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Castor Oil For Biodiesel

Castor oil, owing to its chemical structure has the potential to be used as a bio-fuel in place of petrol-based fuels. In the last few years, there has been a growing debate on whether castor oil can be an effective biofuel (biodiesel) stock.

Interested to know if castor oil can be an efficient bio-fuel and bio-diesel?

Analyze the following:

  •  Characteristics of oils or fats affecting their suitability for use as fuel
  •  Characteristics of efficient bio-fuels and bio-diesels
  •   How does the bio-diesel derived from castor oil rate on the above aspects
  •  Based on the above three aspects, preliminary inference for “Can Castor Oil  Make a Good Biodiesel?”


Characteristics of Oils Affecting their Suitability for Use as Fuel

The following aspects need to be considered while evaluating a plant oil feedstock for biofuel.

·         Melt Point or Pour Point

·         Cloud Point

·         Flash Point (FP)

·         Iodine Value (IV)

·         Viscosity

·         Aniline Point/Cetane Number (CN)

·         Density

·         Ash Percentage

·         Sulfur Percentage

·         Potassium Percentage


 Characteristics of Efficient Bio-fuels and Bio-diesel

Biodiesel is noteworthy for its similarity to petroleum-derived diesel fuel, while at the same time having negligible sulfur and ash content. Bioethanol has only about 70% of the heating value of petroleum distillates such as gasoline, but its sulfur and ash contents are also very low. Both of these liquid fuels have lower vapor pressure and flammability than their petroleum-based competitors – an advantage in some cases (e.g. use in confined spaces such as mines) but a disadvantage in others (e.g. engine starting at cold temperatures).

Engine Manufacturers Association (EMA) Recommended Guideline on Diesel Fuel 


Test Method


#1 DF(1)


#2 DF(1)

Flash Point, °C min.

D 93



Water, ppm max




Sediment, ppm max

D2276 or D5452



Distillation % Vol. Recovery, °C

D 86



90%, max.




95%, max.




Kinematic Viscosity, 40 °C

D 445

1.3 - 2.4

1.9 - 4.1

Ash, % max.

D 482



Sulfur, % max.

D 2622



Copper Corrosion, max.

D 130



Cetane Number, min.

D 613



Cetane Index, min.

D 4737



Rams Carbon, 10% residue max.

D 524



API Gravity, max.

D 287



Lubricity, g. min.




Accelerated Stability, mg/L max.

D 2274



Detergency - L10 Injector

CRC Rating



Depositing Test

% Flow Loss



Low Temperature Flow, °C

D2500 or D4539



Microbial Growth





 How does bio-diesel derived from castor oil rate on the above aspects?

·     Iodine Value   : The transesterified castor oil has an iodine value of about 85. This is quite an acceptable value for biodiesel. The lower the iodine value, the better the fuel will be as a biodiesel. 

·         Cetane Number: The higher the cetane number, the better is the fuel as a diesel. The Cetane Number of most biodiesel fuels are higher than petro-diesel (cetane number of petro diesel is about 45, while for most biodiesel, the cetane number falls in the range 45-65), and the cetane number of castor oil biodiesel is in acceptable range for diesel engines.

·         Melting Point : 5ºC. This is acceptable for diesel engines.

·        Solidification Point: Castor oil has a very low solidification point (-12ºC to -18ºC). This is a positive characteristic for colder climates, since it implies that the biodiesel from castor oil solidifies fewer times than those biodiesels with higher solidification points.


·        Density: Castor oil, before transesterification has a density of 0.956-0.963 g/ml (@ 20 degrees C. The conversion into alkyl esters decreases the density by a small extent, hence one can expect the castor oil based biodiesel to have a density of about 0.9 g/ml. (Comparative values are approx 0.74 g/ml for gasoline and 0.85 g/ml for diesel). While the castor oil biodiesel has a density somewhat higher than petro-diesel, this is unlikely to be a bottleneck as the difference is not very high.

·        Flash Point: 260oC. It compares favourably with other vegetable oils.

·        Cloud Point: < -7oC; within acceptable range.

·        Pour Point: At a pour point of about -32°C, it compares well with other plant oils, and is acceptable in diesel engines.

·         Ash content: Castor oil has an ash content of about 0.02%

·        Sulfur %: is less than 0.04%

More analysis on the above in terms of various aspects can be found from the Comprehensive Castor Oil Report

 Evaluation Table for Castor Oil as Biodiesel Candidate

 A comparison on various parameters is made for castor oil properties with those suggested for suitable diesel fuel as well for biodiesel. Refer to the above section for more details of comparison


Suitability of castor oil

Iodine Value


Cetane Number

Less than minimum prescribed

Melting Point


Solidification Point



Slightly higher than diesel, but this is unlikely to pose problems

Flash Point


Cloud Point


Pour Point


Ash Content


Sulfur Percetange




Heating Value

Slightly less than diesel, but within acceptable limits

Water Content

Higher than prescribed



API Gravity




Carbon Residue


Acid Number


Phosporus Content


Free Glycerine

Higher than prescribed

Distillation Temperature



Higher than prescribed


 Following are some of the initiatives that are being taken in order to explore the viability of castor oil as a biodiesel feedstock.

In January 2012, Israel based plant breeding company, Evogene Ltd., launched a wholly owned subsidiary, Evofuel Ltd., to accelerate the development and commercialization of castor bean varieties in Brazil for biodiesel and biojet fuel production. Evofuel, then entered into an a collaboration with T6 industrial  to develop castor bean varieties and evaluate them under rain fed conditions as an effective drought tolerant and oil yielding crop in Argentina.

Earlier, in 2010, Evogene Ltd. conducted a Life Cycle Assessment (LCA) of biodiesel production from castor bean varieties. Results showed that Evogene's castor bean biodiesel

  • Reduces net GHG emissions by 90% in the U.S. and more than 75% in Brazil compared with conventional diesel, if grown in non-arable or marginal land.
  • Exceeds the GHG savings achieved with soybean biodiesel, with reductions for the U.S. of 43% compared to soybean.

The Petroleum Corporation of Jamaica along with the Caribbean Agricultural Research and Development Institute (CARDI, launched a pilot project in 2011 to trial biodiesel production from castor oil and Jatropha. The research and development phase of the project will involve the cultivation and harvesting of six varieties of the oil nuts, to determine their oil content, harvesting potential and relative productivity.  The oil nuts will be cultivated on mined-out bauxite lands between April, 2011 and March, 2014.

In 2012, Rokim Group Limited based in Kenya, started growing hybrid castor beans for the production of high grade bio diesel for the utilization in road transport, power generation and industrial sector in Kenya.

In Nov 2012, Mexican researchers at the University of Puebla (BUAP) have begun experimenting with biodiesel production from castor oil, fuel that will later be used to run the university’s transport system. The pilot plant under development will produce up to 72,000 liters of biodiesel daily.

 In India, the Center for Jatropha Promotion, CJP is researching farming castor in conjunction with the Pongamia Pinnata and Indian Mustard.


More insights, facts and data on the Castor Biodiesel is available from the Comprehensive Castor Oil Report