people hired
thanks to the induced employment
generated by Hera in 2017
million euro
Investments in innovation and
digitalization. 13 projects in smart city,
circular economy and 4.0 utilities
of reused soil
in projects implemented in 2016
and 2017

Atmospheric emissions generated by waste-to-energy plants

All of Hera Group’s waste-to-energy plants are equipped with fume treatment and process and emission control systems, designed and built so as to attain:

  • elevated fume treatment performances in all process conditions;
  • elevated management versatility;
  • elevated reliability of emission control systems.

In order to meet these goals, the new plants and those that have been renovated (Modena, Bologna, Ferrara, Forlì, Rimini) are equipped with the following systems:

  • double reaction and filtration system to lower the concentrations of particulate, hydrochloric acid, hydrofluoric acid, sulphur dioxide, heavy metals, dioxins and furans and aromatic polycyclic hydrocarbons (the Modena plant has a bag filter and an electrostatic precipitator);
  • double reaction system (catalytic and non-catalytic) to reduce concentrations of nitrogen oxides;
  • double fume monitoring system for process control: the two systems measure the concentrations of the main pollutants emanating from the oven and downstream of the first reaction and filtration phase, on the basis of which a calculation is made of the volume of reactants required to ensure treatment levels that guarantee respect for legal emission limits and which are, on average, 80-90% below these;
  • continuous double monitoring system for chimney emissions: one as a reserve for the other in order to guarantee the continuity of the analysis of concentrations in atmospheric emissions.

The possibility of using double treatment and monitoring systems in series (in parallel as regards chimney monitoring) allows the above objectives to be successfully pursued.

This paragraph also contains data on the Faenza (operated by Enomondo, 50% owned by Herambiente and not consolidated using the line-by-line method), equipped with a double reaction system (catalytic and non-catalytic) to reduce concentrations of nitrogen oxides.

The Padua, Pozzilli and Trieste plants have a single reaction and filtration system to lower the concentrations of particulate, hydrochloric acid, hydrofluoric acid, sulphur dioxide, heavy metals, dioxins and furans and aromatic polycyclic hydrocarbons, a single reaction system for reducing nitric oxide concentrations (double for Padua) and a single fume monitoring system.

In addition to the aforementioned activities, the following operations are carried out on an annual basis to monitor emissions and environmental impact:

  • timely controls of the chimneys, at a frequency set by the Integrated Environmental Authorization, for those parameters which cannot be continuously monitored, using certified inspectors;
  • checks on soil fallout of pollutants: through external monitoring programmes in collaboration with the University and research agencies, deposition analyses are performed on soil, ground and vegetation etc., in order to ascertain that the emissions, in addition to being within the legally established limits, do not have any significant impact on the surrounding environment.
Atmospheric emissions generated by waste-to-energy plants
t 2015 2016 2017
Particulates 7.3 6.4 6.2
Hydrochloric acid 17.0 15.6 17.4
Nitrogen oxides 744.4 703.7 705.3
Sulphur oxides 13.7 11.7 14.9
Carbon monoxide 75.6 72.7 83.0
Hydrofluoric acid 0.8 0.7 0.6
Total Organic Carbon 8.9 9.4 10.4
Waste treated in the plants (thousands of t) 1,425 1,439 1,403
Net electricity generated (MWh) 871,786 828,906 802,675
Thermal energy produced (MWh) 219,864 239,282 265,920

The data are calculated using continuous measurement systems which are subject to the approval of the supervisory bodies at the time of authorization for operation of the plant. The procedures used by individual plant systems to collect and calculate the volume of substances released are not completely standardized. Including the Enomondo waste-to-energy plant.

Mass flow analysis shows an improvement with respect to hydrofluoric acid emissions (-7.2% compared to 2016) and total dust emissions (-2.6% compared to 2016), while the other substances analysed increased. Note, furthermore, that for all continuously monitored pollutants, the concentrations at the chimney, in 2017 were once again much lower than the regulatory limits: from a maximum of 97% below the regulatory limits for sulphur oxides to a minimum of 59% for nitrogen oxides.

With regard to pollutants not monitored continuously, total emissions can be estimated on the basis of the results of the analyses performed during the year. In 2017, 154 kg of metals were emitted (200 in 2016), along with 0.55 kg of aromatic polycyclic hydrocarbons (0.66 in 2016) and 40.9 mg of dioxins (24.3 in 2016). All values are at least 94% below regulations.

The results of the emission measurements at Hera Group’s waste-to-energy plants confirm that, since they are equipped with the best technologies available and run in the most efficient manner possible, these plants emit levels of particulate, dioxins and furans, aromatic polycyclic hydrocarbons and metals that are far below the emission limits. Compared with the other parameters, subject to continuous monitoring, at plants equipped with the double reaction sulphur oxide reduction system (Bologna, Ferrara, Forlì, Modena, and Rimini) the concentrations were not only well below the regulatory limits, but also below the limits set by local authorities, which are much more stringent than national regulations.

Legislative Decree 133/2005 requires continuous monitoring of flue emissions for seven parameters. In addition, in the Ferrara, Forlì, Modena and Rimini plants, mercury is also continuously monitored.

Atmospheric emissions
Including the Enomondo waste-to-energy plant.
Compliance of waste-to-energy plant atmospheric emissions with regulations pursuant to Legislative Decree 133/2005

The plant renovation process has resulted in a significant improvement in the abatement percentages of pollutant emissions:

  • in January 2008 two new lines of the Ferrara waste-to-energy plant became fully operational;
  • since the beginning of 2009 the new Forlì plant is fully operational;
  • in April 2010, the new line 4 of the Modena waste-to-energy plant became operational;
  • in October 2010, the new line 4 of the Rimini waste-to-energy plant became operational;

In 2017, the average concentrations of the atmospheric emissions of the waste-to-energy plants were 14.5% of the regulatory limit. This means that in 2017, emissions were 85.5% below the limit, while in 2003 the percentage stood at 59%. The levels of parameters that do not require continuous monitoring (total metals, polycyclic aromatic hydrocarbons, dioxins and furans, cadmium and thallium, mercury) are also below regulatory limits: between -94% and -99%. Excluding the two AcegasApsAmga plants and the Pozzilli and Enomondo plants, the values in 2017 (13.4% of regulatory limits) are slightly higher than they were in 2016 (12.9%), in line with 2015 (13.4%) and almost halved compared to 2005 (25.5%).

Compliance of waste-to-energy plant atmospheric emissions

Atmospheric emissions from waste-to-energy treatment plants compared to authorization limits – continuously monitored parameters (optimal values <100%)
% 2015 2016 2017
Bologna (FEA) waste-to-energy plant 27.3% 27.1% 28.3%
Ferrara waste-to-energy plant 10.2% 10.7% 10.2%
Forlì waste-to-energy plant 20.8% 21.3% 22.2%
Modena waste-to-energy plant 19.5% 17.4% 16.7%
Ravenna waste-to-energy plant (special waste) 12.2% 11.6% 11.4%
Faenza (Enomondo) waste-to-energy plant 15.9% 16.9% 20.7%
Average 17.6% 17.5% 18.2%

The Integrated Environmental Authorizations relating to the plants in Ferrara, Forlì and Modena also require the continuous monitoring of mercury.
The same indicator was calculated for the six plants with authorization limits that are more stringent than Italian regulations for 2017 (for the eight continuously-monitored parameters on average the limits set by the authorizations are 73% of the limits laid down in Legislative Decree 133/2005); the data are shown in the table above. The results are excellent also in this case: the concentrations are, on average, 81% below the most restrictive limits. That the limits set by the individual authorizations are different depending on the plant, meaning that it is not possible to compare the n.

As to parameters for which Legislative Decree 133/2005 does not require continual monitoring (total metals, aromatic polycyclic hydrocarbons, dioxins and furans, cadmium and thallium, and mercury), in 2017 the Hera Group took a total of 708 samples, a considerably higher number than the 225 required by national regulations. In the 6 plants for which the IEAs require a higher number of samplings than required by law, 658 samplings were made (up compared to 8 samplings in 2016) compared to the 524 required. In 2017, as in previous years, Hera plants complied with the authorization limits for amounts of waste treated, their type and, where present, their geographical origin.

Thermal capacity saturation percentage of the plant
% 2015 2016 2017
Bologna (FEA) waste-to-energy plant 93% 93% 93%
Ferrara waste-to-energy plant 95% 97% 98%
Forlì waste-to-energy plant 87% 95% 94%
Modena waste-to-energy plant 95% 94% 95%
Ravenna waste-to-energy plant 100% 100% 98%
Rimini waste-to-energy plant 99% 100% 99%
Pozzilli waste-to-energy plant 100% 98% 95%
Faenza (Enomondo) waste-to-energy plant 93% 100% 100%
Weighted average on thermal power 95% 97% 96%

Excluding AcegasApsAmga.

Given that in 2017 the waste-to-energy plants indicated in the table treated quantities of waste substantially in line with the authorized quantities, and given the calorific value of this waste, the average percentage of the thermal capacity was 96%. This means that in 2017 the plants were used at 96% of their potential.

Natural gas is used by the waste-to-energy plants during start-up and shut-down and to support combustion if the calorific value of the waste being treated is low: the overall consumption of 2017, excluding Hestambiente and the Enomondo plant, was over 8 million m3. Compared with 2016 there was an increase in methane consumption by over 860,000 m3 despite the 2% decrease in waste treated. This increase is mainly due to an increase in methane consumption at the plants at Ravenna, Forlì, Bologna and Ferrara, in part compensated by the decrease of consumption in the Ravenna incinerator and in the Modena waste-to-energy plant.

Electricity generated in relation to waste disposed of
KWh/t before-revamping 2016 2017 2017 Delta (before revamping)
Ferrara waste-to-energy plant 251 484 395 57%
Forlì waste-to-energy plant 295 528 513 74%
Modena waste-to-energy plant 282 542 588 109%
Rimini waste-to-energy plant 351 478 468 33%
Weighted average on volumes of waste treated 290 511 503 73%

The performance of some plants is expressed here as the ratio between electricity generated and waste disposed of, highlighting the improvement resulting from their revamping. After revamping the waste-to-energy plants, electricity generation performance improved by 73%.