Science & Process

Renewable diesel has a different molecular structure from biodiesel, which is a methyl-ester primarily made from soybean oil. 

Renewable diesel is a true hydrocarbon, just like diesel, and can be used anywhere diesel is used without modifications to engines or pipelines. 

It has an energy density value equivalent to ultra-low sulfur diesel (ULSD), which is a cleaner burning, lower emission fuel.

It performs well in both cold and warm climates.

Inedible meat and fat are collected from supermarkets, butchers, meat processors and other food service establishments in North America and transported to rendering operations, such as Darling Ingredients’ network of plants. There, the by-products are ground and cooked to separate the fats from the protein material. These recycled fats are used to produce biofuels.

The restaurant industry in the U.S. generates an estimated 2.3 billion pounds of used cooking oil annually. Companies like Darling Ingredients provide restaurants, grocers and other food service establishments with storage tanks or bins to store used fryer oil. During regularly scheduled visits, the service company pumps the oil into dedicated trucks and transports it to their processing plants, where it is cleaned of debris or solid matter and heated to evaporate any water.  The used cooking oil is transported to our Diamond Green Diesel facilities, where we manufacture the renewable diesel.

The used cooking oil and inedible animal fats are pretreated to remove impurities. Next, these fats are processed into renewable diesel by:

• Hydrotreating: Using high pressure hydrogen to remove the oxygen (which is converted to water).
• Isomerization: A chemical process that changes the structure of the molecules without changing the number of atoms. This enables the fuel to be used in cold weather.
• Fractionation: A chemical process to separate the liquid into finished products.
   

Because of its molecular similarity to traditional diesel, renewable diesel can be distributed using existing pipelines used to transport petroleum products, no changes are needed. 

The fuel is sold primarily in California, Canada and Europe, which are markets that mandate low-carbon fuels.