Biodiiseli

Biodiesel is a renewable, biodegradable substitute for conventional diesel fuel produced from biological lipids. It is typically manufactured by a chemical process called transesterification, which converts fats or oils into fatty acid methyl esters (FAME) and glycerol. Biodiesel can be used in diesel engines with little or no modifications, especially in blends with petroleum diesel.

Common feedstocks include vegetable oils such as soybean, rapeseed (canola), and palm oil; animal fats and used cooking oil. Some research programs explore algae as a feedstock. The process requires methanol (or ethanol) and a catalyst, usually sodium or potassium hydroxide, to produce esters and glycerol as a byproduct.

Biodiesel can be used in diesel engines with minimal adjustments, particularly in blends such as B5, B20, or B100 in suitable engines. It often provides improved lubricity and a higher cetane number, but contains less energy per liter than petro-diesel, resulting in slightly lower fuel economy. Cold weather performance varies with feedstock and blend level, and certain engines or seals may respond differently to biodiesel.

Environmental aspects vary with feedstock and farming practices. Lifecycle greenhouse gas emissions can be lower than fossil diesel, and biodiesel generally reduces sulfur and some particulates. However, land-use change, crop choices, and feedstock sustainability influence overall benefits, and food-versus-fuel concerns have driven policy debates in many regions.

Limitations include storage and oxidation sensitivity, potential solvent effects on rubber seals, and higher hygroscopicity. Availability and price depend on feedstock markets and policy incentives. Biodiesel remains a focus of policy support and technology development as a drop-in alternative in transport fuels.