSOs are planning to implement the project with financial support from the European Union’s Connecting Europe Facility (CEF) fund for both studies and construction activities. The Latvian and Estonian TSOs have prepared all necessary preparatory works to include the project in national and EU long-term development planning documents. After confirmation of EU co-financing, the TSOs will decide on the next steps for project implementation.

AST and Elering signed a Memorandum of Understanding (MoU) in October 2023 to start joint activities for the development of the fourth Estonia-Latvia electricity interconnection.