EN05 Energy-related emissions of ozone precursors

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EU-27 emissions of energy-related ozone precursors (weighted by tropospheric ozone formation potentials) decreased by 45 % between 1990 and 2005 (Fig. 3). In 2005, the production and use of energy was responsible for over three-quarters of the total emissions of ozone precursors. Of this fraction, NOx was the most significant pollutant (weighted by tropospheric ozone formation potential) contributing 64 % of the total energy-related emissions. The changes in the emissions of energy-related ozone precursors are thus strongly correlated with the changes observed in NOx emissions (see EN06 ), as this is the most important energy-related ozone precursor.

In the EU-27, the transport sector is the dominant source of ozone precursors and contributed 55 % of the energy-related ozone precursor emissions in 2005 (and 42% of total ozone precursor emissions). Transport sector is also represents the sector with the highest emissions per capita (Fig. 4). The 'energy supply', 'other' and 'industry energy' sources each contributed less than 20 % of the energy-related emissions, respectively.

Although presently the dominant source of ozone precursor emissions, the EU-27 transport sector has experienced the largest decrease in precursor emissions between 1990 and 2005, both in relative (35%) and absolute (55%) terms. These emission reductions were mainly due to the continuing increase in the share of passenger cars equipped with catalytic converters. The energy supply sector also experienced a significant decrease in emissions during this period (-41 %). The decreases in emissions from this sector (primarily NOx) can be attributed to a range of measures, including the increased use of abatement technologies (SCR, EGR,3-way catalytic converters), fuel-switching from coal to gas prompted by the liberalisation of the energy market, the requirements of the IPPC and Large Combustion Plant Directives and improved technology efficiencies (see also EN09; EN19 and EN27). An assessment of NOx trends and discussion of progress towards meeting NECD ceilings is included in the fact-sheet 'EN06: Energy-related emissions of acidifying substances'.

Total energy-related emissions of CO decreased by 55 % during the period 1990-2005 in the EU-27, again mainly due to reduced emissions from the transport sector. Decreases in CO emissions in transport have occurred mainly as a result of catalytic converters on road vehicles. The remaining energy-related sectors also all reduced their CO emissions between 1990 and 2005, although in absolute (kt) terms, their combined emission reduction (-44kt) was significantly less than the reduction achieved by the transport sector (-61 kt).

Total energy-related NMVOC emissions decreased by 56 % in the region over the same period and accounted for less than half (46%) of the total NMVOC emissions in 2005. The majority of energy-related emissions arose from the road transport sector and petrol evaporation in the energy supply sector. NMVOC emissions from the transport sector have decreased by more than half since 1990, again primarily due to the introduction of catalytic converters on cars. For the EU-15, emissions of NMVOC in 2005 are significantly higher than the 2010 targets of the NECD for EU Member States (expressed as TOFP) and substantial emission reductions are therefore still required to reach the target. However, across the new EU-12 Member States, good progress has been made in reducing NMVOC emissions, and energy-related and non-energy related emissions are already below the aggregated 2010 emission target.

Methane emissions formed less than 1 % of total ozone precursor emissions in 2005, largely as a result of its low tropospheric ozone formation potential weighting factor relative to the other pollutants. Compared with the other pollutants that contribute to ozone formation, the significance of methane is therefore relatively small.