Following the approach outlined above an ordered ‘priority’ list is obtained providing a list from greatest to least magnitudes of emission flux for each of the community sector to primary, common emission source combination.
Given that the primary objective of this inventory is to provide direction for emission reduction strategy decisions, an understanding of the amount to which each community sector and emission source contributes is particularly valuable.
Chapter 5
Community Inventory -
Applied Methodology
This chapter presents a detailed description of the inventory methodology that is selected for application within the present study. Discussed here is the actual quantitative method as well as discussion on the practicalities that are associated with its application.
As defined in section 4.1, the objective of this methodology is to derive an approximation for greenhouse gas emissions, broken down into primary, com- mon emission sources as well as community sectors. Also discussed previously is the perspective from which this methodology is to be approached. Accordingly, consideration is given here to the top-down approach.
Further to this, the present chapter attempts to add value to the method- ology, as adopted by the study. That is, where possible, a comparative discussion is made on the options available for such an inventory within the context, thus providing justification and validity to the methodology employed.
5.1
Conversion to Carbon Dioxide Equivalent
Greenhouse gases are numerous and varied within our atmosphere, each possessing a different amount of global warming potential. In order to quantify emission flux it is necessary to derive a quantity for which each type of greenhouse
gas can be made comparable. Carbon dioxide equivalent (CO2e) is the conven-
tional quantity used to achieve this. CO2eis the equivalent amount ofCO2 that
would cause the same amount of global warming potential for a given amount of greenhouse gas, when measured over a specified timescale (generally, 100 years).
Carbon dioxide equivalent (CO2e) is calculated by multiplying the global warming
potential of a gas in terms of CO2, by the mass of the gas. The present study
adopts carbon dioxide equivalence to define the greenhouse gas emission inventory and thus structure an assessment of the current state of emission flux within the municipality of Brighton.
The following is a list of the six major greenhouse gas species and their
global warming potentials (GWP) in terms of CO2:
• Carbon dioxide (CO2)
• Methane (CH4) - GWP is 21 times that ofCO2
• Nitrous oxide (N2O) - GWP is about 310 times that ofCO2
• Hydrofluorocarbons (HF Cs) - GWP is 100 to 3800 times that ofCO2
• Perfluorocarbons (P F Cs) - GWP is 5000 to 10000 times that of CO2
• Sulphur hexafluoride (SF6) - GWP is 23900 times that of CO2
Under the United Nations Framework Convention for Climate Change (UN- FCCC) and its Kyoto Protocol, all parties including Australia are required to estimate fluxes for each of these six key greenhouse gases [UNFCCC, 2008]. Fur- thermore, emissions must be classified according to the six sectors identified by
the IPCC, as discussed in section 4.6. This greenhouse gas inventory and report- ing approach is in accordance with the Common Reporting Format (CRF) that is adopted by the federal government under these international agreements. The present study adopts an alternative approach that is considered here to be more appropriate for informing decision-making of mitigation measures on the local level, where by sectors and common emission sources are accounted for separately and then ordered by severity.
Each of the primary emission sources defined in the previous chapter produce significant amounts of greenhouse gas which must be converted to carbon dioxide equivalence. There are two methods of achieving this. That is, to apply the global warming potential factor to a given mass of the gas, as described above. Or alternatively, to apply a conversion factor to a given quantified activity or process. In terms of the present study, for most cases it is much easier to quantify the activity or process causing the emission and apply accepted conversion factors to derive carbon dioxide equivalence. This is therefore the approach adopted.
Such conversion factors are in many cases dynamic, dependent on environ- mental and social conditions, varying in time for different locations. They are also open to a developing scientific knowledge base that leads to regular updates to standard factor derivation methods. The Australian authority on conversion factors is the Australian Government and its Department of Climate Change [De- partment of Climate Change, 2008a]. Much of what is accepted by them is directly obtained from the international authority, the International Panel for Climate Change [IPCC, 1988]. The present study therefore implements conversion factors as specified by Department of Climate Change [2008a], for the year as defined in the inventory scope.
The proceeding subsections show conversion methodology, as adopted by the present study.
5.1.1 Electricity usage
The following conversion factor is defined for Tasmania, for the financial year of 2007/2008:
kgCO2e= 0.13P (5.1)
Where: P is the power used in the calendar year of 2007 (kW h)
[Department of Climate Change, 2008a]
5.1.2 Fuel usage (including both fuel usage and fuel usage due to travel)
The following procedure and conversion factors are defined for fuels:
EC EF Unleaded Petrol 34.2 67.1 Aviation Gasoline 33.1 66.7 Natural Gas 46.5 60.7 Diesel 38.6 69.5 LPG 25.5 59.9 Wood 16.2 15.6
Table 5.1: Fuel Conversion Factors
Where: EC is the energy content of the fuel (GJ/tonne)
EF is the emission factor (kgCO2e/GJ)
[Department of Climate Change, 2008a] The carbon dioxide equivalent is thus:
kgCO2e=EC×EF ×MF (5.2)
Where: MF is the amount of fuel used in the calendar year of 2007 (tonnes)
5.1.3 Waste
For general co-mingled municipal waste, the following conversion factor is defined:
Co-mingled volume to weight ratio = 0.12 (5.3)
kgCO2e= 1.11MW (5.4)
Where: MW is the amount of waste (kg)
[Department of Climate Change, 2008a]