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Automakers reply that they don’t warranty fuel and they don’t single out biodiesel. The high-pressure injectors used in modern diesels demand a very clean and stable fuel, so the suppliers that make the injectors as well as the automakers are gun-shy about endorsing higher levels of biodiesel—until its quality standards are taken to a level comparable to Europe.
Understanding the differences between FAME and NERD could help put these squabbles to rest.
Defining FAME and NERD
FAME is Fatty Acid Methyl Ester. This is traditional biodiesel, produced by processing raw vegetable oil or animal fats through a chemical process called transesterification. The resulting product is chemically different from petroleum diesel, has different properties, and meets a different quality standard. The most common feedstock for FAME biodiesel in the U.S. is soybean oil, but in Europe rapeseed or canola oil is typically used. Refined and recycled restaurant vegetable oil also is used by some biodiesel producers. Most of the biodiesel available in the United States is the FAME type.
On the other hand, NERD renewable diesel has properties similar to petroleum diesel and minimizes blending issues. It has a higher cetane level (for improved ignition), a lower cloud point (for better cold weather performance), higher renewable content, greater fuel stability (for better storage), a broader choice of feedstock, and lower NOx and greenhouse gas emissions compared to FAME biodiesel.
NERD is Non-Esterified Renewable Diesel. There are several varieties of this type of biodiesel, also known as renewable diesel. The most advanced of these is produced through hydrotreating—the same process that is already used in today’s petroleum refineries. During hydrotreating, hydrogen replaces other atoms such as sulfur, oxygen, and nitrogen and converts the oil’s triglyceride molecules into paraffinic hydrocarbons. The first refinery using the NERD process to produce renewable diesel was recently opened by Neste Oil in Porvoo, Finland, in Summer 2007.