On 31 May 1999, Terna was established within theEnel Group, by way of implementation of Italian Legislative Decree No. 79/99[6] which within the context of the process for the deregulation of the Italian electricity sector, sanctioned the separation between ownership and management of the national transmission grid.[7]
On 23 June 2004, following the Prime Minister's Decree issued on 11 May of the same year, Terna was put on sale with anIPO onBorsa Italiana.[8]
In November 2005, Terna acquired a business unit from GRTN, as defined by the Prime Ministerial Decree of 11 May 2004.Cassa Depositi e Prestiti became the relative majority shareholder.[9]
In 2011, the Terna Group reorganized its corporate structure, establishing a holding company overseeing two fully owned operational subsidiaries: Terna Rete Italia and Terna Plus, each with its own CEO and board of directors.[12]
In 2013, Terna initiated strategic projects, including the “Capri-Torre Annunziata” submarine cable connectingCapri to mainland Italy.[13][14] The same year, Terna and its French counterpartRTE began work on enhancing theItaly-France interconnection via the new “Piedmont-Savoy” line,[15][16] which became operational in 2023.[17]
In 2015, Terna acquired the high-voltage grid of theFS Italiane Group[18] and started developing new national and international interconnection infrastructures, including SA.CO.I.3 (Italy-Corsica-Sardinia)[19][20] and links withMontenegro (inaugurated in 2019)[21][22] andAustria (operational in 2023).[23][24]
To support efficiency improvements and environmental protection investments in its national infrastructure, Terna issued its firstGreen bond worth €750 million in July 2018,[25] becoming the first Italian utility to do so.[26] Additional green hybrid bonds followed in 2022 (€1 billion)[27] and 2024 (€850 million).[28]
In 2022, Terna launched the Tyrrhenian Link interconnection project betweenCampania andSicily,[29][30] followed in 2023 by the Adriatic Link project betweenMarche andAbruzzo.[31][32] That year, Terna also activated the submarine connection betweenElba Island andPiombino.[33] Internationally, the company developed the world's longest direct-current cable laid along a highway between Italy and France[34] and initiated the first submarine direct-current connection between Europe and North Africa, linking Italy andTunisia.[35][36]
In April 2023,Giuseppina Di Foggia was appointed CEO and General Manager, becoming the first woman to lead a major publicly listed Italian company.[37][38] The same year, Terna launched its 2023-2032 Development Plan,[39] featuring over 30 infrastructure projects, including the Hypergrid project,[40] utilizing high-voltage direct current (HVDC) technologies to double exchange capacity and achieve Italy’s energy transition and security objectives.[41] The Plan was updated in 2025.[42][43]
On 6 November 2024, Terna signed a binding agreement with Areti, a company controlled byAcea, for the acquisition of part of the high-voltage power grid in themetropolitan area ofRome, marking a step in the process of streamlining and unifying the management of the national transmission grid.[44]
In March 2025, Terna Energy Solutions, the Group company managing non-regulated activities, was reorganized by integrating expertise previously managed by other subsidiaries. Specifically, Altenia was established, bringing together allsystem integrator activities that had previously been managed separately by LT, Terna Energy Solutions, and Avvenia.[45]
Also in 2025, the Terna Foundation, established in July 2024, was officially presented to the public to promote greater inclusion and broad access to the world of energy through projects and initiatives focused on three main areas of intervention: the dissemination of an energy culture, promoting literacy also through educational initiatives involving younger generations; combating energy poverty; and programs that foster access to the labor market and new professional opportunities in the energy sector.[46][47]
As aTransmission System Operator, Terna is responsible for thetransmission, management, and dispatching of electricity across the Italian high- and extra-high-voltage grid.[48] It ensures a constant balance between energy demand and supply while promoting the country’senergy and digital transition through the progressivedecarbonization of the electricity system and increased integration ofrenewable energy sources.[49][50]
Terna plans, designs, and builds interconnection infrastructures within Italy and abroad to ensure the country’senergy security.[51] It also maintains existing infrastructures and works to minimize their impact onbiodiversity andlandscapes.[52] Operating as anatural monopoly, Terna is regulated by the Italian Authority for Energy, Networks, and the Environment (ARERA).[49]
To safeguard its assets, Terna has created an organization capable of protecting the company's physical and technological infrastructures, also through the prevention and management of episodes of corporate fraud. In this framework, in order to guarantee the maximum safeguarding of said infrastructures and investments, it has signed memoranda of understanding, first of its kind and type with theMinistry of the Interior, Carabinieri and Guardia di Finanza.
On April 1, 2009, Terna acquired 100% of Enel High Voltage Lines S.r.l. from Enel Distribuzione S.p.A. The company owned 18,583 kilometers of high-voltage electricity grid, purchased for €1,152 million. This acquisition brought Terna's ownership to 98.5% of the national grid.[62]Since 2009, Terna has managed these assets using the same approach previously adopted by Enel, outsourcing grid management to third-party companies through national tenders. These companies include Consorzio Arcobaleno, Consorzio Golden Lucano, and Siel.
Certificate and Golden Bronze Medal of Excellence, First Class, forPublic Merit[90]
"For participation in the seismic event of April 6, 2009, inAbruzzo, due to the extraordinary contribution made with the deployment of human and instrumental resources to overcome the emergency."— Rome, Decree of thePresident of the Council of Ministers, October 11, 2010
2010 and 2013: Terna received the International Utility Award from theEdison Electric Institute as the best-performing European utility for total shareholder return over the past three years.[91]
2023: Terna won the Best ESG Rating Award fromStandard Ethics for its commitment to biodiversity protection.[94]
June 2023: TheEdison Electric Institute awarded Terna the International Edison Award for its innovative Italy-France electrical interconnection project, which is entirely invisible and environmentally impact-free.[95][96]
In 2025, Terna obtained the Top Employers Italy 2025 Certification awarded by the Top Employers Institute, a global human resources certification body.[97][98]
^Established in March 2025, it brought together all system integrator activities that had previously been managed separately by LT, Terna Energy Solutions, and Avvenia.
Certificate and Golden Bronze Medal of Excellence, First Class, forPublic Merit[90]
Media related toTerna (TSO) at Wikimedia Commons
