Yellow grease is derived from used cooking oil from the fast-food industry. It is used to feed livestock, and to make soap, make-up, clothes, rubber, detergents, and biodiesel fuel.
It is distinct from brown grease; yellow grease is typically used-frying oils from deep fryers, whereas brown grease is sourced from grease interceptors. Yellow grease can also refer to lower-quality grades of tallow (cow or sheep fat) from animal rendering plants.
Yellow grease is traded as a marginally valuable commodity, and has traditionally been used to spray on roads as dust control, or as animal feed additive, but has become a feedstock for biodiesel production. Although most biodiesel is produced from renewable plant sources, yellow grease is attractive because it is inexpensive and its use converts waste into fuel.
The term has been in use for some time. A source from 1896 describes it as follows: "Yellow grease is made by packers. All the refuse materials of the packing houses go into the yellow grease tank, together with any hogs which may die on the packers' hands."
Famous quotes containing the word yellow:
“The prairies were dust. Day after day, summer after summer, the scorching winds blew the dust and the sun was brassy in a yellow sky. Crop after crop failed. Again and again the barren land must be mortgaged for taxes and food and next year’s seed. The agony of hope ended when there was not harvest and no more credit, no money to pay interest and taxes; the banker took the land. Then the bank failed.”
—Rose Wilder Lane (1886–1968)