INTRODUCTION

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1 EMISSIONS AND EMISSION INVENTORIES

Substances emitted into the atmosphere by human and natural activities are the cause of many current and potential environmental problems, including:

• acidification
• air quality degradation
• global warming/climate change
• damage and soiling of buildings and other structures
• stratospheric ozone depletion
• human and ecosystem exposure to hazardous substances.

It is necessary to have quantitative information on these emissions and their sources in order to help:

• inform the policy makers and the public
• define environmental priorities and identify the activities and actors responsible for the problems
• set explicit objectives and constraints
• assess the potential environmental impacts and implications of different strategies and plans
• evaluate the environmental costs and benefits of different policiesli>
• monitor the state of the environment to check that targets are being achieved
• monitor policy action to ensure that it is having the desired effects
• ensure that those responsible for implementing the policies are complying with their obligations.

There are many types of sources of atmospheric emissions and many examples (often millions) of each type, for example:

• power plants
• refineries
• incinerators
• factories
• domestic households
• cars and other vehicles
• animals and humans
• fossil fuel extraction and production sites
• offices and public buildings
• trees and other vegetation
• distribution pipelines
• fertilised land
• land with biological decay.

It is not possible to measure emissions from all of the individual examples of these sources or, in the short term, from all the different source types. In practice, atmospheric emissions are estimated on the basis of measurements made at selected or representative samples of the (main) sources and source types.

The basic model for an emission estimate is the product of (at least) two variables, for example:

• an activity statistic and a typical average emission factor for the activity, or
• an emission measurement over a period of time and the number of such periods emissions occurred in the required estimation period.

For example, to estimate annual emissions of sulphur dioxide in grams per year from an oil-fired power plant you might use, either:

• annual fuel consumption (in tonnes fuel/year) and an emission factor (in grams SO2 emitted/tonne fuel consumed), or
• measured SO2 emissions (in grams per hour) and number of operating hours per year.

In practice, the calculations tend to more complicated but the principles remain the same.

Emission estimates are collected together into inventories or databases which usually also contain supporting data on, for example: the locations of the sources of emissions; emission measurements where available; emission factors; capacity, production or activity rates in the various source sectors; operating conditions; methods of measurement or estimation, etc.

Emission inventories may contain data on three types of source, namely point, area and line. However, in some inventories all of the data may be on area basis - region, country, sub-region etc.

Point sources - emission estimates are provided on an individual plant or emission outlet (usually large) usually in conjunction with data on location, capacity or throughput, operating conditions etc. The tendency is for more sources to be provided as point sources as legislative requirements extend to more source types and pollutants as well as more openness provides more such relevant data.

Area sources - smaller or more diffuse sources of pollution are provided on am area basis either for administrative areas, such as counties, regions etc, or for regular grids (for example the EMEP 50x50 km grid).

Line sources - in some inventories, vehicle emissions from road transport, railways, inland navigation, shipping or aviation etc are provided for sections along the line of the road, railway-track, sea-lane etc.

2 INTERNATIONAL REQUIREMENTS FOR EMISSION INVENTORIES

2.1 Long Range Transboundary Air Pollution Convention

The Convention on Long Range Transboundary Air Pollution (LRTAP) was adopted in Geneva in 1979. Reporting of emission data to the Executive Body of the Convention is required in order to fulfil obligations regarding strategies and policies in compliance with the implementation of Protocols under the Convention. These Protocols are:

• the Helsinki Sulphur Protocol (1985)
• the Sofia NOx Protocol (1988)
• the Geneva VOC Protocol (1991)
• the Oslo Sulphur Protocol (1994)
• the Aarhus Protocols on Heavy Metal and on Persistent Organic Pollutants (POPs).

Parties should use the draft reporting procedures (EB.AIR/GE.1/1997/5) and are required to submit annual national emissions of SO2, NOx, NMVOC, CH4, CO and NH3 and various heavy metals and POPs using the 11 main source categories (level 1 of SNAP, Selected Nomenclature for sources of Air Pollution) by the 31 December following each year. For example, Parties were requested to submit data for 1997 to the Executive Body (UNECE/CLRTAP Secretariat) by 31 December 1998. Parties are invited to also report emissions of more detailed sub-sectors (SNAP level 2).

Parties are also required to provide EMEP periodically with emission data within grid elements of 50km x 50km, as defined by EMEP and known as the EMEP grid.

Parties should use the EMEP/CORINAIR Atmospheric Emission Inventory Guidebook both as a reference book on good emission estimation practice and as a check-list to ensure that all relevant activities are considered and their emissions quantified. Parties should indicate where the Guidebook methodology has been used and where not. If another methodology has been used Parties are requested to provide additional explanatory information.

2.2 United Nations Framework Convention on Climate Change (UNFCCC)

"The ultimate objective of this Convention and any related legal instruments that the Conference of the Parties may adopt is to achieve stabilisation of greenhouse gas concentrations at a level that would prevent dangerous anthropogenic interference with the climate system. Such a level should be achieved within a time frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner." (Article 2).

All Parties to the Convention shall "develop, periodically update, publish and make available to the Conference of the Parties, in accordance with Article 12, national inventories of anthropogenic emissions by sources and removals by sinks of all greenhouse gases not controlled by the Montreal Protocol, using comparable methodologies to be agreed upon by the Conference of the Parties;" (Article 4, paragraph 1(a)).

Parties are required to report emissions and sink estimates by 15 April for the last year but one of carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), perfluorocarbons (PFCs), hydrofluorocarbons (HFCs) and sulphur hexafluoride (SF6). For example data for 1997 should be reported by 15 April 1999 to the UNFCCC Secretariat. Parties should also provide information on emissions of carbon monoxide (CO), nitrogen oxides (NOx) and non-methane volatile organic compounds (NMVOCs) and are encouraged to provide information of emissions of sulphur oxides (SO2).

UNFCCC requires Parties to use the Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories ("IPCC Guidelines"). Parties may use different methods ("tiers"), giving priority to those methods which are believed to produce the most accurate estimates, and Parties can also use national methodologies which they consider better able to reflect their national situation provided that these methodologies are compatible with the IPCC Guidelines and are well documented (FCCC/SBSTA/1999/L.5).

Within the framework of UNFCCC continuing efforts are aimed at improving transparency, consistency, comparability, accuracy and completeness of inventories, resulting in proposals for a new detailed "common reporting format" (CRF) and for preparing and providing access to, an annual updated, detailed and complete national inventory report for all years. These proposals are expected to be adopted at COP5 in Bonn (25 October - 5 November 1999). This would mean Parties would be requested to start with the new Common Reporting Format (CRF) on a trial basis in the years 2000 and 2001.

Within the IPCC-OECD-IEA Programme on Inventories, and continued in 1999/2000 by the IPCC Task Force on Inventories, guidance has been developed on Good Practices as well as on Managing Uncertainties. The guidance document "Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories" was finalised, accepted and published in 2000. Guidance includes advice on choice of methodology, emission factor, activity data, and uncertainties, and on a series of quality assessment and quality control procedures, which may be applied during the preparation of inventories. It is available from the IPCC National Greenhouse Gas Inventories Programme, Technical Support Unit. C/O Institute for Global Environmental Strategies, 1560-39 Kamiyamaguchi, Hayama, Kanagawa, Japan 240-0198; E-mail mailto:tsu@iges.or.jp. Alternatively it may be downloaded from their website at: http://www.ipcc-nggip.iges.or.jp

2.3 Amended Council Decision 99/296/EC on a Monitoring Mechanism of Community CO2 and other Greenhouse Gas Emissions

The European Community has adopted Council Decision 93/389/EEC to help monitor progress towards stabilisation of the total CO2 emissions by 2000 at the 1990 level in the Community as a whole.

In 1999 this Decision has been amended by Council Decision 99/296/EC (26 April 1999) Amending Decision 93/389/EEC for a monitoring mechanism on CO2 and other greenhouse gas emissions. The original Decision of 1993 has been amended to allow for the updating of the monitoring process, in particular regarding:

• the post 2000 monitoring of greenhouse gas (GHG) emission limitations and reductions,
• the application to all six Kyoto Protocol greenhouse gases (carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), perfluorocarbons (PFCs), hydrofluorocarbons (HFCs) and sulphur hexafluoride (SF6),
• the requirements of the Kyoto Protocol to the UNFCCC for the EU and its Member States. The EU committed to a reduction of the emissions of the six Kyoto Protocol gases by 8% in 2008-2012 from 1990 levels.

According to Article 3.2 “Member States shall each year, not later than 31 December, report to the Commission their anthropogenic CO2 emissions and removal by sinks for the previous calendar year. Member States shall also report national inventory data on emissions/removal of the six Kyoto GHG on an annual basis. They shall report to the Commission by 31 December year Y their final data for year Y-2, and provisional data for year Y-1. (Art 3.2). For example data for 1997 should be reported by 15 April 1999 to the Commission. According to Article 3.3 "The Commission shall establish inventories of emission/removal in the Community and circulate them by 1 March".

Member States shall also report by 31 December on the most recent projected emissions for the period 2008-2012, and as far as possible, for 2005 (Art 3.2).

Inventories are established in accordance with the methodologies accepted by IPCC and agreed upon by the Conference of Parties (art 3.1).

The Commission shall take furthers steps to promote the comparability and transparency of national inventories and reporting (Art.3.2).

3 ATMOSPHERIC EMISSION INVENTORY METHODOLOGY

There have been several major international initiatives over the past 10 years that have built on each other and helped develop the emission inventory methodology to its current state. These include:

• the OECD Control of Major Air Pollutants (MAP) Project
• the DGXI Inventory
• the CORINE Programme and subsequent work by the European Environment Agency Task Force
• the Co-operative Programme for Monitoring and Evaluation of the Long Range Transmission of Air Pollutants in Europe (EMEP)
• the IPCC/OECD Greenhouse Gas Emissions Programme.

3.1 OECD/MAP Project

The MAP Project was designed (OECD, 1990) to:

• assess pollution by large scale photochemical oxidant episodes in Western Europe and
• evaluate the impact of various emission control strategies for such episodes.

The Project started in 1983 and the report on the work was published in 1990.
The MAP emission inventory covered the following pollutants:

sulphur dioxide - SO₂
nitrogen oxides - NO_x, and
volatile organic compounds - VOC, including natural emissions.

The inventory quantified point and area source emissions in nine main source sectors from 17 European OECD countries - the current 15 Member States (excluding the former German Democratic Republic) plus Norway and Switzerland.

The nine main source sectors were:

• mobile
• power plant
• non-industrial combustion
• industry
• organic solvent evaporation
• waste treatment and disposal
• agriculture and food industry
• nature
• miscellaneous

In most but not all cases the inventory was compiled from emission estimates submitted officially by each country. OECD worked closely with each country and with the CEC (which funded activity on the inventory to regroup emission estimates into the OECD source sectors and to help countries complete their inventories).

3.2 The DGXI Inventory

In 1985, the CEC Environment Directorate (DGXI) funded the compilation of an emission inventory for the EU12 Member States (Spain and Portugal joined the European Community during the course of the work) in 1980 and 1983.

The aim of the DGXI Inventory was (CITEPA, 1988) to collect data on emissions from all relevant sources in order to produce a database for use in the study of air pollution problems and to base policy measures in the field of air pollution control.

The inventory covered four pollutants - SO₂, NO_x, VOC and particulates - and recognised 10 main source sectors:

• utility power plant
• industrial combustion plant
• district heating
• oil refineries and petrochemical plant
• domestic heating
• industrial processes
• solvent use
• transportation
• agriculture
• nature.

The work, which was completed with the publication of the report in 1988, was carried out under contract by a group of four national laboratories/consultancies in collaboration with the Member States and OECD, who were simultaneously compiling the MAP Inventory.

3.3 CORINE and the EEA Task Force

Council Decision 85/338/EEC (OJ, 1985) established a work programme concerning an "experimental project for gathering, co-ordinating and ensuring the consistency of information on the state of the environment and natural resources in the Community". The work programme was given the name CORINE - CO-oRdination d'INformation Environnementale and include a project to gather and organise information on emissions into the air relevant to acid deposition - CORINAIR. This project started in 1986 with the objective of compiling a co-ordinated inventory of atmospheric emissions from the 12 Member States of the Community in 1985 (CORINAIR 1985).

The CORINAIR 1985 Inventory covered three pollutants - SO2, NOx, and VOC (total volatile organic compounds) - and recognised eight main source sectors:

• combustion (including power plant but excluding other industry)
• oil refineries
• industrial combustion
• processes
• solvent evaporation
• road transportation
• nature and
• miscellaneous.

The project also developed:

• a source sector nomenclature - NAPSEA, Nomenclature for Air Pollution Socio-Economic Activity and SNAP, Selected Nomenclature for Air Pollution - for emission source sectors, sub-sectors and activities
• a Default Emission Factor Handbook and
• a computer software package for data input and the calculation of sectorial, regional and national emission estimates.

The CORINAIR 1985 Inventory was developed in collaboration with the Member States, Eurostat, OECD and UNECE/EMEP.

The Inventory was completed in 1990 and the results have been published (Eurostat, 1991; CEC, 1995) and widely distributed in tabular and map forms.

Pending a decision on the location of the EEA, it was agreed in 1991 to produce an update of CORINAIR for 1990 (CORINAIR 1990). This update has been performed in co-operation with EMEP and IPCC-OECD to assist in the preparation of inventories required under the Long Range Transboundary Air Pollution (LRTAP) Convention and the Framework Climate Change Convention (FCCC) respectively.

The CORINAIR90 system was made available to:

• the 12 member states of the European Community in 1990: Belgium, Denmark, France, Germany, Greece, Ireland, Italy, Luxembourg, Netherlands, Portugal, Spain and United Kingdom
• - 5 EFTA countries: Austria, Finland, Norway, Sweden and Switzerland
• 3 Baltic States: Estonia, Latvia and Lithuania
• 9 Central and Eastern European countries: Albania, Bulgaria, Croatia, Czech Republic, Hungary, Poland, Romania, Slovakia and Slovenia and
• Russia.

This collaboration:

• produced a more developed nomenclature (source sector split) - SNAP90 - involving over 260 activities grouped into a three level hierarchy of sub-sectors and 11 main sectors
• extended the list of pollutants to be covered to eight:

sulphur dioxide (SO₂)
oxides of nitrogen (NO_x)
non-methane volatile organic compounds (NMVOC)
ammonia
carbon monoxide
methane
nitrous oxide
carbon dioxide

• extended the number of sources to be considered as point sources (there were over 1400 large point sources in the CORINAIR85 inventory)
• recognised that an emission inventory needs to be complete, consistent and transparent
• extended the availability of the CORINAIR system to 30 countries
• increased awareness of CORINAIR and the need to produce an inventory within a reasonable time-scale to serve the requirements of the user community (policy-makers, researchers etc).

The CORINAIR 1990 Inventory recognises 11 main source sectors (as agreed with EMEP, see below):

• Public power, cogeneration and district heating plants
• Commercial, institutional and residential combustion plants
• Industrial combustion
• Production processes
• Extraction and distribution of fossil fuels
• Solvent use
• Road transport
• Other mobile sources and machinery
• Waste treatment and disposal
• Agriculture
• Nature.

a are provided on large point sources on an individual basis and on other smaller or more diffuse on an area basis, usually by administrative boundary at the county, department level (NUTS level 3). The sources to be provided as point sources are:

• Power plant with thermal input capacity >=300MW
• Refineries
• Sulphuric acid plant
• Nitric acid plant
• Integrated iron/steel with production capacity >3Mt/yr
• Paper pulp plant with production capacity > 100kt/yr
• Large vehicle paint plant with production capacity > 100000 vehicles/yr
• Airports with >100000 LTO cycles/yr
• Other plant emitting >=1000t/yr SO₂, NO_x or VOC or >=300000t/yr CO₂

The Goal of CORINAIR90 is to provide a complete, consistent and transparent air pollutant emission inventory for Europe in 1990 within a reasonable time scale to enable widespread use of the inventory for policy, research and other purposes.

Completeness covers two aspects: the CORINAIR90 system is available to almost all countries of Europe and the SNAP90 nomenclature has been designed to provide a comprehensive list of activities generating emissions of the eight pollutants to be quantified.

Consistency will be provided by the systematic application of the CORINAIR methodology - by using the CORINAIR software and the SNAP90 nomenclature - to provide emission estimates.

Transparency will be achieved through the provision within the inventory of activity statistics/data and emission factors (or details of emission measurements where available) used to calculate emissions and through the supply of full references to the sources of these data.

Initial data from CORINAIR90 became available in early 1994 and the project was completed and a series of reports prepared during 1995 and early 1996.

The work was finalised and published by the EEA in 1996 and 1997 (see under section 5).

3.4 EMEP

The Cooperative Programme for Monitoring and Evaluation of the Long Range Transmission of Air Pollutants in Europe (EMEP) formed by a Protocol under the Long Range Transboundary Air Pollution Convention has arranged a series of workshops on Emission Inventory Techniques to develop guidelines for estimation and reporting of emission data for SO_x, NO_x, NMVOCs, CH₄, NH₃ and CO under the Convention. The 1991 Workshop agreed to recommend that:

• a task force on emission inventories should be established by the Executive Body of the Convention to review present emission inventories and reporting procedures for the purpose of further improvement and harmonisation, and
• the EMEP Steering Body should approve the guidelines prepared by the workshop for estimation and reporting for submission to the Executive Body of the Convention.

These guidelines included a recommendation that emission data should be reported as totals and at least for the 11 major source categories agreed with the CORINAIR project and other experts for the CORINAIR 1990 Inventory (see above).

The proposed task force was set up under the EMEP Steering Body with leadership from the United Kingdom and support from Germany and the European Community (including the European Environment Agency).

The objectives of the task force are to:

• provide a technical forum to discuss, exchange information and harmonise emission inventories including emission factors, methodologies and guidelines