Reducing environmental impact


To reduce the impact of power lines on local communities and the environment, Terna can implement a series of solutions, which are described below. 

Work on the grid 

Rationalization is complex work, which involves several grid components at the same time and often includes the dismantling of some grid segments and the construction of new lines. 

Rationalization work mainly consists in: 

  • replacing plants with better ones, such as, for example, introducing new 380 kV connections to replace a larger number of lower-voltage lines;
  • eliminating parts of the grid whose usefulness is nil or negligible after the construction of new infrastructures constituting an upgrade;
  • integrating new grid components, for example stations, to avoid having to upgrade saturated lines.

When rationalization is possible, the construction of a new plant may also have the effect of reducing the geographical space occupied by power lines, due to removal of old lines. Above all, near towns and cities, rationalization projects make it possible to reduce the presence of electricity infrastructure in areas of gradual urbanization. Of all the rationalizations envisaged by the Development Plan, there are many more demolitions than new constructions, with a net positive effect in terms of the presence of power lines around the country. Dismantling stretches of line, made possible by the construction of new power lines, is the most significant contribution benefiting the environment that derives from grid development activity.  

Burial of cables eliminates or reduces the negative impact on the landscape typical of stretches of overhead lines. For this reason, burials are often requested by the local institutions as the first option for the construction of new lines. In reality, burial entails various technical and economic problems: buried lines are less reliable over time compared with overhead power lines and require a much longer time to repair in the event of a fault: for this reason they often do not guarantee an adequately secure electricity system and service continuity. In addition, buried cables bring greater impacts in the construction stage – for example in terms of road traffic – and also much higher construction costs (normally from five to ten times the cost of an overhead line).

Reclassification provides for conversion of existing power lines to a higher voltage, through the construction of new conductors and supports in place of the existing ones. This action can involve replacement of the old support with a larger one which therefore takes up more space. However, reclassification has the advantage, compared with the construction of a new line, of generally using pre-existing infrastructural corridors, avoiding the occupation of new portions of the territory.

Requalification projects are aimed at reducing the population's exposure to electromagnetic fields (see the box below), for example by using taller supports. Requalification may also involve moving the route and at the same time dismantling stretches close to urban areas. 

Electric and magnetic fields: the legal limits

The main reference values for the emission of electric and magnetic fields currently provided for by the law (Prime Minister’s Decree of July 8, 2003) are the following:

  • exposure limits: in case of exposure to electric and magnetic fields at a frequency of 50 Hz generated by electricity lines, the limit is 100 microteslas for magnetic induction and 5 kV/m for the electric field, understood as effective values;
  • values of concern: as a precautionary measure of protection from possible long-term effects connected with exposure to magnetic fields generated at the grid frequency (50 Hz), at playgrounds, homes, schools, and places where people stay for at least four hours a day, the value of concern for magnetic induction is 10 microteslas, understood as the median value over 24 hours under normal operating conditions;
  • quality objectives: in planning new power lines near playgrounds, homes, schools, and places where people stay at least four hours a day, and in planning new settlements and areas such as the aforementioned in the vicinity of electric lines and installations already present, in order to gradually minimize exposure to electric and magnetic fields generated by power lines operating at a frequency of 50 Hz, the quality objective is set at 3 microteslas for the value of magnetic induction, understood as the mean value over 24 hours under normal operating conditions.

The values of the three parameters, and in particular the value of concern (10 microteslas) and the quality objective (3 microteslas) show that Italian legislation has adopted the precautionary principle expressed in Article 15 of the Rio Principles. Observance of the law in its activities implicitly entails Terna’s adoption of the same principle.

Terna carries out inspections of its lines to ensure compliance with the limits set out by current legislation. In the event of any reports and requests by responsible bodies and administrations, Terna provides the data needed to assess effective exposure to electric and magnetic fields generated by its plants. 

Measures adopted in the planning stage

Terna can reduce the impact of power lines on the landscape, identifying routes in areas with good landscape compatibility and choosing supports which integrate well with the territory. In the last few years Terna has expanded the alternatives available, also making use of the design of new supports by internationally-famous architects. For the construction of new electricity stations similar considerations apply.


In the case of existing plants, mitigation measures are aimed at reducing visual impact and/or improving integration into the environment of the structures which make them up. In particular, Terna develops masking systems for station fences, requalifies buildings and makes use of naturalistic engineering techniques. 


Construction-site management

To manage construction sites Terna has adopted an Operating Instruction – “Management of environmental aspects during plant construction” – to ensure observance of the environmental policy adopted by the Company. Specifically, it establishes that construction site areas and new access roads be positioned, as far as compatible with technical and planning needs, in zones with less vegetational value (agricultural areas).

However, if the areas contain natural or semi-natural habitats, at the end of construction work, environmental regeneration and requalification works must be undertaken, to restore the area to a condition as close as possible to its preceding one. The timing of the construction site stages must take account of the vital needs of the species potentially involved, avoiding high-impact activities during reproductive periods for said species.

Furthermore, particular care must be taken in managing waste produced on the construction site, in accordance with the relevant regulations in force, such as avoiding spills and the temporary storage of polluting substances.

Contract work

The prescriptions on environmental matters that are applied in work contracts awarded to external firms are formulated in accordance with the provisions of the applicable environmental laws and the prescriptions of the ISO:14001 standard and include aspects such as: preventing contamination of groundwater and limiting damage to vegetation, managing accidental events, minimizing atmospheric emissions and noise, vehicle use, and correctly managing waste and excavated earth (on this subject see also the paragraph “Relations with suppliers”).