16 Dec 2012

How to Make Oil From Plastic (theory)

Among the many irremediable wounds that man is inflicting upon the environment, the improper disposal of waste plastic is growing into an alarming issue of concern. 

Despite its amazing properties of strength, durability and its light weight, plastics have a major drawback: they can take up to 500-1000 years to naturally degrade. So if plastic had been discovered 500 years ago, and if Shakespeare used to brush his teeth, then his toothbrush would still be lying somewhere in England!

Some other issues with waste plastic are that it affects humans, animals and marine life; it causes soil infertility where dumped; and only 8% of all plastic waste is recycled! Sounds a trifle, right! Another lesser known factual reality is that for the production of plastic, 7% of the global crude oil is consumed, which is more than China's total crude oil consumption. 

So what do we do with these ever-growing mounds of plastic waste? Bury plastic underground? Burn it? Or launch it into space! These solutions are more disastrous than the problem itself.


The Japanese inventor Akinori Ito popularized the ingenious idea converting waste plastic back into fuel oil through plastic pyrolysis. Pyrolysis is a thermochemical decomposition of organic material at elevated temperature without the participation of oxygen.

Akinori Ito displaying his
pyrolysis machine for home
In this process long polymer molecules are broken down into shorter chains of hydrocarbons with the help of heat and pressure. Essentially the process is mimicking the natural process by which organic materials are broken down into oil in the nature which takes million of years. The pyrolysis process does this with intense heat in a closed system in a short amount of time. A catalyst can be used to lower the temperature and increase the yield. Other substances which can be pyrolyzed are biomass, waste tire, lubricating oils, coal and petroleum residues; waste tire pyrolysis being the most popular and the most profitable of them all. 

The basic process of pyrolysis goes as follows:

1. Shredding
Firstly, the waste material must be segregated and, if possible, be cleaned. Then it is shredded to speed up the reaction and to ensure that the reaction is complete. 

2. Anaerobic heating 
The shredded material must be heated in a controlled manner in an oxygen-free reactor. One of the most crucial factors in this operation is maintaining the right temperature(~430C for plastic) and the rate of heating, as they define the quality and the quantity of the final product. 

3. Condensation

The gas that comes out from the reactor must be condensed by passing it through a condensation tube or by directly bubbling it in water. 

4. Distillation 

This mixture of oil that you obtain can be used as furnace oil but it isn't sufficiently pure for engines. If you want to use it as engine fuel, you need to extract and purify the desired products from the mixture through fractional distillation. 

Some benefits of pyrolysis are that the process does not generate harmful pollutants and that the by-products can be used as fuel for running the plant. In the case of plastic, some
 of the valuable fuels and solvents that can be extracted through waste plastic pyrolysis are gasoline, kerosene, diesel, benzene, toluene and xylene. And a kilo of waste (typically PP) can yield upto a litre of fuel whereas the incineration of the same quantity of plastic would produce 3 kilos of CO2! 

So through this process of pyrolysis, the bane of abhorrent plastic waste, can now become a boon and a source of abundant fuel. This will reduce plastic in landfills, reduce emissions and be a reliable alternative to the depleting fossil fuels. Don't trash your future. Act now!