HVO and Carbon: How Renewable Diesel Reduces Emissions Across Every Scope
A practical guide to what changes - and what doesn't - when you switch from fossil diesel to HVO.
Switching to HVO renewable diesel cuts emissions, but the question fleet managers, sustainability managers, and NGER auditors most often ask is: which emissions, measured how, and under which framework? The answer depends on where in the fuel's lifecycle you look. Here is a clear breakdown across every relevant scope.
Data note: Combustion emission factors cited in this article are drawn from the National Greenhouse Accounts (NGA) Factors 2025, published by the Australian Government. Additional lifecycle and pollutant reduction figures are sourced from peer-reviewed industry research and OEM technical documentation.
The Three Lenses: Scope 1, Scope 3, and Lifecycle
Greenhouse gas emissions from fuel are typically measured at three points. Each tells a different part of the story and each matters for a different reporting or decision-making context.
Direct / Tailpipe Emissions
What comes out of the exhaust when the fuel is burned. This is what you report under NGER as direct emissions.
Indirect / Production Emissions
Emissions from producing, refining, and transporting the fuel before it reaches your tank - the upstream footprint.
Well-to-Wheel
The complete picture - from feedstock collection through to final combustion. The most comprehensive measure of a fuel's true climate impact.
Full Lifecycle (Well-to-Wheel): Up to 90% Reduction
The headline figure for HVO is its full lifecycle greenhouse gas reduction of up to 90% compared to conventional fossil diesel. This is the measure most commonly cited by OEMs, sustainability teams, and government policy documents - and it is the most meaningful single number for organisations setting net-zero targets or reporting against science-based pathways.
This reduction is primarily driven by the feedstock. Fossil diesel draws carbon from ancient reserves, adding net-new CO₂ to the atmosphere. HVO is made from waste materials, used cooking oils, animal fats, agricultural residues, whose carbon was recently part of the natural cycle. Processing and transport emissions are also significantly lower than the equivalent upstream chain for crude oil refining.
Scope 1 Direct Combustion Emissions: Zero CO₂ Under the NGA
When HVO burns, it does produce CO₂ just like fossil diesel. So how can its Scope 1 CO₂ factor be zero?
The answer lies in where that carbon came from. Fossil diesel releases carbon that has been locked underground for millions of years - it is a net addition to the atmosphere. HVO's carbon was absorbed from the atmosphere by living organisms in the recent past. When it is released on combustion, it simply returns carbon that was recently part of the natural cycle. This is what the NGA calls biogenic carbon, and under the NGA 2025, the Scope 1 CO₂ combustion factor for HVO (paraffinic diesel) is zero.
For organisations reporting under the National Greenhouse and Energy Reporting (NGER) scheme, this is significant: switching to HVO eliminates your direct combustion CO₂ from day one - without carbon offsets, fleet replacement, or infrastructure changes.
HVO does carry trace combustion emissions of methane (CH4) and nitrous oxide (N2O) - approximately 0.01 kg CO2-e per litre in total. These are the same minor non-CO2 combustion emissions present in biodiesel, and they are reported under the NGA. The CO2 component, however, remains zero.
Scope 1 Beyond CO₂: NOx and Particulate Matter
Scope 1 emissions are not limited to greenhouse gases. HVO also delivers meaningful reductions in two other exhaust pollutants that carry significant health and regulatory implications:
Reductions in particulate matter (PM) are consistently observed across engine types, primarily due to HVO's zero aromatic content and high cetane number. Studies report reductions ranging from 30-65% in typical fleet conditions, with manufacturer testing of Renewable Diesel and HVO reporting up to 85% in controlled conditions [2]. Cummins' own testing of the QSK95 generator set recorded 30-60% PM reduction [3]. These reductions are particularly significant for enclosed and underground environments (mining operations, tunnels, and data centre generators) where diesel particulate exposure carries serious health risks under tightening workplace exposure limits.
NOx reductions are more variable and depend heavily on engine technology, injection calibration, and load conditions. The ISO20400 report cites reductions of 19-30% for standard HVO [2]; a peer-reviewed urban fleet study found a 7% local reduction potential for modern Euro 4-6 passenger vehicles [4]; and engine optimisation studies show up to 18% NOx reduction when injection systems are recalibrated for HVO [5]. Operators with older non-aftertreatment engines will typically see the greatest NOx benefit.
Scope 3: Production and Indirect Emissions
The production of HVO, encompassing feedstock collection, processing, refining, and transport to point of use, carries a materially lower carbon footprint than the equivalent upstream chain for fossil diesel. The use of waste feedstocks means there is no energy-intensive primary extraction phase, and the hydrotreatment process is increasingly powered by renewable energy at leading refineries.
For NGER reporters, Scope 3 emissions sit outside the direct reporting boundary but are increasingly relevant to corporate sustainability disclosures, supply chain emissions targets, and investor-facing climate reporting. Organisations committed to full value-chain decarbonisation will find HVO's upstream footprint significantly cleaner than fossil diesel's - contributing to the overall 90% lifecycle reduction figure.
For NGER reporting, use the Scope 1 NGA factor - zero CO2 combustion emissions for HVO. For sustainability disclosures, net-zero strategy, or science-based targets, the full lifecycle figure (up to 90% reduction) provides the most complete picture of HVO's climate benefit. Both figures are legitimate; the right one depends on the reporting framework you are working within.
Summary: Changes When You Switch to HVO
Total GHG reduction vs fossil diesel across the full fuel chain. [1]
Biogenic carbon - not counted as a net atmospheric addition under the NGA. [1]
Typical fleet reductions of 30-65%; up to 85% in controlled manufacturer testing. [2] [3]
Varies by engine type and calibration. Greatest benefit in older non-aftertreatment engines. [2] [4]
HVO is a direct drop-in replacement. No modifications, no blending limits, no disruption.
Scope 1 CO2 is zero under the NGA - no offsets needed to eliminate direct combustion emissions.
Sources:
Disclaimer: This article is intended as a general information resource only. Lifecycle reduction figures and pollutant reduction percentages (NOx, PM) are drawn from the sources listed above and may vary depending on feedstock, production pathway, engine type, load conditions, and whether after treatment systems are fitted. This content does not constitute legal, regulatory, or technical advice. Organisations should verify applicable figures with their fuel supplier and relevant reporting authority.