‘Low carbon’ is a claim about a fuel’s whole life, not just its exhaust. Behind that claim sit agreed definitions of what counts, methods for measuring emissions across the full life cycle, and rules set by governments, certification schemes and markets.
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One journey from claim to proof
Sustainability is defined and measured, and every claim is then proven along the supply chain. The highlighted steps are the ones covered on this page.
This page
Define
How sustainability is defined, and who sets the rules.
This page
Measure
How life-cycle emissions are measured and assessed.
Prove
How each claim is proven along the supply chain.
What ‘low carbon’ means
A low carbon liquid fuel produces lower greenhouse gas emissions than the fossil fuel it replaces, measured across its full life cycle . That means everything counts: growing or collecting the feedstock, making the fuel, moving it, and using it.
Two fuels can be used in much the same way and still have very different carbon footprints. The difference is everything that happens before the fuel reaches the engine.
The key idea
Low carbon is a comparison, not a guarantee. It describes emissions. On its own it does not tell you how the feedstock was grown, who grew it, or what happened to the land and water it came from. Those questions are covered by sustainability criteria, set separately by certification schemes and fuel frameworks.
What sustainability covers
Different schemes and markets define sustainability in different ways . Most cover four broad areas.
4
Resource use and circularity
Making productive use of wastes, residues and co-products, and using energy efficiently.
In practice: Australian research finds more than half of crop residues can be harvested for fuel while keeping the soil benefits of stubble retention . See Food, fuel and fibre.
How emissions are measured
Life-cycle assessment (LCA) is the method used to add up a fuel’s emissions from feedstock production through to end use. It lets different fuels be compared on the same basis , and it shows whether a fuel meets the minimum emissions reduction a scheme requires .
System boundary: everything inside is counted
Feedstock
Growing or collecting the material: farm inputs and land effects counted.
Processing
Converting the material into fuel: process energy counted.
Transport
Moving feedstock and fuel between each step.
Combustion
Burning the fuel: the final emissions in the journey.
Co-products such as canola meal and glycerine leave the boundary here and carry their share of emissions out of the total.
= Life-cycle emissions: the total a low carbon claim is judged on, compared with the fossil fuel it replaces
Three rules every scheme sets
Every scheme decides where the counting starts and stops, how shared emissions are split, and how much saving a fuel must show.
What life-cycle assessment does not cover
Biodiversity, working conditions and water stress sit outside a greenhouse gas calculation. Land-use change is handled differently by different schemes. CORSIA adds a land-use change value to the total . Other rules manage it by restricting which feedstocks qualify . This is why emissions measurement is used alongside sustainability criteria and independent audits, not instead of them .
Who sets the rules, and what each kind of rule does
Several different kinds of rules lay out how a fuel can be claimed as low carbon, and they do different jobs.
A · Emissions accounting
Measures and records how much greenhouse gas is produced in making a product. It does not judge anything else about the fuel.
B · Sustainability certification
Independent certification bodies audit producers against broader criteria covering land, water, biodiversity, labour and communities, laid out in certification schemes.
C · Market rules
Government rules that decide which fuels count towards a target or an obligation, and what a fuel must achieve to qualify.
Framework
Set by
What it does
Where it applies
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Resources
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