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Turn Used Cooking Oil into Biodiesel

Biodiesel is a more environmentally friendly alternative to conventional diesel, as it is derived from recycled vegetable oils and fats from waste rather than being a direct derivative of petroleum. Diesel engines can run on biodiesel fuel without needing modifications, and both are equivalent in energy efficiency and fuel economy.

Commercial establishments with kitchens, such as hotels, restaurants, and cafeterias (Horeca sector), are required by law to recycle their waste oil. Although individuals can also do so by going to mobile or fixed points in their localities, the biofuel industry in our country is mainly supplied by the Horeca sector. To dispose of this waste, the industry must turn to authorized waste managers such as Fatsgreen, who take care of the collection, transport, and shipment to biofuel production plants.

Once at the plant, used oils are heated to remove any water they may contain. They must then be filtered to remove as much solid food debris as possible. Filtering is carried out in several stages—the first consists of a vibrating sieve that prevents the passage of the larger pieces. A second sieve collects the smaller particles. Although the oil may appear clean to the naked eye after two stages of filtration, it may still contain microscopic debris that must be removed in the third stage. In this stage, the oil passes through several filters capable of retaining debris smaller than one micron.

The result is called "feed cargo," which can, in turn, be mixed with animal or vegetable fats from agriculture. This resulting oil is combined with methanol, known as wood alcohol or methyl alcohol (CH3-OH), along with a catalyst to trigger the chemical reaction. The reaction occurs at a controlled pressure and temperature, resulting in glycerin and biofuel. Glycerin, among other uses, can end up in our bars of soap. Biofuel, on the other hand, must undergo quality control.

You have to check whether the result is optimal, and a flammability test is carried out. To do this, the fuel is heated to 135ºC, and a flame is applied to it to see if it burns. If it does, the biodiesel must continue to react to remove more methanol. If not, biofuel is ready to fuel our engines.

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