The global petroleum refining industry stands at a historic crossroads. For over a century, crude oil has been the dominant feedstock for producing transportation fuels, lubricants, and petrochemical building blocks. Today, driven by tightening environmental regulations, corporate net-zero commitments, and growing societal pressure to decarbonize, refiners are actively exploring and integrating renewable feedstocks into their operations. This transition is not merely an incremental improvement but a fundamental rethinking of what a refinery can be: a flexible processing hub capable of converting both fossil and renewable carbon sources into cleaner products. While challenges remain significant, the momentum behind renewable feedstocks in petroleum refining is building, pointing toward a future where the refinery plays a central role in the circular carbon economy.

The Shift Toward Renewable Feedstocks: Drivers and Motivations

The push for renewable feedstocks in refining is propelled by multiple converging forces. Policy frameworks are a primary driver: the European Union's Renewable Energy Directive (RED II), the US Renewable Fuel Standard (RFS), and California's Low Carbon Fuel Standard (LCFS) all create economic incentives for lower-carbon fuels. Carbon pricing mechanisms and emissions trading systems further tilt the economics in favor of renewable alternatives. Beyond regulation, investor pressure and consumer demand for sustainable products are reshaping corporate strategies. Major oil companies such as BP, Shell, and TotalEnergies have announced ambitious targets to expand renewable fuel production from waste oils, animal fats, and biomass. In addition, the aviation sector's commitment to sustainable aviation fuel (SAF) provides a powerful demand pull for hydroprocessed esters and fatty acids (HEFA) and other renewable pathways. The convergence of these drivers is accelerating research and deployment, making renewable feedstocks not just an experimental niche but a strategic priority for the refining industry.

Key Renewable Feedstock Types

Renewable feedstocks encompass a diverse range of organic materials that can be converted into fuels, chemicals, and bioproducts. Understanding their characteristics is critical for refineries selecting the most viable and scalable options for co-processing or dedicated units.

Waste Oils and Fats

Used cooking oil (UCO), animal fats (tallow, yellow grease), and inedible corn oil are among the most commercially advanced feedstocks. They are rich in triglycerides and free fatty acids, making them suitable for hydroprocessing to produce renewable diesel and SAF. The supply, however, is limited by collection infrastructure and competition from other uses such as oleochemicals. Prices are volatile and sensitive to global biodiesel mandates.

Vegetable Oils

Palm oil, soybean oil, canola oil, and rapeseed oil are fully proven feedstocks but raise concerns about land-use change, deforestation, and competition with food supply. The industry is moving away from virgin food-grade oils toward lower‑impact sources like waste and residues. Nonetheless, some regions continue to rely on virgin oil where waste supplies are insufficient.

Lignocellulosic Biomass

Woody residues, agricultural waste (corn stover, wheat straw), and energy crops (miscanthus, switchgrass) provide a more abundant and non‑food competing resource. They require conversion via gasification or pyrolysis to produce bio-intermediates such as syngas or bio‑oil, which can then be upgraded in a refinery. The technology readiness level for cellulosic feedstocks is lower than for fats and oils, but significant progress is being made in commercial-scale plants.

Algae

Microalgae and macroalgae offer the potential for high oil yields per acre without competing for agricultural land. Despite decades of research, the cost of cultivation, harvesting, and oil extraction remains prohibitive for large-scale fuel production. Algae are more likely to enter higher-value markets (nutraceuticals, cosmetics) before scaling into commodity fuels, but breakthroughs in genetic engineering and photobioreactor design could eventually change the cost curve.

Waste Plastics (Chemical Recycling)

While distinct from biomass-based feedstocks, end-of-life plastics represent a growing source of renewable or circular feedstocks. Pyrolysis and depolymerization convert mixed plastic waste into liquid hydrocarbon fractions (naphtha, waxes, oils) that can be fed into a steam cracker or hydrocracker to produce olefins and new plastics. This aligns with the concept of a circular economy and reduces fossil feedstock demand.

Technologies Enabling Integration into Refineries

Refiners are deploying a suite of technologies to handle renewable feedstocks, either by co-processing them alongside crude oil fractions in existing units or by building dedicated plants. The choice depends on feedstock type, desired product slate, and infrastructure compatibility.

Hydroprocessing (HEFA Route)

Hydroprocessing is the most commercially mature and widely adopted technology for renewable feedstocks. In this process, triglycerides and free fatty acids from oils and fats are reacted with hydrogen at high temperatures and pressures over specialized catalysts. The reaction removes oxygen in the form of water (hydrodeoxygenation) and carbon dioxide (decarboxylation), producing straight‑chain paraffins. These n-paraffins are then isomerized and cracked to produce renewable diesel, jet fuel, and naphtha. Neste, a global leader, has been producing renewable diesel from waste oils for over a decade using its NEXBTL technology. Co‑processing with petroleum fractions in existing hydrotreaters is also possible, though catalyst deactivation and hydrogen consumption require careful management.

Pyrolysis and Upgrading

Fast pyrolysis thermally decomposes lignocellulosic biomass in the absence of oxygen to produce bio‑oil, biochar, and non‑condensable gases. Raw bio‑oil is acidic, oxygen-rich, and unstable, requiring hydrodeoxygenation to be compatible with refinery units. The resulting upgraded bio‑oil can be fed alongside crude oil into an FCC unit or a hydrocracker. Several demonstration and commercial plants, including those by Ensyn and Honeywell UOP, are producing cellulosic renewable diesel via this route. The challenge is the high cost of upgrading due to hydrogen demand and catalyst fouling from oxygenates and minerals.

Gasification and Fischer-Tropsch Synthesis

Gasification converts any carbonaceous feedstock into syngas (CO + H₂), which can be cleaned and catalytically converted into hydrocarbon liquids via Fischer-Tropsch (FT) synthesis. The technology is well established for coal and natural gas (GTL), and is being demonstrated with biomass and waste. The products (naphtha, diesel, waxes) are virtually identical to petroleum-derived equivalents. Velocys is a notable developer of small-scale gasification-to-liquids plants. Capital intensity and scale are major barriers, but the fuel is considered a “drop‑in” that requires no modifications to the fuel distribution network.

Biochemical Conversion (Fermentation and Anaerobic Digestion)

Microorganisms and enzymes can convert sugars and starch (first-generation) or lignocellulosic hydrolysates (second-generation) into ethanol, butanol, or other alcohols. These alcohols can be dehydrated to olefins (ethylene, propylene) for chemical production, or blended into gasoline (ethanol). The production of cellulosic ethanol at commercial scale has been slower than anticipated, with companies like POET-DSM and Abengoa facing technical and financial hurdles. However, advances in engineered yeast and enzyme cocktails are improving yields and reducing costs.

Catalytic Upgrading of Biomass-Derived Intermediates

New catalytic pathways are being developed to directly convert biomass feedstocks into drop‑in hydrocarbons without separate syngas or pyrolysis steps. Examples include catalytic fast pyrolysis, aqueous phase processing, and hydrodeoxygenation of bio‑oil over noble metal catalysts. Pioneered by institutions like the National Renewable Energy Laboratory (NREL) and companies such as Anellotech, these routes promise lower capital intensity and higher carbon efficiency, but remain at the pilot or demonstration stage.

Challenges in Scaling and Economics

Despite rapid progress, the widespread adoption of renewable feedstocks in refining faces significant barriers.

Feedstock Cost and Availability

Waste oils and fats are limited in supply; global UCO collection is estimated at roughly 10–15 million tonnes per year, enough to replace a small fraction of petroleum diesel demand. Vegetable oils are more abundant but compete with food and have higher land and water footprints. Lignocellulosic feedstocks require expensive logistics for collection, storage, and pretreatment, adding 20–40% to total cost. Price volatility of feedstocks is a persistent challenge for project financing.

Infrastructure and Capital Requirements

Existing refinery units (hydrotreaters, FCCs, reformers) are designed for petroleum fractions. Retrofitting to handle high‑oxygen, acidic, or high‑mineral feedstocks demands investments in corrosion‑resistant materials, new feed injection systems, waste water treatment, and hydrogen supply. Integration with dedicated units (e.g., a hydrodeoxygenation stage before the FCC) adds capital expenditure. The payback period for such investments is uncertain, especially when carbon credit revenues fluctuate with policy cycles.

Hydrogen Consumption and Carbon Intensity

Technologies for hydroprocessing oxygen‑rich feedstocks require substantial hydrogen, which is often produced from natural gas reforming with associated CO₂ emissions. Unless the hydrogen is sourced from green electrolysis or the reformers are equipped with carbon capture, the carbon intensity of the final fuel may not achieve the expected reductions. The blue hydrogen pathway (reforming + CCS) or direct use of renewable hydrogen is critical to maximizing the environmental benefits.

Catalyst Performance and Deactivation

Renewable feedstocks carry impurities (chlorides, metals, phosphorus, alkali) that poison hydroprocessing catalysts. Catalyst cycles are shorter, and regeneration becomes more complex, increasing operating costs. Research continues into more robust catalysts, including those based on NiMo and CoMo supports modified with promoters to resist deactivation.

Regulatory Uncertainty

While policies have spurred growth, the renewable fuel industry remains vulnerable to changes in mandates, trade disputes, and subsidy phase‑outs. The expiry of the US blender’s tax credit, periodic adjustments to the RFS volume obligations, and differing treatment of indirect land‑use change in EU directives create market uncertainty. Investors require stable, long‑term policy signals to commit capital to new renewable fuel capacity.

Opportunities and Future Potential

Despite these challenges, the opportunity set for renewable feedstocks in refining is transformative.

Carbon Footprint Reduction

Drop‑in renewable fuels can reduce lifecycle greenhouse gas emissions by 50–90% compared to their fossil counterparts, depending on feedstock and process. For hard-to-electrify sectors like aviation, marine, and heavy‑duty road transport, these fuels are the most viable near‑term decarbonization option. The International Energy Agency (IEA) forecasts that sustainable biofuel production must triple by 2030 to meet net‑zero goals.

Circular Carbon Economy

Refineries that integrate renewable feedstocks and chemical recycling of plastics become nodes in a circular carbon system. Waste materials are returned to the value chain rather than incinerated or landfilled. The concept of “molecular recycling”—breaking polymers back into monomers or hydrocarbon intermediates—aligns with the strengths of a hydrocracker or fluid catalytic cracking (FCC) unit. Companies such as Eastman and Dow are investing in this approach.

Co‑processing as a Bridge Strategy

Co‑processing small percentages (typically 5–20%) of renewable feedstocks in existing hydrotreaters, FCC units, and cokers allows refineries to gain experience without building dedicated plants. This approach reduces initial capital outlay and provides a pathway for gradual transition. Many refiners, including Marathon Petroleum and Phillips 66, have successfully co‑processed bio‑oils in FCC units at pilot and commercial scale. The products are fully fungible with conventional fuels.

Expanding Beyond Fuels: Bio‑Based Chemicals

The refining industry is not only about energy; it is the source of most petrochemical building blocks. By switching feedstocks to bio‑based sources, refineries can produce renewable naphtha for ethylene crackers, biobased BTX aromatics, and renewable propane. This unlocks higher‑margin markets. The mass‑balance approach, where certified renewable materials are allocated to specific product streams through the supply chain, is gaining traction in the chemical industry.

Industry Examples and Real‑World Progress

Several companies are already demonstrating the viability of renewable feedstocks in refining at commercial scale.

  • Neste (Finland) is the world’s largest producer of renewable diesel and SAF from waste oils and fats, with capacity exceeding 5 million tonnes per year. Their Porvoo and Rotterdam refineries are dedicated hydroprocessing units (NEXBTL). Neste is also exploring liquefied waste plastics as a feedstock.
  • Phillips 66 (USA) has co‑processed bio‑oils at its San Francisco and Wood River refineries, achieving thousands of barrels per day of renewable gasoline and diesel. The company plans to convert the San Francisco Refinery (Rodeo facility) to a 100% renewable feedstocks facility by 2024.
  • TotalEnergies (France) has been co‑processing vegetable oils in the Grandpuits refinery and is building a dedicated HEFA unit at La Mède, alongside a solar farm and a biorefinery for medical hand gels.
  • Ensyn (USA/Canada) operates several commercial pyrolysis units converting wood residues into RTP™ bio‑oil, which is then upgraded to renewable gasoline and diesel at their refinery in Pennsylvania (Renewable Energy Group partnership).
  • Velocys (United Kingdom, USA) is developing commercial plants for gasification of municipal solid waste to produce jet fuel via Fischer-Tropsch, with the Altalto project (UK) as a flagship.

These examples demonstrate that the technology is proven and can be economically viable, especially in regions with strong policy support and high carbon credit prices.

The Role of Policy and Investment

The pace at which renewable feedstocks penetrate the refining system is tightly linked to government policies and private investment. Carbon pricing, low-carbon fuel standards, and blending mandates create markets for renewable fuels, while grants and loan guarantees de‑risk first‑of‑a‑kind projects. The US Inflation Reduction Act (IRA) includes substantial tax credits for sustainable aviation fuel, clean hydrogen, and carbon capture, all of which directly benefit renewable fuel projects. Similarly, the European Innovation Fund and Horizon Europe programs support large‑scale demonstration of advanced biofuel technologies. Private investment is also flowing: venture capital and corporate venture arms are investing in novel conversion technologies—from catalytic routes to synthetic biology approaches—promising higher yields and lower costs. The synergy between public policy, corporate R&D, and venture investment will determine how quickly these technologies scale.

Conclusion: A Strategic Transition, Not a Revolution

The integration of renewable feedstocks into petroleum refining is not an overnight revolution but a strategic, multi‑decade transition. The fundamental unit operations—distillation, hydroprocessing, cracking, reforming—remain relevant; what changes is the source of the carbon molecules entering the front door. By embracing a diverse portfolio of feedstocks—waste oils, biomass, plastics, and eventually captured CO₂—refineries can reduce their carbon intensity while continuing to produce essential products. The path forward requires sustained investment in new technologies, cooperative policy frameworks, and a willingness to accept incremental progress alongside ambitious pilot projects. For the industry, the future of refining will be defined not by the end of oil, but by the beginning of a truly carbon‑managed era where renewable feedstocks occupy a central role. The refineries that adapt today will be the leaders of tomorrow’s low‑carbon energy system.