5.1 Sector overview (CRF 3)
Solvents and related compounds are a significant source of emissions of NMVOC. This sector includes emissions from chemical cleaning substances used in dry cleaning, printing, metal degreasing and a variety of industrial and household uses. Also included are emissions from paints, lacquers, thinners and related materials.
Emissions from the solvents and other product use sector in 2003 comprised 31.61 Gg of NMVOC. This is an increase of 30.4% from 24.24 Gg in 1990. The categories dominating the sector are NMVOC emissions from paint application and other uses (Figure 5.1.1).
|Category||Gg NMVOC||Percent of total|
|Degreasing and drycleaning||0.85||2.7|
In 2003, N2O emissions from anaesthesia use totalled 0.16 Gg N2O or 48.36 Gg CO2 equivalent. This is a 16.4% increase over the 1990 baseline.
New Zealand's relatively small manufacturing base results in lower solvent use compared to many other countries. Ethanol and methanol are the only solvents produced in New Zealand and the majority of both products are exported. All other solvents are imported, including some ethanol and methanol (for quality and price reasons).
5.1.2 Methodological issues
The IPCC guidelines (IPCC, 1996) do not provide detailed methodologies for emissions from solvents and other product use, but documents two basic approaches for estimating emissions - consumption and production based estimates. The IPCC guidelines note that for many applications of solvents, the end uses are too small-scale, diverse and dispersed to be tracked directly. Therefore, emission estimates are generally based on total consumption and an assumption that once these products are sold to end users, they are applied and emissions produced relatively rapidly. For most surface coating and general solvent use, this approach is recommended. The New Zealand inventory estimates solvent emissions with a consumption-based approach. Information is obtained via a survey of industry and industry organisations (CRL Energy Ltd, 2004). Worksheets for the solvents and other products sector are included in Annex 8.3.
Emission factors are developed based on the likely ultimate release of NMVOC to the atmosphere per unit of product consumed. The emission factors are applied to sales data for the specific solvent or paint products. The four categories of solvents and other products specified in the CRF are detailed below.
Consumption and emissions from paints and thinners are based on information from Nelson (1992) and the Auckland Regional Council (1997). Additional information for 1993 to 1996 was provided by the New Zealand Paint Manufacturers Association.
Degreasing and dry cleaning
Consumption of perchloroethylene is assumed to equal the volume of imports. Import information is supplied from Statistics New Zealand.
Chemical products (manufacturing and processing)
The solvents tetrabutyl urea and alkyl benzene are used in the production of hydrogen peroxide. Emissions are provided by the sole producer of hydrogen peroxide in New Zealand. The hydrogen peroxide plant has an on-line, continuous, activated-carbon solvent recovery system. Solvent losses are recorded annually.
Losses of ethanol (and other minor components such as methanol, acetaldehyde and ethyl acetate) are monitored in the three ethanol plants in New Zealand. Using these figures, an emissions factor for NMVOC of 0.6 kg per hectolitre (100 litres) has been calculated. Ethanol used for alcoholic beverage production has been reported under food and drink production in the industrial processes sector.
This category includes NMVOC emissions from domestic and commercial solvent use in the following areas: household products, toiletries, rubbing compounds, windshield washing fluids, adhesives, polishes and waxes, space deodorants, and laundry detergents and treatments. Consumption data are obtained from a survey of the industry and Auckland Regional Council (1997) data. In the degreasing/drycleaning, printing and aerosols sub-categories, it is assumed that import data provided more consistent estimates than the Auckland Regional Council data. It is assumed that the emissions rate per capita derived by the United States Environmental Protection Agency (USEPA) are applicable to the average product use in New Zealand (CRL Energy Ltd, 2004). The emissions factor used (cumulative total for all products) is 2.54 kg NMVOC per capita per year (USEPA, 1985).
N2O for anaesthesia
Activity data for 2003 are obtained from the importer of N2O. The importer supplies its competitor with its requirements so the figure represents full coverage of N2O use in New Zealand. Most of the N2O is used for anaesthesia and the production of Entonox (a 50/50 mix of nitrous oxide and oxygen for pain relief). There is a very small amount used in motor sports and some is used in scientific analysis. No activity data are available for emissions in 1990-2003. Emissions are back-calculated for using the New Zealand population data as a surrogate for the emissions level. The calculated implied emissions factor is 0.039kg N2O per capita.
5.1.3 Uncertainties and time-series consistency
Estimates of uncertainty are based on the assessment of the consultant (CRL Energy Ltd, 2004) which is based on information provided by industry in the questionnaires and discussions with respondents. The overall uncertainties are assessed to be:
- paint application: +60% (activity levels for paint application appear to significantly over-estimate paint sales)
- degreasing/drycleaning: +30%
- chemical product emissions: +20%
- printing, aerosols and domestic/commercial use: +80% (individual uncertainties are assessed to be +50%, +20% and +60% respectively)
- N2O for anaesthesia: +5% for annual imports.
5.1.4 Source-specific QA/QC and verification
The consumption data from Auckland Regional Council (1997) and Nelson (1992) were compared to import data and discrepancies analysed and clarified by the consultant. There are considerable uncertainties and inconsistencies in applying the USEPA per capita emission factors based on international experience. Nevertheless, there is generally very little information available on New Zealand use of the various products and their consequent NMVOC emissions.
5.1.5 Source-specific recalculations
Data in this sector for the 2003 inventory are derived using the same method used for previously reported data. No changes have been made to the methodology.
5.1.6 Source-specific planned improvements
There are no planned improvements for this sector. There are large uncertainties, however the emission levels from the solvents and other products sector are negligible compared to other sectors. In accordance with Good Practice, New Zealand will continue to focus its inventory development on key source categories (IPCC, 2000).