Strategic Revamps Can Offer a Cost-Efficient Fast Track to Renewable Fuel Production

April 28, 2026

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by Ole Frej Alkilde and Lars Jørgensen (Topsoe/Biofuels Digest) Growth in renewable fuels is offering refineries and new entrant producers opportunities with significant potential. Incentivization, mandates and regulations, from the EU’s ReFuelEU Aviation regulations to the US Renewable Fuel Standard developments, are creating an expanding market – and early movers can take full advantage.

But the clock is already ticking when it comes to renewable diesel and sustainable aviation fuel first mover advantages. Building greenfield capacity answers part of this challenge, but for existing refineries, converting what already exists toward renewables offers a fast-turnaround, and lower CAPEX option.

Hydroprocessing units designed for fossil fuel treatment can produce renewable diesel and SAF with modifications. The principle is the same. Hydrogen treatment under pressure and temperature over catalyst beds. The chemistry shifts, however, meaning oxygen-rich feedstocks like vegetable oils and animal fats demand different catalyst loadings, material selection or metallurgy upgrade and heat integration to petroleum fractions. These differences are manageable through revamp engineering that preserves the core asset while adapting it to new molecules.

And the good news? Revamps are commercially proven for defined feedstock windows and hydrogen availability, provided front-end studies are done rigorously. Twenty years of commercial operation have demonstrated this approach delivers reliable renewable fuel production. The question refiners now face is less about technical feasibility and more about implementation strategy.

Understanding the spectrum from co-processing to full revamp

The conversion of existing hydroprocessing units to renewable service spans a wide spectrum of intervention levels, each with distinct technical and commercial implications.

Low-level co-processing (typically 5–10%) represents the lightest-touch entry point. At these levels, well-pretreated renewable feedstocks can often be introduced with limited changes to hardware.

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As renewable content increases beyond 10–20%, constraints become more pronounced. Hydrogen consumption rises, heat release profiles change, and corrosion risks increase due to halogens and higher water partial pressure. At this scale, revamps typically require targeted metallurgy upgrades, revised heat integration, hydrogen system debottlenecking and, in some cases, pretreatment enhancements.

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Full renewable conversion (up to 100%) represents the most extensive revamp scope. Units are operated exclusively in renewable service, often with dedicated feedstock logistics and product handling. While this maximizes renewable fuel output, most designs intentionally retain the ability to revert to fossil operation ...

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How can refinery revamps deliver fast renewable fuel market entry?

A grassroots renewable diesel or SAF facility typically requires 24 to 36 months from final investment decision to first production.

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Staged implementation manages capital and risk

Few refineries operate with unlimited capital budgets or the ability to shoulder extended downtime. Revamp projects can come in phases that work within these constraints.

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This gradual approach gives refineries operational flexibility that can be significant strategically. If feedstock costs spike or policy support weakens, the unit can revert to fossil processing. When conditions improve, renewable production resumes.

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Technical challenges have known solutions

The most significant technical challenge in converting fossil hydroprocessing units to renewable service is hydrogen availability. Deoxygenation reactions consume five to ten times more hydrogen than conventional hydrotreating. Units operating near hydrogen balance in fossil mode are therefore frequently hydrogen-limited when processing renewable feeds. In many revamp projects, hydrogen compression or supply capacity becomes the single largest capital item and ultimately sets the maximum achievable throughput.

Reactor volume and configuration present another common constraint.

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Heat management also changes materially.

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Corrosion management deserves particular attention. Vegetable oils and animal fats contain chlorides, fluorides and other halogens that accelerate metal degradation in certain temperature and pressure regimes. Water and CO/CO2 production from oxygen removal creates additional corrosion pathways.

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None of these challenges represents a fundamental barrier. They require systematic engineering evaluation and targeted capital investment.

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The study phase determines project success

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Refineries should see the study as a strategic planning exercise rather than a box to tick off. They ideally should involve operations personnel who understand current unit performance and limitations, commercial teams who can validate feedstock supply and product offtake, and corporate development to ensure the revamp aligns with broader decarbonization commitments and capital allocation priorities.

Hydrocracking units offer particular advantages

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Importantly, hydrocrackers also typically include fractionation sections that enable direct SAF production rather than just renewable diesel.

A US refinery converted a mild hydrocracking unit directly into combined SAF and renewable diesel production.

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Planning for emerging feedstocks

Fats, oils and greases represent first-generation renewable feedstocks with established processing routes. The next wave involves more challenging molecules. Plastic pyrolysis oils, woody biomass liquids and other bio-crudes require more severe hydrotreatment and pose distinct corrosion and catalyst challenges. These materials contain higher heteroatom concentrations and more complex aromatic structures.

Refineries planning revamps today should consider future feedstock flexibility in their design basis.

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Moving from evaluation to execution

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Most fundamentally, they recognize that their existing asset base represents an advantage rather than a liability. Converting proven equipment to new service delivers faster, cheaper and often more flexible outcomes than greenfield construction.

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10-step refinery checklist before undertaking a renewable revamp

1. Business and strategic framing
• What is the target product slate (renewable diesel vs SAF vs both)?
• Is speed to market or long-term flexibility the primary objective?
• What is the opportunity cost of repurposing this unit from fossil service?

2. Feedstock definition and security
• Which feedstocks will be processed (UCO, animal fats, bio-crudes)?
• Are supply volumes contractually secured at assumed prices?
• What are the contaminant levels (chlorides, phosphorus, metals, acidity)?
• Is additional pretreatment required to protect the hydroprocessing unit?

3. Hydrogen system assessment
• Current hydrogen balance and margin
• Compressor capacity and limitations
• Hydrogen purity requirements
• Options for debottlenecking (recovery, new compression, SMR expansion)

4. Unit hardware and metallurgy
• Reactor volume and internals suitability
• Materials of construction in corrosion-prone areas
• Heat exchanger network and furnace capacity
• Separator and cold-end system robustness

5. Heat release and operability
• Exothermicity management at higher renewable ratios
• Temperature control strategies
• Water handling and separation capacity

6. Catalyst and cycle strategy
• Renewable-specific catalyst selection
• Loading patterns for staged revamps
• Expected cycle length and regeneration strategy

7. Integration and logistics
• Feedstock storage and handling requirements
• Product segregation and blending
• SAF logistics and airport pipeline access where relevant

8. Regulation and certification
• Sustainability certification (e.g. ISCC, RSB)
• GHG accounting methodology
• Eligibility for regional mandates and incentives

9. Phasing and execution
• Can the project be staged to manage capital and risk?
• Alignment with turnaround schedules
• Operator training and startup planning

10. Organizational readiness
• Involvement of operations, engineering and commercial teams
• Clear ownership of feedstock procurement and product offtake READ MORE