Lecture 11: Allocation

Transcription

1 Environmental Life Cycle Assessment PSE 476/WPS 576 Lecture 11: Allocation Fall 2016 Richard A. Venditti Forest Biomaterials North Carolina State University Raleigh, NC Go.ncsu.edu/venditti 1

2 Allocation Allocation: partitioning the input and output flows of a process or a product system between the product system under study and one or more of the other product systems (ISO 14044: 2006E)

3 Allocation Procedures (ISO standards) Step 1: allocation should be avoided Increasing the level of detail. By dividing the unit process into 2 or more sub-processes and tracking data for both separately System Expansion. Expanding the system to include the additional functions of the related co-products Refs: Michael Hauschild, DTU

4 Allocation Procedures (ISO standards) Step 2: partition the inputs and outputs between products in a way that reflects underlying physical relationships Number of parts Mass Volume Step 3: partition the inputs and outputs between products in a way that reflects other relationships between them economic value Refs: Michael Hauschild, DTU

5 Avoidance of Allocation: Divide the process A factory makes television sets and also makes car radios. The factory utilizes 50,000 kwh every month. The electrical power used during days in which TV manufacture occurs is twice the amount than when radios are being made. In a month 8000 TV s and 2000 radios are produced on average. What is the amount of electricity that can be attributed to a TV and a radio? The factory is closed on weekends. 5

6 Avoidance of Allocation: Divide the process 6

7 Avoidance of Allocation: System Expansion A landfill disposes of 50 tons of waste by burning and produces 550 kwh per ton. The process emits a total of 400 kg of CO2eq per ton of waste burnt. Use system expansion to determine the emission per ton of waste processed for the following cases for the alternate source of electricity: Anthracite coal Natural Gas Biodiesel 7

8 Avoidance of Allocation: System Expansion 8

9 Allocation Issues: Co-products: Co-products Allocation: a single process produces multiple products simultaneously Burdens can be partitioned by mass flows, volume flows, piece flows monetary values. Must use process/product knowledge to determine partioning method Example for paper production: paper, Tall Oil, turpentine, electricity Emissions Raw Matls Power System Product B Product A 9

10 Allocation Issues: Co-products: A truck travels 800 km delivering 10,000 kg of food. The truck has the following emission.094 kg CO2e/tonne km. The following is transported: 800 packages of spices, 0.5 kg per pkg, price: $800/kg 8000 packages of flour, 1 kg per pkg, price $30/kg 400 packages of rice, 4 kg per pkg, $1/kg Use allocation procedures to allocate the emission to the total of each type of food. Also determine the emission per kg of each type of food. By package By mass By value

11 Allocation Issues: Co-products: Total emissions: Total packages: Total Mass: Total Value:

12 Allocation Issues: Co-products: Item Allocation Allocation Factor Total Allocated Flow, kg CO2e Emission kg CO2e /package Emission kg CO2e /kg food Spice Flour Rice

13 Allocation Issues: Co-products: Mass Allocation Allocation Factor Total Allocated Flow, kg CO2e Emission kg CO2e /kg food Spice Flour Rice

14 Allocation Issues: Co-products: Economic Allocation Allocation Factor Total Allocated Flow, kg CO2e Emission kg CO2e / kg food Emission kg CO2e / $ food Spice Flour Rice

15 Allocation Issues: Recycling Recycling Allocation: virgin product is recycled or re-used in a subsequent life There exists operations that are required by the virgin and the recycled products (shared operations: GREY BOXES BELOW) Non-shared operations directly attributed to a product: WHITE BOXES BELOW Many ways to allocate the burdens of the shared operations: which one to use??? Primary material production (V 1 ) Production of Product P1 (P 1 ) Recycling of Product P1 (R 1 ) Production of Product P2 (P 2 ) Recycling of Product P2 (R 2 ) Production of Product P3 (P 3 ) Use of Product P1 (U 1 ) Use of Product P2 (U 2 ) Use of Product P3 (U 3 ) End of life (W 3 ) 15

16 Allocation Methods: Recycling: Cut off method: loads directly caused by a product are assigned to that product (V1 to L1, R1 to L2, R2 and W3 to L3) Approximation with closed loop recycling. Equal burdens. All lives of a product share equal the shared operation loads. Relative loss of quality: shared operation loads partitioned according to quality of products Waste treatment is inevitable consequence of raw material extraction (V1 and W3 to L1)(R1 to L2)(R2 to L3) Man made products are valuable that must be replaced by virgin resources if lost as waste (V1 and W3 to L3) (R1 to L1)(R2 to L2)

17 Allocation Issues: Recycling Use cut off, approx. of closed loop, and quality methods to calculate emissions of each product R1=R2= 3 units of emissions, U1=U2=U3=0, P1=P2=P3=1 V1= 4 unit of emissions, W3=1 Relative quality of products: Q1=1, Q2=0.75, Q3=0.5 Primary material production (V 1 ) Production of Product P1 (P 1 ) Recycling of Product P1 (R 1 ) Production of Product P2 (P 2 ) Recycling of Product P2 (R 2 ) Production of Product P3 (P 3 ) Use of Product P1 (U 1 ) Use of Product P2 (U 2 ) Use of Product P3 (U 3 ) End of life (W 3 ) 17

18 Allocation Issues: Recycling Use cut off, approx. of closed loop, and quality methods to calculate emissions of each product 18

19 Summary Co-products Allocation Avoidance of Allocation System expansion Divide the process Allocation by Item, physical quantity, other quantity Allocation factor Allocated flow/emissions Recycling allocation Shared operations Non-shared operations Cut off Equal burdens. Approximation with closed loop recycling Relative Loss of quality Waste treatment is inevitable consequence of raw material extraction Man made products are valuable that must be replaced by virgin resources if lost as waste 19