Carbon Footprint of Supply Chains: A Scoping Study (2013) / Chapter Skim
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From page 64... ...
5 DEVELOPING A DECISION TOOL In this chapter the proposed three-tier architecture for the decision tool is presented along with the specific elements it requires. Next, a number of example scenarios for calculation are provided to illustrate some of the issues that must be considered when designing the tool.
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From page 65... ...
for supply chains may not be the ideal tool for use in specific programs, and thus the decision of whether the tool should support such approaches is a question for the implementation of the design, and is left outside the scope of this report. THREE-TIER APPROACH Three-tier software architecture divides software in to three layers to allow developers to modify and change the tiers independently96.
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factors, the data must store the necessary information for the model tier to calculate distances, including the ability to locate points and calculate a route between them. ELEMENTS Together the specifications for each tier describe the workings of the tool.
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users enter data in the rows for each entry. A screenshot of version 2.3 of the GHG Protocol Mobile Combustion97 tool is shown in Figure 18.
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Figure 20: NTM Basic Freight Calculator Data Entry Each of these interfaces represents a method of direct entry. The user inputs all the information necessary to calculate the emissions, and the tool performs no additional processing.
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Figure 21: EcoTransIT World Web Interface The network builder approach, combined with the ability to do direct data entry when the exact details are known, provide the necessary capabilities for users to calculate emissions for transportation given a wide range of possible data types and availability. The interface of these data entry capabilities with the actual calculations is covered in the section on the model elements.
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From page 70... ...
by factors such as mode, lanes, or even in/out of specific destinations. In addition a number of activity parameters, such as tons shipped, miles traveled, and ton-miles, can be reported and used to provide KPIs related to overall efficiency.
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More complex route determinations can be made through the addition of detailed Geographic Information System (GIS) data.
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DATA LAYER The data layer is concerned with storing information required to support the logic of the model layer. It provides the data requested by the elements of the model, but does not provide any logic of its own.
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EMISSIONS FACTORS The most important data element for the actual calculation of emissions is the available emissions factors. The model layer supports three methods of calculation, and the data layer must provide emissions factors appropriate to each method.
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factors may further differ based on the specific country, as the IPCC recommends countries develop specific emissions factors that account for the technology and quality of the oil specific to that country. This leads to a range of possible emissions factors depending on the assumptions made.
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Using the previous example of 1000 gallons of diesel fuel consumed this produces the following results. 1000 gallons x of 0.03009 g CH4/gallon = 30.09 g CH4 1000 gallons x 0.02832 g N2O/gallon = 28.32 g N2O The values can be converted to carbon dioxide equivalents by multiplying each value by the global warming potential of the gases.
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From page 76... ...
The inclusion of biofuels introduces a second complication -- the need to separate emissions from fossil fuels from biomass. This can be seen explicitly in the factor forE85 Ethanol, where the 15% assumed to come from standard gasoline produces 1.3215 kg of CO2, while the remaining 85% ethanol is assumed to produce 4.726 kg of CO2.
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The use of emission factors that consider a greater level of depth in the measurement increase the total impact of transportation by including the emissions related to the production of fuel. Using the default emission factor for diesel we calculated earlier and comparing it to the WTW numbers produced by GREET provide the following results for the combustion of 1000 gallons of diesel.
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ACTIVITY BASED METHODS When direct fuel consumption data is not available a number of activity-based methods are available. While considered less accurate than fuel-based methods for CO2 calculations, they offer advantages in terms of more easily acquired data and the ability to estimate future emissions from predicted transportation demand.
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The NTM program does not collect specific data from carriers, but rather uses the ARTEMIS simulation tool to calculate fuel consumption for a number of different scenarios108. These scenarios account for different sizes of vehicles, % loaded, road type, and driving conditions.
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related to a specific amount of goods are considered. In the second case, the shipper may not know the specific vehicle and distance that were used.
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GHG Protocol Road Vehicle – Light Goods Vehicle – Petrol – Engine Size 1.305 – 1.74 tonnes (US EPA) 0.297 kg CO2/ton-mile CO2 2,970 GHG Protocol Road Vehicle – Light Goods Vehicle – Petrol – Engine Size 1.305 – 1.74 tonnes (UK Defra)
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comprehensive solution capable of calculating distances for all possible shipments is not currently available. Origin Destination Mode Method Distance (miles)
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OTHER ISSUES In addition to the issues related to the development of appropriate emissions factors and methods there is also the question of how such methods can be combined for more complicated scenarios. There are two particular scenarios worthy of further attention.
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Calculation Method Estimated Travel Distance (miles) Estimated CO2 (tonnes)
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Figure 23: Delivery Scenario A number of possible approaches could be used. The emissions could be divided equally, with each customer being charged for 50 kg CO2.
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means of allocation. In some cases this may be more representative of the true drivers of system behavior, and may be preferred.
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TASK 2 -- COMPILE EMISSIONS FACTOR DATABASE TASK 2.1 – COLLECT EXISTING EMISSIONS FACTORS Based on the review of methods and proposed definition in Chapter 1, a database of emissions factors must be compiled to support the calculation methodologies. Based on the working definition of the carbon footprint of the supply chain, these emissions factors should consider a well-to-wheel system boundary.
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TASK 4.2 -- INTEGRATE SELECTED TECHNOLOGY WITH CALCULATION TOOL Based on the technology or technologies defined in Task 4.1, an interface to the data entry system of Task 3.2 must be implemented. The service shall take the origin, destination, and modes entered by the user and return the calculated distance between the points.
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TIMELINE Given the tasks outlined for a future tool, there is significant flexibility in the time and cost required to implement the tool based on the desired level of sophistication. The GHG Protocol tool is perhaps one of the most popular tools in use, but is little more than a Microsoft Excel spreadsheet.
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This tool would meet the needs of a basic carbon calculator suitable for wide use, but would be limited due to the static nature of the tool. Users would be limited by the available choices of factors and locations.
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shared and used by shippers to calculate their own emissions. This capability requires the ability to calculate and store company specific emissions factors, make these factors available to users, and protect any sensitive information.
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96 Ramirez, A
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