The journal Sustainable Chemistry One World published a comprehensive review by Hassan Bouaik et al. on the pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More of macroalgal biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More for bio-oil, biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More, and biosyngas production. This study highlights the growing global interest in aquatic biomass as a renewable energy source and its environmental advantages. Pyrolysis, a thermochemical process, is identified as a particularly efficient method for converting biomass into valuable energy products, including biochar, bio-oil, and biosyngas. The review delves into the various pyrolysis methods and how operating parameters like temperature, heating rate, and residence timeResidence time refers to the duration that the biomass is heated during the pyrolysis process. The residence time can influence the properties of the biochar produced.   More influence the yield and quality of the resulting products.  

The study reveals that slow pyrolysis, characterized by lower temperatures and longer residence times, is optimal for producing biochar, a carbon-rich solid with applications in soil fertility enhancement and carbon sequestration. Conversely, fast pyrolysis, which involves higher temperatures and shorter residence times, maximizes bio-oil production, a liquid biofuel with potential as a substitute for fossil fuels. Intermediate pyrolysis offers a balance between biochar and bio-oil yields, while flash pyrolysis, utilizing very high heating rates, is geared towards biofuel production. Catalytic fast pyrolysis and microwave-assisted pyrolysis are also discussed, showcasing their potential to enhance product quality and yield. Co-pyrolysis, the simultaneous pyrolysis of macroalgae with other biomass or waste materials, is presented as a strategy to further improve bio-oil properties and overall process efficiency.  

The review emphasizes the importance of optimizing pyrolysis parameters and feedstockFeedstock refers to the raw organic material used to produce biochar. This can include a wide range of materials, such as wood chips, agricultural residues, and animal manure. More selection to achieve desired product outcomes. Macroalgae are highlighted as a promising renewable resource for bioenergy production due to their rapid growth, high oil content, and minimal competition with agricultural land. The versatility of pyrolysis products is underscored, with biochar finding applications in environmental remediation, bio-oil as a potential biofuel, and biosyngas as a source of energy and chemical feedstock. The review concludes by advocating for the development of cost-effective and sustainable pyrolysis methods to maximize the potential of macroalgae for bioenergy production.  

SOURCE: Bouaik, H., Madihi, S., El Harfi, M., Khiraoui, A., Aboulkas, A., & El Harfi, K. (2025). Pyrolysis of macroalgal biomass: A comprehensive review on bio-oil, biochar, and biosyngas production. Sustainable Chemistry One World, 5, 100050.