32
to core modeling principles such as mass balance with a generic background system.
The background provides the foreground with auxiliary input, such as electricity
supply for material production, and uses the products exclusively supplied by the
foreground as intermediate requirements in turn.
The foreground of extended dynamic MFA comprises dynamic stock models of
the materials and products studied and process models of the industries that are part
of the material cycles studied. The foreground system is balanced for the products
and material that are within the scope, and the background system supplies energy
and other ancillary inputs to operate the stocks and processes in the foreground.
Environmental impact assessment is carried out for the satellite accounts of relevant
emissions from both foreground and background. Because extended dynamic MFA
contains process models, considers the background economy, and uses impact
assessment, one can also consider these models as macro-LCAs of the total service
provided by the stocks studied, carried out as dynamic studies with scenarios for
future development. The foreground model of extended dynamic MFA contains
markets at all stages, preserves co-production, and contains rules for substituting
secondary material for primary material. It can therefore be reformulated as combination of a physical waste-I/O model with the by-product technology assumption
combined with a dynamic stock model of the products studied.
THEMIS integrates LCA and I/O modeling and combines the so-obtained hybrid
model of interindustry fl ows with environmental impact assessment via satellite
accounts. It also contains elements that are commonly found in dynamic MFA :
THEMIS’s foreground system is coupled to a dynamic stock model of electricity
generation assets, so that material demand for building new assets and recycling of
old ones is determined from the turnover of the capital stock in mass-balanced
manner.
3.4 The Relation between Prospective IE Models
and Consequential LCA
The desire to study the potential future consequences of a decision has been a longstanding motivation for industrial ecology research, and a few recent examples were
cited above. In LCA, this desire has led to the concept of consequential life-cycle
assessment (CLCA) , which “is designed to generate information on the consequences of a decision” (Ekvall and Weidema 2004 ). While the concept of a consequential LCA is intriguing, it is also poorly defi ned and subject of controversy
(Brandão et al. 2014 ; Dale and Kim 2014 ; Finnveden et al. 2009 ; Hertwich 2014 ;
Plevin et al. 2014a ; Suh and Yang 2014 ; Zamagni et al. 2012 ). CLCA was initially
defi ned as a result of the debate on how to allocate emissions and inputs of processes with multiple products to the respective outputs. It focused on the marginal
effect of producing an additional unit of output of a specifi c product or of recycling
such a product (Ekvall and Weidema 2004 ). Such allocation problems are addressed
through systems expansion in CLCA, so that the assessment of a product depends
S. Pauliuk and E.G. Hertwich
to core modeling principles such as mass balance with a generic background system.
The background provides the foreground with auxiliary input, such as electricity
supply for material production, and uses the products exclusively supplied by the
foreground as intermediate requirements in turn.
The foreground of extended dynamic MFA comprises dynamic stock models of
the materials and products studied and process models of the industries that are part
of the material cycles studied. The foreground system is balanced for the products
and material that are within the scope, and the background system supplies energy
and other ancillary inputs to operate the stocks and processes in the foreground.
Environmental impact assessment is carried out for the satellite accounts of relevant
emissions from both foreground and background. Because extended dynamic MFA
contains process models, considers the background economy, and uses impact
assessment, one can also consider these models as macro-LCAs of the total service
provided by the stocks studied, carried out as dynamic studies with scenarios for
future development. The foreground model of extended dynamic MFA contains
markets at all stages, preserves co-production, and contains rules for substituting
secondary material for primary material. It can therefore be reformulated as combination of a physical waste-I/O model with the by-product technology assumption
combined with a dynamic stock model of the products studied.
THEMIS integrates LCA and I/O modeling and combines the so-obtained hybrid
model of interindustry fl ows with environmental impact assessment via satellite
accounts. It also contains elements that are commonly found in dynamic MFA :
THEMIS’s foreground system is coupled to a dynamic stock model of electricity
generation assets, so that material demand for building new assets and recycling of
old ones is determined from the turnover of the capital stock in mass-balanced
manner.
3.4 The Relation between Prospective IE Models
and Consequential LCA
The desire to study the potential future consequences of a decision has been a longstanding motivation for industrial ecology research, and a few recent examples were
cited above. In LCA, this desire has led to the concept of consequential life-cycle
assessment (CLCA) , which “is designed to generate information on the consequences of a decision” (Ekvall and Weidema 2004 ). While the concept of a consequential LCA is intriguing, it is also poorly defi ned and subject of controversy
(Brandão et al. 2014 ; Dale and Kim 2014 ; Finnveden et al. 2009 ; Hertwich 2014 ;
Plevin et al. 2014a ; Suh and Yang 2014 ; Zamagni et al. 2012 ). CLCA was initially
defi ned as a result of the debate on how to allocate emissions and inputs of processes with multiple products to the respective outputs. It focused on the marginal
effect of producing an additional unit of output of a specifi c product or of recycling
such a product (Ekvall and Weidema 2004 ). Such allocation problems are addressed
through systems expansion in CLCA, so that the assessment of a product depends
S. Pauliuk and E.G. Hertwich