Biodiesel should, on paper, be one of the easiest wins in the UK’s decarbonisation toolkit. It is a drop-in renewable fuel that can be blended with or substituted for fossil diesel in existing engines, requiring no costly fleet replacement or new refuelling infrastructure. It reduces lifecycle carbon emissions by up to 85% compared with fossil diesel, supports waste valorisation through the use of feedstocks such as used cooking oil and tallow, and contributes to energy security by diversifying domestic fuel supply. Yet investment in UK biodiesel production and distribution infrastructure has slowed markedly in recent years, and the principal reason is not technological but political.
The UK Government’s evolving timelines for phasing out the sale of new diesel vehicles have introduced a level of uncertainty that makes long-term capital allocation to biodiesel exceptionally difficult. For investors, lenders, and project developers alike, the question is no longer whether biodiesel works, but whether the market it serves will exist long enough to justify the investment. This article unpacks that tension and examines what it means for the future of biodiesel infrastructure in the UK.
The UK’s Shifting Diesel Phase-Out Landscape
From 2030 Ambitions to Policy Reversals
The trajectory of UK diesel phase-out policy has been anything but linear. In November 2020, the Government announced that the sale of new petrol and diesel cars and vans would be banned from 2030, with hybrids permitted until 2035. The commitment was bold and was widely interpreted as a clear signal that the internal combustion engine was on a defined path to obsolescence. Industry responded accordingly: automotive manufacturers accelerated electric vehicle programmes, and downstream fuel sectors began reassessing their long-term strategies.
Then, in September 2023, Prime Minister Rishi Sunak pushed the ban on new purely petrol and diesel vehicles back to 2035, citing concerns about the cost burden on consumers and the readiness of charging infrastructure. The reversal sent shockwaves through the energy and automotive sectors, not because 2035 was an unreasonable date in isolation, but because it demonstrated that the timeline was politically negotiable. When the Labour government took office in 2024, it reinstated the 2030 target for the ban on new purely petrol and diesel cars, while maintaining 2035 for vans and further clarifying exemptions. Each policy shift, regardless of its direction, has compounded uncertainty and made it harder for investors to model long-term demand with confidence.
Where Biodiesel Sits in the Regulatory Framework
It is important to recognise that biodiesel policy operates in a related but distinct regulatory space. The Renewable Transport Fuel Obligation (RTFO) requires suppliers of transport fuel to ensure that a specified percentage of the fuel they supply comes from renewable sources. Biodiesel is one of the primary compliance routes under this obligation, and the RTFO has been the single most important policy driver for the UK biodiesel market.
However, the RTFO’s effectiveness as an investment signal is undermined when the broader policy environment suggests that the vehicles consuming those fuels will be progressively eliminated. Investors do not evaluate biodiesel projects in a regulatory vacuum; they assess them against the backdrop of the entire transport decarbonisation strategy, including vehicle sales bans, zero-emission vehicle mandates, and emissions trading developments. When that overarching strategy appears unstable, confidence erodes across the board, even in policy mechanisms like the RTFO that have themselves remained relatively consistent.
The Investment Horizon Problem
Mismatched Timelines Between Infrastructure and Policy
The core difficulty facing biodiesel infrastructure investment is a fundamental mismatch between the payback periods that capital-intensive projects require and the shrinking demand horizon implied by diesel phase-out targets. A new biodiesel production facility or a significant upgrade to an existing one typically requires capital expenditure measured in tens of millions of pounds. Payback periods of 15 to 25 years are standard for projects of this nature, depending on scale, feedstock arrangements, and offtake agreements.
Set against this, even the more generous 2035 phase-out date for new diesel vehicle sales implies a progressively declining addressable market from the mid-2030s onward, as the existing diesel fleet ages and shrinks through natural attrition. For a project reaching financial close in 2025, the commercial window may already feel uncomfortably tight. This does not mean the economics are unworkable today, but it does mean that every year of policy delay or reversal compresses the investment case further and raises the required rate of return to levels that many projects cannot sustain.
The “Stranded Asset” Fear
Closely related to the timeline mismatch is the growing anxiety around stranded assets. The concept, familiar from broader fossil fuel divestment debates, refers to infrastructure that becomes economically unviable before it has recovered its capital costs. In the context of biodiesel, the fear is concrete rather than theoretical: a plant commissioned in 2026 and designed for a 20-year operating life could find itself serving a market that has contracted dramatically by the time it enters its second decade of operation. Lenders and equity investors are acutely sensitive to this risk, and it is increasingly shaping the terms on which capital is made available, if it is made available at all.
This anxiety is not limited to new builds. Existing operators are deferring maintenance capital expenditure and postponing efficiency upgrades precisely because the long-term demand outlook does not justify the spend. Some smaller producers have already exited the market entirely. The result is a gradual erosion of the UK’s installed biodiesel capacity, a trend that is difficult to reverse once skilled workforces disperse, supply chain relationships lapse, and planning permissions expire or become contested.
Compounding Factors Beyond the Phase-Out Date
Feedstock Competition and Supply Chain Pressures
Demand-side uncertainty would be challenging enough in isolation, but biodiesel investors must also contend with growing pressures on the supply side. Used cooking oil (UCO), tallow, and other waste fats that form the backbone of UK biodiesel feedstock supply are increasingly contested resources. The emerging sustainable aviation fuel (SAF) sector, buoyed by strong policy mandates of its own, competes for many of the same feedstocks, often at prices that biodiesel margins cannot match. Post-Brexit trade dynamics have further complicated UCO imports, adding logistical cost and regulatory friction to supply chains that were previously more fluid. The net effect is a tightening feedstock market that squeezes margins precisely when demand certainty is most needed to justify continued operation.
The Electric Vehicle Transition’s Uneven Pace
Compounding the picture is the fact that the electric vehicle transition is not proceeding evenly across all transport segments. While passenger car electrification has gained meaningful momentum, aided by falling battery costs and expanding charging networks, segments such as heavy goods vehicles, agricultural machinery, construction plant, and rural transport remain far from viable electrification. Battery weight, range limitations, charging infrastructure gaps, duty cycle demands, and the sheer capital cost of fleet replacement mean that diesel will remain the dominant fuel in these sectors for years, potentially decades, beyond the headline phase-out dates for passenger cars.
This creates a paradox for biodiesel. The near-term case for the fuel is arguably stronger than ever in hard-to-electrify sectors, yet the long-term investment case remains clouded by policy signals calibrated primarily around passenger vehicles. The resulting limbo is itself one of the most significant barriers to decisive capital commitment.
Navigating the Uncertainty: What Needs to Change
The Case for Technology-Neutral Decarbonisation Policy
If the UK is serious about maximising the contribution of all available decarbonisation tools, a shift toward technology-neutral policy frameworks would go a long way toward restoring investor confidence in biodiesel. Rather than prescribing the retirement of specific powertrain technologies by fixed dates, such frameworks reward measurable carbon reduction outcomes regardless of how those outcomes are achieved. Several European markets, notably Germany and Sweden, have adopted greenhouse gas reduction mandates for transport fuel suppliers that are agnostic as to whether the carbon saving comes from electrification, biofuels, or hydrogen. A comparable approach in the UK would allow biodiesel to compete on its merits and would give investors a policy signal anchored in outcomes rather than technology bets.
Strategic Roles for Biodiesel in Hard-to-Electrify Sectors
Beyond broader policy reform, there is an urgent need for the Government to explicitly acknowledge and codify the strategic role of biodiesel in sectors where electrification is impractical. Heavy goods transport, off-road machinery, marine, and certain rail applications are all areas where biodiesel or its advanced derivatives, such as hydrotreated vegetable oil (HVO), can deliver substantial emissions reductions today without waiting for technologies that remain at an early stage of commercialisation. Sector-specific mandates or ringfenced RTFO obligations for these applications would create pockets of durable demand that are insulated from the passenger vehicle phase-out timeline, providing investors with the visibility they need to commit capital.
Conclusion
The uncertainty weighing on UK biodiesel infrastructure investment is not a reflection of any deficiency in the fuel itself. Biodiesel remains a proven, scalable, and cost-effective decarbonisation tool with an established supply chain and a ready market. The challenge is almost entirely one of policy design: phase-out timelines that have shifted repeatedly, a regulatory framework that inadvertently penalises transitional fuels, and a failure to distinguish between sectors where electrification is imminent and those where it remains distant.
The risk of inaction is significant. If the UK allows its domestic biodiesel production capacity to wither through investment starvation, it will find itself more reliant on imported fuels at precisely the moment when energy security and domestic supply chain resilience matter most. A more nuanced, outcome-oriented policy approach could unlock substantial private investment and ensure that biodiesel plays the bridging role it is uniquely positioned to fill. The question is whether policymakers will recognise this before the window of opportunity narrows further.…
