Biomass residues for bioenergy products: a case study of rice straw from food-energy-water nexus perspective
Mengshan Lee1,2, Chia-Chun Lin2, Ying-Chen Lin2, Pei-Te Chiueh2
1National Kaohsiung First University of Science and Technology; 2National Taiwan University, Taiwan
Bioenergy products are attractive renewable energy sources as they allow simultaneously reduction in fuel-associated environmental impacts and increase in economic value of the food products. Production of second-generation biofuels, which utilizes biomass residues such as crop residues or urban wastes for bioenergy products, is expected to foster the transition towards sustainable bioenergy systems. This case study focuses on the use of rice straw for production of bioenergy products in Taiwan. This study first introduces a framework for understanding of the influence of biomass-residue-based bioenergy products on the complex relationship between food, energy and water, and proposes a tool for quantifying the interactions between the three (i.e. food-energy-water nexus). Life cycle assessment approach is also incorporated into the tool for evaluation of the environmental impacts associated to the products.
Taiwan has self-sufficiency ratio of rice over 90% and the rice straw is considered as a potential raw material for bioethanol or biochar production. Growing of rice showed the highest water footprint as compared to other energy crops (e.g. corn and sugarcane). Use of rice straw for bioethanol production revealed comparable environmental benefits in greenhouse gas reduction. Coal substitution from rice straw-derived biochar reduced approximately 5% of environmental impacts from resource-use, climate change, ecosystem quality and human health. Evaluation of the benefits from various bioenergy mix was also conducted in this study using the proposed framework and nexus tool. Regional distribution of the quantitative results were visualized using Geographical Information System (GIS) software. The results from this study is expected to support future policy making and resource management strategies.