۱٫ Introduction

۲٫ Methods

۳٫ Results

۴٫ Discussion

۵٫ Conclusions

References

Abstract

The improper disposal of agriculture residues (ARs) (such as open burning of straw) in China leads to waste of energy potential and atmospheric environmental problems. Converting ARs to energy is of importance for regional energy and environmental sustainability. In order to help decision-makers select optimal technologies among multiple alternatives and promote the development of ARs-to-energy industries, this study conducts integrated assessment and prioritization of seven bioenergy technologies (BETs). A criteria system consisting of four aspects (environmental, technological, economic and social aspects, in total 15 criteria) is constructed. Life cycle environmental and techno-economic assessments are conducted within the boundary ranging from ARs collection and transportation, energy conversion to final use of bioenergy products. Combined with the results of the life cycle assessments and the advices from two groups of experts, the fuzzy Analytic Hierarchy Process (AHP) is adopted to determine the weights of the criteria and quantify the performances of the BETs. Based on the results of the fuzzy AHP, the VIKOR method is finally employed to determine the sustainability sequence of the BETs. From single-dimensional performance, direct-combustion power generation has the best environmental benefit; briquette fuel has the best economic benefit. From performances of integrated-dimensions, direct-combustion power generation, gasification power generation and briquette fuel are recognized as the most sustainable technologies under both the environmental priority situation and economic priority situation. The methods and results presented are expected to provide reference to development planning of ARs as well as other types of bioenergy.

Introduction

China is a large agricultural country with abundant agricultural bioresources. It could produce more than 0.7 billion tons of agricultural residues (ARs) every year (Qiu et al., 2014). Most of the ARs are directly burned in fields causing serious environmental issues, such as smog and haze (Sun et al., 2017). In addition, China is the largest energy-consuming country, surpassing even the USA (Yang et al., 2018). It prompts to exploit bioenergy as alternative renewable energy to enhance energy security, reduce Greenhouse Gas (GHG) emissions, increase business opportunities, and accelerate rural economic development, especially in the developing countries (Liu et al., 2018; Wang et al., 2017a). In 2016, the Chinese national energy administration formulated the development goal in the “medium and long-term development plan for bioenergy”, where the target of replacing 58 million tons of standard coal (tce) by using bioenergy annually by 2020 was proposed (National Energy Administration, 2016). In this context, converting ARs to energy has become a promising pathway to regional energy and environmental sustainability. ARs can be converted through numerous bioenergy technologies (BETs) to divergent forms of energy products including heat, power, biofuels or a combination of them (such as converting straw to power, bioethanol, briquette fuel, biogas etc.) (Lo, 2014; Song et al., 2015a). It is usually difficult to select suitable and sustainable energy conversion technologies for ARs (Ren et al., 2014) as different BETs have different performances in terms of economic benefits, environmental impacts, technological concerns and social-political aspects (Sharma et al., 2013). Furthermore, bioenergy systems often have high level of uncertainties that are difficult to quantify because the data available are often vague, incomplete or inconsistent.