Biodiesel is a diesel like, biodegradable and non-toxic fuel produced from organic material. The organic raw material used for producing bio-diesel includes fatty substances such as vegetable oils, waste cooking oil, animal fat and non-edible plant oils. The properties of bio-diesel resemble closely to petroleum based diesel. Also, existing diesel engines do not require major modifications in order to run on bio-diesel. Thus, scientists all over the world are considering it as a substitute to diesel.
Nomenclature of biodiesel blends:
Like ethanol blends, there is a specific method to denote bio-diesel blends. Consider the following example.
Where B stands for bio-diesel
10 denotes the percentage of biodiesel in blend by volume
Thus, in simple terms, B10 means 10% biodiesel and 90% diesel.
Similarly, B50 means 50% biodiesel + 50% diesel while B100 means 100% bio-diesel.
There are several techniques available for converting the organic material into bio-diesel such as microemulsion, pyrolysis or thermal cracking and transesterification. Among these, transesterification has achieved commercial success worldwide.
Transesterification is a reaction between the raw material and a suitable alcohol which takes place in presence of a catalyst. Generally, industries prefer using methanol or methyl alcohol. However, other alcohols are also effective. In transesterification, large triglyceride molecules present in the oil are converted into straight chain molecules. Thus, technically, bio-diesel is a 'mono alkyl ester'.
Advantages of biodiesel:
- As bio-diesel has higher cetane number compared to petroleum diesel, it helps in reducing ignition delay during combustion process.
- Higher cetane rating also ensures better combustion.
- Reduces emission of CO, CO2 and unburnt hydrocarbon.
- It has better lubricity which reduces wear of the engine parts.
Disadvantages of biodiesel:
- As energy content of bio-diesel is less (almost 9% lower) compared to diesel, fuel economy or average of vehicles running on it lowers slightly.
- NOX emissions of the engine increase while running on bio-diesel.
- Use of bio-diesel may cause cold staring problems for engines.
- Using homemade bio-diesel can cause serious damage to engine.
Biodiesel in India:
According to the Indian government, fuel blend B20 will be regularly used throughout the country by year 2017. However, some reports suggest that the target is difficult to meet and at present only B5 is available in some outlets.
Here is a list of some of the bio-diesel manufacturers in India: