The Development Plan and reduction of the electric system’s CO2 emissions

The construction of new lines and stations provided for by the Development Plan will produce positive effects not only in terms of service security and the final cost of electricity, but also in reduced emissions by the electric system. The effects achievable upon completion of the Plan will be of three kinds:

  • reduction of grid losses;
  • improvement of the production mix and interconnection with other countries;
  • connection of plants using renewable energy.

Overall, the reduction of CO2 emissions within the time horizon of the 2013-2022 Plan could reach an amount of approximately 12.5 million tonnes a year.

Reduction of grid losses

Grid losses depend on, among other things, the distance the electricity travels on the transmission grid. Simplifying as much as possible, the further the point of consumption (of withdrawal from the NTG) from the point of production (of delivery into the NTG), the greater the losses for the same consumption. In addition, for the same distance the losses are more on a lower voltage line.

Development work that improves the grid mesh brings withdrawal and consumption points closer: all other conditions being equal, it leads to a reduction in grid losses. The same result is produced by upgrading a stretch of the grid, for example when a 380 kV line replaces one at 150 kV over the same route.

With the completion of the work set out in the 2013 Development Plan, the decrease in losses at the peak could reach a power value of 200 MW, corresponding to a reduction in grid energy losses estimated at around 1,200 GWh/year. Assuming that the reduction of these losses is equivalent to a reduction in production from combustible sources, it can be stated that the work can also have the added positive effect of a decrease in CO2 emissions, somewhere between 500,000 and 600,000 tonnes every year. 

Improvement of the production mix and interconnection with other countries

One of the main purposes of developing the electricity transmission grid is to overcome transport limits between “electricity zones”. The existence of these limits impose a number of restrictions on the possibility of production by more efficient generation units, that is to say units which pollute less in terms of CO2 emissions, and at the same time makes production by obsolete stations necessary for grid security.

The work envisaged in the Development Plan, together with the expansion of interconnection with other countries, would enable a more efficient production mix than the current one, with a larger proportion of production by plants with higher yields. The same quantity of final consumption would thus be covered with a smaller quantity of fuel: the benefits are quantifiable as a reduction in CO2 emissions of up to 6,200,000 tonnes a year.

Connection of plants using renewable energy

The main contribution to the reduction of CO2 emissions comes from connecting production plants using renewable sources which are among the projects in the 2013 Development Plan. The production of energy from renewable sources has been a fast-growing potential source of energy in the last few years. In particular, generation plants using wind and photovoltaic energy have increased considerably, above all in the regions of the South and the Italian islands. Specifically, in 2012 the installed power reached figures of around 17,000 MW for photovoltaic and around 8,000 MW for wind energy.

One of Terna’s main tasks is to plan the upgrading of the grid in order to encourage production of electricity from renewable energy sources by trying to overcome any grid and operating limitations that could limit input of such energy into the grid, which is entitled to dispatching priority. The limitations on production using non-programmable renewable sources (NPRSs) can be divided essentially into two categories:

  • limits due to problems of operating the electricity system securely, associated, that is, with dispatching constraints that require verification of the generation-load balance also in the event of a sudden lack of production capacity from non-programmable renewable sources.
  • limits directly attributable to insufficient transmission capacity of the portions of grid (in general High Voltage) to which plants using non-programmable renewable sources are connected.

The development solutions planned in response to these critical issues therefore include both actions to strengthen sections of the primary grid, which make it possible to indirectly reduce the limits on the operation of NPRS production, and actions to locally expand the sub-transmission grids to which the NPRS generation is directly connected.

Besides this work, NPRS collection stations on the Extra High Voltage grid are planned. These will make it possible to limit the construction of new power lines which would otherwise be necessary (see also the paragraphs dedicated to electricity system security, smart transmission solutions and accumulation systems in the section devoted to Responsibility for the Electricity Service, and in the Profile).

The works included by Terna in the 2013 Development Plan will release about 4,700 MW of power from renewable sources, thus obtaining a reduction of CO2 emissions amounting to about 5,900 kt of CO2/year.

MAIN WORKS IN THE DEVELOPMENT PLAN WITH EFFECT ON INPUTS OF ENERGY FROM RENEWABLE SOURCES

Category Work Power from renewable sources (MW)
Grid upgrading indirectly functional to the reduction of operating limitations in dispatching generation, which favour production from Non-Programmable Renewable Sources 380-kV “Sorgente-Scilla-Rizziconi” power line and upgrading of the EHV grid in Sicily 1,000
Upgrading of interconnection capacity between Sardinia and Corsica/continental Italy 500
New 380 kV “Aliano-Montecorvino” power line 900
380 kV “Foggia-Villanova” power line 700
Upgrading of 380 kV “Foggia-Benevento” power line 500
Work to upgrade and decongest EHV and HV grid sections into which Terna feeds production from Non-Programmable Renewable Sources. Upgrading the transmission grid in southern Italy 1,100