logo di stampa inglese

RSI Utility

You are in: The Environment and Future Generations » Greenhouse gas emissions

Greenhouse gas emissions

Greenhouse gas emissions of plants subject to the Emissions Trading scheme
The primary and most common gas responsible for the greenhouse effect is carbon dioxide, which is produced during combustion processes. Starting with the Kyoto Protocol, over the last 25 years, numerous international agreements have been signed for the purpose of regulating and controlling greenhouse gas emissions.
The 2008-2012 period is the "first commitment period" to the Kyoto Protocol objectives of reducing greenhouse gas emissions, to be achieved in Europe with the EU-ETS (European Union Emission Trading System), a cap & trade type mechanism used to define the maximum greenhouse gas atmospheric emissions permitted in Member States, even if, for now, only carbon dioxide (CO2) has been considered. Member States have assigned the maximum emission quotas to operators with plants that fall within the field of application. The Hera Group plants involved are combustion plants with a maximum overall thermal furnace power of 20 MWt: waste to energy plants fuelled by waste are excluded from the mechanism. The Ministry for the Environment assigns maximum annual quotas for carbon dioxide emissions, expressed in metric tons of CO2, to each of the plants. Every year it is then necessary to quantify and submit the emissions produced to inspection, comparing them to the assigned quotas. If the emissions are below the authorised levels, the excess quotas constitute an asset with an economic value that can be realised in a special dedicated market; vice versa, if emissions are too high, the missing quotas must be purchased from the market. As a result all operators have an incentive to contain the greenhouse gas emissions of their plants as far as possible and through a mechanism that gradually reduces the annual overall cap it is possible to comply with the Kyoto Protocol global policy and targets in order to contain environmental impact.

Kyoto Protocol compliance ratings
PlantPower (MW)Type200920102011
ACER Barca (Bologna)28.8Thermal power153%208%130%
ACER Pilastro (Bologna)32.8Thermal power276%906%449%
Berti Pichat plant (Bologna)25.7Cogeneration plant49%49%53%
COGEN (Bologna)26.9Thermoelectricity cogeneration and thermal power75%87%91%
Ecocity (Bologna)33.8Thermoelectricity cogeneration and thermal power176%186%178%
San Giacomo (Bologna)21.7Thermal power163%176%171%
Canal Bianco (Ferrara)92.3Thermal power88%91%35%
Casalegno (Imola)222.7Cogeneration plant174%59%61%
Montericco (Imola)20.2Thermoelectricity cogeneration and thermal power24%0%1%
Giardino (Modena)33.4Cogeneration plant-58%59%
SAFTA (Piacenza)41.3Cogeneration plant43%48%50%
Weighted average89%57%56%

The Kyoto protocol compliance rating (%) indicates real emissions divided by assigned quantities. A value over 100% indicates that the level of authorised emissions has been exceeded. The quotas referring to the Casalegno Imola has been recognized as "new entrant" plant. The quotas referring to the Giardino di Modena plant are estimates, as these are still to be assigned.

There are 11 Hera Group plants authorised to emit greenhouse gases on the basis of Emissions Trading legislation, involving total installed furnace power of 579.6 MW; there are no variations with respect to the previous year. The carbon dioxide emissions recorded in 2011, which came to 240,359 metric tons, are also in line with the 2010 figure. The exceeding of authorised quotas at some plants is a consequence of a level of quotas authorised on the basis of historic consumption patterns pre-2005, a year in which district heating was less developed. Furthermore, we note that the cogeneration plant in Imola Montericco was decommissioned in 2010.

Overall greenhouse gas emissions

The Group plants produced total greenhouse gas emissions of 655,866 metric tons of CO2 equivalent. The 7% increase in emissions in the 3 years in question is due to the start-up of new plants and is nonetheless lower than the increase in energy produced by these plants in the same period (+24%).

Total greenhouse gas emissions of plants
Waste-to-Energy plants 415,046378,575415,552
Plants authorised according to Emissions Trading directive200,121240,855240,314

In addition to these emissions, there are also the emissions deriving from landfills, losses in the gas network and motor vehicles, which are estimated at 793,393 metric tons. Indirect emissions from electricity consumption were 231,577 metric tons.
The following components were considered:

  • landfills: methane from biogas which is given off by the landfill matter, plus carbon dioxide from the combustion of tapped biogas;
  • waste-to-energy plants: carbon dioxide from the combustion of waste, from which the portion corresponding to biodegradable substances was removed;
  • district heating: carbon dioxide from the combustion of methane;
  • losses in the gas network: estimated as the difference between the methane input into Hera stations and the methane invoiced to customers; thus, this calculation includes real losses (due to breakage of pipes) and administrative or apparent losses (errors in meter measurement, errors in estimates of consumption at 31 December);
  • motor vehicles: carbon dioxide from the use of fuels.

Landfill emissions were estimated using a mathematical model based on the amount of waste disposed in eleven landfills in each year, type, composition and biodegradability of waste and amount of tapped biogas.
Waste-to-energy plant emissions were based on direct chimney measurements. For district heating, the heating of sites and electricity consumption, the calculations are made using coefficients provided in the Emissions Trading regulation, while emissions for motor vehicles and gas network leaks are calculated using coefficients from readings.