Particle emissions from microalgae biodiesel combustion and their relative oxidative potential

Area of Science:

• * Combustion science and renewable energy sources.
• * Environmental engineering and emissions control.

Background:

• * Microalgae are a promising feedstock for sustainable biodiesel production, offering cleaner alternatives to petroleum diesel.
• * Biodiesel properties, particularly fatty acid methyl ester (FAME) composition, significantly impact combustion characteristics and emissions.

Purpose of the Study:

• * To investigate and compare particle emissions from microalgal biodiesel and higher plant biodiesel at various blend ratios.
• * To analyze the influence of microalgal biodiesel's unique FAME composition (long carbon chains C20-C22) on particle characteristics and oxidative potential.

Main Methods:

• * Combustion tests were performed using microalgal and higher plant biodiesels at different blending ratios.
• * Particle emissions, including nucleation mode particles, and reactive oxygen species (ROS) were measured.
• * Analysis focused on the correlation between FAME chain length, unsaturation, and emission profiles.

Main Results:

• * Lower blend percentages (<20%) of microalgal biodiesel reduced particle emissions more effectively than higher blends.
• * Higher blends (>20%) led to increased nucleation mode particle emissions, attributed to microalgal biodiesel's physical properties (low volatility, high density).
• * Particles from microalgal biodiesel combustion exhibited lower oxidative potential (ROS) compared to conventional diesel.

Conclusions:

• * Microalgal biodiesel with high polyunsaturated FAMEs (≥C20) may not yield the same particulate matter (PM) emission benefits as conventional biodiesel.
• * Optimizing microalgal biodiesel composition, specifically reducing long-chain polyunsaturated FAMEs, is crucial for maximizing PM reduction.
• * Further research into FAME profiles is needed to enhance the environmental performance of microalgal biodiesel.