31
3.2.2 Prospective Modeling Using the THEMIS Model
Large-scale deployment of more effi cient and renewable energy technology can
substantially reduce the environmental footprint of the global economy. It also leads
to large changes in the carbon footprint of energy-intensive products and services
such as materials or transportation. For example, the environmental superiority of
electrically propelled passenger vehicles compared to gasoline-driven ones depends
to a large extent on the carbon intensity of the electricity supply (Hawkins et al.
2013 ). Prospective LCAs of future technologies need to account for these different
framing conditions, for example, by conducting a scenario analysis with different
mixes of energy carriers and conversion technologies. Possible future mixes are
commonly determined by integrated assessment models, such as the TIMES/
MARKAL model family (Loulou et al. 2005 ), which stands behind the Energy
Technology Perspectives of the International Energy Agency (OECD/IEA 2010 ).
The technology mixes determined by such models can be used to build future scenarios for LCA databases, so that the market mix for certain products like electricity
resembles the mix in the IAM scenarios. A thus modifi ed LCA database can be used
to conduct prospective attributional LCAs of future consumption.
The THEMIS model (Technology-Hybridized Environmental-Economic Model
with Integrated Scenarios) is a recent implementation of this principle (Gibon et al.
2015 ). It provides insights into the “comparative environmental impacts and
resource use of different electricity generation technologies” (Hertwich et al. 2015 ).
THEMIS has four main features: (1) Its core is a nine-region integrated hybrid LC
inventory model, which is a combination of foreground information on the specifi c
technologies studied, a background LC inventory database of generic processes like
materials production and transport, and MRIO tables to cover processes not contained in the LC background. (2) The historic technology mixes for electricity generation in the nine model regions were replaced with those obtained from the IEA
baseline and BLUE MAP scenarios (OECD/IEA 2010 ) to build prospective future
LC inventory models for 2030 and 2050. (3) The gradual transformation from the
current to alternative future electricity mixes until 2050 was modeled with an agecohort- based stock model of electricity generation assets, so that for every model
year, the economy-wide impacts for building up new, operating, existing, and disposing of retiring electricity generation technology can be determined (Hertwich
et al. 2015 ). (4) Exogenous scenario assumptions on the improvement of energy
effi ciency, capacity factors, and technology in the production of several major materials including aluminum, copper, nickel, iron and steel, and others were taken from
a prospective study on effi ciency improvement (ESU & IFEU 2008 ).
3.3 The Relation between Prospective IE Models and MFA ,
LCA, and I/O Analysis
The prospective IE models are built upon the established IE methods MFA , LCA,
and IOA. They are integrated hybrid models of society’s metabolism, in the sense
that they combine a foreground system with high level of detail and strict adherence
2 Prospective Models of Society’s Future Metabolism: What Industrial Ecology Has…
3.2.2 Prospective Modeling Using the THEMIS Model
Large-scale deployment of more effi cient and renewable energy technology can
substantially reduce the environmental footprint of the global economy. It also leads
to large changes in the carbon footprint of energy-intensive products and services
such as materials or transportation. For example, the environmental superiority of
electrically propelled passenger vehicles compared to gasoline-driven ones depends
to a large extent on the carbon intensity of the electricity supply (Hawkins et al.
2013 ). Prospective LCAs of future technologies need to account for these different
framing conditions, for example, by conducting a scenario analysis with different
mixes of energy carriers and conversion technologies. Possible future mixes are
commonly determined by integrated assessment models, such as the TIMES/
MARKAL model family (Loulou et al. 2005 ), which stands behind the Energy
Technology Perspectives of the International Energy Agency (OECD/IEA 2010 ).
The technology mixes determined by such models can be used to build future scenarios for LCA databases, so that the market mix for certain products like electricity
resembles the mix in the IAM scenarios. A thus modifi ed LCA database can be used
to conduct prospective attributional LCAs of future consumption.
The THEMIS model (Technology-Hybridized Environmental-Economic Model
with Integrated Scenarios) is a recent implementation of this principle (Gibon et al.
2015 ). It provides insights into the “comparative environmental impacts and
resource use of different electricity generation technologies” (Hertwich et al. 2015 ).
THEMIS has four main features: (1) Its core is a nine-region integrated hybrid LC
inventory model, which is a combination of foreground information on the specifi c
technologies studied, a background LC inventory database of generic processes like
materials production and transport, and MRIO tables to cover processes not contained in the LC background. (2) The historic technology mixes for electricity generation in the nine model regions were replaced with those obtained from the IEA
baseline and BLUE MAP scenarios (OECD/IEA 2010 ) to build prospective future
LC inventory models for 2030 and 2050. (3) The gradual transformation from the
current to alternative future electricity mixes until 2050 was modeled with an agecohort- based stock model of electricity generation assets, so that for every model
year, the economy-wide impacts for building up new, operating, existing, and disposing of retiring electricity generation technology can be determined (Hertwich
et al. 2015 ). (4) Exogenous scenario assumptions on the improvement of energy
effi ciency, capacity factors, and technology in the production of several major materials including aluminum, copper, nickel, iron and steel, and others were taken from
a prospective study on effi ciency improvement (ESU & IFEU 2008 ).
3.3 The Relation between Prospective IE Models and MFA ,
LCA, and I/O Analysis
The prospective IE models are built upon the established IE methods MFA , LCA,
and IOA. They are integrated hybrid models of society’s metabolism, in the sense
that they combine a foreground system with high level of detail and strict adherence
2 Prospective Models of Society’s Future Metabolism: What Industrial Ecology Has…