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Alternative energy sources, derived from biomass feedstocks, are important for China's energy security. To evaluate China's capacity for bioenergy in the future, Geographic Information System (GIS) techniques were adopted to identify potentially productive marginal areas for the growth of 16 energy crops and to comprehensively estimate their biomass and bioenergy production potential under three scenarios. The results showed that a total of 267.23 Mha (i.e., million hectare) of marginal land was available for energy crop production. When assessing the suitability of individual environments for each type of energy crop, the largest total land area of a lignocellulosic energy crop, an oil energy crop, and a lignocellulosic energy tree were 3.64 Mha (Miscanthus spp.), 45.44 Mha (Jatropha curcas L.), and 63.55 Mha [Haloxylon ammodendron (C. A. Mey.) Bunge], respectively. In addition, the proposed production of bioethanol [Sorghum bicolor (L.) Moench], biodiesel [Swida wilsoniana (Wanger.) Sojak], and bio-electricity [H. ammodendron] in the baseline scenario met 31.83%, 26.08%, and 9.2% of ethanol demand for E10, diesel, and electricity in 2016, respectively. Furthermore, if upland and forest land could be used to produce bioenergy, the bioethanol substitution rates of ethanol for E100, diesel, and electric power were calculated as 62.63%, 153.94%, and 60.47%, respectively, for 2040. The results indicated that China's future energy demands could not be satisfied by simply depending on energy crops in most situations. Future bioenergy should be developed based on reliable supplies of several types of biomass materials and dedicated biochemical or thermochemical conversion processes, among other renewable energy sources. [ABSTRACT FROM AUTHOR]

Plant density substantially affects sorghum (Sorghum bicolor (L.) Moench) productivity. Therefore, density optimisation plays a pivotal role in crop management practices. A 2-year field experiment was conducted on sandy loam marginal land in Ordos, Inner Mongolia, China, to (1) determine the mechanism underlying the impact of plant density (i.e. 6.0, 7.5, 9.0, 10.5 and 12.0 plant m−2) on biomass yield, quality and photosynthetic efficiency and (2) determine the optimum plant density for sweet sorghum variety GT-3 and biomass sorghum variety GN-4. Results indicate that plant height, leaf area index (LAI), leaf area duration (LAD) and biomass yield increased as plant density increased, but tiller number, stem diameter and net assimilation rate (NAR) decreased. The growth period between elongation and anthesis dates was crucial to sorghum productivity; during this period, LAD was the determining factor for biomass yield. Increase in plant density up to 10.5 plant m−2 led to a high LAI level, an extended LAD, a high and stable NAR and a positive balance between photosynthesis and respiration processes, all of which contributed to highest biomass yield (13.2 t ha−1). Ultimately, sweet-type variety GT-3 demonstrated the highest theoretical ethanol yield (4147 L ha−1) and relative feed value (112.3%) compared with biomass-type variety GN-4. [ABSTRACT FROM AUTHOR]

Waste cooking oil (WCO) can serve as a feedstock for producing biodiesel, which would not only address food security and waste disposal but also has the potential to reduce emissions of greenhouse gas (GHG) and particulate matter of 2.5 μm or smaller (PM). In this study, we assessed restaurant waste oil (RWO) availability in China and conducted life cycle analysis (LCA) of GHG and PM emissions of RWO-based biodiesel using the GREET model. The results showed that the amount of RWO in China varies between 0.56 and 1.67 million tons in 2013 and between 0.54 and 1.63 million tons in 2014. Life cycle analysis estimated reduction of GHG and PM emissions through the use of RWO-based rather than petroleum-based biodiesel of 82 kg CO-Eq. (90 %) and 0.92 g PM (46 %) respectively per 100 km driven by busses in 2014 in Shanghai, China. Given the total amount of RWO available in 2014 in China, the potential mitigated annual GHG emission ranges, in China, are 1.51 ∼ 4.52 × 10 tons of CO-eq and 16.94 ∼ 50.83 tons of PM. [ABSTRACT FROM AUTHOR]