Energy production: fossil and renewable energy sources

With the goal of increasing generation of renewable energy, in line with the development plan outlined in the Industrial Plan, in 2021 Acea acquired a further 4 MW in the photovoltaic segment and installed 16 MW, thus reaching 72.5 MW in total.

GROUP PLANTS

Through Acea Produzione, the PV Companies¹²⁷ and Acea Am- biente, the Group generates electricity primarily from renewable sources. The majority of production is provided by hydroelectric plants and another significant portion, also partially renewable, from waste-to-energy plants utilising paper-mill waste and Solid Recovered Fuel (SRF).

Acea Produzione is equipped with plants for generation from re- newables, both hydroelectric and photovoltaic, and fossil fuels (ther- moelectric), with the latter primarily through the high-efficiency co-generation plant of the Tor di Valle power plant, which had greater availability during the year. At this power plant, activity was also completed for construction of the third co-generation unit, composed of a 9.5 MWe internal-combustion engine, with an increase in installed power from 19 MW in 2020 to 28.5 MW in 2021.

The power park includes:

• seven hydroelectric power stations located in the Latium and Abruzzo regions for a total of 122 MW,
• 2 thermoelectric power stations located within the Municipal- ity of Rome area: Montemartini (78.3 MW)128 and Tor Di Valle (28.5 MW), for 8 MWe total available installed capacity,
• one photovoltaic park, for a total of 5 MWp.

The generation of energy from waste-to-energy processing is as- signed to Acea Ambiente, taking place at two plants located in San Vittore del Lazio and Terni, and both with percentages of biodegrad- able material (renewable source) varying between 40% and 50%. The total gross electrical power currently available is approximately 58 MWe.

In addition, Acea Ambiente produces electricity using biogas derived from the anaerobic digestion process at the Orvieto Technol- ogy Hub and the composting plants of Aprilia and Monterotondo Marittimo.

Table no. 48 – Installed power of the electric power stations of Acea Produzione

(*) The CAR plant in Tor di Valle provides district-heating service in the area south of Rome.

The installed capacities of the Group, which overall amount to approximately 346 MW¹²⁹, are presented in Chart no. 51, distinguished by energy source.

Chart no. 51 – Installed electrical power of the Group broken down by energy source (MW) (2021)

ELECTRICITY PRODUCED

In 2021 overall gross generation of electricity increased by 10%, rising from 916 GWh in 2020 to 1,009 GWh in 2021. This increase is due to several factors: greater rainfall in the year influenced hy- droelectric generation (up 15%), the new photovoltaic component (+5% energy generated) and the waste-to-energy sector (+3%). This latter increase was due to Terni plant experiencing a lower number of shutdowns, making it more efficient in terms of energy usage compared to the previous year. The production of biogas also increased, above all thanks to the Aprilia plant, now running at full capacity. For further details, see the Environmental Accounts.

The share of electricity generated by renewable sources, about 698 GWh, is predominant, corresponding to approximately 69% of the total, with the following contributions:

• 7 GWh from hydroelectric power,
• 5 GWh from waste-to-energy,
• 4 GWh from biogas (Orvieto, Aprilia and Monterotondo Marittimo plants)
• 6 GWh from solar panels (see Chart no. 52 and Table no. 49)¹³⁰.

After completion of upgrading and actions to increase efficiency in 2021 the only revamping that took place involved the Sant’An- gelo power plant, with the goal of optimising use of available water resources, with the same specifications in terms of installed power and authorised by concession.

In addition, Acea Produzione and Acea Ato 2, are collaborating on a particularly important project rooted in the development of synergies between the businesses managed by the Group. The project involves installation of an additional two 1.5-MWe internal combus- tion engines at the Tor di Valle High Efficiency Cogeneration Plant (CAR), which will be powered by the biogas from the adjacent Acea Ato 2 Roma Sud treatment plant. The Tor di Valle plant will in turn provide the treatment plant with thermal energy to heat the sludge in the digesters¹³¹ (see info. box for details). Construction of a 267.3 kWp photovoltaic plant has been authorised at the same power station. The worksite, launched in November 2020, was closed in 2021 and the plant is currently operational.

A significant portion of the energy from waste-to-energy produc- tion, as already noted, is associated with the combustion of the bio- degradable fraction of waste used as a primary source. In particular, the renewable share of the fuel (SRF) entering the San Vittore del Lazio plant was 43.0% of the total of waste-to-energy production in 2021, while at the Terni plant this share was 43.4%. The percent- ages are in line with 2020 for both plants, but lower than years previous to the pandemic. In fact, a change in SRF composition was recorded, particularly for the San Vittore del Lazio plant, which is probably linked to the strict limitations applied in the restaurant industry and catering through canteens in schools and business, etc.

Chart no. 52 – Electricity produced subdivided by primary energy source (TJ) (2021)

Table no. 49 – Electricity produced (by primary energy source) (2019-2021)

(*) 1 GWh = 3.6 TJ.
(**) Photovoltaic includes the production at the plants located on sites of the water area (Acea Ato 2 and Acea Ato 5) for a total of 1 GWh produced.

THERMAL ENERGY PRODUCED

La Centrale termoelettrica di Tor di Valle ha generato circa 99 GWh di energia termica. Il calore generato è stato utilizzato per servire un bacino di 42.680 abitanti in zona sud di Roma (Mostacciano, Torrino e Mezzocammino), attraverso una rete di teleriscaldamento che serve una volumetria pari a 3.861.163 metri cubi¹³². Nell’ultimo biennio sono state sostituite 35 delle attuali 361 sottostazioni termiche afferenti alla rete del teleriscaldamento, per migliorare l’efficienza del processo e l’affidabilità del servizio all’utenza (si veda anche il paragrafo Strategia e Sostenibilità, Il Piano di Sostenibilità 2020-2024 e gli obiettivi operativi).

La Società Ecogena, certificata in qualità di ESCo (Società di Servizi Energetici) ai sensi della norma UNI CEI 11352:2014, sviluppa le iniziative di efficienza energetica per il Gruppo e ne rendiconta gli esiti al Gestore dei Servizi Energetici (GSE) per l’ottenimento dei Titoli di Efficienza Energetica (TEE).
Tra le attività affidate ad Ecogena sono incluse anche la progettazione e la realizzazione di impianti di cogenerazione e trigenerazione¹³³ per la produzione, in modo combinato, di energia elettrica, calore e freddo.
Nel 2021, gli impianti cogenerativi gestiti, abbinati a reti di teleriscaldamento, per effetto della conclusione di due contratti riferiti agli impianti presenti nelle regioni Lazio e Umbria, sono passati ad una potenza elettrica complessiva di 1,9 MW (era di 4,9 MW nel 2020).
Per dettagli relativi alla produzione del triennio si veda la tabella n. 50.

Tabella n. 50 – La produzione di energia da impianti di Ecogena e i titoli di efficienza energetica TEE (2019-2021)

NOTE: Other information on EECs is provided in the Energy savings section of the chapter The use of materials, energy and water.

¹²⁷For the PV Companies included, see Disclosing sustainability: methodological note.
¹²⁸The power station is operational only in the event of extraordinary energy demand, and operation can also be managed remotely from the control room at the Tor di Valle Power
Station.
¹²⁹The photovoltaic plants of AdF and the Terni waste-to-energy plant are not included (as they are owned by AdF and Acea Ambiente, respectively): the former produced and self-consumed 12.5 MWh in 2021, while the latter produced 444.3 MWh of which 61% was consumed on site.
¹³⁰The photovoltaic plants of AdF and the Terni waste-to-energy plant are not included (as they are owned by AdF and Acea Ambiente, respectively): the former produced and self-consumed 12.5 MWh in 2021, while the latter produced 444.3 MWh of which 61% was consumed on site.
¹³¹In January 2021, the request was submitted to the Ministry for the Environment (MATTM) for preliminary verification for application of an EIA.
¹³²Data from August 2021.
¹³³Cogeneration, i.e. the combined production of electrical and thermal energy, allows high efficiencies to be achieved, between 80 and 90%. Trigeneration, which is a special application of cogeneration, allows use of a part of the thermal energy recovered in order to produce cooling energy in the form of cooled water for air conditioning in rooms or for industrial processes