5. Emission Calculation Methodology 5.1. Scope 1 Emissions 5.1.1. Vegetation Clearing
Vegetation clearing is considered as a Scope 1 emission source as the removal of vegetation leads to the release of carbon that was stored in the biomass and surrounding soil, predominantly as carbon dioxide (CO 2 ). Additionally, it can also result in the release of methane (CH ₄ ) and nitrous oxide (N ₂ O). Reporting of vegetation clearing is not required under the NGER scheme and thus no emission calculation methodologies associated with vegetation clearing are given in the National Greenhouse and Energy Reporting (Measurement) Determination guidelines (NGER, 2008). To calculate an estimate of the GHG emissions associated with vegetation clearing, the Greenhouse Gas Assessment Workbook for Road Projects developed by the Transport Authorities Group (TAGG, 2013) was utilised. The workbook outlines a methodology for estimating GHG emissions from vegetation clearing using the following steps: 1. Determine maximum potential biomass (or maxbio) class for the proposed project area using the maps located in Appendix A of the workbook; 2. Determine the vegetation classes to be cleared (e.g. open forest, open woodland) and the area to be cleared. Vegetation class can be determined using Table 1 of the workbook and the Major Vegetation Groups (MVG) as defined under the National Vegetation Information System (NVIS); 3. Look up the vegetation clearance emission factors using vegetation class, potential maximum biomass class and Table 2 of the workbook; and 4. Multiply the area of vegetation with the corresponding emission factor. The TAGG methodology makes the following assumptions: • All carbon pools (i.e. woody, non-woody, debris and soil) are removed; • All carbon removed is converted to carbon dioxide and released to the atmosphere; and • Sequestration from revegetation of the project site is not included. This is considered a conservative approach for estimating GHG emissions from vegetation removal. The proposed project area falls within maxbio class 3 and the associated emission factors are outlined in Table 3. The resulting emissions calculated are detailed in Section 6.1.1.
Table 3. Scope 1 Emission Factors for Vegetation Clearing
Emission Factor (kg CO 2 - e/GJ)
Regional Ecosystem
Vegetation Class
Short Description
MVG
Open forest in sheltered gorges on coarse- grained sedimentary rocks Eucalyptus decorticans , Lysicarpus angustifolius , +/- Eucalyptus spp. , Corymbia spp., Acacia spp. woodland on coarse-grained sedimentary rocks Corymbia citriodora open forest on igneous rocks (granite)
MVG 2 - Eucalypt tall open forests MVG 5 - Eucalypt Woodlands MVG 5 - Eucalypt Woodlands
11.10.2
B
237
11.10.4b
D
307
11.12.6
D
307
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