Manufacture of bioethanol from vegetable and fruit Wwe In Sri Lanka

Abstract

According to statistics more than 40% of vegetables and fruits get wasted in Sri Lanka due to poor packing, handling, transport, storage and the high prices of vegetables and fruits, leading to reduced demands and longer storage times, which results in a high percentage perishing before they are sold to the final consumer. There are fruit and vegetable markets in all the major cities in Sri Lanka, which generate thousands of tons of vegetable and fruit market waste (VFMW) every day, causing major solid waste problems in these cities. The Local authorities dispose VFMW on valuable commercial land, which are converted into open dumps, causing soil, water and air pollution, as well as, bad smell, spread of disease, breeding of insects and pests. The main objective of the project was to find an environmentally, technically and economically feasible solution to the VFMW problem faced by all the major cities in Sri Lanka, by conversion of VFMW into Bio-Ethanol (BE). Fuel Ethanol (FE) is 99% pure Ethanol with a very small water content. FE can be blended with gasoline in the ratio 10-20 volume parts of FE to 90-80 volume parts of gasoline, without phase separation. Moreover, FE blended gasoline can be directly used as fuel in gasoline vehicles without any modifications to their engines. FE is currently manufactured in various parts of the world with readily fermentable agriculture based carbohydrate sources, such as, sugarcane, tapioca, wheat, com, etc. Although there are technologies to manufacture of FE from wood by hydrolysis of cellulose, these echnologies are still not commercialized. Since, agriculture based raw materials and their processing costs are much higher than naturally occurring raw materials, such as, crude oil and coal, the cost of production of FE is much higher than traditional fuels such as, gasoline, diesel, etc. In most of the countries that are producing FE, such as Brazil, heavy subsidies are given by the government to sustain the FE industry, since FE is a renewable source of energy, whereas, crude oil and coal are nonrenewable and the reserves in the world are rapidly depleting. Although considerable advances have been made in the manufacture of FE in the world, literature surveys do not indicate any significant research with respect to manufacture of FE from VFMW. Hence, laboratory scale research was carried out by the authors of this paper to study the possibility of manufacturing FE by fermentation of VFMW followed by distillation. Results showed that the process is technically and economically feasible, since, VFMW can be obtained at zero cost, compared to the high cost of traditional agricultural raw materials. Based on lab research and appropriate calculations, it was found that the cost of production of FE was around Rs.28.00 per litre. The fact that, the selling price of gasoline in Sri Lanka is Rs. 104.00 per litre (May 2007 price) and lO-20% of FE can be added to gasoline clearly indicates that there is a substantial profit margin available to entrepreneurs who wish to invest on a FE plant using VFMW as the main raw material. Apart from being technically and economically viable,manufacture of FE from VFMW will be extremely environment friendly, since, it will minimize 1502 56 pollution of air, water and land and also have a zero carbon dioxide emission (compared to crude oil and coal based systems which have a net carbon dioxide emission of 3 tons per ton of fuel burnt), thereby earning carbon credits to Sri Lanka, that can be converted into valuable foreign exchange through international carbon trading.