5.1 Sector overview (CRF 3)
This sector includes emissions from chemical cleaning substances used in dry-cleaning, printing, metal degreasing and from the use of paints, lacquers, thinners and related materials. The emissions arise from the evaporation of the volatile chemicals when solvent-based products are exposed to air.
The only direct greenhouse gas reported in this category is nitrous oxide (N2O) emissions from anaesthesia use. In 2008, N2O emissions from anaesthesia use totalled 31.0 Gg carbon dioxide equivalent (CO2-e). This was a decrease of 10.5 Gg CO2-e (25.4 per cent) from the 1990 level of 41.5 Gg CO2-e.
However, this sector is a significant source for non-methane volatile organic compound (NMVOC) emissions. In 2008, NMVOC emissions from the solvent and other product use sector were 34.8 Gg, or 20.3 per cent of total NMVOC emissions. This was a decrease of 10.5 Gg (43.3 per cent) from the 1990 level of 24.3 Gg of NMVOCs. The categories dominating the sector are NMVOC emissions from paint application and other domestic and commercial-use (Figure 5.1.1) subcategories.
Figure 5.1.1 Change in New Zealand’s emissions of NMVOC from the solvent and other product use sector from 1990 to 2008
|1990 Gg NMVOC||2008 Gg NMVOC|
|Degreasing and dry-cleaning||0.8||0.7|
Note: The per cent change for chemical products is not applicable (NA) as there is no activity data available for 1990.
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
Detailed methodologies for emissions from the solvent and other product use sector are not provided in the revised 1996 Intergovernmental Panel on Climate Change (IPCC) guidelines (IPCC, 1996). Two basic approaches for estimating emissions – consumption and production-based estimates – are documented. 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. Activity data is obtained by an industry survey (CRL Energy, 2006) and extrapolated for the 2006 and 2008 calendar years.
Emission factors are developed based on the likely final release of NMVOCs to the atmosphere per unit of product consumed. The emission factors are applied to sales data for the specific solvent or paint products. The subcategories of solvents and other products specified in the common reporting format are detailed below.
Activity and emissions data for 2006 and 2008 were extrapolated from the 2005 survey data. Consumption and emissions from paints and thinners were based on information from Nelson (1992) and the Auckland Regional Council (1997). Additional activity data for 1993 to 1996 was provided by the New Zealand Paint Manufacturers’ Association.
Degreasing and dry-cleaning
Dry-cleaning activity and emission data were extrapolated from 2005 activity data for the 2006 and 2008 calendar years. Most dry-cleaners in New Zealand use perchloroethylene and a small number use white spirits. Trichloroethylene has never been used in dry-cleaning but it is used in degreasing, for instance, in the leather manufacturing industry. In general, solvent losses from the dry-cleaning industry have reduced substantially as closed circuit machines and refrigerated recovery units are increasingly used. Consumption of perchloroethylene and trichloroethylene are assumed to equal the volume of imports. Import data was supplied by Statistics New Zealand. Degreasing is not estimated in New Zealand.
Chemical products (manufacturing and processing)
The solvents tetrabutyl urea and alkyl benzene are used in the production of hydrogen peroxide. Emissions of NMVOCs were provided by Degussa Peroxide Ltd. The hydrogen peroxide plant has an online, continuous, activated-carbon solvent recovery system. Solvent losses were recorded annually as the difference between input solvent and solvent collected for incineration.
Losses of ethanol (and other minor components such as methanol, acetaldehyde and ethyl acetate) were monitored in the three ethanol plants in New Zealand. Using these values, an emission factor for NMVOCs of 6 g/litre was calculated. Ethanol used for alcoholic beverage production has been reported under food and drink production in the industrial processes sector.
The emissions for 2008 are the same as for 2006.
Other – printing ink use
There is one major printing ink company in New Zealand with approximately 50 per cent of the solvent ink market share. The company provided a breakdown on the type of ink used. Approximately 50 per cent of inks used are oil inks (paste inks) containing high boiling temperature oils. These are evaporated off during heat setting, but the volatiles are generally treated in a solvent burner that minimises emissions. The remaining 50 per cent of inks are liquid, and 60 per cent of these are solvent inks (the remaining 40 per cent are water based).
Due to data availability, data has remained unchanged since 2005.
Other – aerosols
Approximately 25 million aerosol units are sold in New Zealand each year. The average propellant charge is 84 grams and 95 per cent are hydrocarbon-based. Total NMVOC emissions in 2008 were 1.68 Gg. This is based on the assumption that the units are fully discharged within two years of purchase.
Other – domestic and commercial use
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. Emissions for this category are based on a per capita emission factor. The emission factor used is 2.54 kg NMVOC/capita/year (United States EPA, 1985). It is assumed that the emissions rate per capita derived by the United States Environmental Protection Agency is applicable to the average product use in New Zealand (CRL Energy, 2006). Population data is from the Statistics New Zealand website. As at December 2008, the population was estimated to be 4.25 million.
Nitrous oxide used for anaesthesia
The sole importer of bulk N2O into New Zealand provided activity data for the 2008 calendar year. 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 half-and-half mixture of nitrous oxide and oxygen for pain relief). There is a very small amount used in motor sports and scientific analysis.
5.1.3 Uncertainties and time-series consistency
Estimates of uncertainty are based on information provided by industry in the questionnaires and discussions with respondents (CRL Energy, 2006). The overall uncertainties are shown in Table 5.1.1.
|HFC source||Combined uncertainty estimates (%)|
5.1.4 Source-specific recalculations
There were no recalculations for this sector.
5.1.5 Source-specific planned improvements
There are no planned improvements for this sector. There are large uncertainties; however, the emission levels from the solvent and other products sector are negligible compared with other sectors. In accordance with good practice, New Zealand will continue to focus its inventory development on key source categories (IPCC, 2000).