|Waste-to-energy plants (51% renewable)||382,420||367,638||347,481|
|Combustion of landfill biogas||32,807||50,527||56,373|
|Combustion of landfill biogas in third-party plants||32,728||12,280||12,922|
|Combustion of digester biogas||21,735||19,966||22,309|
|Combustion of purification plant biogas||5,355||6,036||6,139|
|Total renewable sources||477,578||458,419||446,937|
|Cogeneration operated as a service||169,589||128,194||127,538|
|Total cogeneration + turboexpansion||526,552||498,449||435,889|
|Waste-to-energy plants (49% non-renewable)||378,715||365,283||333,854|
|Total traditional sources||378,715||365,283||333,854|
Electricity production from renewable sources was 446 GWh (-3% compared with 2017) as a result of a decrease in the total electricity produced by the waste-to-energy plants and consequently also the share of renewable energy. All the other renewable sources (excluding photovoltaic, which decreased slightly) increased, compared to 2017.
Electricity production from cogeneration decreased (-16%) due to lower production at the Imola Casalegno cogeneration plant (-50 GWh produced) for a lower number of hours of scheduled operation. The production of hydroelectric power is zero for the years 2017 and 2018, due to the sale of the hydroelectric plant Cavaticcio in Bologna.
Overall net electricity produced by the Group plants, therefore, fell by 8%.
Electricity produced from renewable sources is equal to 36.7% of the total in 2018, up compared to the previous year. 35.8% is generated by cogeneration and turboexpansion, high energy efficiency systems. Together, the two categories account for 72.6% of the electricity produced. The remaining production has a high level of environmental sustainability, as it is energy recovered from waste-to-energy transformation for the share exceeding 51%.
Incentives to generate electricity using green certificates are awarded to plants fuelled by renewable sources which started operating by 31 December 2012 and to cogeneration plants combined with district heating networks which started operating by 31 December 2009. In both cases, the amount of energy incentivised is not exactly equal to the amount of electricity produced. In the first case, for plants that started operations after 2007, multiplication coefficients were introduced that take into account the plant’s technology: for example, if landfill biogas is used, the recognition awarded is calculated by multiplying the energy generated by 0.8. For non-agricultural biomass with a short supply chain, the factor is 1.3. In the second case, the incentive is proportional to the sale of cogenerated useful heat to district heating network users. Starting from 2016, any remaining right to the issue of green certificates has been converted into an incentive for the electricity produced, as required by Italian Ministerial Decree of 6 July 2012.
For waste-derived electricity, the energy recognised for earning incentives, and to which the above-mentioned factors apply, is limited to the biodegradable portion, since it is considered a renewable source by European and Italian regulations. Italian Ministerial Decree of 6 July 2012 defines the criteria for evaluating this portion on a flat rate basis, set at 51% for waste-to-energy plants that use municipal waste downstream from separate waste collection. In calculating the share of energy produced from renewable sources, a figure of 51% was considered for both electricity and thermal energy produced from waste-to-energy plants, applying the flat-rate criteria. This percentage was assumed as applied to all waste disposed of in waste-to-energy plants (municipal and special) and for all the three years considered, in order to have consistent terms of comparison defined in accordance with the regulations in force. The one exception is the special-waste waste-to-energy plant in Ravenna, whose production is given a biodegradability coefficient of nearly zero since the waste it treats is considered non-renewable, because it comes from industrial processes.
For cogeneration plants, the Ministerial Decree of 4 August 2011, implementing Legislative Decree 20/2007, establishes the methods for calculating cogeneration production and the performance level the cogeneration process must achieve in order to qualify as high-performance cogeneration. The subsequent decree of the Ministry of Economic Development of 5 September 2011 determines a new support regime for cogeneration: this incentive is based on white certificates and is recognised by the Energy Services Manager, after attributing the qualification of cogeneration, according to the actual primary energy savings achieved.