Thermochemical Conversion of Waste Materials to Energy

Thermochemical conversion encompasses a suite of high‐temperature processes that transform waste polymers, biomass and organic residues into usable energy carriers such as gases, liquids and solid chars. Central approaches include pyrolysis, gasification and hydrothermal liquefaction, each operating under controlled temperature, pressure and atmosphere to break chemical bonds and restructure feedstocks. Pyrolysis employs an oxygen‐free environment to produce bio‐oils, syngas and biochar, while gasification introduces a limited oxidant to yield a hydrogen‐ and carbon monoxide–rich synthesis gas. Hydrothermal liquefaction treats wet biomass under sub‐ or supercritical water conditions to generate a biocrude oil without energy‐intensive drying. Catalytic depolymerisation and co-processing strategies further enhance selectivity towards transport fuels, high-value chemicals and hydrogen. Advances in reactor design, catalyst development and co-feed integration have improved yield, reduced carbon intensity and enabled valorisation of mixed and contaminated waste streams. Globally, thermochemical routes offer scalable pathways for decarbonising power generation, producing sustainable transport fuels and closing material loops in a circular economy, thereby addressing waste management and climate challenges in a unified framework.

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Thermochemical Conversion of Waste Materials to Energy publication trend

The graph below shows the total number of articles in thermochemical conversion of waste materials to energy across all publications each year (not limited to Nature Index journals).

Technical terms

Pyrolysis: Thermal decomposition of organic matter in the absence of oxygen to produce bio-oil, syngas and biochar.

Gasification: Partial oxidation of carbonaceous feedstocks at elevated temperature to generate a hydrogen- and carbon monoxide–rich syngas.

Hydrothermal liquefaction: Conversion of wet biomass under high-pressure water into a crude-like biocrude without prior drying.

Biocrude: Complex oil produced from biomass or mixed waste via hydrothermal processes, amenable to upgrading into transport fuels.

Catalytic depolymerisation: Breakdown of polymer chains into smaller hydrocarbons or monomers through the action of solid catalysts under controlled conditions.

References

1. Green hydrocarbons and fuels from municipal polymer waste co-fed with natural gas using a batch catalytic slurry process. Green Technologies and Sustainability (2024).
2. Multilayer plastic film chemical recycling via sequential hydrothermal liquefaction. Resources Conservation and Recycling (2023).
3. Co-liquefaction of Macroalgae with Common Marine Plastic Pollutants. ACS Sustainable Chemistry & Engineering (2019).