The fourth Estonian-Latvian electricity interconnection

The project has cross-border significance at the Latvian, Estonian, and European levels. It is included in strategically important development documents in Latvian and European levels, e.g., the Latvian Power Transmission System 10 years Development Plan, the Latvian Transmission System Operator’s Annual Statement, the European 10 Years Network Development Plan (TYNDP), the list of Projects of Common Interest / Projects of Mutual Interest (PCI/PMI) and others. All these activities will give possibility to attract European Union co-financing for the project in the future. 

To ensure the secure and stable operation of the project, it is also necessary to reinforce the internal 330 kV electricity transmission network in both countries. For the secure and stable operation of interconnection, the 330 kV transmission line Ventspils–Brocēni–Varduva is being developed in Latvia, and the 330 kV transmission line on Saaremaa is being developed to connect the project to the Estonian 330 kV transmission network. 

New interconnection also provides efficiency of electricity market development in both countries. In the Baltic region, Latvia and Estonia are currently connected by three 330 kV overhead interconnections. However, the growing interest in renewable energy connections to the transmission network and the increasing need for cross-border electricity exchanges require additional transmission capacity. 

In this context, the development of the fourth interconnection between Estonia and Latvia is a strategic priority to increase system flexibility, increase security of supply, and support the large-scale integration of renewable energy sources to the transmission network, particularly offshore wind projects in the Baltic Sea, which are expected to contribute to lower electricity prices in Latvia and Estonia. 

In June 2026, the technical study, asked by AST and Elering and prepared by the Italian energy consultant CESI S.p.A. confirmed that the construction of the fourth Estonia-Latvia interconnection will significantly increase the security of supply of the Baltic Sea region and will also facilitate the integration of larger volumes of renewable energy into the transmission network. The study included modelling of network security and stability, as well as the interconnection impact to the electricity transmission systems of both countries, considering the development trends of both countries’ systems and the increasing share of renewable energy. 

The consultant proposes implementing the interconnection as 275 kV high voltage alternating current (HVAC) solution due to the relatively short length of the offshore route – approximately 100 km. The interconnection will consist of two three-phase cables providing interconnection capacity around 700 MW. 

As part of the study, a preliminary route survey of the interconnection was prepared for the sea and to the nearest onshore substation in each country. The study analysed and proposed the most environmentally friendly route for the interconnection, taking into account environmental protection zones and the specific characteristics of maritime spatial planning. 

EIA of the project was started on February 23, 2026, when AST submitted the initial environmental assessment application to the State Environmental Service (SES) for the preliminary assessment of the environmental impact of the proposed interconnection. SES did the preliminary assessment (No. AP26SI0066) and, on March 23, 2026, issued the decision on the necessity to prepare full EIA for the proposed activity. On March 25, 2026, SES issued Decision No. 11.17/AP/2922/2026 on the application of the cross-border environmental impact assessment procedure for the "Fourth Estonia–Latvia Electricity Interconnection". As the project may have cross-border environmental impacts, in accordance with environmental legislation, the materials were submitted to the competent environmental authority in Estonia. 

The initial public consultation of the planned Estonia-Latvia interconnector was organised from May 22 to June 30, 2026. Two public discussion meetings were organized in impacted municipalities to inform the public about the planned project development. The presentation from the public discussions meetings can be found here. 

According to national legislation, on July 6, 2026, AST submitted all public discussions materials and written request to the State Environmental Service to issue an environmental impact assessment Program for the planned 4^th interconnection between Estonia and Latvia. The EIA Programfor the 4th Estonian-Latvian electricity interconnection development in the territorial waters of Latvia in the Baltic Sea, in Ventspils and Ventspils district was issued on July 21, 2026. 

The public procurement for EIA study and selection of EIA consultant will be organised at the end of 2026. 

The transmission system operators of both Latvia and Estonia have completed all necessary preparatory works to include the project in national and European Union development documents, which is a precondition for receiving co-financing.