Chris Dore

AEA Energy and Environment

Uncertainties in the UK Heavy Metal Emissions Inventory

UK Emissions Inventory ProgrammeFunded by Defra: RMP2106

Contents

1. Principles of Uncertainty

2. Combustion Sources

3. Non-Combustion Sources

4. “Missing” & Non-Anthropogenic Sources

5. Mapping Emission Estimates

6. Conclusions

1. Principles of Uncertainty

Combination of uncertainties

Point sources- combination of random independent errors Area sources- one EF, prone to bias.

1. Principles of Uncertainty

0%

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As Cd Cr Cu Hg Ni Pb Se V Zn

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Non-fuelGaseousLiquidSolid

2. Combustion SourcesSolid

Coal, Coke, Anthracite & SSFImportant for As, Cd, Cr, Pb, Be and a major source of Mn, Hg & Se

Point Sources Well characterised, and emissions data are reported. Hence no bias is

expected. But possible issues associated with extrapolation of few measurements

All coals UK coals Minimum Maximum Minimum Maximum Arsenic <0.1 311 2 73 Beryllium 0.002 14 0.4 3 Cadmium <0.004 10 <0.3 3.4 Chromium 0.5 84 3 45 Copper 0.2 160 12 50 Lead 0.3 270 8 63 Manganese 1 1400 11 250 Mercury 0.01 1.8 <0.2 0.7 Nickel 0.06 342 8 35 Selenium <0.1 20 1 4 Vanadium 0.2 180 8 150 Zinc 0.4 1600 30 200

Concentrations (ppm) of metals in bituminous coals (Smith 1987)

2. Combustion Sources Solid

Coal, Coke, Anthracite & SSF

In 2005, over 2/3 of UK steam coal was imported ~80% from Russia/South Africa, 13% from

Columbia/Indonesia. Distribution with the ranges shown is not known.

Fugitive emissions from Coke Ovens

Area Sources Median values taken from a wide range Fuels assumed to be the same as coal Limited information on PM control Potential for significant bias

2. Combustion Sources Petroleum

Petroleum FuelsImportant for all metals except Cr and Hg, major sources of Be, Cd, Ni,

Se, V & Zn

Metal emissions are primarily associated with petroleum coke, waste lubricants & fuel oil (higher metal contents)

However, large volumes of gas oil, DERV and petrol are consumed, giving notable contribution, despite their lower metal contents.

Point Sources

Variability would result in little impact on emissions total

Area Sources Metal content taken from literature values Fuel oil: variability of 2-4 times the mean value Gas oil/DERV: very variable metal content data Waste lubricants (10% of Pb): factor of ~10 variability metal content

2. Combustion Sources Pb in Petrol

Pb in Petrol, and Unleaded Petrol

UK uses EF’s based on measurement data Pb content of “unleaded” = 0.04 mg/l (UKPIA 2003) 70% assumed to be released to air Small when compared to the limit value (5 mg/l)

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1970 1975 1980 1985 1990 1995 2000 2005

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Other Stationary Combustion TransportPublic Electricity and Heat Production Iron and SteelOther industrial combustion: Lubricants Production Processes

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Pb (2005)

Pb

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Transport and Mobile

Processes (incl electric arc)

Iron (Scinter plant)

Lubricants

Domestic and IndustrialCombustion

Power Gen & Incineration

2. Combustion Sources

Burning of CCA Treated Wood “CCA” Cu, Cr As treated wood. Major source for As, important for Cr

Data available on As consumed in CCA preservatives. But v difficult to estimate the quantities of wood burned Cr and Cu emissions extrapolated from As data Estimates could be out by a factor of 20.

Cremation Well characterised in the UK Uncertainties of Hg would give a maximum impact of 10% increase to

the UK total.

Other Fuels Scrap tyres, MSW and wood in power stations Not a particularly large source

3. Non-Combustion Sources

Metal Industry Processes Important for most metals

Includes processes at steelworks (sintering and blast, basic oxygen, & electric oxygen furnaces), foundries, 1° Al production, 2° Pb & Al production, and various other non-ferrous metal processes

Variety of point source data and literature data. Estimates are likely to only include stack emissions, and

fugitives are therefore not accounted for.

Chloroalkali Processes Important for Hg

The main source is associated with the ventilation air from the cell room

Very difficult to asses for a variety of reasons, assume that the emission could be underestimated by a factor of five (also used for other fugitive emissions)

3. Non-Combustion Sources

Tyre & Break Wear Important for Zn and Cu

Estimates are a fixed fraction of PM10 emission from these sources

Tyre wear is easy to estimate, but PM10 emission less so. UK specific data. Metal concentrations in tyres are highly variable (less so for HGV’s).

Metal content of brake linings is fairly well characterised. Emissions per vkm vary by nearly an order of magnitude. UK specific data.

“Odd and Ends” A variety of other sources included in the inventory (fireworks, glass

manufacture, waste incineration etc.)

4. Missing & Non-anthropogenic Sources

“Missing” Sources Accidental/malicious fires

dwellings, factories, other buildings, vehicle fires

Demolition

Corrosion/abrasion of metal structures

Galvanizing

Non-thermal processing of scrap metals e.g. shredding of scrap metals

Part B industrial processes e.g. cement batching, quarrying, powder coating

Abrasion of road surfaces by motor vehicles

4. Missing & Non-anthropogenic Sources

Non-anthropogenic Sources Natural Sources

not currently included or estimated. Estimates available from Ilyin & Travnikov (2005)

Marine Sources not currently included or estimated. Estimates available from Ilyin &

Travnikov (2005)

Resuspension Estimates available from Ilyin & Travnikov (2005) suggest

significant contributions for Pb and Cd (trebling the 2004 Cd emissions in the UK).

However estimates from Vincent and Passant (2006) for Cd, Pb, As, Ni suggested resuspension was not a major source.

5. Mapping Emission Estimates

6. Conclusions

Conclusions There are areas where improvements need to be made However we are currently limited by data availability

Recommendations for Future work Point Sources: Obtain more information on whether fugitive emissions are

included in current estimates Combustion Sources: Obtain more comprehensive data on metal content

of fuels Brake and Tyre Wear: Review and consolidate existing literature

information “Missing” Sources: Make some initial estimates by improving PM10

estimates (not straightforward!) Natural Sources: Incorporate estimates into emissions inventory

Validation & Verification After conducting these improvements, reassess the estimates derived from

modelling in light of updated emissions inventory estimates.

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