Development Plan and Environmental Sustainability

Grid upgrading

Grid upgrading is a complex process which simultaneously affects a number of grid elements, often including the removal of some grid portions and the construction of new lines.

Grid upgrading measures are mainly implemented as follows:

  • by replacing some systems with others of higher capacity, e.g. introducing new 380 kV(kilovolt=1,000 Volts) unit of measurement of voltage. connections to replace a larger number of lower-voltage lines;
  • by eliminating parts of the grid that have little or no usefulness, following new constructions to strengthen the grid;
  • by avoiding to improve the systems, for the most part power lines, that have reached saturation, by including new grid elements, such as power stations.

When grid upgrading is possible, the construction of a new system also implies a reduction in the area of land occupied, due to the removal of old lines. In all grid upgrading activity, as provided for in the DevelopmentWorks on the electricity grid which lead to the adjustment or upgrading of the transport, transformation,connection and interconnection capacity, or an increase in operating flexibility of the grid, or the removal ofgrid elements. Plan, demolitions are far in excess of new constructions, with a net positive effect in terms of freeing the land from the presence of electric lines. For this reason, dismantling sections of lines, following the construction of new power lines, represents the most significant contribution of grid development to benefiting the environment.

Highlight: 10 projects for sustainable development

CO2 emission reduction and development plan

Building new lines and substations included in the Development Plan produces positive effects not only in terms of the service’s safety and final costs of electricity, but also in terms of reducing emissions produced from the Electricity System. The effects are traceable to three categories:

Reducing grid losses
Grid losses depend, among other things, on the distance electricity must travel along the electricity transmissionElectricity transport and transformation activities along the interconnected high- and very high-voltage grid forthe purposes of delivery to customers, distributors, and recipients of self-produced energy. grid. In simple terms, the further the point of consumption (of withdrawal from the NTG) from the productionGeneration of electrical energy, in any way. point (of injection into the NTG), the greater the losses based on the same consumption amounts. Furthermore, based on the same distance, losses are greater on a lower voltage line. Development measures that improve the grid’s meshing shorten the distance between the points of withdrawal and of consumption. Based on other conditions, the consequence is a reduction in grid losses. The same result is produced by strengthening a segment of the grid, for example, when a 380 kV line replaces one at 150 kV along the same route.
With the completion of the projects included in the 2008 Development Plan, reducing peak losses could reach a power of 150-180 MW, to which a reduction of grid losses corresponds of approximately 1,000 GWh/year. If this reduction in losses coincides with an actual saving of fossil fuel, it is then possible to state that these measures can have as an added value also a reduction of CO2 emissions that ranges between 400,000 and 600,000 tons a year.
The estimate was made based on similar conditions: a change in consumption or in the location of the production plants could give different results (also see indicator EN17 for additional information regarding Terna’s possibilities for controlling grid losses).

Improving the production mix
The principal objectives of developing the National Transmission Grid include overcoming the transportation limits between “electricity zones”. The existence of these limits places restrictions regarding the possibility of producing electricity from more efficient plants, namely less polluting in terms of CO2 emissions and also makes it necessary for the grid’s safety production from obsolete plants.
Measures planned in the Development Plan could render a more efficient production mix possible with a greater production share from higher yield plants. The same quantity of final consumption could then be met with a lower fuel consumption: the benefits can be quantified in CO2 reductions up to 2,500,00 tons a year.

Connecting renewable source systems

The main contribution to emission reduction derives from connecting production facilities powered by renewable sources, as included in the Development Plan. Electricity generation from renewable sources represents an energy potential that has undergone a strong growth in recent years. In particular, wind energy has registered a considerable increase, especially in the South of Italy and on the islands. One of Terna's tasks is to plan reinforcements to the NTG in order to encourage production from renewable sources, by seeking to overcome any grid/operationThe methodical use of power plants and accessories according to procedures codified in the implementationof the decisions regarding the operation of the Grid. Operation includes:• the running of the plants in order to carry out Terna’s orders and autonomous deliveries; • emergency assistance following fault or anomalies; • operations for going offline and for the security of the plants; • the monitoring of the status of the plants; • plant inspections. restrictions that carry the risk of influencing operators, who benefit from a priority right for dispatchingThe activity aimed at issuing provisions for the coordinated use and operation of production plants, thenational transmission grid, the grids connected to the same, and ancillary services of the electricity system..

The influence on wind energy production can essentially be attributed to two categories:

  • limitations caused by a safe operation of the Electricity System, i.e. linked to dispatching restrictions that require the generation/load balance to be verified, even in the event of sudden failure of production capacity from renewable sources that cannot be planned in advance. These limitations, which are temporary and concentrated only during low load hours, are also indirectly related to an insufficient transmission capacity on a number of critical sections of the grid, specifically on the islands, and therefore they can be reduced by strengthening the primary EHV transport system;
  • limitations directly attributable to an insufficient transmission capacity of portions of the grid (generally HV) to which the renewable source systems that cannot be planned in advance are connected.

The development solutions designed to deal with the above-mentioned problems include both measures to strengthen the primary grid sections (e.g. SA.PE.I. and the interconnection of Sicily to the mainland), which indirectly enable reductions in the influence on the operation of wind power station production, and measures to locally upgrade the sub-transmission grids into which wind power is directly injected. In addition to these projects and pursuant to Legislative Decree no. 387/03, new wind energy collector stations on the 380 kV primary grid have been planned and are in the process of obtaining authorization, which will result in limiting the construction of new 150 kV power lines that would otherwise be necessary.
Below is a list of the main development projects planned in the 2007 Development Plan that are entirely or partly aimed at encouraging electricity production using renewable sources that cannot be planned. For each measure or group of measures, the benefits linked to the reduction of restrictions, intended as freed power capacity from wind sources, i.e. no longer subject to risks of limitation for the purposes of ensuring grid safety and the Electricity System safety, have been determined.


ProjectsPower from renewable sources
Grid strengthening is indirectly necessary for the reduction of the operating constraints in the dispatching of generated power,
which encourage production from renewable sources that cannot be planned
380 kV “Sorgente - Scilla - Rizziconi” power line and improving the EHV grid in Sicily
Improving the interconnection capacity between Sardinia and the Italian mainland and between Sardinia and Corsica
Measures to strengthen and decongest portions of HV grid into which power produced from renewable sources
that cannot be planned is directly injecte
Strengthening the transmission grid in the area outlined by Foggia, Benevento, and Salerno

Highlight: Priority to wind power

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