Goal & Scope + Inventory Flashcards
What must the goal define?
- Intended applications of the results
- Decision context and reasons for carrying out the study
- Target audience
What must the scope define?
- Function, functional unit, reference flow
- Initial choices (system boundaries and data quality)
- Needs for critical review
What is the definition of a reference flow?
Amount of products necessary to fulfill the amount of function
specified by the functional unit
“What must be purchased in order to fulfill the function?”
What is the definition of key parameters?
Necessary values to relate the reference flows to the functional
unit
Ex: product life, number of uses, amount of energy used
What is the definition of economic/intermediary flow?
Linking 2 unit processes. One (or more) represents the function of the unit process. Human intervention.
What is the definition of an environmental/elementary flow?
Linking the unit process with the environment. Environmental intervention.
What is the definition of a cradle-to-gate study?
LCA comparing different manufacturing processes for the same product. The product being unchanged, the use and end-of-life stages are the same and can be excluded.
What is the definition of a gate-to-grave study?
LCA on municipal waste management. The stages before the end
of life are the same and can be excluded.
What is the techno sphere?
The techno sphere can be understood as everything that is intentionally “man made” and also includes processes that are natural in origin, but manipulated by humans.
Economic flows stay within the techno sphere
What is the ecosphere?
The ecosphere is “the environment” or “nature”, and can be understood as everything which is not intentionally “man-made”
Elementary flows go across the boundary between the ecosphere and techno sphere
Why are human activities associated with production unit processes excluded?
Many of these activities would occur even if there was no production, they would occur elsewhere (for other process).
Ex. water use and wastewater, energy use, commuting
Why are data requirements relevant?
To be able to evaluate the validity of the results and fulfill the goal of the study.
They should also take into account quantitative and qualitative aspects of the data and collection methods (i.e., data quality, source, type, nature, aggregation level)
What are the important aspects of data quality?
Temporal coverage Geographical coverage Technological coverage Precision Completeness
Define a primary data source
Primary data is specifically collected to do the LCA and directly concerns the studied product.
Define a secondary data source
Secondary data is not specifically collected to do the LCA (ex. data from literature on a process)
What approaches are used to handle multifunctional processes?
- Division approach
- Expansion approach
- Allocation by physical relationship
- Allocation by other relationship
If allocation can be avoided, multifunctional processes should be analyzed in which ways?
- Division approach: the multifunctional process is divided into sub-processes and the input/output is collected related to each sub processes
- Expansion approach: the product system boundaries are expanded to include the additional functions related to the coproducts
If allocation can’t be avoided, multifunctional processes should be analyzed in which ways?
Allocation approach: the inputs/outputs of a system should be partitioned between its coproducts or functions in a way that reflects the underlying physical relationships (or other relationships) between them
What are the challenges of the expansion approach?
- The equivalence between the coproduct of the multifunctional process and the product of the avoided system is not always exact
- The identification of the unit processes making up the avoided autonomous system is not always easy
- These processes themselves can be multifunctional
What are examples of relationships by which the allocations approach allocates its inputs/output?
Physical properties: mass, volume, surface, energy content, elemental composition, product units
Economic value + more
What are the two visions in LCA
Attributional
Consequential
Describe attributional system modelling
System modelling approach in which inputs/outputs are attributed to the functional unit of a product system by linking and/or partitioning the unit processes of the system according to a normative rule.
Attributional LCA seeks to cut out the piece with the dotted lines that belongs to a specific human activity
What are the environmental impacts related to the allocated shares of the activities that have contributed to the production, consumption, and disposal of the product?
Describe consequential system modelling
System modelling approach in which activities are linked so that they are included in the product system to the extent that they are expected to change as a consequence of a change in demand for the functional unit.
Consequential LCA seeks to capture the change in environmental exchanges that occur as a consequence of adding or removing a specific human activity
What are the environmental impacts related to the full share of those activities that are expected to change when producing, consuming, and disposing of the product?
Define the Life Cycle Inventory (LCI)
LCI relates all inputs and outputs of all process to the functional unit and aggregates them
What are the steps to prepare for data collection?
- Identification of processes for which data will be collected
- Specification of data documentation (format, requirements)
- Instructions for data collection
- Identification of data sources
What are types of data sources (i.e., where can data be obtained) ?
Real processes
Models of estimations
Inventory databases or literature
Internal databases/reports
How is data validated?
- Verify if data meets the quality requirements
- Perform mass/energy balances for primary data
- Perform comparative analysis with other data
- Missing data treatment
What are the two types of databases?
Disaggregated/connected (data available for each unit process, links are explicit, inventory must be recalculated each time)
Aggregated (data available at the product system level only, black boxes, represent the cradle to gate inventory)
In what ways are disaggregated databases advantageous?
- Possibility to adapt datasets
- Validity
- Contribution analysis
- Possibility to create distributed datasets
In what ways are aggregated databases advantageous?
- User friendliness
In what situations is the infrastructure a greater contributor than the process?
Wind and hydro electricity
