Life Cycle Water Footprints of Nonfood Biomass Fuels in China

Abstract

This study presented life cycle water footprints (WFs) of biofuels from biomass in China based on the resource distribution, climate conditions, soil conditions and crop growing characteristics. Life cycle WFs including blue, green and gray water were evaluated for the selected fuel pathways. Geographical differences of water requirements were revealed to be different by locations. The results indicated that water irrigation requirements were significantly different from crop to crop, ranging from 2-293, 78-137, and 17-621 m(3)/ha, for sweet sorghum, cassava, and Jatropha curcas L., respectively. Four biofuel pathways were selected on this basis to analyze the life cycle WF: cassava based bioethanol in Guangxi, sweet sorghum based bioethanol in Northeast China, Jatropha curcal L. based biodiesel in Yunnan and microalgae based biodiesel in Hainan. The life cycle WFs of bioethanol from cassava and sweet sorghum were 3708, and 17 156 m(3) per ton of bioethanol, respectively, whereas for biodiesel produced from Jatropha curcas L. and microalgae, they were 5787, and 31 361 m(3) per ton of biodiesel, respectively. The crop growing stage was the main contributor to the whole life cycle of each pathway. Compared to blue and green water, gray water was significant due to the use of fertilizer during the growing of biomass. From the perspective of the WF, cassava based bioethanol in Guangxi and Jatropha based biodiesel in Yunnan were suitable for promotion, whereas the promotion for microalage based biodiesel in Hainan required improvement on technology.

Regional water footprints of potential biofuel production in China

“…The life-cycle WFs of Jatropha oil in Mozambique are reported to be as high as 15,264 L of water per L of Jatropha oil [46]. In China, the WFs of Jatropha -based biodiesel are estimated to be relatively low [40]. Generally, the water footprints of each biofuel show significant regional differences.…”

Technical Feasibility and Comprehensive Sustainability Assessment of Sweet Sorghum for Bioethanol Production in China

“…Meanwhile, sustainability and economic feasibility studies of bioethanol production have mainly focused on a specific region or a single aspect of the bioethanol production process [33,35,[66][67][68][69][70][71][72][73]. In addition, comprehensive assessment of sustainability and economic feasibility of sweet sorghum for bioethanol have been insufficient, even among various diverse areas across China.…”

“…In this study, great differences in economic output were observed between Wuyuan County and Gulang County in GX, mostly because the sweet sorghum variety in Gulang County is late-maturing and no-heading and has a higher stalk biomass; thus, stalk from Gulang County commands a higher price (57 USD/t) than from Wuyuan County (33 USD/t). Previous sweet sorghum life cycle assessment studies revealed that the GHGs were produced at their highest levels during the planting stage, as a result of N-fertilizer production and application, as well as the use of diesel fuel for farm machinery during this stage [22,71]. Other research [76] reported that in the North China Plain, using diversified crop rotation planting, the production of N fertilizer made the largest contribution to GHG emissions among all agricultural inputs, accounting for an average of 45% of emissions.…”

Water footprint of crop production for different crop structures in the Hebei southern plain, North China

“…In recent years, many researchers have used the WF to evaluate water use in agricultural production (Bocchiola et al, 2013;Chapagain and Hoekstra, 2011;Chapagain and Orr, 2009;Gheewala et al, 2014;Jefferies et al, 2012;Lamastra et al, 2014;Mekonnen and Hoekstra, 2010;Shrestha et al, 2013;Y. B. Wang et al, 2014;Xu et al, 2014;Zang et al, 2014;Suttayakul et al, 2016). The WF of crops reflects the water consumption of different crops, and can focus on local crop products.…”