The evolving landscape of enzymatic biodiesel production

The biodiesel sector has undergone significant market changes in recent years, leading to the emergence of new processing and technological solutions.
In Europe, the EU’s Renewable Energy Directive III (RED III) is driving substantial change in the biodiesel sector, which has already seen major market evolution and technological progress.
The directive sets binding renewable energy targets for 2030: 42.5% overall, and either 29% for transport energy or a 14.5% reduction in transport greenhouse gas intensity.
To meet these targets, palm oil-based biodiesel is excluded from target calculations, while biodiesel from selected waste and residue sources is granted double-counting (that is, 1 kg of biodiesel produced from waste counts as 2 kg), effectively providing a multiplier effect.
Globally, the integration of biodiesel into conventional diesel is increasing.

Mandates

A prime example is Indonesia, which has recently implemented a nationwide B40 mandate, requiring a 40% biodiesel blend in diesel fuel.
This rapid progression from the previous B35 standard marks a new phase for biodiesel production in Southeast Asia.
In Indonesia, the primary feedstock for biodiesel production is palm oil — a readily available local resource that offers logistical efficiencies for raw material acquisition.
The evaluation of new large-scale biodiesel investments increasingly hinges on the ability to process lower-value feedstocks, including locally available palm fatty acid distillate (PFAD), palm oil mill effluent (POME), and high-acidity crude palm oil (CPO) — by-products of extraction and refining.
Additionally, recent competition for low-grade feedstocks from hydrotreated vegetable oil (HVO) and sustainable aviation fuel (SAF) producers has significantly reshaped the market.
These new industry participants, with a focus on large-scale production, are now competing for traditional biodiesel feedstocks, primarily targeting lower-grade materials.
In response to this evolving market, the demand for flexible feedstock processing technologies has become paramount, prompting many producers to re-evaluate enzymatic biodiesel.

Path forward

Although this technology has existed for some time, its widespread adoption was previously hindered by the cost-effectiveness of conventional transesterification.
The current need to utilise increasingly lower-quality feedstocks, previously deemed unsuitable, has revitalised enzymatic biodiesel, positioning it as a viable — and in certain cases, advantageous — option.
The enzymatic route to biodiesel production follows a relatively straightforward operational sequence (as shown in Figure 1).
Depending on the input materials, a basic preparation phase may be required.
This initial processing is designed to remove solid particles or other unwanted substances, such as proteins or impurities, that could interfere with enzyme-driven reactions.
The prepared feedstock is then passed through a series of enzyme-catalysed reaction vessels.
Inside these reactors, it interacts with methanol and enzymes under relatively low-temperature conditions (typically below 45°C), producing a raw methyl ester product and glycerol.
The specific biochemical transformation depends on the enzyme used, but the most common types perform a two-stage function.
First, they break down triglycerides, diglycerides, and monoglycerides into free fatty acids (FFAs) and glycerol.
The glycerol remains unchanged in the next step, while the same enzyme then catalyses the reaction between the FFAs and methanol, ultimately producing the desired methyl ester.
The time required to complete the reaction depends on the initial FFA content of the feedstock.
Higher FFA levels — common in lower-grade materials — accelerate conversion.
After the reaction, the crude methyl ester is separated from the glycerol by-product. It then undergoes further purification to meet biodiesel quality standards such as EN14214, ASTM, SNI, or others.
Purification procedures may vary by technology provider but generally include neutralisation to reduce residual FFAs to regulatory levels.
Recoverable fatty substances can be reprocessed within the facility to increase overall yield.
A biodiesel distillation step — similar to a modified version of traditional transesterification for lower-grade inputs — may be added, depending on feedstock type and product specifications.
Finally, enzymatic biodiesel production includes a methanol recovery system to reclaim unused methanol.
However, only 98% methanol purity is required, making the purification stage more sustainable than in traditional transesterification.

Economic viability

Economic viability is the starting point when comparing upgraded transesterification (adapted for lower-grade inputs) to enzymatic biodiesel.
Proven technologies — such as esterification with glycerol for converting FFAs into a glyceride mix, stripping to reduce FFAs, oil washing, and specialised bleaching — provide reliable means to improve existing transesterification plants.
For existing facilities, retrofitting is typically more cost-effective, particularly in today’s competitive market.
However, for new installations, the enzymatic route is becoming increasingly attractive due to several advantages:
• CAPEX: While capital expenditure depends on the specific technology, enzymatic biodiesel facilities generally have a smaller footprint and lower installation costs compared to alternatives offering similar feedstock flexibility.
• Yield: Yield is a key investment consideration.
Many lower-quality feedstocks contain high FFA levels, which must be converted into mono-, di-, and triglycerides before transesterification via glycerol esterification.
However, achieving very low residual FFA levels — combined with prolonged high-temperature processing (often exceeding 200–220°C) — promotes polymerisation.
This is especially problematic with unsaturated feedstocks and reduces yield during distillation, as polymers remain in the residue.
Additional stripping is also required to remove excess FFAs and monoglycerides, and although the by-product can be recycled, this increases production costs and the risk of polymer formation.
By contrast, enzymatic processing occurs under mild conditions, completely avoiding polymerisation and ultimately delivering higher yields.
• Flexibility: The enzymatic method is more adaptable to varying feedstocks, as it is not limited by FFA levels.
Transesterification, on the other hand, requires a complex and expensive pre-treatment setup regardless of the feedstock, leading to higher upfront investment.
• Materials: Equipment requirements also differ.
Some transesterification pre-treatment methods, especially for acidic feedstocks, require mineral acids, necessitating corrosion-resistant materials and adding complexity.
Enzymatic processing avoids these challenges.
Enzymes are non-corrosive, eliminating the need for specialised materials and simplifying design.

Summary

In conclusion, this article has highlighted the key benefits of enzymatic biodiesel over transesterification for new plant builds.
For existing transesterification facilities, switching entirely to enzymatic production may not offer sufficient return on investment to justify the transition.
The key decision for biodiesel producers now lies in choosing the right technology for future investments — prioritising feedstock flexibility and long-term availability.
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