A complete guide to sustainable fuels

Transport is under pressure to decarbonise. For fleets, logistics operators, infrastructure businesses and public sector organisations, the question of how to decarbonise is pressing.

Sustainable fuels are playing a central role in that transition. They offer immediate carbon reduction, compatibility with existing vehicles, and scalable deployment whilst waiting for full electrification.

This guide explains what sustainable fuels are in 2026, why they matter, how they work, and how organisations can use them to reduce emissions today.

What are sustainable fuels?

Sustainable fuels are designed to reduce greenhouse gas emissions compared to conventional fossil fuels. They are typically produced from renewable, recycled or low-carbon sources and are intended to support decarbonisation across transport, industry and infrastructure.

The most common types of sustainable fuels in 2026 are:

●      Biofuels such as biodiesel and bioethanol

●      Hydrotreated Vegetable Oil (HVO)

●      Renewable petrol and diesel blends

●      Synthetic fuels (e-fuels)

●      Hydrogen in specific applications

For most UK fleet and commercial operators, sustainable fuels mean low-carbon liquid fuels that can be used in existing diesel engines, providing an immediate and practical way to reduce emissions swiftly.

Why sustainable fuels matter for transport

Transport remains one of the largest sources of carbon emissions in the UK. While electrification is accelerating in passenger vehicles, it is a different story for heavy-duty fleets, construction plants, logistics and long-distance transport because they still rely heavily on liquid fuels.

Alternative renewable fuels are key for transport decarbonisation because they:

●      Deliver immediate lifecycle carbon reductions

●      Require little or no vehicle replacement

●      Support net-zero goals

●      Reduce dependence on fossil diesel

●      Help organisations meet Scope 1 emissions targets

For many businesses, they provide the opportunity to lower emissions whilst operating within the diesel infrastructure which already exists.

Types of sustainable fuels

Sustainable fuels include several technologies, each suited to different applications and stages of decarbonisation.

Biodiesel (FAME)

Biodiesel, also known as FAME (Fatty Acid Methyl Ester), is produced from renewable feedstocks and can be blended with mineral diesel in varying proportions.

Common fuel blends include B10, B20 and B30, which refer to the blend proportion, with B30 being the lowest proportion of diesel, and therefore the least emissions-heavy. This blend offers greater carbon reduction while maintaining broad compatibility with commercial engines when approved by manufacturers.

Argent’s high-blend solution, Dieselite (B10 – B30), is designed for fleets seeking meaningful emissions reduction without switching fuel infrastructure, at a cost similar to standard road diesel.

Hydrotreated Vegetable Oil (HVO)

HVO is a diesel alternative product that can be manufacturerd using first or second-generation feedstocks. Whilst similar to fossil diesel and can be used as a direct replacement in modern diesel engines, there are key differences to take into account, such as density and lubricity.

HVO provides significant carbon savings, strong performance even in cold weather, and the ability to store it for a long time without losing stability.

It is widely used by fleets seeking a fuel alternative that requires minimal operational adjustment.

For a deeper comparison of HVO and biodiesel, see our dedicated HVO vs Biodiesel guide.

Bioethanol & renewable petrol blends

Bioethanol is commonly blended into petrol in the UK, such as E10. It is more relevant to petrol-powered vehicles and light transport, rather than heavy-duty diesel fleets.

While important in passenger car decarbonisation, it plays a smaller role in commercial diesel operations.

E-Fuels (Synthetic fuels)

E-fuels are synthetic fuels created using renewable electricity, low carbon hydrogen and captured carbon dioxide. They are designed to replicate fossil fuels while reducing lifecycle emissions.

At present, e-fuels are emerging technologies, and their real-world use is limited at present due to feedstock availability and economics. Over time, they may support sectors that are difficult to electrify.

Hydrogen & other alternatives

Hydrogen is often discussed alongside sustainable fuels, particularly for heavy goods vehicles and industrial use. However, infrastructure, storage and cost challenges mean it is still developing at scale.

For most UK fleet operators today, sustainable liquid fuels remain the most practical near-term solution.

How sustainable fuels reduce carbon emissions

Sustainable fuels reduce carbon emissions primarily through lifecycle savings.

Unlike fossil fuels, which release carbon stored underground, biofuels and renewable fuels are derived from materials that are part of the current carbon cycle. Many are produced from waste or by-products, reducing overall environmental impact.

Carbon reduction depends on the following factors:

●      Feedstock source

●      Production process

●      Transport and distribution

●      Blend percentage

In regulated markets such as the UK, sustainable fuels must align with frameworks such as the Renewable Transport Fuel Obligation (RTFO) and the International Sustainability & Carbon Certification (ISCC), which ensures traceability and verified carbon savings.

For organisations reporting under ESG or Scope 1 frameworks, sustainable fuels provide measurable emissions reductions without changing infrastructure, such as needing to replace vehicles or engines.

Sustainable fuels vs electrification

Electrification will become a key part of transport decarbonisation, but it is not widespread yet because the electric transport infrastructure currently available is more suited to passenger vehicles and shorter, predictable travel.

At the moment, electrification is less suited to heavy goods vehicles, construction and off-road transport, long-haul journeys, and remote or infrastructure-based operations. 

Liquid fuels, therefore, remain operationally critical for those wanting to reduce emissions today from existing vehicles. Sustainable fuels and electrification are actually complementary solutions because many organisations adopt a mixed strategy, which involves electrifying when it is possible to do so, and using sustainable fuels where the existing infrastructure needs to remain in place.

Are sustainable fuels compatible with existing vehicles?

Many sustainable fuels are designed as ‘drop-in’ replacements for standard diesel for large fleets of heavy-duty vehicles. This means the fuel can be used by existing engines and refuelling infrastructure with no modification. Therefore, emissions reductions are immediate because vehicles and infrastructure can remain the same.

This is not always the case, but in general:

●      Biodiesel blends up to B20 are compatible with most diesel engines, and cost comparable to the price of standard road diesel

●      Higher blends may require OEM approval

●      HVO can often be used as a direct replacement in many modern engines

●      Infrastructure requirements are minimal compared to hydrogen or electric charging networks

Before transitioning, operators should confirm manufacturer guidance and fuel specifications.

Argent supplies fuels produced to recognised standards such as EN14214 for biodiesel components, helping ensure quality and consistency. With full compliance with UK and EU fuel specifications, every batch is subject to rigorous quality assurance before loading and dispatch.

Cost considerations and ROI

Cost is still a barrier for some fleet operators in switching to sustainable fuels, as many options can carry a price premium compared to conventional diesel. However, this isn’t the full picture. Some lower-carbon fuels, such as higher-blend biodiesel, can be cost comparable to standard road diesel. When reviewing sustainable fuels and cost considerations, the total cost should take into account:

●      Operational savings: Clean‑burning fuels can cut maintenance and improve uptime.

●      Revenue uplift: Meeting customer or tender ESG criteria can win contracts.

●      Keeping existing infrastructure: Avoided capital expenditure on new vehicles and reduced infrastructure investment

●      Brand and reputation: Investment in ESG positions an organisation as innovative and conscious, potentially resulting in revenue benefits.

For many organisations, sustainable fuels offer a lower-barrier entry point into decarbonisation compared to wholesale fleet replacement.

Sustainability and fuel certification

Not all fuels marketed as “green” deliver the same environmental benefit. Certification and compliance are critical. Sustainable fuels have to meet both regulatory sustainability rules and independent certification standards that prove emissions savings, traceability, and ethical sourcing.

In the UK, sustainable fuels typically align with:

●      Renewable Transport Fuel Obligation (RTFO): to earn RTFCs, fuels must meet RTFO sustainability criteria and prove at least 65% lifecycle GHG savings in many cases.

●      Traceable, waste-derived feedstocks: Feedstocks must meet strict sustainability criteria under UK regulation, including traceability. They must not be sourced from land with high biodiversity or high carbon stock (such as primary forest or peatland), and must avoid significant land-use change.

●      Verified greenhouse gas savings: Fuels must deliver a minimum lifecycle GHG reduction versus the fossil comparator.

●      European fuel quality standards: These set minimum environmental and performance standards for petrol, diesel and blends such as EN14214 (for biodiesel components)

Working with a trusted supplier helps ensure that sustainability claims are robust, auditable and suitable for reporting.

How to transition to sustainable fuels

Transitioning to sustainable fuels can be swift, but still requires a process of assessment, trailing and implementation. A typical pathway includes:

1. Assessing fleet composition, infrastructure and fuel usage
2. Identifying suitable fuel blends or alternatives
3. Reviewing manufacturer guidance
4. Trialling fuel in controlled conditions
5. Scaling deployment across operations

Many organisations begin with lower blends such as B10 before progressing to higher blends such as B20 and beyond, or exploring renewable diesel alternatives. Working with a specialist supplier ensures technical guidance, supply reliability and alignment with sustainability goals.

The future of sustainable fuels

Looking ahead, sustainable fuels are expected to remain a core component of UK transport decarbonisation. Sustainable fuels are expected to move from niche to mainstream in hard‑to‑electrify sectors, especially in aviation, shipping and heavy freight, where direct electrification is harder. While hydrogen will also expand, heavy-duty transport and industrial sectors will continue to require high-energy-density liquid fuels.

Innovation is expected to accelerate in:

●      Advanced biofuels

●      Synthetic fuels

●      Feedstock optimisation

●      Carbon accounting and traceability

For the foreseeable future, sustainable fuels offer one of the fastest and most practical routes to measurable emissions reduction.

Taking the next step

If your organisation is reviewing its decarbonisation strategy, take a look at:

●     Our Sustainability approach

●      The difference between HVO and Biodiesel

●  Dieselite (B10 – B30) high-blend biodiesel

Reducing transport emissions does not have to mean waiting for new infrastructure. With the right fuel strategy, meaningful carbon savings can begin today. Speak to our team.

Frequently Asked Questions