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Plastic production

  

Plastic consumption has quadrupled over the past 30 years, driven by growth in emerging markets.  Global plastics production doubled from 2000 to 2019 to reach 460 million tons [OECD, 2022].

  

Plastic waste

  

Globally, 9% of plastic waste is recycled, 19% is incinerated, 50% ends up in landfill and 22% is mismanaged (evades waste management systems and goes into uncontrolled dumpsites: is burned in open pits or ends up in terrestrial or aquatic environments) [OECD, 2022].

  

As a result, global plastic waste generation more than doubled from 2000 to 2019 to 353 million tons [OECD, 2022], and the amount of plastic waste generated worldwide is projected to triple by 2060, to surpass one billion ton [STAT, 2023].  There is now (2022) an estimated 30 million tons of plastic waste in seas & oceans, and a further 109 million tons has accumulated in rivers [OECD, 2022].  According to specialists, it would take more than 450 years to biodegrade.

  

Figure 1 shows plastic waste generation by industry sector, highlighting the "packaging sector".  Since packaging tends to have a much lower product lifetime than other products (such as construction or textiles), it is also dominant in terms of annual waste generation [OWID, 2018].

  

Plastic recycling

  

There are two types of plastic recycling: mechanical & chemical; mechanical recycling involves sorting, cleaning, and shredding them to make pellets, which can then be fashioned into other products.  This approach works very well if plastic wastes are sorted according to their chemical composition.

  

Chemical recycling, in contrast, turns the plastic into an energy carrier or feedstock for fuels.  There are two main processes by which this can be done: gasification & pyrolysis.  One of the advantages of plastic waste-to-fuel is that plastic doesn’t have to be separated into different types [WR, 2023].  A modern office can produce a considerable amount of waste, ranging from plastic packaging to small or medium-sized electronic devices: these products are sometimes difficult to separate & recycle properly. 

  

Gasification & pyrolysis are alternatives to incineration.  The main goal of incineration is to destroy the waste, thus keeping it out of landfill: the heat released from incineration might be used to produce steam to drive a turbine and generate electricity.  But, burning plastic is actually one of the highest GHG emitting forms of energy production.

  

Plastic to fuel

 

Plastic pyrolysis plants have already been built in the UK, Japan, and the U.S.  Some advantages of converting plastic waste into fuel include:

  

• Relatively low-cost.

• The plants that convert waste to fuel are producing fuels from combustible materials, which are either hard to recycle or non-recyclable, preventing those materials from ending up in a landfill.

• The produced fuels can be tailored to a certain need, such as transportation, where heat is required. This makes them suitable alternatives to fossil fuels.

• It can be burned with a lower carbon footprint than fossil fuels.

• There is potential to expand the materials used to metal waste and others that may not be easily recyclable.

  

Pyrolysis is one of the most popular processes in converting plastic waste into fuel.  Figure 2 shows the pyrolysis process, with plastics as input and petrol & diesel as output.