In general much of the discussion on the process for developing UEFs for liquid fuels would also apply to UEFs in other sectors. Some of the differences include:
UEFs for the stationary energy sector in particular are likely to be far more common than the liquid fuels sector. Therefore the administration resource requirement may be greater, although, as with liquid fuels, the officials’ role is one of process management rather than actually doing a great deal of groundwork.
The amount of variation from a DEF allowed before a UEF can be used is likely to be fuel dependent. This is because the natural variation of each fuel is different along with its measurement accuracy. While the principles used to establish the variation factor should be the same, it is likely that one may need to be developed for each group of fuels (e.g. one for coal, one for gas, etc) and each process.
Where verifiers are required for process emissions there may be no straight-forward certification reference that can be used in any legislation. If this is the case, alternatives need to be explored (preferably working off some external certification rather than including a list of acceptable verifiers in the legislation).
There may need to be some adjustment to what is acceptable for ensuring continued applicability of the UEF depending on the fuel. For instance there may be less variation in some of the fuel streams compared with liquid fuels so a single sample can be more representative (therefore less frequent samples may be required on an ongoing basis). What is decided in this area should also relate to any decisions around frequency of review of DEFs.
Appendix 1: Plot of default emissions factors
The following graph plots the emission factors for the default liquid fossil fuels. It highlights that the default emission factors of the commonly used liquid fossil fuels almost cover a continuous range between 2.1 and 3.1 tCO2/kl.