1 Background, aim, and scope
2 Goal and scope definition
3 Main features
3.1 Balancing carbon inputs and outputs
3.2 Multifunctionality and allocation
The study shall identify the processes shared with other product systems and deal with them according to the stepwise procedure presented below: |
(a) Step 1: Wherever possible, allocation should be avoided by: |
1. Dividing the unit process to be allocated into two or more subprocesses and collecting the input and output data related to these subprocesses |
2. Expanding the product system to include the additional functions related to the coproducts... |
(b) Step 2: Where allocation cannot be avoided, the inputs and outputs of the system should be partitioned between its different products or functions in a way that reflects the underlying physical relationships between them; i.e., they should reflect the way in which the inputs and outputs are changed by quantitative changes in the products or functions delivered by the system. |
(c) Step 3: Where physical relationship alone cannot be established or used as the basis for allocation, the inputs should be allocated between the products and functions in a way that reflects other relationships between them. For example, input and output data might be allocated between coproducts in proportion to the economic value of the products. |
Source: ISO 2006b. |
-
Coproduction: a multifunctional process having more than one functional outflow and no functional inflow
-
Combined waste processing: a multifunctional process having no functional outflow and more than one functional inflow
-
Recycling: a multifunctional process having one or more functional outflows and one or more functional inflows (including cases of combined waste processing and coproduction simultaneously)
-
Substitution on the basis of an avoided, hypothetical process
-
Partitioning on a physical basis, in this case, on the basis of the carbon content (C-content) of the functional flows
-
Partitioning on an economic basis using the shares in revenues (market prices × quantity of functional flows; see Guinée et al. 2004)
-
The surplus method, which means ignoring additional functional flows that are not strictly needed for the product system under study. The coproduct is then ignored and all burdens are allocated to the main product
4 A simple hypothetical example
4.1 Price situation 1
4.2 Price situation 2
4.3 Price situation 3
5 Results
Functional flow | ||
---|---|---|
Wood | Wood residues | |
Quantity | 1 m3
| 0.1 m3
|
C-content allocation | ||
C-content | 1 kg/m3
| 1 kg/m3
|
C-flow | 1 kg | 0.1 kg |
Allocation factor
| 0.91 | 0.09 |
Economic allocation | ||
Price (€/m3) | 9 €/ m3
| 2 €/ m3
|
Revenues (€) | 9 € | 0.2 € |
Allocation factor
| 0.9783 | 0.0217 |
Surplus method | ||
Allocation factor, if 100% allocated to wood
| 1 | 0 |
Substitution | ||
Production of wood: reference system A producing wood at the cost of −75 kg biogenic CO2/m3 wood and 5 kg CO2/m3 wood | CO2 (kg) of unallocated system minus −70 kg CO2 of reference system A |
Functional flow | ||
---|---|---|
pellet | wood residues | |
Quantity | 1 p | −0.1 m3
|
C-content allocation | ||
C-content | 1 kg/p | −1a kg/m3
|
C-flow | 1 kg | 1 kg |
Allocation factor
| 0.91 | 0.09 |
Economic allocation | ||
Price | 15 €/p | −15 €/m3
|
Revenues | 15 € | 1.5 € |
Allocation factor
| 0.909 | 0.091 |
Surplus method | ||
Allocation factor if 100% allocated to wood residues
| 0 | 1 |
Substitution | ||
Waste management of wood residues: reference system B for waste processing of wood residues (landfill) at the cost of 100 kg CO2/m3 wood residues | CO2 (kg) of unallocated system minus 10 kg CO2 of reference system B |
Functional flow | ||
---|---|---|
electricity | pellet | |
Quantity | 1 kWh | −1 p |
C-content allocation | ||
C-content | 0 kg/kWh | −1 kg/p |
C-flow | 0 kg | 1 kg |
Allocation factor
| 0 | 1 |
Economic allocation | ||
Price | 15 €/kWh | −10 €/p |
Revenues | 15 € | 10 € |
Allocation factor
| 0.6 | 0.4 |
Surplus method | ||
Allocation factor if 100% allocated to pellet
| 0 | 1 |
Substitution | ||
Waste management of pellet: reference system C for waste processing of pellet at the cost of 10 kg CO2/pellet | CO2 (kg) of unallocated system minus 10 kg CO2 of reference system C |
Price situation 1 | Price situation 2 | Price situation 3 | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Allocation method | Allocation method | Allocation method | ||||||||||
C-content allocation | economic allocation | surplus method | substitution | C-content allocation | economic allocation | surplus method | substitution | C-content allocation | economic allocation | surplus method | substitution | |
Growing of trees |
−9.091
|
−2.17
|
−100
| |||||||||
Maintenance | 0.09091 | 0.0217 | 1 | |||||||||
Logging | 0.09091 | 0.0217 | 1 | |||||||||
Industrial processing | 0.9091 | 0.217 | 10 | |||||||||
Processing (pellets) | 5 | 5 | 5 | 5 | 4.545 | 4.545 | 5 | |||||
Electricity generation (cofiring) |
10
|
10
|
10
|
10
|
10
|
10
|
10
|
10
|
6
| |||
Processing (board) |
10
| |||||||||||
Processing (furniture) | ||||||||||||
Waste treatment discarded furniture | ||||||||||||
Waste treatment of wood residues alternative A (landfill) |
−10
|
−10
| ||||||||||
Production of wood alternative A |
75
| |||||||||||
−5 | ||||||||||||
Total (including biogenic CO2) | 699.992 | 5.261 | 15 | −3 | 14.545 | 14.545 | 10 | 5 | 0 | 6 | 0 | 0 |
Total (excluding biogenic CO2) | 609.092 | 13.087 | 5 | 12 | 4.545 | 4.545 | 0 | 5 | 0 | 0 | 0 | 0 |
Price situation | Allocation methods | |||
---|---|---|---|---|
C-content allocation | Economic allocation | Surplus method | Substitution | |
Price situation 1, including biogenic CO2
| 65% | 35% | 25% | 115% |
Price situation 1, excluding biogenic CO2
| 70% | 74% | 75% | 40% |
Price situation 2, including biogenic CO2
| 27% | 27% | 50% | 75% |
Price situation 2, excluding biogenic CO2
| 77% | 77% | 100% | 75% |
Price situation 3, including biogenic CO2
| 100% | 70% | 100% | 100% |
Price situation 3, excluding biogenic CO2
| 100% | 100% | 100% | 100% |
6 Discussion
7 Conclusions
8 Recommendations and perspectives
-
The LCA methodology itself should be expanded with guidelines for those issues that follow from science, logic, or consensus. We think that the inclusion of biogenic CO2 is one such issue, where there are clear and compelling arguments (see Rabl et al. 2007).
-
In the policy regulation that demands LCA to be the basis of the decision, additional guidelines should be specified that perhaps do not (yet) have the status of being scientifically proven or are generally agreed upon, but that serve as a set of temporary extra guidelines.