Energy Conservation and LED Applications in Water Bamboo Farming

How can agricultural production balance water demand, energy consumption, and environmental sustainability? This seminar featured Professor Yung-Pin Tsai, a Lifetime Distinguished Professor in the Department of Civil Engineering at National Chi Nan University. Speaking on “Sustainable Agricultural Water Management and Low-Carbon Strategies,” he shared his team’s experience working with water bamboo farmers in Puli. From energy-efficient LED lighting and agricultural residue reuse to field water quality monitoring and smart irrigation, Professor Tsai explained how the team combines farmers’ experience with scientific methods to explore low-carbon agricultural practices suited to local needs through hands-on work and dialogue.

Puli’s water bamboo is renowned for its slender, white stems with few black spots. Yet maintaining stable production also presents challenges related to energy consumption and environmental sustainability. Professor Tsai shared how his team collaborates with farmers to explore low-carbon practices through nighttime lighting, agricultural residue reuse, and irrigation management.

To promote growth and increase yields, farmers make extensive use of high-pressure sodium lamps at night, each consuming approximately 400–450 watts. This lighting has turned the Puli Basin into a “city that never sleeps,” creating substantial electricity demand and affecting nighttime ecosystems.

Through spectral analysis of the plants, the team identified pronounced absorption peaks in the red and blue wavelengths. Based on these findings, they developed LED modules with a red-to-blue light ratio of approximately 6:1 and added reflectors to improve lighting uniformity. Initially, farmers worried that replacing their lamps might affect their harvests. Professor Tsai gradually built trust by committing to cover potential crop losses, allowing field trials to proceed. According to the seminar presentation, the trials achieved electricity savings of approximately 70%, while yields increased and quality remained stable.

After accumulating data from repeated trials, the team helped the Nantou County Government secure approximately NT$4.5–4.6 million in energy conservation subsidies across two funding rounds to support farmers in replacing their lamps. According to figures shared by the speaker, the initiative has covered 37 hectares, with approximately 1,600–1,800 lamps replaced. However, annual subsidies of around NT$2.5 million remain limited relative to the needs of the entire production area, prompting the team to seek partnerships that could accelerate the transition.

Agricultural Residue Reuse and Biochar Research

Water bamboo husks and other agricultural residues were often disposed of through open burning, affecting local air quality. In searching for alternatives, the team initially explored extracting stigmasterol, a compound with potential applications, from the husks. After considering extraction costs and practical benefits, however, they shifted their research focus to biochar.

Professor Tsai explained that biochar has the potential to adjust soil pH, adsorb certain heavy metals, and store carbon over the long term. It therefore represents a promising direction for resource circulation and carbon reduction. Converting agricultural residues into biochar and applying it appropriately to farmland could reduce open burning while creating additional value from these materials.

The team sought subsidies for a medium-sized biochar furnace, but the project could not proceed because of difficulties in securing the required local matching funds. They subsequently turned to developing smaller units, hoping to process residues locally and return the resulting biochar to nearby fields. However, World Café discussions with farmers revealed a major practical obstacle: farmers lacked the time and labor needed to collect the residues. Beyond equipment, arrangements for collection and operation also require solutions developed together with the community.

Water Resource Management and Smart Monitoring

Citing survey findings, Professor Tsai noted that groundwater extraction in Puli approaches 100 million metric tons annually. Groundwater levels have declined, and some areas are already experiencing difficulties accessing water. Water use per unit of farmland can vary by more than twentyfold among farmers, even though both high- and low-use farms produce good-quality water bamboo. This suggests considerable scope for comparing and improving water management practices.

The team has pursued two approaches. First, they discuss water-saving practices with farmers; some participating farms have achieved water savings of approximately 10%–26% without reducing yields. Second, they install field monitoring equipment to collect data on air temperature, water temperature, and oxidation-reduction potential (ORP), examining the relationships among environmental conditions, irrigation practices, and plant growth.

Water requirements vary across the growth stages of water bamboo, with water temperature and quality requiring particular attention during stem swelling. The team initially considered water temperature the main factor influencing irrigation. After observing that farmers continued pumping water even in winter, however, they began investigating the need for water replacement and the water conditions reflected by ORP readings, gradually refining their research direction.

The team later used the rate of stem diameter expansion as an indicator of growth and harvest readiness. Combining multivariate analysis with AI algorithms, they explored more suitable irrigation strategies. Because field data collection is challenging, more complete data for the stem-swelling stage became available only after sustained monitoring and adjustments, laying the groundwork for further analysis and improvement.

Looking Ahead | From Low-Carbon Production to Local Identity

With limited subsidies and a slow pace of equipment replacement, the team is actively seeking corporate ESG partnerships and exploring carbon credit mechanisms. They hope that corporate support for lighting upgrades and low-carbon facilities can accelerate the transition across the production area.

To address the specific requirements of plant lighting, the team is also working with businesses to develop a methodology for low-carbon water bamboo production. As reported at the time of the seminar, the methodology had passed the Ministry of Environment’s preliminary review and was awaiting further assessment. Meanwhile, the team continues to calculate product carbon footprints, hoping to pursue carbon labeling in the future so that farmers’ efforts to improve equipment and production practices receive greater recognition and support.

The team also continues to observe nighttime ecosystems following the lighting changes. Acoustic surveys are being used to record the activity of frogs and other species, building a body of data to assess potential ecological benefits. Interdisciplinary collaboration has also produced an AI image recognition system, with wearable devices being explored to help farmers identify plants ready for harvest and reduce the physical strain of repeatedly bending down to inspect them.

At the close of the seminar, Professor Tsai shared his vision: that one day, Puli’s water bamboo fields could complete their transition to energy-efficient lighting under the purple glow of red and blue LEDs. By connecting this transformation with local identity and tourism, Puli could become an internationally recognized “Purple Town.” From a single lamp to an entire field, this vision illustrates how sustainable agriculture depends on the continued integration of scientific research, farmers’ experience, and interdisciplinary collaboration to become part of everyday practice.