biodiesel

Biodiesel is a renewable diesel substitute produced from biological feedstocks such as vegetable oils, animal fats, or used cooking oil. It is made through a transesterification reaction with an alcohol (typically methanol) in the presence of a catalyst, yielding fatty acid methyl esters (FAME) as the main product and glycerol as a byproduct. Biodiesel is designed to be a drop-in replacement or blend component for conventional diesel fuel.

Feedstocks for biodiesel are diverse, including soybean, rapeseed (canola), palm, and sunflower oils, as well as animal fats and recycled greases. The process can use methanol or ethanol, and production facilities vary in scale. Biodiesel products are standardized to meet specifications such as ASTM D6751 in the United States and EN 14214 in Europe. It can be used as B100 (100% biodiesel) or blended with petroleum diesel in common ratios like B5, B20, or higher, depending on engine compatibility and climate conditions.

Environmental and performance considerations vary with feedstock and production methods. Compared with petroleum diesel, biodiesel generally lowers net lifecycle greenhouse gas emissions, is biodegradable, and offers better lubricity with lower sulfur content. However, energy content is typically lower, and NOx emissions may rise slightly in some engines. Biodiesel also exhibits higher propensity for cold weather gelling and can have stability and storage considerations, requiring appropriate handling and additives.

Economic and sustainability aspects are influenced by feedstock availability, land use, and policy incentives. While biodiesel can reduce fossil fuel dependence and emissions, its environmental benefits depend on feedstock choices, farming practices, and supply-chain efficiency.