Vegetable oils have long been used by humans throughout the entire world for a variety of applications, including traditional uses such as cooking, food ingredients, medicinal ingredients, lubrication, and heating and lighting as well as more recent uses such as motor oil, lubricants, drying oils, alternative diesel fuel, raw materials for biodiesel, and so on.

In order to distinguish vegetable oil for fuel applications from biodiesel, some people refer to it as waste vegetable oil (WVO) if it is originated from discarded sources such as used restaurant grease, and as straight vegetable oil (SVO) or pure plant oil (PPO) if it has not undergone any chemical treatment or reaction such as transesterification, just as the name implies.

According to the USDA [4, 5], the total world production of major vegetable oils in 2008-2009 includes: 43.19 million metric tons of palm oil, 36.26 of soybean oil, 20.22 of rapeseed oil, 11.46 of sunflower seed oil, 5.15 of peanut oil, 5.10 of palm kernel oil, and 4.72 of cottonseed oil. The world consumption of vegetable oils has been steadily increasing at a rate of 4.5% annual growth and their trade volumes of import and export have also been steadily increasing. See Table 2.1.