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Atmospheric emissions


Total emissions of nitrogen oxides, dust and carbon monoxide arising from energy production and the waste to energy treatment of refuse in 2011 fell compared with the previous year, partly as the result of a lower production of energy and partly following the improvement measures taken to reduce plant emissions. As a consequence of the fact that the system for the catalytic reduction of nitrogen oxides on Group 3 of the Lamarmora (Brescia) cogeneration plant has become fully operational, emissions per kWh of nitrogen oxides from the fossil fuel combustion plants actually fell (from 0.39 to 0.23 g/kWh). The emissions per kWh of the waste to energy plants also decreased.
With the sleeve filters for reducing dust at the Brescia waste to energy plant becoming fully operational, the dust emitted by the waste to energy process has been reduced.
Thermoelectric power is produced by the multi-fuel plants at the Monfalcone (Gorizia) power station where coal, and to a lesser extent fuel oil and biomasses, are mainly used. Thanks to the desulphurization systems installed in 2008, the average concentrations of sulphur dioxide (SO2) in the fumes have been well below legal ceilings: against a limit of 200 mg/Nm3 for the monthly average, the maximum monthly average was 164 mg/Nm3 and 139 mg/Nm3 for sections 1 and 2 respectively, recorded in December 2011, while the average annual concentration was 86.1 mg/Nm3 and 98.0 mg/Nm3 respectively. SO2 emissions from the power station are significantly affected by the tenor of the sulphur to be found in the fuel and consequently by the quantity and quality of the coal used; in particular, this latter substance is liable to vary considerably depending on where it comes from. The increase in the number of tonnes of sulphur dioxide in 2011 over 2010 can therefore be traced to these factors.

Emissions of the waste to energy plants may be found online

A2A follows a policy of maximum transparency and information on all fronts. Consistent with this policy, a new information service dedicated to reporting data relating to the emissions of the Group’s six waste to energy plants was started up in December 2011.

  • It is now possible to consult the page “Quality of the Air” on the institutional website This collects together all the data on the atmospheric emissions of the plants, analysed by region: Lombardy and  Campania.

“Online emissions” allows the reader to view daily data, and data for the previous four weeks, in a homogeneous form; these figures are then progressively memorised and summarised in an ad hoc section.
This approach enables a complete and exhaustive vision of the plants to be obtained and an accurate check of the concentrations in the air.

A2A follows various programmes for reducing emissions:

  • it is planned to strengthen the catalysers at the Brescia waste to energy plant to reduce emission levels of NOx and at the same time reduce the usage of ammonia;

  • in 2011 improvement measures on the desulphurization reactor began at the Lamorma power station, together with measures to increase the surface area of the sleeve filters, which will allow a significant reduction in the concentration of sulphur oxides (SO2) in the fumes to be achieved and enable the best environmental performance currently possible in the sector to be reached.

Air quality monitoring plan at Milan Silla 2

Sampling activities continue at the Milan Silla2 waste to energy plant, as specified in the environmental monitoring plan drawn up by ARPA and the Milan Polytechnic (as agreed in the Protocol of Understanding signed with the authorities and the neighbouring municipalities). This plan, which has a four year term, envisages two campaigns a year. Chemical analyses are carried out on the samples withdrawn to test for the existence of certain specific pollutants (such as dust, dioxins, polycyclic aromatic hydrocarbons, metals). All the results will be sent to the signatories of the Protocol of Understanding.

A2A places specific emphasis on the emissions of the waste to energy plants. The Group’s plants are equipped with reduction systems that are in line with the best available technologies for limiting emissions of the “traditional” pollutants and those emitted in smaller quantities, the “micro-pollutants”. To eliminate the latter, “active carbons” are injected into the fume flow and these absorb the undesired particles on their surface, eliminating them from the gases that escape into the air. These carbons “charged” with the micro-pollutants are then retained by suitable filters and disposed of as waste or, if possible, recovered.
A total of 0.024 grams of dioxins were emitted by the Group’s plants in 2011, a result achieved thanks to concentrations in the fumes that are kept much lower than legal limits, one ten-billionth of a gram per cubic metre (0.1nm/Nm3).
Emissions of polychlorinated biphenyl (PCB), metals and polycyclic aromatic hydrocarbons (PAHs) are monitored with a predetermined frequency to ensure that legal limits are complied with. The concentrations measured are always lower than the legal limits and have been somewhat variable, in certain cases below the measurability threshold.