What new safety challenges are there in biofuel production?

As the world races to decarbonize transportation and power, biofuels, ranging from first-generation biodiesel and bioethanol to advanced drop-in fuels, have emerged as key transition fuels.  

Made from plant oils, crop residues, algae, or waste materials, biofuels are renewable and often lower in net CO₂ emissions than fossil fuels.  

But behind their environmental appeal lies a set of unique process safety and monitoring challenges.

Instrumentation professionals in refining, storage, and combustion environments must navigate risks such as microbial contamination, water ingress, spontaneous combustion, and unpredictable emissions behaviour.  

As the biofuels sector scales up, robust safety monitoring becomes just as important as sustainability credentials.

The hazard profile of different biofuels

The most common biofuels include:

• Biodiesel (FAME): fatty acid methyl esters from vegetable oils or animal fats
• Bioethanol: fermentation alcohol from sugar/starch crops or cellulosic biomass
• Hydrotreated Vegetable Oil (HVO): drop-in diesel substitute made by hydrogenation
• Advanced biofuels: made from lignocellulose, algae, or waste gases (e.g., FT-biofuels, bio-syngas)

Each has a distinct production process and hazard profile. Many can be blended with fossil fuels or used neat but they don’t behave identically, and that’s where safety challenges arise.

1. Water contamination and microbial growth

Biofuels, especially FAME biodiesel and bioethanol, are hygroscopic, meaning they absorb water from the air. Water promotes microbial growth (especially in tanks and pipelines), leading to biofilm fouling, filter blockages, and microbiologically influenced corrosion (MIC).

How to respond:

• Water-in-fuel analysers (capacitive, Karl Fischer, or IR-based)
• Microbial contamination sensors or ATP-based biofouling monitors
• Differential pressure sensors across filters to detect clogging
• Tank-level temperature and pressure sensors to track decomposition-linked gas buildup

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2. Thermal instability and peroxide formation

Certain biofuels, like used cooking oil-derived biodiesel, can contain unsaturated fatty acids that degrade over time.

This leads to acid formation, polymerization, or even peroxide accumulation in storage, particularly under heat or light.

How to respond:

• Thermal stability analysers (oxidation stability test units)
• Peroxide test strips or online monitors in storage quality control labs
• Tank temperature and UV exposure sensors to prevent degradation

3. Spontaneous combustion

Cloths or filters soaked in biodiesel have caused spontaneous combustion in waste bins or storage rooms, especially when derived from polyunsaturated oils.  

The auto-oxidation of methyl esters can release heat in confined spaces.

How to respond:

• Ambient temperature sensors near rags, filter storage and solvent waste bins
• Fire detection systems with hydrocarbon smoke/vapor recognition
• Thermal cameras or IR sensors for bulk storage risk areas

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4. Emissions variability and NOx formation

Biofuels burn cleaner in terms of particulate matter and sulphur oxides but often produce higher NOx emissions due to oxygen content.  

In engines, blends like B20 or neat biodiesel can change combustion temperatures and emission profiles.

How to respond:

• CEMS for NOx, CO, and PM
• In-cylinder temperature and pressure sensors in test engines
• Fuel composition analysers to quantify blend ratios and oxygenates

5. Fuel instability and phase separation

Blends of bioethanol with gasoline (e.g. E10, E85) can undergo phase separation if water levels rise, leading to poor engine performance and safety concerns during transport.  

Similarly, FAME biodiesel can precipitate at low temperatures (“cold flow” issues).

How to respond:

• In-line fuel quality analysers for water content, density and phase stability
• Cold filter plugging point (CFPP) testers and cloud point sensors
• Real-time viscosity and temperature monitors in pipelines and blending units

Lessons from the ground

A UK transport depot fire was traced back to improperly stored biodiesel-soaked rags.

Investigators found spontaneous oxidation of rapeseed-based fuel caused heat buildup and ignition in a poorly ventilated area.

Multiple military and aviation test programs noted engine knocking and NOx spikes when running high-percentage biofuels under varying humidity and load, causing retrofitting of combustion monitoring systems.

A European biodiesel plant reported corrosion in stainless steel tanks due to microbial activity at the water-fuel interface.  

Implementation of microbial activity sensors and regular biocide dosing followed.

These incidents highlight the need for comprehensive monitoring and ongoing quality assurance, especially in mixed-feedstock or off-spec fuel scenarios.

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How regulation is catching up

The EU Renewable Energy Directive (RED III) sets stringent traceability and performance standards for biofuels, indirectly pushing for enhanced instrumentation for emissions verification, water content, and origin tracking.

In the U.S., the EPA’s RFS (Renewable Fuel Standard) program requires fuel producers to demonstrate feedstock compliance and emissions reductions, driving adoption of on-line analysers and sampling validation systems.

ICAO’s CORSIA initiative, focused on sustainable aviation fuels (SAFs), sets lifecycle emissions caps that demand real-time purity and stability monitoring.

Instrumentation has become central not only to safety but to certifying compliance with global carbon and air quality targets.

So, how safe are biofuels, really?

Biofuels bring undeniable climate and air quality benefits, but they are chemically and biologically active materials.  

They interact with water, oxygen, metals, and microbes in ways fossil fuels typically do not. For instrumentation professionals, that means:

• Revisiting old assumptions about stability and emissions
• Deploying new tools for microbial, peroxide, and phase monitoring
• Using emissions and fuel composition analysers not just for engines, but for fuel integrity during storage and blending
• As the biofuels industry scales up, the role of real-time monitoring and intelligent instrumentation will only grow.  

Ensuring that these fuels remain safe, stable, and clean from production to combustion is a challenge that can’t be solved by chemistry alone. It requires smart sensors, careful integration and constant vigilance.

By Jed Thomas