The increase in generation from Non-Programmable Renewable Sources (FRNP) may require more resources for dispatching services for the security of the electricity system; however, it has the effect of reducing the resources traditionally provided for this purpose by relevant thermoelectric and hydroelectric plants (i.e., with total capacity of associated generating units not less than 10 MVA). Therefore, the quantities of energy up and down, with the associated economic counter-values, that Italian relevant plants traded, from 2014 to 2021, both on the energy markets (Day-Ahead Market (MGP) and Intraday Market (MI)) and service markets (Dispatching Services Market ex ante (MSD) ex ante and Balancing Market (MB)), at the national level and by market zones, were analyzed.

Plants were grouped on the basis of primary source: coal-fired, gas-fired, oil-fired, hydro, further subdivided into reservoir, reservoir, generation and pumped storage plants. Energy exchanges and countervailing values were also assessed for plant types that operate only on PGMs and IM: run-of-river hydro, biomass or waste-fired thermoelectric, geothermal, photovoltaic, wind (onshore).

The results show the strong contribution of gas-fired plants, as also appears from the composition of the generation mix. For example, the energy sold on MGP by these plants in the eight years considered varied between 39 percent and 62 percent of the total sources analyzed. Among other sources, the largest sales on MGP come from coal (4 percent to 23 percent), wind (7-9 percent), and flowing hydro (6-10 percent). MI, MSD ex ante and MB each have total energy exchanges on the order of 1/10th of sales on MGP. The distribution of these exchanges among the different sources is quite similar on MI up and MI down, with a lower dominance of gas than on MGP due to a larger contribution of pumped storage, both up and down, wind down, and coal down.

On MSD ex ante, on the way up gas (58-74%) is followed by coal (10-35%) and oil (2-18%); on the way down gas (65-99%) is followed by coal (up to 25%) and pumping (up to 13%). On MB, on the way up gas (68-76%) is followed by pumping (9-18%) and coal (6-15%), and similarly on the way down gas (57-79%) is followed by pumping (9-21%) and coal (2-17%). For the four markets, the economic volumes are distributed among the technologies fairly similarly to the energies, with a few exceptions.

In summary, we can see the growing importance over the years of FRNPs and the significant role of pumping, especially in balancing; the contribution of the more emissive fossil sources is still significant, although declining.