1 D r a f t Life Cycle Assessment A product-oriented method for sustainability analysis UNEP LCA Training Kit Module g – Multifunctionality, allocation & system boundaries

The problem Definitions and typologies Solutions to the multifunctionality problem Allocation according to ISO System boundary and allocation Economic allocation Conclusion Contents D r a f t

The problem (1) electricity production with cogeneration of heat (CHP) electricitycoal generatorfly ash heat function 1 function 2 not a function D r a f t There are processes which have more than one function –“multifunctional processes” not a function

The problem (2) electrolysis of sodium chloride chlorine (Cl 2 ) caustic soda (NaOH) hydrogen gas (H 2 ) sodium chloride (NaCl) electricity 3 functions D r a f t

The problem (3) refinery process naphthakeroseneheavy fuel oil crude oil 3 functions D r a f t

6 6 The problem (4) Two problems; –How should the environmental impacts of these processes be allocated to the different product systems involved? –Which processes belong to the product system studied and which do not?

7 7 D r a f t Definitions and typologies (1) Functional flow –any of the flows of a unit process that constitute its goal product outflows of a production process waste inflows of a waste treatment process Multifunctional process –a unit process yielding more than one functional flow co-production (multi-output) combined waste processing (multi-input) recycling (input-output)

8 8 D r a f t Definitions and typologies (2) general process product waste product waste single-output process 1 functional flow

9 9 D r a f t Definitions and typologies (3) general process product waste product multi-output process 2 functional flows

10 D r a f t Definitions and typologies (4) general process waste product waste product waste single-input process 1 functional flow

11 D r a f t Definitions and typologies (4) general process waste product waste multi-input process 2 functional flows

12 D r a f t Definitions and typologies (5) general process product waste product waste product waste input-output process 2 functional flows

13 D r a f t Definitions and typologies (6) general process product waste product waste product multi-input-output process 4 functional flows

14 D r a f t Definitions and typologies (7) Allocation problem –partitioning (the inputs and outputs of) unit processes among product systems Multifunctionality problem –a broader issue cutting right across LCA inventory modelling what are the functional flows of every process? which processes are multi-functional processes? how to resolve the problems related to that?

15 D r a f t Definitions and typologies (8) Problem –whenever a product system needs product 1, it also produces product 2 Possible solutions –more refined data collection –system expansion –substitution –partitioning (=allocation) –surplus

16 D r a f t Definitions and typologies (9) (More refined data collection) –… not really allocation, but more re-iteration of data collection System expansion –add extra function(s) to the functional unit –… but are you still doing the LCA of a product?

17 D r a f t Definitions and typologies (10) Substitution method –defining an “avoided” process with subsequent “avoided” interventions/impacts –… but which process is avoided? Partitioning method –effectively splitting the multifunctional process into several monofunctional processes –… but what basis for splitting? (Surplus method) –ignoring co-products

18 D r a f t Solutions to the multifunctionality problem (1) Allocation problem is artefact of wishing to isolate one function Artefacts can only be cured in an artificial way; there is no “correct” way, even not in theory Solution should be consistent in itself, and with main modelling principles

Solutions to the multifunctionality problem (2) What to do with the extra heat? electricity production electricity coalgenerator fly ash coal mining equipment generator production steel fly ash treatment gypsum heat D r a f t

20 D r a f t Solutions to the multifunctionality problem (3) Two main strategies for dealing with multifunctionality: –accept extra functions as composite reference flow (“system expansion”) –get rid of extra functions by an extra modeling step (“allocation”) subtracting “avoided” burdens (“substitution”) allocating only part of burden to function needed (“partitioning”)

Solutions to the multifunctionality problem (3) electricity production electricity coalgenerator fly ash coal mining equipment generator production steel fly ash treatment gypsum heat composite functional unit: 2 reference flows D r a f t System expansion –change system boundary –include extra function(s) in functional unit –must also do this for the other alternatives

Solutions to the multifunctionality problem (4) Substitution –change system boundary –add extra process –subtract “avoided” process –with consequences upstream and downstream electricity production electricity coalgenerator fly ash coal mining equipment generator production steel fly ash treatment gypsum heat heat production coal heat avoids avoided process D r a f t

Solutions to the multifunctionality problem (5) Partitioning –allocate only a part of the process to the function considered –with consequences upstream and downstream electricity production electricity coalgenerator fly ash coal mining equipment generator production steel fly ash treatment gypsum heat allocate only part of the inputs and outputs to single function D r a f t

24 D r a f t Solutions to the multifunctionality problem (6) Comparison of solutions on three aspects: functional unitflow diagramprocess data system expansionrevised (for all alternatives) enlarged (for other alternatives) same substitutionsameenlarged (with avoided processes) same partitioningsame changed (by multiplying with allocation factors)

25 D r a f t Solutions to the multifunctionality problem (7) Problems with the three solutions: problem system expansionyou don’t answer the question you started with substitutionwhich processes are avoided? partitioningwhat are the allocation factors?

26 D r a f t Allocation according to ISO (1) D r a f t

27 D r a f t Allocation according to ISO (2) Step 1: Wherever possible, allocation should be avoided by: –dividing the unit process to be allocated into two or more sub-processes and collecting the input and output data related to these sub-processes –expanding the product system to include the additional functions related to the co-products

28 D r a f t Allocation according to ISO (3) Step 2: Partition inputs and outputs in a way which reflects the underlying physical relationships between them –not necessarily mass of molar flows Step 3: Partition inputs and outputs in a way which reflects other relationships between then –e.g., in proportion to the economic value of the products

Allocation according to ISO (4) System expansion versus substitution A.-M. Tillman et al. Choice of system boundaries in life cycle assessment. Journal of Cleaner Production 2:1 (1994), p.24 D r a f t

30 D r a f t System boundary and allocation (1) electricity production waste treatmentTV use electricity fly ash price < 0 reference flow

31 D r a f t System boundary and allocation (2) electricity production chemical plantTV use electricity heat price > 0 reference flow

32 D r a f t System boundary and allocation (3) electricity production generator plantcoal mining coal generator price > 0 reference flow

33 D r a f t System boundary and allocation (4) electricity production pallet productioncoal mining coal wood waste price < 0 reference flow

34 D r a f t System boundary and allocation (5) Price/direction determines: –if a process is to be included –if allocation is needed for a process –extent to which a process in included There is something to say for economic allocation –price<0: exclude –price>0: include a bit –price>>0: include a lot

35 D r a f t co-product System boundary and allocation (6) electricity production downstream processTV use electricity by-product price > 0 reference flow price >> 0price < 0 waste

36 D r a f t Economic allocation (1) Allocation factors based on shares in proceeds –no absolute values needed –any monetary unit, if the same –any base year, if the same total amount produced  economic value/unit

37 D r a f t Economic allocation (2) Problems –market prices not known –fluctuating prices –inflation –trends in real prices –market distortions –markets not yet existing –… Some solutions suggested in CML’s Handbook on LCA

38 D r a f t Conclusions Transparency crucial in drawing system boundaries and solving the multifunctionality problem –what are the flow diagrams of the systems? –which flows are goods, which are wastes? –where are the multifunctional processes? –how is the multifunctionality problem solved in each of these? system expansion: what is the function added? (also in the other alternatives) substitution: what is the avoided process? partitioning: what are the allocation factors?