Potential Reductions in Greenhouse Gas and Fine Particulate Matter Emissions Using Corn Stover for Ethanol Production in China

Abstract

Corn stover is an abundant raw material that can be used to produce ethanol and reduce air pollution. This paper studied the potential reductions in greenhouse gas (GHG) and fine particulate matter (PM 2.5 ) emissions across China if corn stover was used for ethanol production. Field surveys in nine provincial regions were conducted. Life-cycle assessment (LCA) was used to assess the GHG and PM 2.5 emissions from a corn stover based ethanol system. The LCA system boundaries included several process stages from corn planting to ethanol fuel used in vehicles. Corn stover geographical distributions and emission reduction factors were combined. Results showed that the total surplus quantity of corn stover in China was 86.2 million metric tons (Mt) in 2015. It was sufficient to reach the ethanol production target set by the Chinese government. In the scenario that 38.5 Mt or 44.6% of corn stover surplus were used for ethanol production, the total potential emission reductions were 36.5 Mt CO 2 -eq GHG and 450.9 kt PM 2.5 . Among the 31 provincial regions in China, the reduction potentials varied from 0.001 to 8.9 Mt CO 2 -eq for GHG and from 0.013 to 109.7 kt for PM 2.5 . This study provided useful information to policy makers, researchers and industry managers who work on environmental control and corn stover management.reported that the available agricultural residue as feedstock for bioenergy production could amount to 55.2 Mt, among which 41.1% could be utilized for bioethanol production by 2025 in China [17].China has been the largest GHG contributor in the world since 2005 and emitted about 29% of the worldwide GHG in 2015 [18]. The PM 2.5 concentrations in 310 out of 362 cities in China exceeded critical levels of 35 µg m −3 in the first quarter of 2016 [19]. Moreover, the gasoline and diesel consumptions from 2003 to 2014 increased by 58% and 51% in China, respectively [20]. The fuel consumption in transportation was identified as a major source of CO 2 and PM 2.5 [21][22][23]. Additionally, the in-field burning of crop residue significantly increased GHG and PM 2.5 emissions, accounting for 107 Mt of CO 2 emissions annually from 1999 to 2008 [24] and contributing 12% of the annual mean PM 2.5 emissions in Beijing, China [25].Previous studies [13,26-28] mainly focused on life-cycle GHG emissions mitigation of corn stover based ethanol production by comparing it with gasoline production. For instance, developing commercial-scale corn stover based ethanol plants could displace fossil fuels and reduce GHG emissions [26]. Spatari et al. [27] showed that the GHG emissions were 65% lower in 2010 for a light-duty vehicle fueled by E85 (i.e., a blended fuel comprising 15% gasoline and 85% ethanol derived from corn stover) compared with petroleum fuel. Ethanol from corn stover could reduce life-cycle GHG emissions by 90-103% relative to gasoline in the United States [28]. Recently, Zhao, et al. [13] reported that the use of pure fuel ethanol produced from corn stover in China could lead to a GHG emission reductions ...