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The Greenhouse gases: HFCs, PFCs and SF6

APPENDICES

1. GWP values for F-gases

Table 1.a F-gases relevant for Denmark, their chemical formulas and Global Warming Potential (GWP) values used for reporting to the UN Climate Convention and the Kyoto Protocol

1. Mixture consisting of 52 % HFC-143a, 44 % HFC-125 and 4 % HFC-134a.
2. Mixture consisting of 53 % HCFC-22, 13 % HFC-152a and 34 % HCFC-124.
3. Mixture consisting of 38 % HCFC-22, 60 % HFC-125 and 2 % propane
4. Mixture consisting of 25 % HFC-125, 52 % HFC-134a, and 23 % HFC-32.
5. Mixture consisting of 46 % HFC-143a and 7 % HFC-125.
6. A HCFC mixture consisting entirely of HCFCs, where the GWP - in accordance with the climate convention guidelines - is 0, since the mixture does not contain greenhouse gases. The real GWP value is 1,440.
7. Mixture consisting of 50 % HFC-32 and 50 % HFC-125
8. Mixture consisting of 50 % HFC-125, 50 % HFC-143a.
   

2. GWP contribution from HFCs, PFCs, and SF₆, 1993-2020.

The table below shows the time series 1993-2007 and the 2008-2020 projections of F-gases as GWP contributions.

The emission projections are determined by starting with a ‘steady state’ consumption using 2007 as the reference year and the cut-off dates for the phasing-out of specific substances, cf. the Statutory Order regulating certain industrial greenhouse gases.

The calculated GWP contribution expresses actual emissions, adjusted for imports and exports (the latest basis of calculation).

Table 1. GWP contribution from HFCs, PFCs, and SF₆ in 1 000 tonnes CO₂-equivalent, 1993-2020

3. Specification of methods and assumptions for emission calculation

click here to see Tabel "Specification of methods and assumptions for emission calculation".

4. Good Practice Guidance compliance in DK F-gas calculation 2007

The Danish F-gas emissions are calculated for the historical years up to 2007. The time series of emissions are calculated using Good practice principles and the series goes back to 1993, but are to be considered complete from the year 1995.

Key Source Categories

F-gases are determined as a key source category. The contribution of F-gases to national greenhouse gas emission is approx. 1.3 % of total emission excl LULUCF in the most recent historical years of the inventories.

Future trend scenarios

A trend scenario is elaborated until 2020. The scenario is bases on a “steady state” trend but with an inclusion of dates for out phase of determined substances as stated in legal acts.

Methodology

In the following the relevant decision trees from the GPG (Good Practice Guidance) chapter 3 are investigated with respect to the Danish F-gas calculations compliance with GPG.

For the Danish calculation of F-gases it is basically a Tier 2 bottom up approach which is used, while data is reported from identified importers and users of F-gasses in DK. As for verification using import/export data a Tier 2 top down approach is applied. In an annex 4 to the F-gas emission report 2006 (Environmental Protection Agency), there is a specification of the applied approach for each sub source category.

Emission factors

Consumption data of F-gases are provided by suppliers and/or producers. Emission factors are primarily defaults from GPG which are assessed to be applicable in a national context.

In case of commercial refrigerants and Mobile Air Condition (MAC), national emission factors are defined and used. In case of PUR foam blowing of shoe and use of system foam EF are stated by the producer. Because of the relative low consumption from PUR foam blowing of shoes and system foam a certain uncertainty is assessed as acceptable.

Import/export data

Import/export data for sub category sources where import/export are relevant (MAC, fridge/freezers for household) are quantified on estimates from import/export statistic of products + default values of amount of gas in product. The estimates are transparent and described in the annex referred to above.

Import/export data for system foam and commercial refrigerators and stationary air condition are specified in the reporting from importers and users.

Consistency

The time series are consistent as regards methodology. No potential emission estimates are included as emissions in the time series and same emission factors are used for all years.

Reporting and documentation

The national inventories for F-gases are provided on a yearly basis and documented in a yearly report (Environmental Protection Agency, 2004 and 2005).

Detailed data from importers and users and calculations are available and archived in electronic version. The report contains summaries of EF used and information on sources, Further details on methodology and EF are included in annex to the report.

Activity data are described in a spread sheet for the current year. The spread sheet contains the current year as well as the years back. The current version is used with spreadsheet for data for the current year linking to the Danish inventory databases and for the CRF format. In case of changes to the previous reported data this is work out in spreadsheet versions accordingly and reported with explanations as required in the CRF format.

Source specific QA/QC and verification

Comparison of emissions estimates using different approaches

Inventory agencies should use the Tier 1 potential emissions method for a check on the Tier 2 actual emission estimates. Inventory agencies may consider developing accounting models that can reconcile potential and actual emissions estimates and may improve determination of emission factors over time.

This comparison has been carried out in 1995-1997 and for all three years it shows a difference of approx. factor 3 higher emissions by using potential emission estimates.

Inventory agencies should compare bottom-up estimates with the top-down Tier 2 approach, since bottom-up emission factors have the highest associated uncertainty. This technique will also minimise the possibility that certain end-uses are not accounted for in the bottom-up approach.

This exercise has been partly conducted since data from importers (top down) are assessed against data from users (bottom up) to ensure, that import and consumption are more or less equal. The consumption reported from users are always adjusted to the import of substances, which are the most exact data we have.

The uncertainty due to this is, if not all importers are identified because new imported are introduced to the DK market.

National activity data check

For the Tier 2a (bottom-up) method, inventory agencies should evaluate the QA/QC procedures associated with estimating equipment and product inventories to ensure that they meet the general procedures outlined in the QA/QC plan and that representative sampling procedures were used.

No QA/QC plan specifically for the F-gas calculation is developed. However, QC procedures were carried out as described below.

The spread sheets containing activity data has incorporated several data-control mechanisms, which ensure, that data estimates do not contain calculation failures.  A very comprehensive QC procedure on the data in the model for the whole time-series has for this submission been carried out in connection to the process which provided (1) data for the CRF background Tables 2(II).F. for the years (1993)-2002 and (2) provided data for potential emissions in CRF Tables 2(I). This procedure consisted of a check of the input data for the model for each substance. As regards the HFCs this checking was done according to their trade names. Conversion was made to the HFCs substances used in the CRF tables etc. A QC was that emission of the substances could be calculated and checked comparing results from the substances as trade names and as the "no-mixture" substances used in the CRF.

Emission factors check

Emission factors used for the Tier 2a (bottom-up) method should be based on country-specific studies. Inventory agencies should compare these factors with the default values. They should determine if the country-specific values are reasonable, given similarities or differences between the national source category and the source represented by the defaults. Any differences between country specific factors and default factors should be explained and documented.

Country specific emission factors are explained and documented for MAC and commercial refrigerants and SF6 in electric equipment. Separate studies has been carried out and reported. For other sub source categories, the country specific emission factor is assessed to by the same as the IPCC default emission factors.

Emission check

Since the F-gas inventory is developed and made available in full in spread sheets, where HFCs data are for trade names, special procedures are performed to check the full possible correctness of the transformation to the CRF-format through Acces databases.

Uncertainties

In general uncertainty in inventories will arise through at least three different processes:

1. Uncertainties from definitions (e.g. meaning incomplete, unclear, or faulty definition of an emission or uptake);
2. Uncertainties from natural variability of the process that produces an emission or uptake;
3. Uncertainties resulting from the assessment of the process or quantity, including, depending on the method used,: (i) uncertainties from measuring; (ii) uncertainties from sampling; (iii) uncertainties from reference data that may be incompletely described; and (iv) uncertainties from expert judgement.

Uncertainties due to poor definitions are not expected as an issue in the F-gas inventory. The definitions of chemicals, the factors, sub source categories in industries etc. are well defined.

Uncertainties from natural variability are probably occurring in a short term time period, while estimating emissions in individual years. But in a long time period – 10-15 years, these variabilities levels out in the total emission , because input data (consumption of F-gases) are known and are valid data and has no natural variability due to the chemicals stabile nature.

Uncertainties that arise due to imperfect measurement and assessment are probably an issue for:

emission from MAC (HFC-134a)
emission from commercial refrigerants (HFC-134a)
lead to inexact values of the specific consumption of F-gases.

The uncertainty varies from substance to substance. Uncertainty is greatest for HFC-134a due to a widespread application in products that are imported and exported. The greatest uncertainty in the areas of application is expected to arise from consumption of HFC-404a and HFC-134a in commercial refrigerators and mobile refrigerators. The uncertainty on year to year data is influenced by the uncertainty on the rates at which the substances are released. This results in significant differences in the emission determinations in the short term (approx. five years), differences that balances in the long term.

I connection to the work on the Danish National Inventory report general uncertainty estimates for F-gases has been worked out to make the uncertainties for the Danish inventories complete. Refer this report given in the reference list in the main report

Further improvement of uncertainty analysis with respect to the calculation of F-gas emissions are to be considered in future calculations.

References.

Danish Environmental Protection Agency (2004). Ozone depleting substances and the greenhouse gases HFCs, PFCs and SF6. Danish consumption and emissions 2002. Environmental Project No. 890. http://www.mst.dk/udgiv/publikationer/2004/87-7614-099-7/pdf/87-7614-100-4.pdf

Danish Environmental Protection Agency (2005). Ozone depleting substances and the greenhouse gases HFCs, PFCs and SF6. Danish consumption and emissions 2003. Under publication in English. In Danish: Ozonlagsnedbrydende stoffer og drivhusgasserne HFC'er, PFC'er og SF6. Forbrug og emissioner 2003. Miljøprojekt 987. http://www.mst.dk/udgiv/publikationer/2005/87-7614-546-8/pdf/87-7614-547-6.pdf

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Version 1.0 May 2009, © Danish Environmental Protection Agency