Plastic waste to liquid fuel

However there is a silver lining to this dark cloud. In Nagpur (India) a Professor of Chemistry has invented an eco-friendly catalytic process of producing liquid fuels like gasoline, diesel fuel and LPG. This fantastic information is not well know here in Bangladesh. We should in the national interest contact the company that has been set up by the professor in Nagpur and set up similar plant in Dhaka on joint venture, licensing or any other acceptable commercial basis to really add value to our plastic waste. It will not only solve the unending problems of plastic waste management, but also provide a product that saves foreign exchange.

Based on studies carried out a few years back, Dhaka City Corporation collects over 50,000 tons of plastic waste annually. The average collection rate is around 137 tons per day. Roughly around half of this collected waste is recycled. The balance half of the waste can be converted to liquid fuel. If we can manage to recycle all the plastic waste, we can produce liquid fuel where the value addition scope is much higher. The annual foreign exchange saved in terms of fuel import can be estimated at well over $250 million annually. However this will need a large conversion plant which we may have at a later stage, after the process is set up in a smaller scale and we learn to operate it effectively.

Briefly the conversion process starts with sorting of the plastic waste, and cutting, shredding and crushing into more or less uniform size. The sized waste plastic is fed into a reaction vessel after preheating. The process material (waste plastic) is heated to around 250°C and melted. Depending on the waste plastic melt composition, scavenging material may be needed to remove excess chlorine as Hydrogen Chloride gas through the gas scrubber giving Hydrochloric acid as a by product. The rest of the hydrocarbon gas is separated and used independently. It can be used as a fuel to melt the charge of waste plastic. Molten material (waste plastic) is next fed into the main reactor where reaction temperature is maintained between 300-350°C at atmospheric pressure. Reaction takes place in the presence of small quantities of coal and a catalyst which converts the molten waste plastic to hydrocarbons.

Gaseous hydrocarbons are condensed and separated into liquid and gas streams. The gas stream goes through an absorption column where the remaining traces of chlorine and chlorine compounds are removed. This chlorine free gas can be reused in the process for heating, or generating process power. A similar process, popularly called C2F (conserve & convert to fuel) is also available but the cost of the plant, technology and its operating cost based on normal capital financing is higher.

The estimated cost of production including financial cost (at12% every year) could be about ± Taka 16 per litre of fuel produced. This however does not include any financial subsidy which the government normally provides for imported fuel. Even half of the subsidy based on the cost of imported fuel on commercial basis will considerably reduce the cost per litre of this waste recycled fuel. Further, we can claim carbon credit funds available per UN formulae for using recycled fuel which has not been incorporated and it can further reduce the production cost.

Given this opportunity for recovering useful liquid fuel from waste plastic, which also solves the problem of urban waste management the government should provide all logistic and financial support to this worthwhile enterprise which should be a top priority project for Bangladesh. Private sector should be a party too, it may be on a joint venture basis, to progress the project speedily. This double benefit of environment improvement and availability of much needed liquid fuel is an opportunity we should not miss. Once a plant is set up at Dhaka, it should then be replicated in other urban areas. Assuming that the collection of waste plastics in all urban areas in Bangladesh is double that of Dhaka we can recycle over 275 tons per day of waste plastics.

S A Mansoor is Director Engineering, Partex Group.