Tools for Energy and Material Analysis (GEO4-2326)
Lecture 8: Life Cycle Analysis (LCA)
Summary Article 11: Attributional and Consequential Life Cycle Assessment
- Ekvall (2019)
Summary Article 12: A review of life cycle assessments on wind energy systems
- Davidsson, S. & Höök, M. & Wall, G. (2012)
Life cycle analysis (LCA)
Life-cycle indicators with energy relevance
Carbon foot printing
Recycling indicators
1. Life cycle analysis (LCA)
2. Purpose, application, and scope
3. Two types of LCA: attributional and consequential
4. Four steps in life cycle analysis
Typical LCA question: which of the alternatives is the better one?
• Returnable/reusable glass bottles versus throw-away recyclable glass bottles
• The coffee mug versus the throw away cup (being plastic or paper based)
• Electric cars versus diesel/petrol cars
• Dish washer versus hand washing
Applications of LCA
General: to compare products/alternatives
Examples of LCA applications
1. Provide guidance in product improvement (environmental impact)
2. Product marketing
3. Used in public policy making (public procurement, eco-design regulation)
4. Awareness campaigns (NGOs)
Caution: outcomes LCA very sensitive to assumptions
2 types of LCA
Change-oriented versus accounting
• Attributional (accounting): which part of the life cycle of a product contributes how much to its
environmental impact? > descriptive, level 0, retrospective
• Comparing product/technology A to B without significant system impacts or allocation problems
o Based on average impacts
+ Straightforward
+ Easy to communicate
- Not applicable for large scale implementation of technology
o What are the environmental impacts of cooking with natural gas?
• Consequential (change-oriented): considers wider system impacts > level 1, prospective
• Allocation problems (more than one output, alternative use) and wider system impacts (fuel mix power
generation, learning effects by large scale application)
o Based on incremental or marginal impacts or on modelling approaches
+ More accurate
- More uncertain
o What are the environmental impacts of changing from gas heating to electric heating in the
Netherlands?
1
, ➢ Question: comparing electric excavators to diesel excavators?
o Answer: attributional
➢ Question: large scale replacing coal-fired power plants by wind turbines?
o Answer: consequential
➢ Question: comparing a new CHP plant to a new power only plant?
o Answer: consequential
Life cycle impact categories
- GHG emissions / climate change
- Resource depletion
- Stratospheric ozone depletion
- Acidification (NOx, SO2, NH3)
- Eutrophication (excess nutrients)
Area of protection
- Photochemical smog Categories weighted based
- Human health
- Human toxicity on importance
- Natural environment
- Eco toxicity
- Natural resources One indicator = result of LCA
- Human health
- Man-made environment
- Land use
- Noise
- Accidents
- Ionizing radiation
- Etc.
Four steps in LCA
1. Boundary definition
2. Life cycle inventory
3. Life cycle impact assessment
4. Interpretation / improvement
Step 1: Goal and scope definition
• Set objectives: why is the
analysis conducted?
• Define the product under
study and its alternatives:
what is the function of the
product and what is a proper
functional unit?
• Choose system boundaries:
which inputs and outputs will
be studied? How to collect the required data?
➢ Question: what is a good functional unit which allows to compare the life-cycle performance of a plastic
versus a paper grocery bag?
o Answer: as one plastic bag not necessarily holds the same volume (or weight) of groceries as a
paper bag, the proper functional unit could be either the volume of groceries carried, or the
weight of groceries carried BUT NOT the bag itself (two plastic bag could for example be the right
comparison base for one paper bag or vice vera)
2
,Power generation technologies
For comparing the life-cycle performance of electricity
generation options, the functional unit often chosen is
the amount of power produced (kWh)
➢ Question: what would be an appropriate functional unit when comparing the life-cycle performance of
LEDs and halogen lamps?
o Answer: In the proper comparison you need to include:
1. The light intensity required (lux = lumen/m2)
2. The lifetime of the lamp
Light intensity of 50 lux for 10.000 hours (the lamp itself is not a proper functional unit, since
one LED could replace multiple halogen lamps
Step 2: life cycle inventory (LCI)
Inventory of
• Raw material inputs and energy consumption
• Emissions of solid, liquid, and gaseous waste
Material flow
• Inputs
• Outputs and waste
• Material Flow Analysis (MFA)
Primary material
inputs (tonne)
Material outputs and
waste (incineration,
reprocessing, reuse)
Recycled material
inputs (tonne)
Uncertainties in LCI
1. Choice of system boundaries: the narrower → feasibility improves but uncertainty increases
2. Data issues: data may be available, be even location specific, is of high-quality, but unfortunately too old
• Availability of data
• Use of regional-specific or average global data
• Quality of data
• Shelf-life of data
3
, Databases and software
• Literature
• LCI databases: Ecoinvent
• LCA software: SimaPro, OpenLCA, Ecochain
Step 3: life cycle impact assessment
Analysis of LCI outputs to determine impacts
• Characterisation factors
o Climate change: Global Warming Potential for GHGs (CO2, CH4, N2O, SF6 etc.) → CO2 equivalent
o Acidification: Acidification Potential (SO2, NOx, NHx emissions) → SO2 equivalent
o Health: years of life lost (YYL)
o Water: water consumption (m3)
o Land: Land use (ha)
• Outcomes
o Per functional unit: CO2eq emissions, SO2eq emissions, water consumption, ha etc.
o Weighting of categories: one indicator
Step 4: interpretation
• Weighting and combing individual impact in an overall assessment
• This step may include also other considerations such as social, economic, and political aspects
o Safety and security issues of nuclear (very difficult to tackle by an LCA alone)
o Child labour (covered by social LCA)
Wrap up LCA
1. Attributional or consequential?
o Attributional more straightforward to communicate but also not accurate for large scale
implementation of technology
o Consequential in principle more accurate, but results can be also more uncertain
2. Suitable functional unit is important (considering for example lifetime and functionality)
3. Bigger scope is more accurate but less feasible
4. Subjectivity in outcomes: key assumptions should be communicated and impact weighting of categories
Life cycle indicators with energy relevance
1. Embodied energy or embodied CO2 emissions
2. (P)EBT: (Primary) energy payback time
3. (ERoI): Energy Return on Investment
4. CO2PBT: CO2 payback time
1. Embodied energy or embodied CO2 emissions
- D = detached
- SD = semi-detached
- ET = end-of-terrace
- MT = mid-terrace
- A = apartment
- st = standard
- ret = retrofit
- anew = advance new
- aret = advance retrofit
4
