Use of Models and Facility-Level Data in Greenhouse Gas Inventories

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Use of Models and Facility-Level Data in Greenhouse Gas Inventories Annex 1 shows CITL data; this contains verified emissions from each installation. The CITL data alone will not provide enough data for the GHG inventory compilers. Annex 2 has an example of the detailed returns that a refinery, participating in the UK ETS, makes to the UK Environment Agency. These detailed returns provide a much richer source of data for inventory compilers, and include information about the complexity (Tier) of the method used to estimate the emissions, the fuel consumptions, their carbon contents, calorific values and oxidation factors. Information about carbon contents is particularly valuable as in many cases operators have detailed fuel quality analytical programmes in place and hence the carbon contents are known very accurately. There is also some information about the processes at the reporting site; for example “flare1”, which presumably would mean a flare at the refinery, and “RFG” which means a process using refinery fuel gas 10 . Annex 3 has an example of the detailed ETS data that the UK GHG inventory team is now able to access which is supplied from a database that the UK Environment Agency maintains in its role as the ETS regulator. Using this example, below is a commentary on the information that the data can provide to the UK GHG inventory: • FuelType Some of the fuel nomenclature is clear, and identifying some of the fuels is easy, for example RFG (OPG). The identities of other fuels need be guessed, for example GO - maybe gas oil? The composition of some fuels is unclear, for example F13. • ActivityTier / ActivityData No Tier information is provided for some records, but in most cases this affects only the smaller levels of activities (fuel consumption). The GHG inventory team can analyse the Tier information reported to provide an indication of the accuracy of the estimate. • NCVData Net Calorific data. This field has provided a secondary means to identify fuel type as the GHG inventory compilers can make an assumption of the type of fuel from its NCV. • EFData / EFTier Emission Factor data. Emissions factors are mostly Tier 3, and this implies high accuracy. The UK GHG inventory now uses some carbon emission factor data from the ETS to improve the accuracy of the GHG emissions. For example, the carbon emission factors from coal use in power stations are now taken from the ETS returns, as all the UK coal burning power stations report their carbon contents of coal using a Tier 3 methodology, and these data are updated annually. For sources such as power stations, official energy statistics are likely to be good, and so ETS data can mainly help to improve emission factors. In the case of carbon from catalytic crackers, official energy statistics are likely to be based on estimates. For ETS reporting, carbon emissions are directly measured from crackers. Using ETS data for this source in the UK GHG inventory reduces the uncertainty both from the activity data and the emission factors used in the inventory. The examples above show that for many sectors GHG inventory emission estimates can only be compared with other source data at an aggregated level, combining both multiple sites and multiple emission sources. The individual installation data given in most of the data sets must always be aggregated up before comparison with GHG inventory data. In some cases, multiple source categories in the GHG inventory must also be aggregated to make a comparison possible. For example, in the cement sector, GHG inventory estimates of CO 2 emissions from fuel combustion must be summed with estimates of GHG inventory estimates of CO 2 emissions from the decarbonisation of limestone before they can be compared against the sum of emissions reported for the entire cement sector. The publically available ETS data, accessible via the CITL, is of very limited use to the compilers of GHG inventories. Inventory compilers need to gain access to the more detailed data that is available to the in-country regulators of the ETS. This detailed data will contain information that will help in the compilation of the GHG inventory, and will include estimates of emissions, fuel use, and carbon emission factors. It is important to consider the Tier that has been used; the higher Tier data is the most valuable. Just because data is reported in the ETS does not imply that it is immediately suitable for use in a national GHG inventory. 1.3.2 Reporting coverage of installations across an economic sector The analysis Section 1.3.1 has shown that it is necessary to aggregate up the installation-level data in many data sets before they can be used in the GHG inventory, or in an analysis of the differences between estimates of emissions in the 10 RFG is derived from the crude oil distillation process and is used to fuel boilers, heaters, turbines, etc. RFG is also used as a chemical feedstock (hydrogen source) in some refinery hydrogen plants. Refinery fuel gas composition may vary significantly on relatively short time scales; thus measurements of calorific values and carbon contents must be made at appropriate sampling locations and at sufficiently short time intervals to accurately determine GHG emissions from the combustion. IPCC Expert Meeting Report 74 TFI
Use of Models and Facility-Level Data in Greenhouse Gas Inventories GHG inventory and the EUETS. Many of the source categories reported in the GHG inventory relate to an economic sector such as cement clinker production or electricity generation. In order to use and compare UK GHG inventory data with other data sets, it is necessary for those data sets to cover all or practically all of the installations in those economic sectors. This condition is met for those economic sectors that are characterised by a small number of large installations e.g. electricity generation, cement and lime manufacture, crude oil refineries, coke ovens, steelmaking etc. They all included in the EUETS, although there were temporary opt-outs in the UK for some installations during Phase I (2005 to 2007) when those installations that were included in UK Climate Change Agreements (CCAs) were excluded from reporting emissions data under EUETS. The exclusions due to CCAs covered many sites within the cement and lime sectors, limiting the usefulness of the Phase I EUETS data for comparisons against other estimates for those sectors. A number of very small electricity generation plant on islands off the UK mainland are too small to be included under the EUETS and so no data are available for those sites. The fuels consumed at these sites will be trivial compared with the fuel consumption of the electricity generating sector as a whole so their absence from some data sets is not significant. Other IPCC source sectors include many small- and medium-sized enterprises that are not subject to IPPC or EUETS. This means that it is not possible to aggregate data in the EUETS to cover all of those source sectors as defined in the UK inventory. For example, the GHG inventory source category ‘other industrial combustion’, IPCC sector 1A2f, covers the emissions from fuel use across all types of combustion equipment from the largest boilers and furnaces down to space heating systems similar to those used in the domestic sector. It also covers a wide range of industry sectors including: non-ferrous metals, chemicals, engineering, papermaking, food and drink. The GHG inventory estimates for this source category therefore cover a very large number of installations reporting to the CITL, but also cover an even larger number of additional installations that are too small to be included the EUETS. It is not possible to make a judgement about what proportion of sectoral emissions might be missing from EUETS data sets. Any comparisons of reported emissions are therefore limited to a quality-checking of de-minimis emissions for the source sector, due to the incompleteness of the sector coverage under the EUETS. In the UK, the definition used for combustion installations for ETS purposes currently excludes devices such as furnaces, driers etc where the heat from the combustion is used in the device to perform some process such as melting, drying etc. A more detailed description of the sources included by the UK is given in a regulatory impact assessment report produced by DECC (EU emissions trading scheme (EU ETS) phase II (2008-2012), potential expansion of the scheme. Full regulatory impact assessment, February 2007) 11 . 1.3.3 Reporting protocol for carbon emissions Both the GHG inventory and the EUETS contain detailed information on the sources of carbon emissions, allowing a distinction to be made between carbon emissions from combustion of fossil fuels and carbon emissions from ‘processes’. EUETS data includes information on the use of biofuels, but no emissions data are included in the CITL data set. However, comparison of the EUETS and the Environment Agency’s Pollution Inventory (PI) data for the same installation can help to identify where carbon emissions reported in the PI might include biocarbon. Emissions reported under the ETS should exclude emissions from biocarbon. If verified final emissions were used directly from the CITL there should be no risk of including emissions from biocarbon. However, the raw emissions data taken from the more detailed ETS show instances of companies reporting emissions from biocarbon use – either these are errors in the data, or more probably they represent emissions of fossil carbon from fuels that are mixtures of biofuels and fossil fuels. More clarity in the reporting of fuels would help to resolve this issue. 11 In Phase I, a range of interpretations of the definition of “combustion installation”, and therefore the combustion processes included within the Scheme, were taken by Member States. These were termed narrow, medium and broad referring to the level of inclusion of activities. In its decisions on Phase I NAPs, the Commission rejected the use of the narrow definition but accepted both the medium and broader definitions. The UK followed a “medium” approach, defining a combustion installation as a stationary technical unit that burns fuel for the production of an energy product (which could be electricity, heat or mechanical power). Around half of all Member States interpreted the term more broadly (e.g. the Dutch and Danish NAPs), including all combustion units, whether designed specifically for energy production or not. These inconsistent interpretations have led to competitive distortions in certain sectors. Member States and the Commission have therefore recognised the need for more consistency in Phase II. http://www.decc.gov.uk/assets/decc/what%20we%20do/global%20climate%20change%20and%20energy/tackling%20climate%20ch ange/emissions%20trading/eu_ets/publications/ria-expansion.pdf IPCC Expert Meeting Report 75 TFI
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Use of Models and Facility-Level Data in Greenhouse Gas Inventories

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