M-Press Systems (M) Sdn. Bhd.
Industrial Microwave-, Plasma-, RF- and Control-Systems

Biodiesel Production

Definition of Biodiesel

The word biodiesel stands for diesel fuels based on the esters of lipids (vegetable oils or animal fats), and are meant as an addition or replacement for petrol based diesel fuels for the use in standard diesel engines, i.e. the engines do not need any form of modification in order to use biodiesel. Biodiesel can be used either pure or mixed (blended) with petrol based diesel fuels. To distinguish between different blends, in most countries they are marked with the so-called "B" factor, whereby B100 stands for 100 % pure biodiesel, B20 stands for a blend of 20 % biodiesel and 80 % petrol based diesel, and so on.

While it is sometimes believed that biodiesel has a detrimental effect on lifetime of the combustion engines, biodiesel actually has better lubrication properties than petrol based diesel fuels, and therefore increases the lifetime of the engines' components, especially in case of critical components like high pressure injection pumps, fuel injectors etc. Negative effects are usually caused by the use of materials not compatible with biodiesel, e.g. PVC, rubber and brass, or by the use of low quality biodiesel, which tends to absorb water, which in turn has a negative effect on the engines.

Production of biodiesel

In order to produce biodiesel, vegetable oils or animal fats have to undergo an esterification or transesterification with short-chain alcohols, usually methanol or ethanol. Besides mixing the lipids and the alcohol, the reaction also requires a considerable amount of thermal energy as well as suitable catalysts. In the standard batch process, alcohol and catalysts have to be added in excessively high amounts to archive an acceptable conversion yield. This not only wastes thermal energy required for heating up the excessive amounts of alcohol and catalyst, but because they have to be removed from the final product, this again wastes necessary energy. Please note that the chemical reaction also produces other by-products like glycerine, soap and water, which also have to be removed from the biodiesel. Especially the amount of the produced soap is a direct function of the amount of catalysts added.

In South-East Asia, most lipids used for the production of biodiesel are vegetable based, e.g. palm oil, soy-bean oil and coconut oil, or recycled oils from restaurants and the food processing industry.

Use of microwave energy for the production of biodiesel

As mentioned above, a considerable amount of thermal energy is required to convert the mixture into biodiesel. Furthermore, because the basic reaction has an unfavourable equilibrium, excessive amounts of alcohol as well as catalysts have to be added to increase the conversion yield in the standard batch process, which wastes energy and increases production cost. This is mainly caused due to the fact that the lipid molecules are tightly packed, making it difficult for the alcohol molecules to reach their binding points in the molecule chain to perform the esterification.

To improve the conversion yield and reduce the amount of alcohol and catalysts required, several new technologies were developed, e.g. the high-shear and ultrasonic-reactor technology. For example, the ultrasonic-reactor technology increases the yield by introducing cavitation into the mixture, which not only heats it up, but also causes the molecules to collide at high speeds, which increases the rate at which the alcohol molecules bind to the lipids. However, conversion of electrical energy into ultrasonic energy has a very low efficiency, limiting the overall process efficiency.

Microwave energy, on the other hand, can be produced at a very high efficiency, depending on the output frequency conversion rates of up to 90 % are possible. Because microwave energy penetrates the mixture, with a correctly designed applicator an almost instant and very even temperature increase of the mixture can be accomplished. Furthermore, because the microwave energy acts on the polar molecules within the mixture, they are forced into rapid movements and start colliding with each other, increasing the reaction speed as well as the overall conversion rate. In order to further increase the conversion yield and reduce the amount of energy required, our plants offer the following additional features:

Additional advantages of the design are:

Should you require any further information regarding the above application please contact us.