A perspective on transforming fats, oil, and grease (FOG) into hydrogen: insights on steam reforming catalysts and the case study of Hong Kong using techno-economic analysis and life cycle assessment

The increasing demand for sustainable energy has intensified interest in hydrogen production from renewable sources. Although catalytic steam reforming of methane and other feedstocks has been extensively investigated, research on utilizing fats, oils, and grease (FOG) remains limited and dispersed. This study offers a comprehensive analysis of steam reforming catalysts for FOG conversion, concentrating on nickel-based, noble metal, and metal oxide-supported catalysts initially developed for methane, waste cooking oil, and glycerol. Catalyst performance is assessed in terms of activity, stability, cost, and environmental impact, addressing sustainable catalyst design and recycling principles. FOG management strategies are also explored, with a particular emphasis on Hong Kong, where FOG interception is crucial due to infrastructure constraints. Unlike cities where food waste is ground and flushed through extensive sewer systems, Hong Kong necessitates localized FOG removal to prevent costly blockages and environmental harm. A techno-economic analysis demonstrated the feasibility of producing H₂ at a selling price as low as USD 3/kg H₂, with a carbon capture potential of 0.40 kg CO₂-eq/kg H₂. Life cycle assessment (LCA) further confirmed environmental benefits, indicating the potential to capture 0.14 kg CO₂ per kg of FOG processed. Additionally, the study identifies opportunities for cost reduction through more efficient FOG acquisition and valorization, which can enhance carbon savings and economic viability. Overall, this work underscores the potential of FOG as a renewable feedstock and delineates key research directions for catalyst development and integrated waste-to-hydrogen systems.