Value Adding on Castor - A Tale of Missed Opportunities - Ravi Raghavan

India is the dominant producer of castor oil in the world – a status that the country has in few other commodities. This domination is unlikely to be challenged in the near future thanks to the unique set of agro-climatic conditions, farming habits and history of castor cultivation that the country has. Very little of castor oil is consumed as such and most of it is converted into a slew of derivatives that find diverse applications. This is made possible by the unique chemical structure of castor oil, which is unlike most other oils, and allows for several types of chemical transformations.

India’s dominance in Castor Oil is however not shared when it comes to the derivatives that emerge from it. The derivatives currently produced here are restricted to basic ones, made by simple chemical processes, and much of the value-addition is done elsewhere in the world – all based on purchased castor oil from India. Reams of pages have been written (including by this author) on the need to carry out value addition locally, but little has happened so far.

The time has come for this to change. The Ministry of Chemicals and Fertilisers seems to be seized of this matter, and is said to be considering setting up of a committee to deliberate on the matter and come up with concrete steps that will encourage local entrepreneurs to more comprehensively leverage the resource India is uniquely blessed with.

A primer on the oil

All vegetable oils are triglycerides of fatty alcohols of varying chain lengths, but castor oil is unique in the sense that it has unsaturation and a hydroxyl group that serve as centres for chemical conversion. The principal fatty acid in castor oil is ricinoleic acid – a C18, monounsaturated fatty acid, with a pendant hydroxyl group in C7 position. Again unlike several other vegetable oils, castor oil is unique in that the ricinoleic acid content is nearly 90%, which makes for very predictable properties and performance of the oil and its derivatives.

Direct application of castor oil is limited. The most significant use is as a lubricant thanks to its high viscosity in comparison to other vegetable oils. But the unsaturation present in the oil poses stability issues and it is not preferred for long-lasting applications. Smaller uses include cosmetic formulations (mainly as emollient), as a vehicle for parenteral administration of steroidal hormones and as a purgative.

But the true versatility of the oil comes from the several derivatives that can be made from it. Castor oil can be subjected to a variety of chemical reactions including hydrolysis, saponification, hydrogenation, dehydration, epoxidation, halogenation, caustic fusion and pyrolysis. The products obtained find several direct end-uses, and are also subject to further transformations to yield more advanced products – polymers, fragrance chemicals, polyurethanes etc. Some of these command prices that are 30x or greater than that of the castor oil to which they can be eventually traced back.

Indian scenario

Castor cultivation, and much of the crushing of the beans to expel the oil, is largely restricted to three states of India – Gujarat, Rajasthan and Andhra Pradesh – with Gujarat alone contributing to production and export of over 75% of the country’s castor oil. The castor crop acreage does vary from year to year, and is determined not just by market conditions (local and export) for the oil, but also that of competing crops. In 2017, for instance, farmers reacted to the low price in the previous year, by slashing the acreage under castor cultivation and turned to other more lucrative crops such as groundnut, pulses and other oilseeds. As a result, castor seed availability and production of castor oil both fell in 2017, though carryover stocks from the earlier bumper year made up for much of the shortfall.

One way to make the crop more attractive to farmers is to improve yields of castor seed. While high yielding hybrid varieties have been developed and shown to give yields ranging from 3,000-kg/ha to 5,000-kg/ha, the average yield has remained much lower at about 1,500-kg/ha thanks to poor knowledge of good agricultural practices. The Solvent Extractors Association of India, an industry lobby group, had initiated some efforts for yield improvement and launched a pilot project in two districts of Gujarat, and seen significant increase in yields. These need to be scaled up rapidly to boost overall productivity of castor cultivation and thereby sustain the tempo of farmers to keep growing the crop. The government can help by initiating a mission-made programme, like the Technology Mission on oilseeds and pulses that made a significant impact and raised domestic production of these agricultural commodities.

Derivatives production – at a basic stage

Between 70-80% of the castor oil produced in India is simply exported out as such, and only the balance is processed within the country.

Primary derivatives made include hydrogenated castor oil (HCO), dehydrated castor oil (DCO) and DCO fatty acids, ethoxylated castor oil, Turkey Red Oil, methyl ricinoleate and 12-hydroxy stearic acid (12-HSA). The secondary derivatives produced include alkyd resins, fatty amides, undecanoic acid, heptaldehyde, sebacic acid & its esters, 2-octanol, castor oil polyols etc. But the scale of manufacturing of these derivatives remains small and the industry has found it difficult to match the competitiveness of Chinese producers in global markets.

Recent developments in China that have led to a tightening of environmental norms in the country do offer a window of opportunity for Indian producers to expand market share globally, but this will require the derivatives industry here to invest in technology and modernisation. There are new manufacturing approaches that can improve process economics and Lead to better quality products, but are yet to make a significant dent in the marketplace.

Take for instance the classical route for production of ricinoleic acid – fat splitting using alkali. This requires high energy, has high effluent treatment costs, and suffers from issues with product quality. A BIO-based approach using lipase enzymes has been developed by Novozymes, a global leader in enzymes, which can operate at ambient temperature and pressure and has low capital requirements as a consequence of the reaction conditions. The process does have challenges, but these can be overcome in collaborative technology development programmes – an aspect that the castor oil processing industry has largely ignored so far.

Chemistry unexplored

The full chemistry of castor is yet to be explored in India and the range of products that can be manufactured is vast both in terms of chemistry and in the end-uses they serve. Many fine and speciality chemicals that find use as aroma chemicals, ingredients for making synthetic rubbers, polyurethanes, surfactants, fabric softeners, etc. can be made. Admittedly, many of them will be niche products, but these are the types eminently suitable for manufacture by SMEs that abound in the Indian chemical industry. They can serve several application areas such as soaps, detergents, paints, textiles, lubricants, dyes, plastics, pharmaceuticals, fragrances etc. – all with excellent growth potential.

The timing for broadening the scope of chemicals that can be made from castor oil is now. The industry needs to work closely with R&D institutes such as the Indian Institute of Chemical Technology, part of the CSIR chain of labs, which has a dedicated centre for lipid research that has delivered on some exciting technologies for the benefit of the Indian vegetable oil industry.

The focus needs to change from just shipping out unprocessed castor oil to valorisation to the maximum extent possible. This has been done with great success by Malaysia in relation to palm oil. The oleochemical value chain that the country (and Indonesia) has developed is long and broad, and now serves global markets with great competitiveness. One of the tools used by these two countries to encourage value-addition locally is the levy of a tax on export of unprocessed crude palm oil. Whether such a levy can be imposed in the case of castor oil from India is a matter that needs deliberation, but is not one to be dismissed off hand. It is more than likely that the stakeholders in the industry, with eye on the short term, will oppose any such move.

Though some progress has been made in developing castor oil based value-added products in India, the industry and the country still has a long way to go. Exports of castor oil & derivatives are valued at over Rs. 5,000-crore, but this is overwhelmingly oil. This must change. Now.