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5.3.1.2 Scope Definition
The scope definition serves the purpose of communicating to the audience what is
included and what is excluded from the study. Depending on the goal of the study, there
are several types of scopes including cradle-to-gate, cradle-to-grave, and gate-to-gate.
There are other words that are commonly used to describe these scopes but the ideas
are similar.
- Cradle-to-grave includes all flows and impacts from raw material extraction to
disposal and reuse.
- Cradle-to-gate includes all flows and impacts from raw material to production and
excludes product use and end of life.
- Gate-to-gate only includes flows from production or material processing steps of a
product life cycle.
The scope should be carefully selected considering the potential implications of not
including product stages or phases in the scope of the work. For example, a product
may have lower production emissions but has a shorter lifetime than an alternative
product that would not be considered if a cradle-to-gate boundary was selected. The
scope of the study is often best communicated in a process stage diagram as seen in
Figures 5.2 and 5.3. These types of diagrams list the major unit steps that are considered
within a study and clearly show what is not included in the study.
System Boundary
Biomass Production
T
T
Daystar et al. (2014)
Note: T represents transportation
Direct land
use change
IPCC
Fuel
production
Aspen model
Fuel use
GREET
Chemicals, fuel, and energy production
Ecoinvent database and GREET
Forest
management
Carbon
absorption
Indirect land
use change
Harvest and
Processing
Figure 5.2System boundary diagram of a cradle-to-grave bio-fuels process but excludes indirect
land-use change.
Fertilizer
Herbicide
Diesel
CO 2
Fertilizer
Herbicide
Diesel Diesel Diesel
Processing
Biomass production
Biorefinery
gate
Plantation
establishment Maintenance Harvesting Transportation
Figure 5.3System boundary diagram of a cradle-to-gate biomass production system excluding
processing.
