Biodiesel, also known as fatty acid methyl esters (Fatty Acid Ester) uses the fruit of plants, seeds, vegetable oils or animal fat milk ducts, waste cooking oil and others as materials. It is obtained by lactide reaction (Transesterification reaction) with alcohols (methanol, ethanol). German engineer Dr. Rudolf Diesel (1858-1913) first mentioned the concept of biodiesel. Biodiesel refers to the use of various types of plant and animal fats as raw materials, and alcohols such as methanol or ethanol etherification reaction modified after delivery to make biodiesel eventually become available for use in internal combustion engine kinds of fuel. Biodiesel as a renewable energy source, due to its highlight advantages of high cetane number, nontoxic, sulfur-free, renewable and biodegradable, which is becoming a hot topic in the closely watched study.Advantage of biodiesel while comparing with fossil diesel:

● Higher cetane number of more than 49 (petroleum diesel is 45). Anti-knock performance of biodiesel is better than petroleum diesel.

● Oxygen content of biodiesel is higher than petroleum diesel with up to 11 %. Smaller amount of oxygen required for the combustion process comparing with petroleum diesel. Biodiesel has better combustion, ignition performance than petroleum diesel.

● Aromatic hydrocarbons contain carcinogenic ingredients rather not sulfur, lead, halogen and other harmful substances.

● Biodiesel has no need of diesel engine modification, which can be added directly to use.Flash point of biodiesel is higher than petroleum diesel, which is conducive to the safe transport and storage.

● Biodiesel is paraffin -free, low-temperature fluidity, widely applicable area.Biodiesel is a typical "green energy", the energy consumption for biodiesel production is only 25% of petroleum diesel production. It can significantly reduce combustion emissions. Biodiesel is non-toxic, and bio-degradation rate reaches 98%. The biodiesel technology bio-degradation rate is 2 times faster than petroleum diesel. The production of biodiesel can improve soil applied, ecological protection, and reduce soil erosion. The utilization of catering waste oil biodiesel can reduce waste oil directly into the environment or re-entering the edible oil system, which has a greater environmental values and social value.