In a comment on a LinkedIn post of us, you emphasised gasification as the preferred method of chemical recycling. What are the advantages of this technology over other methods of chemical recycling?

Likharev: Simply speaking, gasification is the most versatile method, both upstream and downstream. On the upstream, it can utilize all types of carbon-containing waste, including plastics, solid communal waste, end-of-life tires, agriculture and animal waste, wood and textile scrap, etc. Gasification converts them to so-called synthesis gas, a mix of carbon oxide, hydrogen, and light hydrocarbons. On the downstream, syngas could be converted to a variety of valuable products like electricity, sustainable fuels or chemicals. Even today’s darling hydrogen could be extracted out of it.

You also mentioned high energy recovery rates and low oxygen consumption in gasification. Can you explain this in more detail?

Likharev: In fact, any carbon-containing waste contains a lot of hidden energy inside. Only a small fraction of it, around 15-20%, is enough to destroy the polymer composition of plastic and dismantle it into individual molecules and atoms. To achieve this process, you need an oxidation reaction to happen, where oxygen compounds with carbon and hydrogen contained in plastic. The trick is how to make this process achieve a high recovery rate of this internal energy, using as little oxygen as possible.

We employ a so-called updraft counterflow reactor, which is the most energy-efficient out of all other types. Within this unit, the internal chemical reactions are so well organized that every Joule of internal energy, extracted from waste by the partial oxidation of carbon, is used to support other reactions like drying, pyrolysis, and tar cracking. Because of this high energy efficiency, oxygen consumption is low.

This brings a lot of benefits. The oxidation zone in the reactor is small and very hot, sometimes exceeding 1200°C. Because of this, hazardous substances are entirely destroyed inside the reactor. Due to this and also because of low consumption of oxygen, the filtration system of outgoing syngas is efficient. Consequently, the gasification equipment could be made small, compact, and affordable. Finally, it could fit into a size of a standard 20-foot container, allowing utilization of waste straight at the spot where it is generated, without the need for transportation. Additionally, electricity produced from waste could be consumed locally.

All of this allows the users of gasification technology to reduce waste landfilling and electricity consumption fees by 20-30%. Sustainability meets profitability here!

Given your experience, how do you assess the role of chemical recycling in the context of the global waste and plastics crisis? What role do you think this technology can play in the future?

Likharev: Current traditional mechanical recycling technologies have limited potential; they can utilize less than 10% of plastic. Advanced thermo-chemical recycling technologies, providing the decomposition of plastic waste into individual molecules and atoms, allow us to recycle all types of plastic and thus counteract plastic pollution without attempting to ban plastic usage itself.

Furthermore, gasification technology could help resolve another huge problem: the greenhouse gas emissions from dumped waste. Landfills produce about 2 billion tons of carbon dioxide equivalent, or 4% of these emissions globally. Gasification of waste instead of its dumping could eliminate this problem, decreasing the carbon footprint from waste by 5 times.

Let’s dump landfills together!

source: Elena Blume (Editorial team K-Mag)

https://www.k-online.com/

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