Other indirect emissions of CO₂


EN17In addition to the emissions corresponding to the consumption of electricity, other indirect emissions caused by Terna’s activities are connected with:

  • grid losses;
  • employee flying

Grid losses

EU12Grid lossesare defined as the difference between the energy injected by producers and imports and end consumption. The losses that are significant for Terna are those associated with the transmission grid. Both measurements are the result of an estimate, which breaks down the total losses of the electricity system (including the distribution networks) in proportion to the voltage levels, beginning with calculations performed assuming particular grid configurations and considering the losses on lines because of the corona effect, directly proportional to the voltage and because of the joule effect, directly proportional to the current, as well as losses in the transformers.

  % with respect to energy demand GWh
  2011(1) 2010 2009 2011 2010 2009
AAT grid
1,23 1,23 1,27 4.077 4.055 4.067
AT grid 1,39 1,39 1,44 4.633 4.608 4.612
(1) Per il 2011 il dato è stato calcolato sui “Dati provvisori di esercizio del Sistema Elettrico Nazionale 2011”; il dato 2010 si riferisce invece ai dati disponibili a consuntivo e pertanto differisce da quanto precedentemente pubblicato.

It should be noted that Terna can only contribute to determining the extent of the losses, which are not completely under its control. To explain this, it is useful to distinguish between dispatching activities and activities for developing the grid.

Dispatching is necessary to ensure the constant balance between injections and withdrawals and to avoid problems of grid security and poor service. These activities take place, according to regulated criteria, within the framework of production set-ups determined by the energy market and therefore cannot be conditioned by Terna with the objective of minimizing losses. On the other hand, it should be noted that the energy market implicitly favors the more efficient productions and thus entails a trend of emission reduction that is much greater than that of grid losses.

With equal production set-ups, the activities of grid development would determine greater efficiency and therefore a reduction of losses. However, the development of the grid leads to production set-ups that were not previously possible and also enables consumption to increase. Furthermore, grid development itself is partly dictated by the need to connect new plants, whose location is not determined by Terna. The overall effect of grid development on losses is therefore not predetermined and not even under the control of the grid operator. Other factors can significantly offset the increase in efficiency ensuing from the development of the grid, in terms of both the absolute quantity of the losses and the losses as a percentage of the total energy consumed.

The CO2 emissions associated with grid losses in 2011 were as follows:

  • for the EHV grid, 1,671,570 tons/year;
  • for the HV grid, 1,899,530 tons/year.

Terna is developing new specifications for the acquisition and use of medium-voltage/low-voltage transformers with “low losses of electricity”. The adoption of the new specifications is in line with Terna’s environmental and energy policy and with the Electricity and Gas Authority’s resolution ARG/elt 348/07. The objective of the new specifications is the construction and acquisition of Ak class transformers, the highest performing, with an average reduction of load losses of 11% with respect to the current values. As far as no load energy losses are concerned, the adoption of the B0 class will lead to an average loss reduction of 28% with respect to the current values, which is non-negligible, given the fact that 50% of the transformers installed are in this working condition to guarantee a reserve that is ready in the event of a breakdown. The reduction will also have an impact on grid losses.

Employee flying

The emissions corresponding to employee flying recorded a slight increase with respect to 2010 (+3%), mostly miles and emissions related to international travels have risen (+36%), because of the increase in the Company’s activities in the Balkans and the Mediterranean area.


  Miles Miles CO2 emissions (tons)
Kind of flight 2011 2010 2009 2011 2010 2009
Domestic 3,174,881 3,065,573 3,511,970 1,048 1,010 1,013
International 1,523,415 1,128,909 1,223,462 367 271 260
Intercontinental 521,433 945,914 1,618,459 109 195 306
Total 5,219,729 5,140,397 6,353,891 1,523 1,477 1,578