Cost-effective sourcing of feedstock is of paramount importance in the production of biodiesel as it can represent up to 80% of total production cost depending on the used raw material. The sources for biodiesel are quite manifold, ranging from oil palm, coconut, sunflower, soybean, rapeseed, canola, linseed, cottonseed, to waste vegetable oils and animal fats such as lard and suet.

GREEN POWER CORPORATION uses palm oil as raw material above all because of the close proximity to a wide net of suppliers in Thailand’s southern region and in order to support Thai agricultural development. The country’s biggest oil palm zone is in Krabi with 40% of all palm plantations, followed by Surat Thani and Chumphon. Oil crops have become the most common raw material for biodiesel in Thailand because of its low cultivation cost and immense productivity. One rai of oil palm yields 10 times more fuel than one rai of soybeans, which is widely used for biodiesel in the US, and 5 times more fuel than one rai of rape seeds, which is widely used in Europe.

More than 80% of the world’s palm oil production comes from Malaysia (14 million tons per year) and Indonesia (12 million tons per year). Thailand’s production output of crude palm oil is currently about 1 million tons per year or 2,740 tons per day. 200,000 tons per year or 550 tons per day are exported (Source: Food and Agriculture Organization, Agriculture Statistics Database).

Oil palms can be harvested all year. After receiving fresh fruit bunches from plantations, they are first being sterilized through a steaming process and then being threshed in order to separate the fruits from the bunch. In a next step their pulps are cracked, cooked, flaked and expanded with steam to maximize the oil yield. The oil as such can then be extracted by means of pressing or through solvent extraction, which, following the removal of the solvent, yields crude palm kernel oil (CPKO) (5% yield) and crude palm oil (CPO) (15-20% yield). After further purification to remove water, sands, and impurities, the extracted oil is ready for storage and refining. The empty fruit bunches are usually returned to the plantations for use as organic fertilizer. The mesocarp fibre and broken shell can be burned to produce steam for the refining process.

After extraction from the bunch CPO looks at room temperature (e.g. 25 C) like a pasty red-colored material. In order to produce a more finished product, fatty acids, color and odor need to be removed through a refining and distillation process. The first step in this refining process is degumming, which hydrates the CPO in order to make various impurities more insoluble so that they can be filtered out. During the following bleaching process the main particles of color bodies as well as metal contamination and oxidizing materials in the oil are being absorbed. Before distillation and deodorization all precipitated material from degumming is filtered out from the bleached oil. Then it is de-aerated and heated to deodorizing temperature to remove any remaining air as well as volatile flavor and odorous compounds. The vapors from the deodorizer are gathered and passed through a layer of packing cooled by circulating acid oil, which results in palm fatty acids distillate as soap. The oil leaving the deodorizer is cooled down for storage and passed through polishing filters to obtain refined bleached deodorized oil.

Palm oil has a balanced ratio of unsaturated and saturated fatty acids. It contains 40% oleic acid (monounsaturated fatty acid), 10% linoleic acid (polyunsaturated fatty acid), 45% palmitic acid and 5% stearic acid (saturated fatty acid). To obtain a free flowing material from the refined bleached deodorized oil, the liquid phase can be separated from the solid phase in a fractionation process. This process keeps the fat at a controlled temperature to allow crystallization and then separates the formed crystals to obtain liquid (palm olein) solid parts (palm stearin) of various melting characteristics.