How we turn plastic into oil

  • Recyclable plastic (i.e. PET, PVC) is separated and recycled by local partners. Non-recyclable plastic (i.e. HDPE, LDPE) is converted back into crude oil in a classic pyrolysis process.
  • In pyrolysis, plastic is decomposed into the three phases, solid (carbon), liquid (crude oil) and gaseous (methane, ethane) at a temperature of approx. 450°C and under exclusion of oxygen.
  • As energy source for heat generation, we use a mix of harmless waste, organic material and charcoal. All recovered materials should be reused sensibly.

In the field of plastic pyrolysis, we want to cooperate with local producers. The proceeds from the recovered oil shall go to the community to finance this strategy on a self-sustaining basis. This should also create new jobs.

The Origin of Petroleum

Source: ecofriend.com

In order to understand the process of pyrolysis (ancient Greek pyr = fire, lysis = dissolution), it is necessary to understand how crude oil is formed. The starting material is remnants of animal and plant plankton that sank to the seafloor millions of years ago. Because there is no oxygen down there, it was not decomposed.
Thus, it remained as sludge on the seabed, which became up to 100m high in certain places. Later, sand and gravel, as well as other sediments, settled over this layer and solidified. Over millions of years, in this isolated and airtight space, under high pressure and at temperatures of approx. 80 to 150°C, a chemical decomposition of the digested sludge took place, from which crude oil and natural gas developed.

The Pyrolysis

The Processing Quantity

Source: wastetireoil.com

The reactors themselves should allow a daily processing volume of approx. 50 to 100kg. In comparison, conventional systems can process up to 150kg per hour. We just want to process the amount of plastic that the community produces every day. This will also reduce the energy consumption for pyrolysis to the necessary minimum. We have to consider that the pyrolysis process has a negative energy balance. Even if plastic can be regenerated up to 70 percent (i.e. up to 70kg oil can be produced from 100kg plastic), the process requires more energy than the regenerated crude oil contains. This is a common problem many big plants are facing today.
Here, too, we work with external partners to test sustainable approaches to generate the necessary energy. For heat generation, we plan a mix of waste that is not polluted with pollutants (paper, cardboard, wood, etc.), dried organic material and charcoal.

The Oil Quality

As simple as the process sounds, it is complicated in practice. The plastic does not consist of crude oil alone, but also contains many other chemical additives that give the plastic the desired properties such as resistance, hardness, etc. In the pyrolysis process, these molecules also enter the gaseous phase and, after condensation, the liquid phase.
The resulting oil therefore also contains these additives, which can become air pollutants during subsequent combustion. This means that these substances must be eliminated or neutralized before they can be used again. The aim is to maintain a similar oil quality to crude oil so that it can be integrated into the local market and thus contribute to the self-financing of the Community Programme.

Soure: researchgate.net