Future projections and life cycle assessment of end-of-life tires to energy conversion in Hong Kong: Environmental, climate and energy benefits for regional sustainability

The increasing focus on environmental sustainability and the pressing need to mitigate climate change have driven innovative approaches in waste management and energy production. Managing growing waste tires requires strategies that address disposal while contributing to energy generation and climate mitigation. This study employs auto regressive integrated moving average modeling to forecast end-of-life tires generation based on vehicle ownership trends in Hong Kong. A life cycle assessment using the ReCiPe2016 method and a genetic algorithm optimization is applied to assess and optimize the environmental and energy impacts of combined heat and power, gasification, and pyrolysis technologies under two scenarios: the baseline scenario, where 50 % of end-of-life tires are utilized for energy production reflecting current practices, and the enhanced scenario, which increases this to 65 % by including end-of-life tires that would otherwise be improperly disposed of. Although the baseline scenario produced slightly more energy, the optimized use of end-of-life tires in the enhanced scenario prioritized substantial climate benefits through strengthened greenhouse gas mitigation. In the enhanced scenario, greenhouse gas emissions were reduced by approximately 357,825 tons of CO₂-eq annually by 2025, leading to a cumulative reduction exceeding 3 million tons by 2030. Additionally, the enhanced scenario demonstrated improvements in reducing air pollutants such as SO₂ and NO_x, further contributing to better air quality. The findings highlight the potential of integrating end-of-life tires-to-energy technologies for sustainable end-of-life tires management, providing a framework for policymakers and stakeholders to develop effective strategies that contribute to environmental sustainability and public health. The study's methodologies and insights can be adapted to other regions, facilitating the creation of tailored waste tire management policies globally.