Wednesday, October 14, 2009

Potential of Indian Butter Tree for Biofuel

Global concerns about the depletion of the world’s non-renewable energy sources and the associated environmental impact of fossil fuel provided the incentives to seek alternatives to petroleum-based fuels. Globally at present, the most widely used fuels are gasoline and Diesel, both coming from fossil fuel. Besides the fear for depletion of fossil fuel, due largely to its non-renewable status, use of gasoline is associated with environmental problems. Aside from being extremely flammable, it contributes to increase hazardous emissions. On the other hand, diesel has higher carbon numbers and it is widely known that it contributes in emissions of high particulate matters, high sulphur dioxide and high poly aromatic hydrocarbons.
The need to consider renewable sources of fuel, with acceptable environmentally friendliness, to meet the ever increasing global energy demands can therefore not be over emphasized. Because of the world’s increasing energy demand and the limited availability of fossil fuels, much research is directed towards development and improvement of alternative renewable fuels. Low-molecular-weight organic liquids can be produced from biomass and can be used or are proposed as fuel for vehicles. The concept of using vegetable oil as a fuel is as old as the combustion engine itself.

Several countries including India have already begun substituting the conventional diesel by a certain amount of biodiesel. Worldwide biodiesel production is mainly from edible oils such as soybean, sunflower and canola oils. Since, India is not self sufficient in edible oil production, hence, some non-edible oil seeds available in the country are required to be tapped for biodiesel production. With abundance of forest and plant based non-edible oils being available in our country such as Pongamia pinnata (karanja), Jatropha curcas (jatropha), Madhuca indica (mahua), Shorea robusta (Sal), Azadirachta indica (neem) and Hevea braziliensis (rubber), no much attempt has been made to use esters of these non-edible oils as substitute for diesel except jatropha.
When we compared to other non-edible oils, not much work has been reported on biodiesel production from Madhuca indica oil (butter tree), which has an estimated annual production potential of 181 thousand metric tones in India. The two major species of genus madhuca found in India are Madhuca indica and Madhuca longifolia. The seeds and oil potential of these trees in the country is 5.00 lakh and 1.8 lakh metric tone respectively. So there is vast resource for the future fuel by which India and Japan both were get benefited.

The conventional method of biodiesel manufacturing is transestrification of fats/vegetable oils to yield fatty acid alkyl esters (i.e., biodiesel) and glycerol in presence of alkaline catalyst. The main factors affecting transestrification are the amount of alcohol and catalyst; reaction temperature, pressure and time; the contents of free fatty acids (FFA) and water in oils.
Reaction time for conventional method either we using an acidic (1-45 h) or basic (1-8 h) catalyst to form the esters is more. In addition, for alkali-catalyzed transesterification, the triglycerides and alcohol must be substantially anhydrous because water causes a partial reaction change to saponification, which produces soap. This soap consumes the catalyst and reduces the catalytic efficiency, as well as causing an increase in viscosity and difficulty in achieving separation of glycerol.
The second complication is the higher amounts of FFA that will increase the saponification process with alkaline catalyst. This unwanted process can consume more catalyst and effect the over all reaction. The soap can prevent separation of the biodiesel from the glycerin fraction. Crude mahua oil contains about 20% FFAs, which is far beyond the 1% level that can be converted to biodiesel using an alkaline catalyst.
Hence, procedures for converting high FFA mahua oil to biodiesel is required as well as the new technique to be discover by which we can immobilized the metal catalyst and passed the oil and methanol during the reaction and save the wastage of catalyst. That will surely minimize the overall cost of the Biodiesel production.
As the global demand of world energy increases, it puts an extra burden on the natural resources. So we have to work a lot regarding the development of biodiesel to cop over this problem. Japan is pioneer in this field. Much work has been done in the “Graduate School of Energy Science, Kyoto University. Kyoto Japan” by Prof. Shiro Saka. India has the resource but research is still in the bottom phase. The mutual cooperation between India ad Japan surely full fill there energy needs.

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