What is biodiesel

Biodiesel is a renewable fuel, which is produced from vegetable oils, usually sunflower oil, soya oil, rape seed oil, etc. It can also be produced from used cooking oil and animal fats. Its physical chemical characteristics are similar to those of mineral diesel.

It can be used in diesel engines, either mixed with mineral diesel in various quantities, or by itself. For biodiesel to be used by itself small changes are required in some diesel engines, such as the replacement of elastomers (pipes, etc), mainly in those manufactured before 1990.

Why biofuels

The connection between the greenhouse effect that is causing the Planet to overheat and the burning of fossil fuels is no longer in doubt. Prognostic models only differ with regard to how quickly climate change will take place and climatic conditions will deteriorate.

The use of biodiesel in diesel engines has significant environmental benefits. It helps to decrease the consequences of the greenhouse effect and reduces exhaust gas emissions. It also contributes to self-sufficiency in energy needs and agricultural growth.

Various European Commission research projects as well as research carried out by independent bodies worldwide have shown that the consumption of one kilogram of biodiesel in place of conventional oil results in the reduction of carbon-dioxide (CO2) emissions by at least 1 kilogram, while in the case of sophisticated biofuels, such as biodiesel from waste materials (used cooking oil, animal fats), the reduction exceeds 3 kilograms. Furthermore, biodiesel has practically zero sulfur content and it biodegrades rapidly.

The extensive use of biodiesel in the EU is one of the basic means of achieving the aims to reduce greenhouse gases set by the Kyoto Protocol. For this reason, the EU is committed to using specific quantities of biodiesel in motor fuels in the member states.

Why biodiesel from cooking oil

The burning of biodiesel, as with all biofuels, produces about the same amount of CO2 that is produced by the burning of conventional fuels. However, this quantity is equal to the quantity of CO2 absorbed from the atmosphere by the plant from which biofuels are derived. Thus, the CO2 balance from the growth of the plant and the burning of the biodiesel produced is zero.

This sustainability, however, is upset by the CO2 emitted into the atmosphere throughout the cycle of biofuel production, that is, from the exhaust gases of agricultural machinery used for the cultivation and harvesting of raw materials, the production of fertilizers, their transport, etc. As a result, the reduction of CO2 in relation to conventional fuels is not 100%, but fluctuates between 50% and 90%. In the case where waste materials, such as used cooking oil and animal fat, are used, the reduction reaches or surpasses 90%. The environmental benefit is double, one being the obvious less greenhouse gas emissions while the other one is the recycle of waste materials which in any other case would have been disposed to the environment.

That is the main reason why the use of biodiesel from waste materials is strongly encouraged by the EU and the quantities of it used as motor fuel count as double in the member states’ obligation to meet their biofuel targets.

Biodiesel and the environment

  • It is not toxic.
  • It does not contain aromatic compounds and sulfur.
  • It is readily biodegradable.
  • It has low Particulate Matter (PM), carbon monoxide, (CO) and hydrocarbon (HC)
  • It contributes a great deal less to the greenhouse effect.

Biodiesel is a clean, non-toxic and biodegradable fuel. It does not contain aromatic compounds. Furthermore, the sulfur oxides (SOx), carbon monoxide, unburnt hydrocarbons and soot emissions that result from its combustion in diesel engines is considerably less. The presence of sulfur in fuels is responsible for the sulfuric oxide (SOx) in exhaust gases, which constitutes one of the main pollutants of conventional diesel. In biodiesel the sulfur content is practically nil. In addition, biodiesel contains significant quantities of oxygen which

renders combustion less incomplete, with the result that the amount of carbon monoxide (CO), unburnt hydrocarbons (HC) and soot (C) in exhaust gases are far less than in conventional diesel. Apart from that, the combustion of biodiesel does not increase or only slightly increases nitrogen oxides (NOx) emissions and contributes to the reduction of the greenhouse effect by the equivalent of at least 3.2 kilos of carbon dioxide for each kilo of biodiesel, as the amount of CO2 released during combustion has already been absorbed by photosynthesis from the producing plant.

The methyl fatty acids (BIODIESEL) production plant of ELIN BIOFUELS S.A.

With the application of state-of-the-art technology in the construction and operation of the factory and throughout the production process, combined with a system that guarantees quality at all stages of production and distribution, Elin Biofuels ensures the production and delivery of biodiesel of excellent quality.

The Elin Biofuels plant is located in the 2nd Industrial Zone of Volos.

The annual production capacity of the plant is 80,000 tn of biodiesel. The production process is controlled by a fully automated optical monitoring system.

Production process

The production process is constant and comprises the following stages:

  • Purification of used cooking oil: Before being used in the production of biodiesel, the used cooking oil undergoes a purification process in order to meet the process specifications standards.
  • Acid Esterification Unit: This unit receives the high acidity UCO, turns its fatty acids into methylesters and gives a mixture of Fatty Acid Methylesters, (FAME) and low acidity oil.
  • Tranesterification Unit: It is the basic production unit of the Plant, where the product of the Acid Esterification Unit undergoes a transesterification reaction under the presence of excess methanol and a basic catalyst (potassium methoxide) towards the production of fatty acid methyl esters (biodiesel). The product of this unit contains numerous compounds (such as methanol, soaps, catalyst, water) that need to be removed.
  • Biodiesel refining unit: Biodiesel produced from the transesterification unit undergoes three washing steps, one of which combines an acidulation step, and then it is vacuum dried so that the levels of water, methanol and remaining catalyst fulfill the EN14214 specifications.
  • Biodiesel Distillation Unit: Biodiesel produced from waste material is further processed to the biodiesel vacuum distillation unit so that any heavy components (such as polymerized fatty acid methyl esters) or traces of sulfur are removed. The final product of the plant is produced in this unit.
  • Glycerine purification unit: glycerine is the main by-product of the production process of biodiesel.
  • Methanol rectification unit: In order to recover the methanol contained in the process water, so that it can be re-used in the production process, it undergoes a distillation step.
  • Water recuperation unit: After the rectification of methanol the water is initially evaporated in a multi effect vacuum evaporator system and then the light ends are separated in a distillation column. The clean distilled water is stored in the tank and is re-used in the process.

Storage Tanks

The storage tanks for the raw material are placed on a reinforced concrete base.

These tanks are 13 in total with a total capacity of 5,429 m3, while the capacity each tank fluctuates between 56 m3 and 1,184 m3.
The produced biodiesel is stored in 6 tanks with a total capacity of 125 m
3 each tank.

Supporting Installations

Electrical Substation

It consists of a 1250 kVA transformer and medium and low voltage boards and a 500 kVA generator that ensure the uninterrupted operation of specific machinery, such as those involved in the production process and a safe emergency shut-down.

Steam production unit

It consists of 2 boilers with a total capacity of 18,000 kg/hour at 10 bar saturated steam.

Water softening unit – Reverse Osmosis Unit

All water used for the steam boilers and the cooling towers is treated in the water softening unit where salts are removed and in the reverse osmosis unit where all the mineral compounds are removed.

Cooling towers

Two cooling towers operate in the plant. The system includes the towers, two depression pumps (or one auxiliary), the tank situated under the tower as well as the automatic top-up system.


A sophisticated ventilation system absorbs the malodorous air from the UCO treatment unit pass it through a water shower system and then leads it to the Biofilter that absorbs all the odor gases and gives out fresh air with a pleasant after-rain forests smell.It is made up of a concrete bed which is full of small pieces of wood that promote the growth of micro-organisms in the appropriate moisture conditions that eat-up the organic substances that cause the bad odor.

Analytical Laboratory

According to Greek law, the final product must fulfill the specifications of the ELOT EN 14214 standard. The laboratory of the plant is fully equipped with all the relevant equipment to ensure the high quality of the final product, perform the relevant tests for the constant monitoring of the whole production process and to perform quality tests in all row materials. Furthermore, the laboratory is very active in research activities on the performance of different origin biodiesels, additives, new products etc., in collaboration with Greek and European research centers and institutes.

Raw Materials

The raw material used for the production of fatty acids methyl esters is oil. This oil is of two types:

a) used cooking oil and animal fats
b) seed oil (sunflower, soya, cotton, etc).

Methanol and catalyst (potassium hydroxide or potassium methylate or sulfuric acid) are used for the transesterification and esterification reactions.

The required alcohol to complete this esterification reaction is methanol. The final product is fatty acids methyl esters (biodiesel) and the by-product glycerine. The transesterification reaction is carried out in two stages to ensure complete reaction of the raw materials. The esterification of the raw material is described by the following reversible reaction: