A plain-language guide to how pyrolysis turns plastic, tyres and other waste into fuel and energy, and why the way the material is heated makes such a difference to what comes out.
What is pyrolysis?
Pyrolysis is the process of breaking down materials with heat in an oxygen-free environment. Because there is no oxygen, the material does not burn. Instead, long molecules such as plastic polymers or tyre rubber are broken into smaller ones that can be collected as oil, gas and solid carbon.
This is why pyrolysis is often called thermal depolymerization. It turns waste that would otherwise go to landfill into fuels and raw materials.
Plastic pyrolysis: turning waste plastic into fuel
In plastic pyrolysis, mixed waste plastics are heated until they break down into vapour, which is condensed into liquid fuel. With the right process control the outputs include diesel fractions, naphtha and carbon products.
PVC is not suitable as a feedstock, because it releases chlorine when heated.
See our plastic to fuel plants →Tyre pyrolysis: tyres to oil and carbon black
End-of-life tyres can be processed the same way. A tyre pyrolysis plant separates a used tyre into pyrolysis oil, recovered carbon black and steel wire, each of which can be sold or reused.
See our tyre pyrolysis plants →Waste to energy
Pyrolysis and related thermal processes can also handle municipal solid waste (MSW), biomass, medical waste and coal. Here the goal is energy: electricity, syngas, synthetic natural gas (SNG) and even sustainable aviation fuel (SAF).
See our waste to energy plants →Flash pyrolysis vs phased pyrolysis
Flash pyrolysis heats material very quickly at relatively high temperatures. It works across a wide range of feedstock, but the rapid heating can lower product quality for materials that need slower, more controlled heating, and the final product can be less stable.
Phased pyrolysis, the approach Technotherm uses, heats material over a series of distinct phases, each with its own conditions, at much lower temperatures over a longer period. The result is significantly more stable, higher quality products, including Ultra Low Sulfur Diesel (ULSD) fractions such as diesel and naphtha.
How do I know if pyrolysis will work for my waste?
Every waste stream is different. The safest way to find out what yields and product quality you can expect is to test a sample of your own feedstock in a lab or pilot plant before you invest in a full-scale plant.
Learn about lab and pilot plant testing →