Guantian Black Gold: water chestnut shell charcoal biomass energy
官田烏金︰菱殼炭生質能源
  • 9
  • 17

          Currently, most of Taiwan's agricultural waste is disposed of by open burning, which causes air pollution and the increase of PM2.5 and carbon emissions that leads to strains in the relationship between environmental authorities and farmers. The future of agricultural waste prompts Professor Hung-ping Lin to pursue a circular economy and reduce energy waste from the perspective of recycling. The circular economy is different from the traditional industrial economic model of mining, manufacturing and discarding. Through redesigning products and business models, it can promote better resource utilization efficiency, eliminate waste and avoid polluting the natural environment.

          Tainan’s Guantian is home to one of the largest water chestnut farm in Taiwan, with an annual output of nearly 3,700 tons. More than 90% of water chestnuts are abandoned for open burning or for incineration after collection by sanitation department. In order to solve this problem, Neng-tung Yen, executive of Guantian District, sought the feasibility of turning waste into energy for reuse and reached out to NCKU chemistry professor Hung-ping Lin. The research team scoured the market and the institutions involved for any technique. Although there are ways to make biochar, it requires the use of extra oil or electricity to produce it. Prof. Lin proposed an innovative way to turn water chestnut waste into biochar, which only requires heating during start-up. The team cooperated with the government to develop this technology, and the district office gathered non-governmental organizations to set up the "Tainan Guantian Black Gold Community Cooperative" to promote the merits of water chestnut shell charcoal. Under the official and non-governmental planning, the campaign was initiated by the government-academia-civil-industry cooperation for recycling and reusing agricultural waste.

          The research team modified the conventional firing method, improved the furnace body, put the water chestnut shell into the furnace with temperature from 700 to 1000°C, controlled air flow, burned the remaining elements in the shell—which turns lignin into charcoal—and installed a detector for filtering at the furnace mouth to avoid secondary pollution. Fifteen to 17 kilograms of water chestnut shells can be transformed into 5 to 6 kilograms of water chestnut shell charcoal each time. After put into mass production, over 1,000 tons of the charcoal can be produced in one year. The charcoal burns itself in a high temperature and oxygen-free environment, resulting in very low carbon dioxide emissions, mitigating secondary pollution to the environment. The carbon fixation effect in the soil is excellent. The annual carbon reduction is equivalent to that absorbed annually by 1.1 Da'an Forest Parks. This innovative way resolves the problem of carbon emissions.

          The team found that the charcoal can be sprayed in the field to preserve fertility, water and soil. Biochar itself is renewable energy and can be used as fuel to become green energy. In the process of producing water chestnut shell charcoal, a large amount of waste heat is generated, resulting in some energy emissions and losses. NCKU Prof. Wei-hsin Chen of aeronautics and astronautics and Prof. Hung-ping Lin jointly proposed the project of "Development of Materials and Systems for Conversion of Thermal Energy Cycle Resources" and received a subsidy for the second phase of the National Energy Program (NEP II) in 2018. The project aimed to recover the waste heat generated during chestnut coal burning, generate electricity from waste heat using thermoelectric chips, and complete the thermal energy cycle and power production. In addition, a wireless monitoring system was built to instantly understand the temperature change in the furnace and power generation data during the firing process to establish a complete example of an energy reuse system.

          Prof. Hung-ping Lin’s research team has devoted many years to energy research. In addition to the above research, he has also worked on mesoporous nanomaterials and metal catalysts. Wastewater from industry contains significant amounts of heavy metals. The team converted this into nano-catalysts, turning pollution into resources, and applied it to catalyze the fuel-to-hydrogen system, providing new opportunities for energy research. This has not only turned pollution into a resource, but also converted fuel into energy, creating a win-win-win situation. At present, the team has also worked with Prof. Wei-Hsin Chen to actively propose a continuing industry-academia program to provide more energy-related research and innovation, hoping to make substantial contributions to energy issues.

          目前台灣農業廢棄物,大部分都是以露天燃燒的方法來處理,造成空氣污染,PM2.5與碳排放量增加,也讓政府環保單位和農民的關係緊張。農業廢棄物的未來促使林弘萍教授從循環再利用的角度出發,達到循環經濟與降低能源浪費。循環經濟(Circular economy)有別於傳統經濟的開採、製造、丟棄的產業經濟模式,透過重新設計產品和商業模式,促進更好的資源使用效率、能消除廢棄物也避免污染自然環境。

          台南官田是全國菱角最大的產地,每年生產近三千七百噸的菱角殼,90%以上菱角殼棄置露天燃燒或垃圾車清運焚化。官田區長顏能通為解決此問題,尋求廢棄物變為能源再利用可行性,找到成大化學系林弘萍教授。研究團隊搜尋坊間、市場上、以及相關單位,雖然有製作生物炭的方式,但需要額外使用油或電來燒製;林弘萍教授提出創新方式,僅啟動瞬間需要加熱,便可變成變成生物炭。團隊將此技術與官方合作,區公所集結民間力量成立「台南市官田烏金社區合作社」,推廣菱殼炭優點。在官方與民間的規劃下,囊括了「官、學、民、產」四個構面的發展,一同研發農業廢棄物循環再利用的契機。

          研究團隊改良傳統燒製方式,改良爐體,將菱殼放入溫度控制在七百到一千度高溫的爐子,控制空氣流量,燒除菱殼內其餘元素,木質素則變成炭,爐口裝設偵側器以及濾淨功能,避免造成二次污染。每回可以將十五到十七公斤的菱殼,轉化產生五到六公斤的菱殼炭。量化後,一年可生產超過一千噸的菱殼炭。菱殼炭在高溫無氧的環境中自體燃燒,排出的二氧化碳非常少,降低對環境造成二度污染,使用在土壤中的固碳效果極佳,一年減碳量可達1.1座大安森林公園,此創新方式減少碳排的問題。

          研究團隊發現菱炭可以撒在田間做保肥、保水、土壤改質之外,生物炭本身即是再生能源,可做為燃料使用,成為綠色能源;而在產生菱殼炭過程,所產生的大量廢熱,即是一種能源排放、損耗。航太系陳維新教授與林弘萍教授共同提出計畫,獲得107年度國家型能源型計畫第二期((NEP Ⅱ)經費補助,回收燃燒過程產生的廢熱,運用熱電晶片進行廢熱發電,完成熱能循環與電力生產。此外也同時建置無線監控系統,能在遠端即時了解燒製過程中,爐內溫度變化、發電量等數據,建立完整的能源再利用系統範例。

          林弘萍教授研究團隊投入能源方面研究多年,除了以上研究,另也對於中孔洞奈米材料、金屬觸媒材料多有著墨;工業上所產生之廢水,含有大量重金屬,團隊將此轉換為奈米觸媒,污染變為資源,進一步應用於催化燃料轉換氫氣系統,對能源研究提供新的契機。此舉不僅將污染變成資源,同時產生燃料轉化為能源,創造三贏。目前也與陳維新教授積極提出延續性產學計畫,提供更多對能源相關研究與創新。希望以自身所學能對能源議題有更多研究與貢獻。