Introduction

This Appendix describes the methodological changes made to the NAEI since the 1997 Inventory.

Methodological Changes in the Estimates

Greenhouse Gases

Carbon Dioxide

The methodology of these estimates is described in Appendix 2. There have been a number of changes in the methodology since the 1997 Inventory. These are:

1. Fuel Combustion

• There has been a revision of emissions from MSW combustion for electricity generation. From 1997 all incinerators generated electricity, so all emissions are reported under Public Power

• There has been a significant revision in offshore gas consumption (+101 kt C)

• There have been some significant revisions in coal and coke consumption in Iron and Steel and Other Industry resulting in a reduction of 244 kt C. A further smaller reduction in emissions has resulted from the reclassification of a small amount of fuel oil from the petrochemical industry to refineries.

• There has been a small transfer of around 24 kt C from Commercial/Public & Agricultural Combustion Residential owing to a reclassification of coke consumption in the energy statistics.

• There has been a significant revision in military aviation emissions (+176 kt C) to take account of known fuel consumption by UK forces abroad.

• Other changes arise from various revisions in the fuel statistics in particular coke, coal, LPG and refinery gas

• Industrial Processes

• Emissions from glass production now include flat glass as well as container glass.. This revision has resulted in an extra emission of 10 kt C.

• The emission of CO₂ from ammonia production has increased. This arises from a revision in the estimates of plant capacity. The revision should have no effect on total emissions as total gas consumption by industry is unchanged.

• Emissions from Iron and Steel Production have increased. This is a result of the inclusion of use of coke for non-ferrous metals feedstocks and an increase in flaring of blast furnace gas,

• Methane

  The methodology of these estimates is described in Appendix 2. There have been a number of changes in the methodology since the 1997 Inventory. These are:

  1. Fuel Combustion
  1. There has been a small increase in the emissions reported under power stations due to a revision of landfill gas utilisation.
• Fugitive Emissions from Fuels

1. There have been small revisions in emissions from the offshore industry, mainly reductions in fugitives and venting but also a small increase in flaring. Overall, these account for a reduction of 4kt methane. Flaring is reported under Waste whilst venting and fugitives are reported under Extraction and Distribution of Fossil Fuels
2. Emissions from the gas distribution network have been revised to take account of high pressure mains. These have increased by 40 kt methane.

Nitrous Oxide

A number of changes have been made in the methodology used for the emission estimates since the 1997 Inventory. These are:

1. The emission factors for nitric acid production have been revised downwards. Emission data from plant operators and the Pollution Inventory (Environment Agency) have allowed the estimation of plant specific emission factors. Emissions have been recalculated back to 1990 using the new factors. Emissions in 1997 have been reduced by 2.6 kt N₂O.
2. Various small changes have been made arising from revisions in the fuel statistics and reclassification of categories.

Industrial Gases: HFC; PFC; SF₆

No changes have been made.

Acidifying Gases

Nitrogen Oxides

A number of changes to the methodology have been made since the 1997 Inventory. These are:

1. Fuel Combustion

1. There has been a small reduction in coke production emissions due to a revision in coke-oven gas consumption.
2. Emissions from military aircraft have been revised upwards to take account of fuel used by UK Forces abroad.
3. There has been a small increase in iron and steel combustion sources due to revisions in the fuel statistics.
4. The methodology for emissions from cement kilns has been revised. Emissions are based on a more complete dataset from the Pollution Inventory (Environment Agency). The revision has increased emissions by 16 kt NO_x

• Transport

1. The road transport methodology has been revised resulting in a 16 kt increase. The main change is the application of a more detailed distribution of journey speeds to the journey types used in the model.

Sulphur Dioxide

A number of changes have been made to the methodology since the 1997 Inventory. These are:

1. Emissions from refineries have increased due to a small amount of fuel oil being reclassified as refinery fuel rather than as consumption by the petrochemicals industry.
2. Emissions from the Iron and Steel Industry have been reduced by 4 kt SO₂ due to revisions in coke consumption data..
3. Emissions from other industrial combustion have been revised downwards. This is as a result of a number of revisions in coal, coke, and oil consumption. Emissions from cement kilns are now based on a more complete set of data reported in the Pollution Inventory .
4. Emissions from the residential sector have been revised upwards based on revised estimates of the sulphur content of anthracite, and the reclassification of some coke from the public service to residential.

Toxic Pollutants

Carbon Monoxide

A number of changes have been made to the methodology since the 1997 Inventory. These are:

1. Fuel Combustion

1. An increase in Other Combustion and Transformation due to a revision in coke oven gas consumption in coke production.
2. Emissions from sinter plants have been revised upwards slightly, based on new data from British Steel showing high CO emissions from Iron and Steel processes. Sinter plants are classified as Iron and Steel Combustion by UNECE.
3. The emissions from cement kilns have been revised based on a more complete data set from the Pollution Inventory (Environment Agency). The revision has reduced emissions by 17 kt CO.
4. Coke consumption by the Public Service has been reclassified as residential, hence the small increase in residential emissions.

• Transport

1. The road transport methodology has been revised resulting in a large reduction of 132 kt in 1997. The main change is the use a more detailed distribution of journey speeds applied to the journey types used in the model.

• Industrial Processes

1. A large emission of 367 kt is now reported under iron and steel processes. This covers blast furnaces, blast furnace gas flaring, electric arc furnaces and basic oxygen furnaces. The increase in emissions of 5 kt CO in 1997 is from basic oxygen furnaces and electric arc furnaces. It is based on recent estimates from British Steel.
2. Emissions from coke production have been revised upwards based on data reported in the Pollution Inventory (Environment Agency). The increase is 25 kt CO.

NMVOC

A number of changes have been made to the methodology since the 1997 Inventory. These are:

1. Fuel Combustion

1. Emissions from cement kilns are now based on data reported in the Pollution Inventory rather than fuel specific emission factors. This has resulted in a reduction in emissions of around 2 kt

• Transport

1. The road transport methodology has been revised resulting in a large reduction of 59 kt in 1997. The main change is the application of a more detailed distribution of journey speeds to the journey types used in the model.

1. Fugitive Emissions from Fuels

1. Emissions from the gas distribution network have been revised to take account of high pressure mains. These have increased by 2 kt NMVOC.

1. Solvent Use

1. Emissions from solvent use have been revised and have fallen by 40 kt in 1997. This is a result of revisions in solvent consumption data for many sources. Most significant are the changes in agrochemicals use and aerosols.

PM₁₀

1. The Pollution Inventory (Environment Agency) now reports data on PM10 emissions as well as total particulate. As a result a number of new sources have been added:

• Cement and Concrete Batching (0.25 kt)
• Aluminium Production (0.66 kt)
• Copper Refining (0.06 kt)
• Other Non-Ferrous metal production (0.23 kt)
• Primary Lead Production (0.12kt)

1. Emissions from cement kilns have been revised downwards based on a more complete set of data reported in the Pollution Inventory. The reduction is around 1.3 kt.
2. Emissions from coke ovens have been revised downwards based on new data reported in the Pollution Inventory. The reduction is around 0.6 kt.

Heavy Metals

1. Emissions from cement kilns are now estimated based on data reported in the Pollution Inventory (Environment Agency) rather than default emission factors. This has resulted in some changes in emissions with increases in emissions of arsenic, mercury and nickel but decreases in chromium, lead and zinc. Emissions of copper from cement kilns have been reported for the first time.
2. There have been significant revisions in emissions from MSW incineration. Since 1997, these have all generated electricity and are reported under power stations, so that the category waste incineration only contains sewage and clinical waste incineration and offshore flaring. Emissions have been revised based on a more complete set of data from the Pollution Inventory (Environment Agency). This has resulted in small increases in emissions of arsenic, copper, mercury and nickel and a large increase in zinc. Emissions of cadmium, chromium and lead have reduced, lead significantly so.
3. A new source has been added – copper refining. This produces significant emissions of arsenic, cadmium, copper, lead and zinc. The emissions are based on data reported in the Pollution Inventory (Environment Agency).
4. Significant emissions of nickel and chromium are reported under iron and steel processes. These emissions are based on data reported in the Pollution Inventory (Environment Agency).
5. Emissions from coke ovens have been revised based on data reported in the Pollution Inventory (Environment Agency). This has resulted in increases in emissions of cadmium, lead, nickel and zinc. Emissions of copper however have reduced slightly

Road Transport

For the 1998 inventory, the main improvements made have been based on a closer examination of the available data on average vehicle speeds monitored on different types of roads and areas in the UK and reported in various DETR publications. This is important because average speed affects emission factors for road vehicles. Hence, the use of more detailed speed information has led to revisions in the average road-type emission factors for each vehicle class.

Improvements have also been made to the emission estimates for motorcycles, using more detailed information on the composition of the fleet and speed-related emission factors for each class of motorcycles. Account has also been taken of the increased use of ultra-low sulphur diesel in the bus fleet since 1997.

References

Environment Agency, (1999)Pollution Inventory, 1998, Personal Communication