Local businesses serve as the foundation of regional economies and cultures, with their value driving economic growth and indicating the unique characteristics of local resources. In Taiwan’s local industries, the water caltrop stands out as a product of historical and cultural significance. Water caltrops are often seen with their shells discarded as waste. As the global community started to invest in sustainable development goals (SDGs), a company named “Guantian Black Gold” has found a way to transform these discarded water caltrop shells into biochar. This innovation has unlocked new possibilities for sustainability by turning waste into a usable resource. Biochar can be further processed into eco-friendly products such as shampoos, hand soaps, and other daily necessities, integrating local agricultural heritage with modern sustainable practices. The actual motivation for this action will not only highlight the potential of reusing agrarian products but also demonstrate the creation of local industries for sustainable development. By giving new life to water caltrop shells, Guantian Black Gold aligns with environmental goals while supporting the local economy and preserving cultural heritage. The reuse of water caltrop shells reflects the importance of innovation in local industries, where tradition can intersect with sustainability to create economic and environmental value. This approach not only reduces waste but also fosters a circular economy, promoting long-term development that benefits communities. Overall, the success can also serve as a powerful reminder that even small, localized efforts can have a significant and lasting impact.