Life Cycle Analysis Flashcards
Important in LCA
stay critical how you interpret outcomes of LCA.
Typical LCA discussion
Plastic vs. paper
re-usable vs. recyclable
LCA differences are based on
- assumptions used
- method of research
the need for a lot of data and assumptions makes the outcome of an LCA not good or wrong. Different people can get different answers trough the methodology
End result of LCA
one indicator
Area’s of protection
- Human health
- Natural environment
- Man-made environment
Area’s of protection lead to
indicators. You determine which areas are important and how much so.
Area’s are influenced by
impacts.
Impacts in LCA
all the different effects a product has.
- GHG emissions
- Resource depletion
- Eco toxicity
- Land use
- Noise
- Pollution
The impacts in LCA
all have to be weighed individually to determine it’s importance
Applications of LCA
comparing products or alternatives
What is the importance of LCA
- Provide guidance in strategic planning (trends in material use)
- Provide guidance in product improvement
- Product marketing
- Provide input in public policy making. (procurement decisions)
LCA in regulations
Eco-design directive. Only appliances with a certain score in LCA can be sold on the European market
4 phases of LCA
1) boundary definition
2) Life cycle inventory
3) Life cycle impact assessment
4) interpretation/improvement
Setting your boundaries
is quite complex and will largely influence the outcome
Setting boundaries is complex
because all parts of the production chain influence your product. Do you want to keep it with materials used only in your manufacturing, or do you want to include all the relevant steps taken in creating the material you use
Decisions made in the design and development phase
have a large contribution to the environmental impacts of the product. There are few emissions in the design/development phase itself, but do determine what materials to use, and how many emissions it might have during the use phase.
Defining an LCA project
- Set objective
- Define the product
- Set boundaries
Under defining the product
defining the functional unit falls
what is the functional unit
the unit you will use which makes comparing your product(s) easy and fair.
-As one plastic bag not necessarily holds the same volume of groceries as a paper bag, the proper functional unit is likely
the volume of groceries carried and not the bag itself
comparing power production options, the functional unit often chosen
is the amount of CO2 (eq) per unit of net kwh of energy produced
Life cycle inventory
- part of the material flow analysis
- makes inventory of raw material and enery consumption, and emissions of wastses.
LCI
life cycle inventory
uncertainties in LCI
- assumptions made regarding system boundaries
- use of regional or global data
- poor quality of data
- unavailable data
The outcome of LCA
is never precise. It is always a range.
Various lyfe cycle indicators pointing at energy or CO2 emissions
- Carbon footprint
- CO2 pay back time
- Energy pay back ratio
- Energy pay back time
Carbon footprint
gr CO2 eq / unit output or product
CO2 pay back time
life cycle CO2 emissions divided by annual avoided CO2 emissions
Energy pay back ratio
Energy out / Energy in
Energy in could be only embodied energy
Life cycle GHG emissions and GHG target setting
- GHG targets are often based on GHG reduction potential analysis
- GHG targets are never life cycle emissions, only direct ghg emission reduction
3 scopes of life cycle inventory GHG emissions
1) Direct emissions (Production and transportation)
2) Indirect emissions (Pruchased electricity)
3) Indirect emissions upstream and downstream (e.g. transportation and distribution, employee communication, product use, end of lifetime)
What is LCA
a tool for assesing and minimizing the impacts of human activity
LCA is used by
Industry, public sector and research institutes to serve a variety of purposes
According to the IPCC, in 2050
20% of electricity can come from wind
Wind power might be clean, but
the effects of building wind parks should be considered as well.
Attributional LCI
the physical flows relevant to environmental impact in and out the life cycle system boundaries.
Consequential LCI
generate information about consequences of actions made by describing how the physical flows relevant to environmental impact will change with certain changes in the life cycle.
Process-chain analysis (PCA)
the actual physcal flow of energy and mass
input-output (I/O) analysis
economic data to estimate the resource use in different ports of the economy
Most often used form of LCA (for windturbines in paper Davidsson et al.)
PCA
Why are LCA’s difficult to compare
the different methodologies can use different unit which makes the outcomes of the LCA incomparable. For example, using the same definition for primary energy in the one, but not the other.
Large differences in …. between … and …
O&M energy use between I/O analysis and PCA.
Either I/O overestimated it, or PCA underestimated it.
Comparing wind turbine LCA’s
should take capacity into account
The capacity factor of a wind turbine
is often overstated by the manufacturer (based on perfect test conditions)
The performance of the turbine will be determined by the location is is placed.
EPBT
Energy pay back time
= amount of tie it takes to “pay back” the energy used of the life cycle
EROI
Energy return on investment
= cumulative electricity generated , divided by cumulative primary energy required.
Energy performance is uscually expressed in
(P) EPBT or (P)EROI
With (P) standing for Primary
Material use in LCA
- Some don’t include it since they don’t look at non-energy resources
- Some studies only look at the bulk, not at the small parts
- Only refined materials are used in the studies
Why should wind turbine LCA’s include small material parts
For the permanent magnets in wind turbines rare earth metal are needed. The mining of these metals can have big environmental impacts including radioactive releases. Therefore this small part that only is a small percentage of materials used in the turbine, can have a big environmental impact which should be included.
Recycling can decrease environmental impact of a wind turbine
over 40%
Recycling in wind turbine LCA’s
A recycling rate of 90% is assumed.
It is unsure if and how much will actually be recycled.
Furthermore, the materials are ‘stuck’ in the turbines during their lifetime.
Why might they decide not to recycle wind turbines
costs for dismantling and recycling might be too high. Especially for off shore wind parks the dismantling costs may outweigh the recycling savings.
Main point on LCA’s (in article)
transparency on assumptions and methods should be increased so results can be checked and compared.
Energy use accounting in LCA
- Often poorly described
- How and should electricity be converted to primary energy
- Electricity mix (and their different, often poor, descriptions) make accounting and comparing more difficult
CO2 intensity of electricity production
since electricity is often a mix, this intensity already accounts for the primary consumption and therefore gives the emissions per produced unit of electricity
