Knowledge from slide shows Flashcards
Name commercial LCA software
openLCA (used in course). GaBi (first widely used, released 1987), SimaPro (also widely used, released 1990).
Lecture 1
What limitations are there to an LCA
- Not including “risk assessment” - LCA only takes environmental concerns into account
- LCA makes generalisations, for example LCA usually does not include “special care for sensitive biotopes” / local ecosystems
- LCA can be challenging, includes difficult decisions
- Many assumptions that can be required to fulfil an LCA is not necessarily applicable to every similar case
Lecture 1
What Strengths are there to an LCA
- LCA applies a life cycle perspective, but it can do more than that:
- LCA provides a holistic perspective for entire systems and their interactions between systems
- LCA is necessary when evaluating new technologies and combinations of these (without LCA, we have no chance to know if the new technologies are a benefit for the environment, or opposite) because:
- LCA identifies “burden shifts” (and these can be prevented)
- LCA is comprehensive: Covers a broad range of environmental impacts (however, not all, and not all to the same “coverage”)
- LCA leads to new insights
- LCA is for decision making.
- LCA is a tool for assessing consequences of decisions for the future
- LCA is quantitative the impact is scaleable when related to the reference unit
- LCA is science-based (but can be challenging to construct and validate using suitable sources)
Lecture 2
What are a qualitative/ semi-quantitative overview and MECO pre-assessment matrix when relating to LCA?
qualitative/ semi-quantitative overview is used to identify and describe which processes are included in the lifespan of a product. It is often viewed in a table where the stages are divided as; Material production, Manufacturing, Use and Disposal. Additionally the table should list all sources relating to the information.
MECO pre-assessment matrix, is a thinking exercise to begin estimating where the highest environmental impact can be found. The matrix is devised by stage and consumption unit.
Stages; Material Production, Product Manufacture, Use & maintenance, Disposal and Total transport
Consumption unit; Material (M), Energy (E), Chemicals (C) and Other (O)
Lecture 3
What important elements are required to include in a Scope definition for an LCA
- Define a functional unit, i.e. a quantification of the primary service provided by the product/system
- Define the reference flows of the system, i.e. the physical flows of product(s) required to deliver the functional unit
- Create a model of the system, i.e. define the nature and volume of processes being part of the system
- Delimit the system, i.e. cut of processes that are insignificant
- Define/identify the spatial and temporal boundaries of the system
- Define the technological level of processes in the system
- Identify the need for a critical review of the study
Lecture 3
What important questions are required to answer in a goal definition for an LCA
- Why is the study made, what is the context?
- Who is the customer and audience of the study?
- Which decisions are to be supported by the LCA?
- Which product/system is studied?
- Which alternative products/systems are studied and compared?
Lecture 3
What is defined as a Foreground/Background system for an LCA?
Foreground system: the specific system studied
Typically the system part on which you have (mainly) primary data
- Also defined as the systems of which the user of the LCA has control to change
Background system: the background technosphere in which the foreground system exist - Typically the system parts on which you mainly have secondary data
- Also defined as the systems of which the user of the LCA has no control to change e.g. impacts of a marked supplied material, here the user can not influence on the impacts related to the upstream processes (material extraction and material production methods)
Lecture 4
What are multifunctional processes / secondary services?
Multifunctional processes are processes that have multiple functions and not all are directly related to the processing of the materials/energy for the functional unit. Examples below: Processes: - The chlor-alkali process - Oil refining - Co-generation of heat and power
Material and energy recovery:
- Use of recovered materials
- Heat and electricity recovery in waste incineration
- Material recovery and recycling
Secondary services are all the flows that come as a result of the process chain for the functional unit, e.g for producing a plastic cup polyethene is required, this comes from a multifunctional oil refining process, where secondary services like Raw oil, gasoline and other Olefins are produced. In consequential LCAs these are accounted as avoided productions where their impact is then reducing the total impact.
Lecture 4
What is The Attributional LCA?
The attributional LCA looks at one product in isolation and strives to isolate the primary service from the secondary services arising in the system in order to identify the environmental impacts from the system which can be attributed to the primary service
- by some means of allocating environmental inputs and outputs to and from joint processes to the products arising from these processes
Lecture 5
What is Marginal supply?
Simply the response to a marginal change in demand on the market in question
Related facts:
- The supply responding to an increase in demand is the most competitive of the non-constrained supplies which are outside the market, but able to enter the market by production increase
- The supply responding to a decrease in demand is the least competitive of the suppliers on the market which have, thus, to decrease the supply to the market
Lecture 5
How do you ensure system equivalence and consequential modelling?
- Ensure system equivalence of primary services by defining a functional unit and normalizing all comared systems to this
- Ensure system equivalence of secondary services through eliminating them by subtracting avoided alternative supplies of the same services
- Make sure to include only marginal supplies ≡ supplies that respond to the studied change in demand
Lecture 9
What are elementary flows when it comes to inventory analysis?
Definition of emission/elementary flows of e.g. chemical compounds:
An emission is occurring when fx. a chemical compound crosses the technosphere - ecosphere boundary
Emission routes:
- Emission to air
- Emission to water
- Emission to soil
Lecture 13
What is the intent behind doing an LCIA?
The aim: Translate (i.e. characterize) LCI results, i.e. elementary flows or interventions that cross the border between the technosphere and the ecosphere (i.e. elementary flows), into potential impacts on:
- Human health
- Ecosystems (function and structure)
- Resource depletion (addressed in a coming lecture)
Please note that we are talking about potential impacts, not actual/real impacts as in environmental risk assessment – we aggregate over time and space
LCIA always relevant
- Even for a LCI data set - as completeness and precision has to be judged on its LCIA results
- For comparative studies it is mandatory
Lecture 13
Where do we find the most modelling uncertainty and interpretation uncertainty in an LCA?
The highest modelling uncertainty lies in the endpoint calculations, this is because many sub calculations have been performed to reach this point. These calculations are done using weighting factors which can widely vary for each method and does not necessarily represent the truth. Different endpoint methods can be the ReCiPe I, H or E - they each have a different perspective based on different temporal scales, 20, 100 and 1000 years respectively.
But the further the data is processed the lesser the interpretation uncertainty, as the data is presented in a more relatable context. When only looking at midpoint results it can be difficult to interpret how the result relates to potential damages as only the quantity of elementary impact is illustrated.
Lecture 16
What steps are there to construct an LCIA?
Classification: Assignment of emissions to impact categories according to their potential effects
“What does this emission contribute to?”
Characterisation: Quantification of contributions to the different impact categories
“How much does it contribute?”
Normalisation: Expression of the impact potentials relative to a reference situation
“Is that much?”
Valuation: Ranking, grouping or assignment of weights to the different impact potentials
“Is it important?”
