biodízel

Biodízel is a renewable diesel fuel produced from biological sources such as vegetable oils, animal fats, or used cooking oil. In its common form, biodízel consists mainly of fatty acid methyl esters (FAME) obtained by transesterification of triglycerides with methanol or ethanol. The resulting product can be used on its own (B100) or blended with conventional diesel in various proportions.

Most biodízel is produced by a base-catalyzed transesterification reaction, using catalysts like sodium or potassium hydroxide. Industrial facilities of different sizes may also use acid catalysis or enzyme-based methods for feedstocks with high free fatty acids. Ethanol-based processes can yield fatty acid ethyl esters.

Feedstocks vary by region and include rapeseed, soybean, palm, and other vegetable oils, as well as recycled cooking oil and animal fats. The choice of feedstock influences cost, sustainability, and product properties, including energy content and cold flow behavior. Biodízel typically has lower sulfur content and a higher cetane number than petro-diesel, but its energy density is somewhat lower, and unsaturated esters can have poorer oxidation stability and cold-weather performance.

In many countries, biodízel is used as a blend with conventional diesel (for example B5, B20, or higher) or as B100 in specific applications. Standards such as EN 14214 and ASTM D6751 define the specification requirements for biodízel quality. Lifecycle assessments show greenhouse gas savings that depend on feedstock and management practices, with potential indirect land-use changes affecting overall benefits.

Potential drawbacks include higher production costs, competition with food or land resources, and compatibility considerations for engines and fuel systems.