Dr. Sanjib Kumar Karmee * Prof Sanette Marx
A new study entitled “Biofuels from spent coffee grounds: Comparison of processing routes” authored by South African researcher Prof Sanette Marx and Odia scientist Dr. Sanjib Kumar Karmee is reported in the journal Biofuels, published by the Taylor & Francis Group. Other authors of the publication are Dr. Roelf Venter, Tony de Milem, Jaco Louw, and Chantelle Truter.
Waste-to-Fuel (WtF) technologies are promising since it reduces dumping of waste in landfills and greenhouse gas emissions (GHG). Furthermore, waste generation increases continually as the world’s population increases and waste thus presents a sustainable feedstock for bio-based fuels and products.
The consumption of coffee is an everyday habit that most people partake of at least once a day. The total global green coffee production reached approximately 9.58 million ton in 2017, of which 15-20 wt.% was disposed of as low-grade beans unfit for human consumption. Approximately, 50% of the produced green coffee beans are processed for coffee drink production and approximately 650 kg of coffee waste is generated for each 1 ton of green coffee produced. In 2017, approximately 6.23 million tons of coffee waste was generated. These coffee wastes can be used for making fuel instead of simply dumping in landfills. The research reported by us is significant since India is among the top 12 coffee-producing countries in the World says Dr. Karmee.
The paper shows hydrothermal liquefaction was more efficient in extracting oil from coffee waste than hexane solvent extraction, both in terms of oil yield and energy retention. Renewable diesel obtained from in-situ hydrotreatment of coffee waste had the highest fuel yield and kerosene fraction and contained no heavy oils. It could thus be concluded that it is better to use hydrothermal liquefaction to extract oil and better to produce renewable diesel than biodiesel from the extracted oil. Furthermore, oil extracted by continuous hydrothermal liquefaction contained valuable components such as phenol, stigmasterol, and caffeine that can be extracted prior to fuel processing to improve the overall economic viability of the process emphasized by the authors.
Further, Karmee added that this strategy can be adopted in coffee waste generating places and has huge potential for farmers and entrepreneurs since it is about the conversion of waste to wealth. It is worth noting that Koraput, Rayagada, Phulbani, and Keonjhar are among the major coffee producing districts of Odisha. Dr. Karmee is a native of Tebhapadar village, Subarnapur district, Odisha; he is currently working as a Principal Scientist at the Sardar Patel Renewable Energy Research Institute, Gujarat.
Continuous hydrothermal liquefaction plant used in this research