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Pyrolysis – Plastic to Fuel (PTF)

Background Plastics are an essential material for modern existence, making up many of the everyday products we use, as well as the packaging that encloses a vast variety of products. As economies continue to expand, the production and consumption of plastics has increased to meet the needs of growing markets. Global plastics production is an estimated 335 million metric tons each year and is growing at a rate of 4% annually. With plastic production increasing, plastic waste generation is also on the rise. The World Bank projects that 1.3 billion metric tons of MSW is generated each year, a number that is expected to grow to 2.2 billion metric tons per year (MTPY) by 2025. 10% of the total MSW produced, or 130 Million MTPY, is plastic.

Problem

The plastic recycling industry handles a large proportion of plastic waste by mechanical recycling. Some plastics however, cannot be recycled by this method, and remain a problem in waste management. An estimated 4.8 to 12.7 metric tons of plastic litter enter the ocean every year and despite global initiatives to reduce it, volumes of marine litter continue to increase as the world’s consuming population grows. Largely rooted in inadequate waste management practices on land, an estimated 80% of marine litter originates from land based sources. These weak systems have led to significant increase in both land based and marine litter increase, which is threatening both human and marine life

Solution

Plastics-to-fuel (PTF) technologies or Pyrolysis is one of the potential solutions to reducing plastic marine litter and the landfilling of end-of-life plastics. Pyrolysis refers to the thermal decomposition of a material in an oxygen-free or limited oxygen environment to produce a mixture of oil similar to crude oil, which can be further refined into transportation fuels. 1 Kg of Plastic waste can generate 750ml of synthetic oil.

Process

The process of thermal decomposition is modelled after natural geological processes that produce fossil fuels. Thermal decomposition breaks down complex polymer molecules into shorter hydrocarbon chains through a process known as depolymerisation. Pyrolysis used for PTF conversion involves introducing a polymer feedstock material into a high temperature chamber ranging between 430-550 degrees Celsius to produce a vapour. Vapours are then condensed into condensable (synthetic crude oil) and non-condensable (synthetic gas) fractions. Synthetic crude oil can then be fractionated onsite, usually by way of fractional distillation, into a range of light, middle and heavy distillate fuel oils.

Advantages

It is a viable waste management technology which can be undertaken on a large scale as well as at small scale level in rural areas.Create green direct and indirect jobs (plastics pickers, segregators, PTF plants etc)PTF is complementary to existing recycling efforts as it typically does not target plastic resins that are highly valued by commodity recycling marketsThe waste plastic to fuel process produces very low emission, due to the capture of almost all of the output, both liquids and gases inside the system.The sulphur content in the synthetic oil is usually less than 18 ppm, and used directly for burring without need of any further process.A wide range of plastics can be converted, especially those plastics that are not suitable or are of high enough quality for recycling.Economically viable – produce fuel at a range of $40-50 per bbl.Produce local source of synthetic crude oil to replace fossil fuel that is imported.

Implementation

This process can be carried out both at a household and industrial level.

Household Implementation:

Acquiring Plastic: Either through household waste or can be bought at 10-15 rupees/Kg.Extraction Process: Can be carried out in a specially constructed mould (Pyrolyzer) or in a Pressure Cooker. The apparatus will be connected to a container filled with water through an outlet.Condensation of Gas to Obtain Raw Fuel: The raw fuel will be deposited on top of the water. (1Kg of Plastic converts to 1L of Raw Fuel).Distillation of Raw Fuel: This process is carried to remove impurities to obtain the final product: Diesel. (1L Raw Fuel gives 750ml of Diesel).

Industrial Implementation

Acquiring Plastic: Through Landfills, Ocean dumping, etc.Extraction Process: Plastic put inside a reactor (Pyrolyzer) and heated to 300-500C.Condensation: This plastic after being heated is sent through a condenser, which is at a temperature of 28-30C.Separation: After being condense the matter is passed through a separator where the liquid fuel is separated from the uncondensed gas.Rough Estimate of 35-40 rupees per litre of diesel, after factoring production costs.

Conclusion

It is very difficult to find alternatives of Plastics. As it usage will grow, so will its waste. We will never be able to recycle more than 1/3rd of plastic commercially and incinerating waste is environmentally hazardous and landfilling plastic waste expensive and suboptimal solution. Further, with limited fossil fuels, high prices and volatility, foreign exchange dependence, increasing pollution from burning fossil fuels, Pyrolysis presents a highly sustainable and commercially viable Plastic waste management technique that creates environmentally friendly alternative to fossil fuels. It can be implemented at both rural and industrial level and generate green jobs. Government should create special incentives for setting up Pyrolysis reactors and usage of synthetic/bio fuel.

Arnav Sethi