The official presentation of the submarine electricity interconnection project between Tenerife and La Gomera took place in the meeting hall of the La Gomera Island Council and was attended by the regional presidents of the Island Councils of La Gomera, Casimiro Curbelo, and Tenerife, Pedro Martín; the Regional Minister for Ecological Transition, the Fight against Climate Change and Territorial Planning, José Antonio Valbuena, and the General Manager of Transmission Division at REE, Eva Pagán.

Regarding the electricity systems of the Canary Islands, it should be noted that they are characterised by the fact that they are small-sized and

isolated systems. These circumstances make them more vulnerable and, therefore, less stable and secure than other larger and interconnected systems. Obviously, the larger and better interconnected an electricity system is, the stronger and more reliable it is, which also increases its chances of integrating renewable energy, which is exactly what will happen in this case. The submarine electricity link between Tenerife and La Gomera will create a larger and more robust electricity system, improving the efficiency and reliability of supply on both islands.

Until now, only the islands of Lanzarote and Fuerteventura have had a submarine electricity interconnection; therefore, the Regional President of the Canary Islands, Ángel Víctor Torres, stressed that this new investment project, which will interconnect Tenerife and La Gomera, "will favour the implementation of new infrastructure for green electricity production, especially on La Gomera, where generation facilities will be able to maximise the island’s abundant natural resources in the form of sun and wind.”

Mr. Torres added that this "will facilitate the reduction of electricity generation costs" and will contribute to "lowering the dependence on fossil fuel imports and enhancing the environmental aspects of both islands."

A planned investment of 103 million euros

This submarine electricity interconnection between Tenerife and La Gomera has enabled the suitable conditions to be established so that La Gomera can be, from an electricity grid point of view, the first island in the Canary Islands to produce more renewable energy than it consumes in a year, thus avoiding the need to resort to other more expensive and polluting fossil fuel energy production systems.

The planned investment to make this interconnection possible is of approximately 103 million euros, and the deployment time for the link and the construction of the two substations, one at each end of the interconnection, will be around 24 months, once all the authorisations and permits have been obtained.

The construction of this interconnection supplements other grid strengthening actions currently being carried out in the west of Tenerife as per the current grid planning and contribute to providing greater security to the electricity system and thus advance the energy transition objectives planned for the Canary Islands.

A plan considered strategic for the Archipelago

The Tenerife-La Gomera interconnection axis, included in the electricity transmission grid planning approved by the Council of Ministers, is a strategic project to advance the energy transition in the Canary Islands.

Upon completion of the environmental and technical studies, and once the Ministry of Ecological Transition and Demographic Challenge had recognised the uniqueness of the project, REE submitted the execution project and the Environmental Impact Study to the Regional Ministry of Ecological Transition, Fight against Climate Change and Territorial Planning, in order to obtain the environmental impact statement as well as the relevant administrative authorisations and permits. 

"The link between Tenerife and La Gomera allows resources to be shared between systems, which means, across the board, a reduced need for energy reserves and installed generation capacity, as well as facilitating the integration of renewable energy by creating a larger and, therefore, more robust and secure system," explained REE's General Manager of Transmission Division, Eva Pagán.

The new electricity axis will include all the infrastructure needed and foreseen to enable the electricity interconnection of the island of La Gomera with the island of Tenerife, which are as follows:

• Underground-submarine double-circuit 66 kV (kilovolts) electricity transmission line, Tenerife-La Gomera (known as Chío-El Palmar), with a transmission capacity of 50 MVA (megavolt-amperes) per circuit. This facility consists of a submarine section of approximately 36 kilometres in length and will run at a maximum depth of 1,145 metres, with two land cable routes on La Gomera and Tenerife.
• New 66 kV electricity substation in Chío (Tenerife), which will be located in the vicinity of the current Guía de Isora substation, far from urban centres and towns.
• New 66 kV electricity substation in El Palmar (La Gomera), to be built in the vicinity of the El Palmar thermal power station, which currently supplies the entire island, with the aim of integrating it into this industrial area, thus minimising the length of new infrastructure connecting the transmission and distribution grids. Maximum use is made of the synergies of the location.

Environmental protection

For the study of the layout of the Tenerife-La Gomera submarine interconnection, as well as the location of the two new substations, a complete environmental inventory of the terrestrial and marine environments has been carried out.

In the case of the marine environment, a specific oceanographic campaign was carried out to obtain a very precise knowledge of the area between Tenerife and La Gomera, including all aspects related to the physical, biological and socio-economic environment in order to be able to define alternative cable routes. The selected route for the interconnection has been designed to minimise the impact on the landscape and to ensure maximum protection of the flora and fauna in the areas along the cable route.

One of the unique construction features used in this project is the use of the horizontal drilling technique to connect the underground cable with the submarine cable. This technique allows the first few hundred metres of the land cable route that connects to the submarine cable section to be installed using a horizontal drilling technique that runs the cable through a micro-tunnel under the seabed, thus eliminating any impact on the biology of the coastal areas used for this interconnection.

Furthermore, to guarantee the protection of the interconnection in the submarine section and thus minimise the risk of external aggressions on the cables, different techniques will be used depending on the geophysical and geological characteristics of the seabed in each cable section.