Plastic To Fuel (Using Pyrolysis)
Why is this a good idea?
Plastics are inexpensive and durable. As a
result, level of plastic production by humans are high. Moreover, the chemical
structure of most plastics renders them to resistant to many natural processes
of degradation. As a result, plastics are slow to degrade. These 2 factors
combined to have led to a high prominence of plastic pollution in the
environment. Another factor is also humans, are not having the habit to recycle
plastics, or even just throwing out our trash into bins. As a result, millions
of animals are killed by plastics every year. However, there are many ways we
can reduce plastic pollution by converting these waste plastics into useful
resources. One of the ways is to reuse plastics and convert them into fuels.
Brief Explanation of how it works
Plastic has to go through a densifier that compresses the plastic pieces into dense material to facilitate easier storage . The pyrolysis process takes place in a chamber where plastic is heated to up to 450°C in the presence of a catalyst and in the absence of oxygen. The plastic is slowly melted and is then converted into gaseous stage. The gas will then be sent into a condenser where condensation will takes place. The gas will be converted into liquid state and is then sent into a oil refiner chamber.
More Details of how it works
Plastic is exposed to high temperature is an
oxygen free environment. The frequency at which plastic molecules vibrates is
directly proportional to the temperature of the molecules. During pyrolysis, as
these molecules are subjected to very high temperatures, this leads to very
high molecular vibrations. At this molecular vibration, every molecule in the
object is stretched and shaken to such an extent that molecules start breaking
down into smaller molecules. As plastic is hard to break down, catalysts are
added to help break the chemical bonds. A catalyst is something that makes a
chemical reaction happen more quickly without itself being changed. Usually,
flyash obtained from coal combustion or zeolite are used as catalyst. This
waste plastic is converted into approximately 80% oil, 15% gas and 5% carbon
black or ash.
(Mool, 2021)
What is Pyrolysis?
Pyrolysis is the thermal decomposition of
materials at elevated temperatures in an inert atmosphere, in the absence of
air. It involves a change of chemical composition.
Advantages
- low cost
- reduces the risk of water pollution
- can be burned with a lower carbon footprint as compared to fossil fuels
- prevent waste products such as non-recyclable papers, plastics, wood waste, and textiles from ending up in landfill as they can be converted into fuel
- convert waste to fuel are producing fuels
from combustible materials. These materials such as, non- recyclable papers,
plastics, wood waste, and textiles are all either hard to recycle or
non-recyclable. This is preventing those materials from ending up in a
landfill. (Environmentally friendly)
- plastic pyrolysis can be used with almost any type of common plastic waste
-
Disadvantages
- Pyrolysis is an energy consuming process. More energy has to be put into treating the waste plastic than can actually be recovered.
- Some concerns around health risks due to energy recovery from the waste
(Burning solid fuels can release nitrous oxides, Sulphur dioxides, particulate matter, and other harmful pollutants. However, these emissions can be managed with continuous regulation and pollution control technologies.)
- Pyrolysis is not ideal for certain types of plastic such as PVC as they have a low liquid product yield (Oil) and contain harmful substances when reacted (Hydrochloric Acid)
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