Indicator Assessment

Energy-related emissions of ozone precursors

Indicator Assessment

Prod-ID: IND-129-en

Also known as: ENER 005

Published 12 Aug 2011 Last modified 11 May 2021

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Topics: Energy

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Energy-related emissions accounted for 87% of all Carbon Monoxide (CO) emissions, 44% of all Non-Methane Volatile Organic Compounds (NMVOC) emissions, 95% of all Nitrogen Oxide (NO_x) emissions and 48% of all Methane (CH₄) emissions from the EEA-32 in 2008. Energy related emissions of these pollutants in the EEA-32 fell by 4%, 3%, 5% and 1% respectively between 2007 and 2008, and since 1990, these emissions have declined by 53%, 59%, 30% and 44% in EEA member countries. The largest reductions in emissions occurred in the road transport sector, largely as a result of the continued introduction of catalytic converters in new vehicles during this period. Energy production and use still remains a significant source of emissions for these precursor pollutants. Reducing energy-related emissions of ozone precursors therefore is a key priority for reducing local and transboundary air pollution and in ensuring that the EU and individual countries meet emission ceiling targets under the National Emissions Ceilings Directive (NECD) and the UNECE Gothenburg Protocol, meet their limit values under Directive 2008/50/EC on ambient air quality and cleaner air for Europe and the Air Quality Framework Directive and its daughter directives.

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Changes (%) in emissions of ozone precursors by source category, 1990-2008, EEA-32

Note: The figure shows the emissions methane CH4; carbon monoxide CO; non-methane volatile organic compounds NMVOCs; and nitrogen oxides NOx.

Data source:

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Contribution of different sectors (energy and non-energy) to total emissions of tropospheric ozone precursors, 2008, EEA-32

Note: The figure shows the emission of NOx, NMVOC, CO and CH4 in 2008

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In the EEA-32, energy related emissions of pollutants contributing to tropospheric ozone formation have decreased by 53% (CO), 59% (NMVOC), 30% (NO_X) and 44% (CH₄) in EEA member countries between 1990 and 2008 (and by 55% (CO), 63% (NMVOC), 35% (NO_X) and 46% (CH₄) in the EU). All sources except international bunkers have decreased (see Figure 1). Energy-related emissions comprise the majority of Tropospheric Ozone Formation Precursors (TOFP) related emissions and accounted for 87% of all CO emissions, 44% of all NMVOC emissions, 95% of all NO_X emissions and 48% of all CH₄ emissions from the EEA-32 in 2008.

The road transport sector is the dominant source of NO_X and CO and contributed 39% and 34% of total emissions in 2008 (see Figure 2) in the EEA countries. Road transport has decreased the most in absolute terms with a 73% (CO), 78% (NMVOC) and 40% (NO_X) reduction seen in the EU-27 from 1990 to 2008 (see Figure 1). Decreases in emissions from the transport sector have occurred largely due to the continued introduction of catalytic converters, in line with Euro standard emission control legislation, which reduce emissions of CO and NO_X.

Energy industries are a significant source of pollutants contributing to tropospheric ozone formation; accounting for 20% of NO_X emissions (see Figure 2). This sector has reduced its emissions by over 13% (CO), 13% (NMVOC), 39% (NO_X) and 38% of CH₄ in EEA-32 since 1990 (see Figure 1). The decreases in emissions from this sector (primarily NO_X) can be attributed to a range of measures, including the increased use of abatement technologies in the transport sector (e.g. selective catalytic reduction (SCR), exhaust gas recirculation (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 in all electricity production and consumption sectors.

Concerning progress in individual countries, emissions of pollutants contributing to tropospheric ozone formation have decreased significantly in most EEA member countries; with the highest reductions reported by Malta (CO), Germany (NMVOC) and Czech Republic (NO_X) and United Kingdom (CH₄) (see Figure 3). Emissions of NO_X increased by over 102% in Turkey. In Turkey nearly half the increase in emissions was from non-road transport, with significant emissions increases also seen from energy industries and manufacturing and construction. Total emissions from Liechtenstein remained small across the period, but increases were seen in the household sector across all pollutants and fugitive emissions despite significant decrease from road transport emissions. Emissions of CO and NMVOC in Romania have increased since 1990, due chiefly to sources categorised under the ‘Other (Energy)’ sector.

Emissions of NOx are responsible for much of the ozone formation occurring in rural areas. In more densely populated regions, in particular close to cities, ozone formation is enhanced by NMVOC emissions. NMVOCs are mainly released from road traffic and the use of products containing organic solvents. NOx and CO are mostly emitted from transport and combustion processes. After release, these precursors are dispersed by wind and atmospheric turbulence. The freshly emitted pollutants mix with other pollutants, including ozone, present in background air, and a complicated process of chemical reactions and continuous dilution takes place.[1]

[1] Tropospheric Ozone in EU - The consolidated report, Topic report No 8/1998

Supporting information

Indicator definition

TOFP is the Tropospheric Ozone Forming Potential of each of the air pollutants that contribute to ozone formation in the troposphere i.e. ‘ground-level’ ozone.

Units

Emissions in ktonnes

Rationale

Justification for indicator selection

Emissions of total non-methane volatile organic compounds, nitrogen oxides, carbon monoxide and methane contribute to the formation of ground level (i.e. tropospheric) ozone. Ozone is a powerful oxidant and can have a range of adverse impacts on both human health and ecosystems. Tropospheric ozone also increases the radiative forcing so diminishing the level of emissions of tropospheric ozone precursors will improve the human and ecosystem health and will also contribute to climate change mitigation.

Tropospheric (ground level) ozone has adverse effects on human health and ecosystems. Emissions of total non-methane volatile organic compounds, nitrogen oxides, carbon monoxide and methane contribute to the formation of ground level (i.e. tropospheric) ozone. High concentrations of ground level ozone have been shown to adversely affect the human respiratory system, and there is evidence that long-term exposure to raised ozone concentrations accelerates the decline in lung function with age and may impair the development of lung function. In the environment, high concentrations of ozone are harmful to crops and forests, decreasing yields, causing leaf damage and decreasing disease resistance. Ozone is also capable of causing damage to man made polymeric materials such as plastics and rubbers.

Scientific references

No rationale references available

Policy context and targets

Context description

This indicator monitors the trend in emissions of energy-related ozone precursors. Emissions of NOx and NMVOCs are both covered by the EU National Emission Ceilings Directive (NECD; 2001/81/EC) and the Gothenburg protocol under the United Nations Convention on Long-range Transboundary Air Pollution (LRTAP Convention; UNECE 1999). Both these instruments contain emission ceilings targets that EU Member States and other countries must meet by 2010. Emission reduction targets for the new Member States have been specified in the Treaties of Accession to the European Union (2003 and 2005 -The Treaty of Accession 2003 of the Czech Republic, Estonia, Cyprus, Latvia, Lithuania, Hungary, Malta, Poland, Slovakia and Slovenia. AA2003/ACT/Annex II/en 2072 / 2005 European Union Consolidated Versions of the Treaty on European Union and of the Treaty Establishing the European Community C 321 E/1) in order that they can comply with the National Emission Ceilings Directive. In addition, the Treaty of Accession for Bulgaria and Romania (2005 - http://ec.europa.eu/environment/air/pdf/eu27_nat_emission_ceilings_2010.pdf) also includes a new target for the EU-27 region as a whole. Targets for the new Member States are temporary and are without prejudice to the review of the NECD. A proposal for a revised NEC Directive (which will set 2020 emission ceiling targets for these ozone precursors pollutants), is expected in 2013. Targets for Bulgaria and Romania are provisional and not binding. Hence, the existing EU25 NECD Target has been used in the following analysis.

The NECD generally involves slightly stricter emission reduction targets than the Gothenburg Protocol. For example, during the period 1990-2010 the EU-15 has NOx emission reduction targets of 52 % and 51% under the NECD and Gothenburg Protocol respectively. For NMVOC, the EU-15 reduction required under the NECD is 55 %, under the Gothenburg reduction target the reduction required is 54 %.

In September 2005 the European Commission released a thematic strategy on air pollution. This strategy sets interim objectives for reducing air pollution impacts across Europe by 2020. The thematic strategy is due to be reviewed by 2013. Other directives influencing emissions of ozone precursors include:

The Integrated Pollution Prevention and Control (IPPC) Directive (96/61/EC) aims to prevent or minimise pollution of water, air and soil by industrial effluent and other waste from industrial installations, including energy industries, by defining basic obligations for operating licences or permits and by introducing targets, or benchmarks, for energy efficiency. It also requires the application of Best Available Techniques (BAT) in new installations from now on (and for existing plants over the next 10 years according to national legislation).
The Large Combustion Plant Directive (2001/80/EC) sets emission limits for licensing of new plants and requires Member States to establish programmes for reducing total emissions.
Directive on Industrial Emissions, coalescing seven existing directives into one namely:

the Large Combustion Plant directive (LCPD);
the Integrated Pollution Prevention and Control directive ( IPPCD);
the Waste Incineration directive (WID);
the Solvent Emissions directive (SED);
the three existing directives on Titanium dioxide on (i) disposal (78/176/EEC), (ii) monitoring and surveillance ( 82/883/EEC) and (iii) programs for the reduction of pollution (92/112/EEC).

Emissions from transport are controlled by a number of Directives. These include: emissions from passenger cars and light commercial vehicles (70/220/EEC, as last amended by Directive 2001/100/EC targeting CO, NMVOCs and NOx); quality of petrol and diesel fuels (98/70/EC) as last amended by Directive 2003/17/EC specifying lower sulphur contents of fuels, (but also indirectly targeting emissions of the primary pollutants CO, NMVOCs and NOx; emissions from non-road mobile machinery (97/68/EC) as amended by Directive 2002/88/EC specifying limits for CO, NMVOC and NOx emissions; and for heavy duty vehicles Directive 88/77/EEC as last amended by Directives 1999/96/EC (which provides the Euro 3 (from October 2000), Euro 4 (from October 2005) and Euro 5 (from October 2008) emission standards for CO, NMVOCs and NOx) and Directive 2001/27/EC (adapting to technical progress Directive 88/77/EEC), and The white paper [COM(2001)370, 12/09/2001] proposing 60 measures to develop a transport system in line with the sustainable development strategy set by the European Council.
The 1994 VOCs Directive (94/63/EC) applies to the operations, installations, vehicles and vessels used for storage, loading and transport of petrol from one terminal to another or from a terminal to a service station
There are no specific EU emission targets set for either carbon monoxide (CO) or methane (CH4). However, there are several Directives and Protocols that affect the emissions of CO and CH4. Carbon monoxide is covered by the second daughter Directive under the Air Quality Directive. This gives a limit of 10 mg m-3 for ambient air quality to be met by 2005. Methane is included in the basket of six greenhouse gases under the Kyoto protocol to the United Nations Framework Convention on Climate Change (UNFCCC), under which limits for greenhouse gas emissions for the period 2008-2012 have been agreed by certain countries.

Targets

Emissions of NOx and NMVOCs are covered by the EU National Emission Ceilings Directive (NECD) and the Gothenburg Protocol to the UNECE LRTAP Convention (UNECE 1999). Both instruments contain emission ceilings (limits) that countries must meet by 2010. See also CSI002

Methodology

Methodology for indicator calculation

Indicator is based on officially reported national total and sectoral emissions to UNECE/EMEP (United Nations Economic Commission for Europe/Co-operative programme for monitoring and evaluation of the long-range transmission of air pollutants in Europe) Convention on Long-range Transboundary Air Pollution (LRTAP Convention), submission 2010. Recommended methodologies for emission inventory estimation are compiled in the EMEP/CORINAIR Atmospheric Emission Inventory guidebook, EEA Copenhagen (EEA, 2009). Base data are available from the EEA Data Service (http://dataservice.eea.europa.eu/dataservice/metadetails.asp?id=1096) and the EMEP web site (http://www.ceip.at/). Recalculations of Member States data may happen. These are fully documented in the EEA report http://www.eea.europa.eu/publications/eu-emission-inventory-report-1990-2009.

Base data, reported in NFR are aggregated into the following EEA sector codes to obtain a common reporting format across all countries and pollutants:

Energy Industries: emissions from public heat and electricity generation, oil refining, production of solid fuels, extraction and distribution of solid fossil fuels and geothermal energy;
Industrial processes: emissions derived from non-combustion related processes such as the production of minerals, chemicals and metal production;
Road transport: light and heavy duty vehicles, passenger cars and motorcycles;
Non-road (other) transport: railways, domestic shipping, certain aircraft movements, and non-road mobile machinery used in agriculture & forestry;
Household and services: emissions principally occurring from fuel combustion in the services and household sectors;
Manufacturing and Constructions: emissions from combustion processes used in the manufacturing industry including boilers, gas turbines and stationary engines;
Other non-energy (Solvent and product use): non-combustion related emissions mainly in the services and households sectors including activities such as paint application, dry-cleaning and other use of solvents;
Agriculture: manure management, fertiliser application, field-burning of agricultural wastes
Waste: incineration, waste-water management;

The following table shows the conversion of Nomenclature for Reporting (NFR) sector codes used for reporting by countries into EEA sector codes:

EEA classification	Non-GHGs (NFR)	GHG (CRF)
National totals	National total	National totals without LUCF
Energy Industries	1A1	1A1
Fugitive emissions	1B1, 1B2	1B
Road transport	1A3b	1A3b
Non-road transport (non-road mobile machinery)	1A3 (exl 1A3b)	1A3a, 1A3c, 1A3d, 1A3e
Industrial processes	2	2
Other non-energy (Solvent and product use)	3, 7A	3
Agriculture	4	4
Waste	6	6
Household and services	1A4ai, 1A4aii, 1A4bi, 1A5a	1A4A, 1A4B
Manufacturing / Construction	1A2	1A2

Methodology for gap filling

An improved gap-filling methodology used in compiling this year's EU‑27 emission inventory means that for the first time a complete EU‑27 time series trend for the main air pollutants (NOx, SOx, NMVOC, NH3 and CO) can be reported to the LRTAP Convention. For the remaining pollutants, one or more Member States did not report emissions for any year meaning that gap-filling could not be applied. For these pollutants, therefore, the aggregated EU data are not yet complete and are likely to underestimate true emissions. See section 1.4.2 Data gaps and gap-filling in European Union emission inventory report 1990 — 2008 under the UNECE Convention on Long-range Transboundary Air Pollution (LRTAP)[1]

[1] http://www.eea.europa.eu/publications/european-union-emission-inventory-report

Methodology references

Methodology reference EMEP/CORINAIR Emission Inventory Guidebook - 2009 This 2009 update of the emission inventory guidebook prepared by the UNECE/EMEP Task Force on Emissions Inventories and Projections provides a comprehensive guide to state-of-the-art atmospheric emissions inventory methodology. Its intention is to support reporting under the UNECE Convention on Long-range Transboundary Air Pollution and the EU National Emission Ceilings Directive. EMEP (2010). Transboundary, acidification, eutrophication and ground level ozone in Europe in 2008

Uncertainties

Methodology uncertainty

The NOx, CO and NMVOC emissions data officially submitted by EU Member States and other EEA member countries follow common calculation (EMEP/EEA 2011) and reporting guidelines (UNECE 2003). CH4 emissions are estimated by countries following IPCC Guidelines (e.g. IPCC 2011).

Nitrogen oxide emission estimates in Europe are thought to have an uncertainty of about +/-20% (EMEP 2009), as the NOx emitted comes both from the fuel burnt and the combustion air and so cannot be estimated accurately from fuel nitrogen alone. However, because of the need for interpolation to account for missing data, the complete dataset used will have higher uncertainty. The trend is likely to be more accurate than the individual absolute annual values - the annual values are not independent of each other.

Uncertainties in emissions of CO are likely to have a similar magnitude of uncertainty as for NOx. NMVOC emissions data have been verified by EMEP and others by means of comparison between modelled and measured concentration throughout Europe (EMEP, 1998). From these studies total uncertainty ranges have been estimated to about +/-50%. Some main source categories are less uncertain.

CH₄ estimates are reasonably reliable as they are based on a few well-known emission sources. The IPCC believes that the uncertainty in CH4 emission estimates from all sources, in Europe, is likely to be about +/-20 %. CH₄ emissions from some sources, such as rice fields, are much larger (possibly an order of magnitude), but are a minor emission source in Europe. In 2004, EU Member States reported uncertainties in their estimates of CH₄ emissions from enteric fermentation as ranging between 0.5 % (UK) and 2.8 % (Ireland) of the total national GHG emissions (EEA 2004).

Incomplete reporting and resulting intra- and extrapolation may obscure some trends.

Data sets uncertainty

No uncertainty has been specified

Rationale uncertainty

No uncertainty has been specified

Data sources

National emissions reported to the Convention on Long-range Transboundary Air Pollution (LRTAP Convention)
provided by United Nations Economic Commission for Europe (UNECE)
National Emission Ceilings (NEC) Directive Inventory
provided by Directorate-General for Environment (DG ENV)

Other info

DPSIR: Pressure
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)

Indicator codes

ENER 005

EEA Contact Info info@eea.europa.eu

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Older versions

14 Jan 2011 - Energy-related emissions of ozone precursors

05 Jul 2010 - Energy-related emissions of ozone precursors

27 Nov 2008 - EN05 Energy-related emissions of ozone precursors

27 Apr 2007 - EN05 Energy-related emissions of ozone precursors

Geographic coverage

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