Butter as a feedstock for biodiesel production

Area of Science:

• Biomass Energy
• Chemical Engineering
• Analytical Chemistry

Background:

• Biodiesel production from diverse feedstocks is crucial for renewable energy.
• Cow's milk butter presents a unique feedstock for fatty acid methyl ester (FAME) production.
• Standard biodiesel quality assays may face challenges with specific FAME compositions.

Purpose of the Study:

• To produce and evaluate fatty acid methyl esters (FAME) from cow's milk butter as a potential biodiesel feedstock.
• To assess the compliance of butterfat FAME with ASTM D 6751 biodiesel standards.
• To investigate methods for improving the quality and stability of butterfat FAME.

Main Methods:

• Esterification/transesterification of cow's milk butter with methanol to produce FAME.
• Assaying the produced FAME according to ASTM D 6751 specifications (flash point, glycerin, sulfur, oxidation stability).
• Supplementation with a commercial antioxidant to enhance oxidation stability.

Main Results:

• Butterfat FAME failed to meet ASTM D 6751 standards for flash point, free/total glycerin, total sulfur, and oxidation stability.
• Short-chain fatty acid esters interfered with flash point and glycerin assays.
• Approximately 725 ppm of antioxidant was needed to achieve the required oxidation stability.

Conclusions:

• Butterfat FAME, without purification, is unsuitable as a sole biodiesel component due to quality standard failures.
• Blending butterfat FAME with other biodiesel feedstocks may yield compliant fuel blends.
• Current biodiesel characterization methods may require adaptation for FAME containing mid- and short-chain esters.