When recent graduate Ethan Carter ’25 set out to design his final project in Engineering V last year, he focused on a challenge close to home: protecting Hawai‘i’s coconut trees from the destructive rhinoceros beetle. His solution – a solar-powered neem oil, soap and water solution dispenser – combined sustainable engineering with real-world environmental impact. By automating the release of a natural pesticide to the tops of trees, Carter’s design offered a practical and eco-friendly way to help curb infestations without harming the ecosystem.
Carter developed the idea in Global Sustainability by Design (GSD), where students apply design thinking to global and local issues. He envisioned a system that could dispense neem oil – an extract the beetles dislike – on a weekly schedule. Powered by a solar panel and controlled by a timer circuit, the device delivers the oil efficiently, minimizing labor and waste.
Working closely with his mentor, Eddie Kinnear, Academy Design, Technology and Engineering Department Head, Carter designed and tested multiple prototypes using OnShape CAD software. He explored different nozzle shapes and spray mechanisms, learning through trial and error how to optimize the dispenser’s reach and reliability. His project combined electronics, fluid dynamics and environmental science – an interdisciplinary approach that reflected Punahou’s commitment to hands-on, problem-based learning.
Although Carter graduated last year, his project lives on as a legacy initiative within the Academy’s engineering program. Current students are continuing to refine the system, experimenting with new capsule designs, spray nozzles and refill methods. The goal is to create a model that can be replicated across Hawai‘i to help fight the coconut rhinoceros beetle’s spread.
For the students now building on Carter’s work, the neem oil solution dispenser is more than an engineering challenge – it’s a reminder of how innovation and sustainability go hand in hand. What began as one student’s idea has grown into an ongoing collaboration to protect Hawai‘i’s trees and promote environmental stewardship.
Photos by Kathleen Connelly