What HVO is
HVO, hydrotreated vegetable oil, is a biofuel used in place of diesel or gas oil (red diesel) in vehicles, plant and generators. In the government conversion factors it is listed as "Biodiesel HVO" on the Bioenergy sheet, with its own factors.
Why the Scope 1 factor is so low
Burning HVO still releases CO2 from the exhaust. The difference is where it is reported. The carbon in HVO came from plants, so it is biogenic. The GHG Protocol says CO2 from burning biomass "shall not be included in scope 1 but reported separately", and the government's direct factors for biofuels "are only made up of CH4 and N2O emissions". So:
| Per litre, 2026 | Scope 1, kg CO2e | Well-to-tank (Scope 3), kg CO2e | Together |
|---|---|---|---|
| Gas oil (red diesel) | 2.75541 | 0.62665 | 3.38206 |
| Diesel (forecourt, average biofuel blend) | 2.58354 | 0.61101 | 3.19455 |
| HVO | 0.03558 | 0.56439 | 0.59997 |
The CO2 from the exhaust is reported as a third, separate figure from the government's "Outside of scopes" sheet. For HVO, almost all of the reported emissions sit in the supply chain: the Scope 3 well-to-tank factor is many times the Scope 1 figure.
A worked example
A contractor's plant and generators use 20,000 litres of gas oil a year, and it switches to HVO:
| Scope 1, tCO2e | Well-to-tank, tCO2e | |
|---|---|---|
| Gas oil | 55.11 | 12.53 |
| HVO | 0.71 | 11.29 |
Scope 1 falls by about 99%, from 55.11 to 0.71 tonnes. Counting well-to-tank as well, the fall is about 82%, from 67.64 to 12.00 tonnes. Both are real changes under the reporting rules, so show both, plus the biogenic CO2 noted separately. The example assumes the same litres before and after; use the litres you actually bought.
The well-to-tank figure moves a lot
The HVO supply chain factor depends on what the fuel was made from. The government bases it on UK averages from the Renewable Transport Fuel Obligation statistics, and its methodology paper warns these are "likely to be highly variable year on year" as suppliers change their feedstocks:
| Factor set | HVO Scope 1, kg per litre | HVO well-to-tank, kg per litre |
|---|---|---|
| 2021 | 0.03558 | 0.2132 |
| 2022 | 0.03558 | 0.35178 |
| 2023 | 0.03558 | 0.27844 |
| 2024 | 0.03558 | 0.559 |
| 2025 | 0.03558 | 0.56439 |
| 2026 | 0.03558 | 0.56439 |
The well-to-tank factor in the 2026 set is 165% higher than in 2021, while Scope 1 hasn't changed. The methodology paper recommends more specific figures where available, because emissions "vary significantly depending on the feedstock source and production pathway". Ask your supplier what your HVO was made from and for its carbon intensity, and keep the answer with your records.
Before you switch
- Check with the maker of each vehicle, machine or generator that it is approved to run on HVO.
- Ask the supplier for the feedstock and carbon intensity of the fuel, so you can show where it came from.
- Record HVO separately from diesel in your fuel data, so each gets its own factor.
- In your Carbon Reduction Plan, describe it as a fuel switch and keep reporting the Scope 3 and biogenic figures.
Our carbon reporting for construction page covers the rest of a site's fuel and plant emissions.
How Carbon Recycling helps
Add HVO with the "Any DESNZ factor" option: search for "HVO" and Carbon Recycling applies the government's Biodiesel HVO factor for your reporting year as Scope 1, and you can add the well-to-tank factor the same way as a Scope 3 entry. Keep gas oil and forecourt diesel on their usual entries, so your report shows both fuels and the drop in Scope 1 is visible year on year. Use the entry's note for the supplier's feedstock details and the biogenic CO2 from the government's "Outside of scopes" sheet.