Development of Low-Cost Algal Tree for Urban CO₂ Capture and Air Purification

Rapid urbanization and vehicular emissions have significantly increased atmospheric CO₂ levels and air pollution in Indian cities, creating the need for sustainable and affordable air-purification technologies. In this study, a low-cost algae-based photobioreactor system named “Algal Tree” was developed for biological carbon capture and urban air-quality improvement under Indian environmental conditions. The project focuses on integrating microalgal cultivation with sustainable waste-utilization and smart urban utility applications. Two outdoor prototype models were successfully developed and deployed for real-time environmental applications. The first mini 25 L capacity prototype was installed at ISBT Dehradun, Uttarakhand, India on 19 May 2025, while the second 100 L capacity model was installed at the university bus stand on 5 June 2025 (World Environment Day). The developed system integrates solar-powered operation, seating facilities, mobile charging, and street-light functionality to improve practical urban usability. The Algal Tree was designed as a cost-effective alternative to large-scale showcase systems while supporting atmospheric CO₂ sequestration, sustainable urban infrastructure, and public environmental awareness. The project also emphasizes renewable energy integration and scalability for future smart-city applications. Ongoing work includes system optimization, biomass utilization studies, and large-scale environmental performance evaluation for sustainable urban deployment. Project Introduction The Algal Tree project focuses on the development of a low-cost algae-based photobioreactor system for urban CO₂ capture, air purification, and sustainable smart-city applications under Indian environmental conditions. The project was developed using waste-utilization and sustainable design approaches to create a practical and scalable environmental technology.