Energy distribution

The distribution network

The distribution network

Areti manages the electricity distribution network at Rome and Formello, extending over about 31,000 km and capable of supplying a basin of about 2.8 million resident inhabitants. In terms of volumes of electricity distributed, about 9,800 GWh/year, Acea is the third largest Italian operator in the sector.
In Table no. 50 the principal plant data is described with reference to the primary and secondary substations and to the overhead and underground distribution lines.

The environmental indicator correlated to the protection of the land and calculated as a percentage share of the underground high voltage (HV) network in relation to the total of the high voltage lines in use (overhead and underground) has improved even more. In fact, the data monitored by year in 2018 were again equal to 46% (44% in 2017); also due to the transformation and modernisation of the high and very high voltage electricity distribution networks.


systems and output   u. m.  2016  2017  2018 
High Voltage/High Voltage - High Voltage/ Medium Voltage primary sub-stations  no.  71  71  70 
High Voltage/High Voltage and High Voltage/Medium Voltage transformers  no.  170  169  166 
transformation power   MVA  7,924  7,921  7,631 
sub-stations in use   no.  13,152  13,159  13,211 
Medium Voltage/Medium Voltage - Medium Voltage/Low Voltage transformers   no.  12,831  12,832  12,838 
transformation power   MVA  6,183  6,203  6,236 
overhead and underground networks      
high voltage network - overhead lines   km  321  310  282 
high voltage network - underground lines   km  243  243  243 
medium voltage network - overhead lines   km  429  419  424 
medium voltage network - underground lines   km  10,180  10,137  10,166 
low voltage network - overhead lines   km  1,646  1,641  1,641 
low voltage network - underground lines   km  17,917  18,147  18,306 

With reference to the electric and magnetic fields, in particular relative to the primary transformer substations, High and Medium Voltage overhead electricity lines and secondary transformer cabins, the possible risks for the health of employees and the community of reference are dealt with, respectively, in the Risks Evaluation Document and in the Corporate Environmental Analyses Document. Areti conducts periodic sample checks in the company’s sites, carried out also following reports by users/customers or External Bodies. Additional checks are conducted by ARPA Lazio 109 following specific requests by the public and customers.


2018 saw the continuation of the plan to modernise the high voltage electricity distribution network (150 kV), defined in the Memorandum of Understanding signed in 2010 among Areti SpA  (formerly Acea Distribuzione), the Municipality of Rome and Terna SpA, which concerned, in particular:

  • the completion of the demolition of the 150 kV Rome North-Cassia overhead line, for a total of 9.8 km and 39 supports, consequent upon the activation of the Flaminia-Cassia high voltage line;
  • the completion of construction works for the 150 kV “Rome North-San Basilio” line, relative to the stretch to be adjusted for a length of 5.5 km with green coloured pylons and tubular supports, consistently with the requirements of the Rome Nature Body;
  • the commencement of construction works for the 150 kV “Rome North-San Basilio” line, relative to the new section from the Rome North Electrical Station for a length of 4 km with green coloured pylons and tubular supports, consistently with the requirements of the Rome Nature Body;
  • the start of the demolition of the 150 kV Flaminia 2 - East Sorting 2 line, for a length of 22.6 km and 74 supports.

Upon completion of the Plan, thanks to the lower energy losses, in addition to improving the service and the related social benefits, there will also be a significant environmental benefit thanks to the significant energy savings expected, amounting to about 58 million kilowatt hours, equivalent to the annual consumption of about 20,000 households.

The management of the electricity distribution network of Rome and Formello is characterised by the continuous improvement of the performances, with particular attention to energy efficiency.
Therefore, initiatives to reduce grid losses continued also in 2018, ranging from the progressive and ongoing replacement of medium voltage levels from 8.4 kV to 20 kV, to the installation of MV/LV transformers with very low losses (see also the chapter on Customers, paragraph Quality delivered).
The activities performed for the smart city that continue to improve the performance of the networks thanks to the evolution and integration of management systems and, in general, the applications of technological innovation in the management of the network, are illustrated in the chapters Customers and Institutions and the company.
Also as a result of the activities mentioned above, energy losses on the grid during the year amounted to approximately 7.2% of the total transported, a slight increase compared to the previous two years.

[109] According to the following legislative references: Legislative Decree no. 81/08; Italian Electro-technical Committee Guide 211-6 first ed. of 01/2001; Prime Ministerial Decree 8/7/2003 “Fixing of the limits of exposure, the values of attention and the quality objectives for the protection of the population from electric and magnetic fields at the network frequency (50Hz) generated by the power lines”.