From trucks to school buses, diesel engines are present in almost all modern transportation systems. They often use petroleum-based fuel, releasing different toxic gases into the environment. Therefore, we need a sustainable alternative to conventional diesel to conserve our environment. Apart from that, fossil fuels are also diminishing rapidly, increasing the need for renewable alternatives.
FAME (Fatty Acid Methyl Esters) biodiesel has emerged as a suitable substitute for petroleum-derived diesel. It is made from different renewable sources and releases fewer greenhouse gases than fossil fuels. Under British Specification, 7% FAME is currently allowed in regular pump diesel. In this post, we will tell you how FAME diesel is made and its pros and cons.
Preparation of FAME Biodiesel
FAME biodiesel is prepared from natural resources, oils or fats. They have high molecular weight and contain long chains of fatty acids, called triglycerides or lipids, that undergo transesterification in the presence of an alcohol to make low molecular weight FAME esters. Reaction conditions are high temperature and a base catalyst. The most commonly use catalyst is potassium hydroxide (KOH).
Transesterification Mechanism
Transesterification is a reversible reaction that takes place by mixing all the reactants in a reaction vessel. Oil/fat and alcohol are the reactants, and a catalyst will boost the reaction speed. Methanol is commonly used alcohol for this reaction as it is readily available and is affordable as well.
During the reaction, 3 alkoxy (R-O) groups detached from the triglyceride and form glycerol with 3 hydroxyl groups from methanol. The remaining triglyceride bonds with the alkyl part of methanol to give FAME.Â
The reaction is endothermic, meaning it will speed up as you raise the temperature. However, you need to increase the pressure in the reaction vessel when exceeding the temperature above 65 degrees Celsius to avoid evaporation of methanol.Â
Commonly Used Oils/Fats for FAME Biodiesel
Almost all types of plant-based oils and animal fats are used to make FAME biodiesel, including:
- Tallow
- Butterfat
- Sunflower oil
- Rapeseed oil
- Soya oil
- Palm oil
Apart from that, waste cooking oil/fat can also be used to make this biodiesel.
Benefits of FAME Biodiesel
FAME biodiesel is not just a substitute for petroleum-derived fuels but also offers some exciting benefits, including:
Sustainable Alternative to Conventional Fuel
The primary benefit of FAME is that it’s a green alternative to regular fuel. Firstly, the manufacturing process has less environmental impact than other fuels. Secondly, it doesn’t contain sulphur, so there will be no emission of SO2 gas during the combustion process.
Safe Option
FAME is a safer option than other fuels as it’s non-toxic and doesn’t cause any specific allergy or irritation when it comes in contact with the skin.
Reduce Greenhouse Gases
FAME, being a biodiesel emit less greenhouse gases during the burning process, playing an essential role in controlling global warming.
Renewable
FAME is a renewable fuel, as it is made from natural resources, such as oils and fats.
Problems in Using FAME Biodiesel
There are specific problems associated with using FAME biodiesel. These problems are:
Contamination Problem
One end of the flame is hygroscopic, enabling it to retain moisture more readily than other fuels. Moisture can contaminate the fuel and lead to diesel bugs, bacterial growth, and yeast development. It is biodegradable, so these microorganisms can easily consume it as a nutrient source. If the problem is left untreated, the fuel becomes useless quickly.
Shorter Shelf Life
The shelf life of FAME is less than other diesels, as hydrolysis and oxidation may take place overtime. As a result, the fuel will discolour and damage the machinery when used.
Poor Performance in Cold Weather
Fatty acid methyl esters may start crystallising at low temperatures, making it difficult to operate the engine. So, it’s not a good option in cold weather.
How to Avoid Contamination Problems?
The problems with FAME biodiesel can be fixed by taking immediate action. To avoid contamination of the fuel, you must regularly inspect the fuel. Professional inspection or testing can be done annually. However, it would be best if you personally look for symptoms of FAME fuel contamination every 2 to 3 months. The main symbols are:
- Water droplets in the fuel tank
- Change of fuel colour or smell
- Issues with your vehicle
- A damaged fuel tanks
If you observe these symptoms, opt for immediate fuel filtration, as neglecting it can become a significant problem.
