Switchgrass-Based Bioethanol Productivity and Potential Environmental Impact from Marginal Lands in China

Xun Zhang,Gang Lin,Jingying Fu,Dong Jiang,Xiaoxi Yan

doi:10.3390/en10020260

Abstract

Switchgrass displays an excellent potential to serve as a non-food bioenergy feedstock for bioethanol production in China due to its high potential yield on marginal lands. However, few studies have been conducted on the spatial distribution of switchgrass-based bioethanol production potential in China. This study created a land surface process model (Environmental Policy Integrated Climate GIS (Geographic Information System)-based (GEPIC) model) coupled with a life cycle analysis (LCA) to explore the spatial distribution of potential bioethanol production and present a comprehensive analysis of energy efficiency and environmental impacts throughout its whole life cycle. It provides a new approach to study the bioethanol productivity and potential environmental impact from marginal lands based on the high spatial resolution GIS data, and this applies not only to China, but also to other regions and to other types of energy plant. The results indicate that approximately 59 million ha of marginal land in China are suitable for planting switchgrass, and 22 million tons of ethanol can be produced from this land. Additionally, a potential net energy gain (NEG) of 1.75 x 106 million MJ will be achieved if all of the marginal land can be used in China, and Yunnan Province offers the most significant one that accounts for 35% of the total. Finally, this study obtained that the total environmental effect index of switchgrass-based bioethanol is the equivalent of a population of approximately 20,300, and a reduction in the global warming potential (GWP) is the most significant environmental impact.

Highlights

The last several decades have witnessed a rapid increase in the use of fossil fuels as urbanization and industrialization have accelerated, and as the major energy resource, fossil fuels have contributed immensely to the modernization of human society [1]
The marginal land suitable for switchgrass in China based on the following principles using the data in Table 1: (1) the land defining principles: deduct the cultivated land resource based on the land use data in China; (2) the ecological protection constraint: deduct the sparse forest land, shrub land and the bottomland for ecological conservation; (3) the stockbreeding development constraint: deduct the high and moderate dense grasslands in the five grazing provinces
According to the analysis of energy efficiency, it appears that Yunnan province could be considered as a priority development zone for switchgrass-based bioethanol in China, followed by the Guizhou, Hubei, and Guangxi Provinces

Summary

Introduction

The last several decades have witnessed a rapid increase in the use of fossil fuels as urbanization and industrialization have accelerated, and as the major energy resource, fossil fuels have contributed immensely to the modernization of human society [1]. With the steady depletion of fossil fuels, an increasing number of problems has emerged such as resource and energy scarcity along with environmental crises [2,3]. The versatility of biomass as a potential energy source has attracted wide attention in recent years [6,7,8]. Biofuel has the advantages of being renewable, clean, beneficial for the environment, and a source of significant economic potential [9]. The biofuel that is most frequently transported around the world is bioethanol [10], and it is a renewable fuel made from plant-based feedstocks that is used in combustion engines [11]. Bioethanol has the potential to address the urgent challenge of our energy needs and pressing environmental issues [12]. The first generation of bioethanol production, primarily extracted from foods crops such as grains, sugar cane and vegetables, was widely used in the USA and Brazil [13]

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Conclusion