Valorization of Agricultural Residues
Valorization of Agricultural Residues
Hoang, Trang; Rotter, Vera Susanne; Le, Hung Anh; Nguyen, Trung Hoang
FG Kreislaufwirtschaft und Recyclingtechnologie
Globally, food and agriculture production consume 30% of the world’s energy and produce around 20% of the worlds greenhouse gas (GHG) emissions . Acknowledging increasing global food demand, this highlights the urgency to move towards a Climate Smart Agriculture in South-East-Asia and beyond to tackle the global climate challenge. Valorization of agricultural residues is a promising approach but faces challenges in technology, logistics and feasibility under current economic and legal conditions. With an average annual increase of more than 6% since 2000, Viet Nam belongs to the countries with the fastest growing GDP . One primary driver for this development is the agricultural sector contributing with 16 % to the national GDP in 2016 . Agricultural production leads inherently to production of residual biomass from crop growing, livestock breeding and food production. Rice with a yield of 45.2 million tons in 2014 (world rank 5) is the most important agricultural GDP contributor3. Nevertheless, it leads to the production of 51.5 million tons of rice straw. Similar to India and China, the majority of the rice straw is burned in the rice fields causing air pollution on a supra-regional scale . Other components of the rice straw, are incorporated into the soil of the flooded paddies, causing CH4 emissions . A second crucial agricultural sector is livestock farming. With 75 million cattle and pigs as well as high annual growth rates (up to 3,7%)3, this sector is rapidly gaining importance for the Vietnamese economy. Due to the lack of compliance with emission control standards (QCVN 62-MT:2016/BTNMT ), this development comes along with adverse environmental effects. Together with the intensive use of fertilizers in the rice fields, the disposal of manure from livestock farming contributes largely to the pollution of water and soils, to the loss of nutrients, and to the emission of greenhouse gases. Frequently, manure is treated in small-scale household biogas digesters (up to 15 cows or 50 pigs). Nationwide the installation of 158,000 plants were supported by the Vietnam Biogas Programme , 47,800 of these plants (more than 30%) are situated in the Mekong Delta. Due to the insufficient heating energy demand at the households, the excess biogas is released to the atmosphere. Furthermore, biogas leaks from the plants altogether result in a methane loss up to 40% , . According to 8,9, , and observations during the surveys of previous Vietnamese-German projects like INHAND and BioRist or UKAVita, also the 1,000 mid- (for 50 to 2,000 pigs or 16 to 80 cows) and large-scale (for > 2,000 pig or > 80 cows) biogas plants show a need for technological improvement along the entire process chain: a) substrate preparation, selection, and mixture, b) reactor design, process management and the conditioning of biogas and c) residues as well as biogas storage treatment and usage. Beyond severe local environmental problems, the future of agriculture needs to be discussed in the context of the Vietnamese energy market and climate policy. In 2011, the Vietnamese government promulgated a Masterplan for power development in which it is stated that the capacity of the bio-energy sector shall be increased to 500 MW by 2020 and 2,000 MW by 2030 (Decision No.: 81208/QD-TTg). Therefore, an adaptation towards efficient and cleanly operating biogas plants is crucial. In 2008 a ‘National Target Program to Respond to Climate Change' had been published to create the necessary conditions for adaptation towards climate change effects and mitigation of GHG emissions. The „Intended Nationally Determined Contribution“ (INDC) indicates that Vietnam is capable of reducing the CO2 emissions, with international support, by 25% by 2030 in comparison to the business as usual scenario (BUA). However, it is important that in searching for appropriate responses to this situation solutions has to be adapted to the local conditions, which means that the specific geographical conditions, climate, culture and society must be considered to contribute to a holistic approach beyond sole technical and administrative solutions but also to enhance science, research and education. After two successful conferences on “Valorization of agricultural residues in Vietnam” in Spring 2017 and 2018 the organizing committee from the Industrial University of Ho Chi Minh City and the Technische Universität Berlin successfully established a joint forum for the Vietnamese scientific community and international scientists and experts. This success has convinced us when announcing the 3rd International Conference “Valorization of Agricultural Residues - Towards Climate-Smart Agriculture in South-East Asia”, and we are glad to present an interesting program sponsored by the DAAD, the German Academic Exchange Service and BMBF, the German Ministry of Education and Research. This year, many contributions are focusing on strategies, technologies and ideas, to mitigate GHG emission from agricultural activities, emphasizing the increasing scientific attention. Therefore, we hope that our conference is a starting point for new scientific ideas, cooperations and innovative solutions to tackle the related challenges.