Life Cycle Assessment (LCA)
LCAs are a tool to evaluate the environmental performance of a product or service.
Standards available: ISO 14040, 14044.
LCAs quantity the environment impacts of a product/service over its full life cycle: material extraction/processing, production, packaging/distribution, use/end-of-life.
This can be quantified through many different indicators: carbon emissions, embodied energy, acidification, ecological footprint, water use, carcinogens etc.
Raw materials/resources converted to either energy or materials. Either way, emissions arise, going to air, water and ground.
‘Classic’ LCA questions:
- Drinking containers: glass bottles vs PET bottles vs aluminium cans
- Nappies: disposable or cotton
- Cars: EVs vs ICE
- Solar panels: does the embodied energy in a solar panel ever pay for itself
Why bother doing LCAs:
- As a design tool: project environmental impacts as you design a product
- Strategic planning: incorporate into product development to see if you are moving towards strategic goals
- Public policy development: government can use these assessments to determine which technologies it should subsidize
- Marketing: promote ‘green’ credentials
Doing an LCA (ISO 14040)
Goal and
scope ----> Interpretation
definition <----
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| v
Inventory ----> Interpretation
deployment <----
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Impact ----> Interpretation
assessment <----
Goal and Scope Definition
Frame the study:
- Key methodological decisions
- What will be included/excluded from the study?
- Reasons for the study
- What is the study about?
- Why are you doing it?
- What will you do with the results?
- Who is the audience? Internal? External? Marketing?
Functional unit:
- Quantification of the primary function of the product or system
- Allows fair comparisons between systems
- e.g. soft-drink packaging
- Main objective: to contain a liquid
- Functional unit: delivering 1L (or a serving) of liquid to a consumer
- e.g. cars
- Main objective: Transport of people
- Functional unit: distance travelled times number of people
- e.g. solar panels
- Main objective: generation of power
- Functional unit: KWh of power generated
System boundary:
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Determining what processes will be included/excluded?
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Attempt to cover at least 95% of environmental impacts associated with the product life cycle
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Hard to know what you are missing; that’s part of the reason you are doing the study
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Typically excludes:
- Capital equipment/maintenance (depending on how much product goes through the machine)
- Human labour (e.g. workers eating) (unless it is very labour-intensive work)
- Accidents
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e.g.
┌── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ──┐ Aluminium Aluminium Transport │ sheet ─────► can ───► to │ production production filler │ ▲ │ │ │ │ │ │ ▼ │ Primary Transport │ aluminium to │ ▲ consumer │ │ │ │ Functional Alumina ▼ unit: delivery │ production Refrigeration ───────┼─► of 1L of a soft ▲ ┌───►of packaging drink to a │ │ ▼ │ │ consumer Bauxite aluminum ▼ │ production recycling landfill │ ▲ ▲ ▲ │ │ │ │ │ Bauxite waste transport │ mining │ electricity water │ (shared processes) System boundary │ └── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ── ──┘
What environmental indicators will you use?
- Should be relevant to the study
- Don’t ignore known issues
- Look at what indicators have been used in similar studies
- Indicators:
- Climate change potential
- Called potential since we are modelling reality, not reality itself
- Emissions of CO_2, CH_4, N_2O, SF_6, CFCs etc.
- Often measured in kilograms of CO_2 equivalent
- Carbon accounting methods (e.g. time horizons) may affect results
- Photochemical oxidation (smog)
- Air emissions of SO_x, NO_x, CO, etc.
- Degradation of volatile organic compounds in the presence of light and NO_x
- Measured in photochomical ozone creation potential (POCP) - kilograms of ethylene equivalents
- Acidification
- Air, soil and water emissions of SO_x, NO_x, HF, etc.
- Release of acids or acid-forming compounds in terrestrial/aquatic systems
- Measured in acidification potential - kilograms of S0_2 equivalents
- Eutrophication/Nutrification
- Air, soil and water emissions of NO_x, PO_x, etc.
- Too many nutrients (nitrogen, phosphorous) and not enough oxygen that leads to algal blooms
- Measured in eutrophication potential - kilograms of PO_4^{3-} equivalents
- Land use
- Sum of land occupied over the life cycle
- Ha/a: occupation over time
- A poor proxy for land use impacts
- Often coupled with soil, water use
- Water use
- Sum of water inputs over life cycle
- Measured in kilo litres of water
- Impact varies with location (e.g. west coast of NZ vs Australian deserts)
- New methods developed to account of water scarcity
- Minerals/fossil fuel depletion
- Measure of pressure/strain on resource use
- Different extraction measures additional energy/resources
- Human toxicity
- Disability Adjusted Life Years (DALY)
- Plus a lot, lot, more
- Climate change potential
Identify data requirements:
- High quality data is essential
- Foreground data
- Data from the original manufacturer (e.g. mass of packaging, energy inputs for a process, emissions)
- Background data
- Data supplied by LCA practitioner (e.g. electricity generation, transport, production of common materials)
- LCA databases available
Inventory Deployment
Document the inventory: report should be transparent and be specific enough that a reader can generate the same results.
LCA practitioner:
- Couple foreground/background data
- Run a preliminary assessment
- Look for gaps/errors
LCA commissioner:
- Often likes to view inventory
- Provide more data to fill in gaps
Impact Assessments
Must characterize the impacts.
May:
- Normalize the impacts relative to a known baseline
- Use weightings to reduce the data to a single or a few numbers
Interpretation
Iterate back to other steps:
- Identify reasons for your results
- 5 whys: you should be able to ask ‘why’ for any question and the answers to those questions five questions
- Check assumptions, data quality, methods
Sensitivity studies: determine effect of key assumptions on your outcomes.
Uncertainty studies: find the effects of data uncertainty on outcomes (Monte Carlo simulations).
Basic LCA
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is the emissions from the emissions source in kg of CO_2 equivalents -
is activity data: quantity of material used -
is emission factor for the emissions source
Process:
- Set the functional unit and system boundary
- Collect data
- Inventory of Carbon and Energy
- Basic emission factors for material production
- NB: shaping processes (e.g. injection moulding plastic) may not be included
- Ministry for the Environment Carbon Accounting Guide
- Emission factors for electricity/fuel use/transport
- Inventory of Carbon and Energy
- Use the above equation, sum results
- Produce a report
Consequential LCAs
Attributional/normal-process LCAs uses historical data, assuming that environmental impact increases linearly with demand.
Consequential LCAs models the consequences from a change in demand and consider displacement effects in the economy.
If in a supply-constrained market, increased demand result in higher prices. Hence, some projects/people will no longer be able to afford that thing and must choose a cheaper alternative which may have different environmental impacts.
e.g. if UC switches the boiler from coal to wood pellets, this increased wood pellet demand may hike prices, forcing someone living in Christchurch to switch to gas for heating their homes.
e.g. in UK, if beef demand increases too much, the additional beef is often imported from Brazil where there can sometimes be deforestation to provide grassland to feed the cows.
Note that increased demand may also lead to a less-than-linear increase in environmental impacts.
Sustainability outcomes are very much inter-twined with the economy.
Case Study: PHEV vs ICE in Australia
Functional unit: 1km of driving.
System includes:
- Mining/processing, fossil fuel extraction
- Transformation of materials into vehicle components, assembly
- Replacement parts, electricity generation/supply, local and international petrol production and supply
- Replacement tyres, fluids
- Disposal
But excludes human labour, road infrastructure (even though PHEV is heavier and hence may wear the road more), overheads and other services.
Needed model of PHEV charging patterns (probability of car charging at a given hour of a day) for households and fleet vehicles. Large spike at 11 pm when electricity got cheaper. Could infer charge duration from average daily use and supported charging speed etc.
Needed data on electricity grid - mix of electricity sources and hence environmental impact changes depending on time as peak load power plants turn on. Need to model how energy generated from different electricity sources would be impacted by increasing energy demand (dependent on the time of day).
Greenhouse gas emissions known for each electricity source, so can model greenhouse gas emissions per unit electricity for a given time of day and hence, emissions be kilometer travelled.
Notes:
- Did not model other impacts e.g. resource depletion
- Use phase modelling critical for electric products
- User behavior profile also very important
- Large-scale EV take-up will require changes to electricity infrastructure
Toy study - Hydrogen Fuel Cells
- Find greenhouse gas impacts for hydrogen production from different sources
- Hydrogen from natural gas currently the cheapest
- Compression and distribution of hydrogen requires lots of energy; this must be modelled as well
- No hydrogen infrastructure available
- Would there be sufficient production capacity if everyone switched?
- Would this decrease petrol prices? If so, would petrol usage actually decrease?
- On-site/local hydrogen production may lead to different conclusions
Case Study: Bio Jet Fuel
- Wheat farm
- After harvesting, sheep eat down the stubble
- belts of shrubby Malle eucalypts planted years ago in hopes of suppressing salt water from sea
- Not useful any more
- Cut them down: strip out leaves etc., convert to biomass, do magic to convert to jet fuel
- ~7 years to reach maturity
- Deep root networks: carbon sequestration
- Functional unit: average A330 flight Perth -> Sydney
- System boundary
- Lots of processing steps, some co-products (e.g. acetic acid)
- Sheep farming included:
- Trees absorb a lot of water/nutrients etc. so less wheat per hectare near the shrub belts
- Hence less food and less sheep per hectare
- But there is growing demand for red meat, so sheep must be displaced to somewhere else
- So consequences of displaced sheep must be modelled
- If all commercial operations were to switch, a lot of land clearing would be required
Ended up being environmentally positive but financially unviable.
Related conclusions:
- Never assume switching to a rewnewable energy system will be better for the environment
- Focus on reducing demand
- Systems thinking: look for second- and third- order effects
Corporate Greenhouse Gas Reporting
NZ Emissions Trading Scheme:
- compulsory reporting for many industries including forestry, agriculture, industrial processes
- Government-regulated methods
Corporate reporting:
- Voluntary
- Usually uses government-defined emission factors
Different standards available; ISO14064 is the main one, but there are also free standards, the Greenhouse Gas Protocol corporate accounting and reporting standard being one of the more well-known ones.
Three scopes:
- Scope 1: direct emissions from the activities the company is responsible for (e.g. emissions from corporate cars being driven)
- Scope 2: emissions associated with electricity usage
- scope 3: consequences of organizational activity (optional)
- Someone elses scope 1/2
- Employee taking a flight
- Outsourced activities
Ministry for the Environment has guide available: plug in yearly organizational fuel use, out pops scope 1 and 2 emissions. Misses some materials/systems though.
Case study:
- RMIT (Melbourne University)
- Scope 1 (fuel use): 4%
- Scope 2 (Electricity): 39% (Victoria uses dirty brown coal for electricity)
- Scope 3: 57%
- Staff superannuation fund: could not divest from dirty companies
- Student travel: train/tram use
- Food
Spheres of influence and control:
- What can I control now?
- Electricity choice
- Waste management
- Carbon offsets
- ~$25/tonne
- Beware of ‘junk’ carbon offsets
- Paying farmers not to cut down trees - turned out they had no right to cut them down anyway
- Wind farms built but not connected to the power grid
- What can I control in the future?
- Procurements, maintenance contracts
- Require sustainability credentials
- Mandated superannuation
- Procurements, maintenance contracts
- What can I influence?
- Pressure on superannuation provider to provide sustainable funds
- Student commuting choices