Sai Liang

Life cycle assessment of biodiesel production in China

This study aims to evaluate energy, economic, and environmental performances of seven categories of biodiesel feedstocks by using the mixed-unit input-output life cycle assessment method. Various feedstocks have different environmental performances, indicating potential environmental problem-shift. Jatropha seed, castor seed, waste cooking oil, and waste extraction oil are preferred feedstocks for biodiesel production in the short term. Positive net energy yields and positive net economic benefits of biodiesel from these four feedstocks are 2.3-52.0% of their life cycle energy demands and 74.1-448.4% of their economic costs, respectively. Algae are preferred in the long term mainly due to their less arable land demands. Special attention should be paid to potential environmental problems accompanying feedstock choice: freshwater use, ecotoxicity potentials, photochemical oxidation potential, acidification potential and eutrophication potential. Moreover, key processes are identified by sensitivity analysis to direct future technology improvements. Finally, supporting measures are proposed to optimize Chinas biodiesel development.

Decoupling analysis and socioeconomic drivers of environmental pressure in China.

Chinas unprecedented change offers a unique opportunity for uncovering relationships between economic growth and environmental pressure. Here we show the trajectories of Chinas environmental pressure and reveal underlying socioeconomic drivers during 1992-2010. Mining and manufacturing industries are the main contributors to increasing environmental pressure from the producer perspective. Changes in urban household consumption, fixed capital formation, and exports are the main drivers from the consumer perspective. While absolute decoupling is not realized, China has in general achieved relative decoupling between economic growth and environmental pressure. Chinas decoupling performance has four distinguishable periods, closely aligning with nation-wide major policy adjustments, which indicates significant impact of Chinas national socioeconomic policies on its environmental pressure. Material intensity change is the main contributor to the mitigation of environmental pressure, except for ammonia nitrogen, solid wastes, aquatic Cu, and aquatic Zn. Production structure change is the largest contributor to mitigate ammonia nitrogen emissions, and final demand structure change is the largest contributor to mitigate emissions of solid wastes, aquatic Cu, and aquatic Zn. We observe materialization trends for Chinas production structure and final demand structure during 2002-2007. Environmental sustainability can only be achieved by timely technology innovation and changes of production structure and consumption pattern.

Virtual atmospheric mercury emission network in China

Top-down analysis of virtual atmospheric mercury emission networks can direct efficient demand-side policy making on mercury reductions. Taking China-the worlds top atmospheric mercury emitter-as a case, we identify key contributors to Chinas atmospheric mercury emissions from both the producer and the consumer perspectives. China totally discharged 794.9 tonnes of atmospheric mercury emissions in 2007. Chinas production-side control policies should mainly focus on key direct mercury emitters such as Liaoning, Hebei, Shandong, Shanxi, Henan, Hunan, Guizhou, Yunnan, and Inner Mongolia provinces and sectors producing metals, nonmetallic mineral products, and electricity and heat power, while demand-side policies should mainly focus on key underlying drivers of mercury emissions such as Shandong, Jiangsu, Zhejiang, and Guangdong provinces and sectors of construction activities and equipment manufacturing. Chinas interregional embodied atmospheric mercury flows are generally moving from the inland to the east coast. Beijing-Tianjin (with 4.8 tonnes of net mercury inflows) and South Coast (with 3.3 tonnes of net mercury inflows) are two largest net-inflow regions, while North (with 5.3 tonnes of net mercury outflows) is the largest net-outflow region. We also identify primary supply chains contributing to Chinas virtual atmospheric mercury emission network, which can be used to trace the transfers of production-side and demand-side policy effects.

Socioeconomic Drivers of Mercury Emissions in China from 1992 to 2007

Mercury emissions in China have increased by 164% during 1992-2007. While major mercury producers were among energy combustion and nonferrous metal sectors, little is known for the socioeconomic factors driving the growth of emissions. In this paper we examine the underlying drivers and their contributions to the change of mercury emissions. Results show that changes in per capita GDP and GDP composition led to increased emissions which offset the reduction of emissions made possible by technology-induced decrease of mercury emissions intensity and changes in final demand mix. In particular, changes in final demand mix caused decreasing mercury emissions from 1992 to 2002 and increasing emissions from 2002 to 2007. Formation of fixed capital was the dominant driver behind the increase of mercury emissions, followed by the increasing urban population and net exports. This systems-based examination of socioeconomic drivers for Chinas mercury emission increase is critical for emission control by guiding policy-making and targets of technology development.

Atmospheric mercury footprints of nations.

The Minamata Convention was established to protect humans and the natural environment from the adverse effects of mercury emissions. A cogent assessment of mercury emissions is required to help implement the Minamata Convention. Here, we use an environmentally extended multi-regional input-output model to calculate atmospheric mercury footprints of nations based on upstream production (meaning direct emissions from the production activities of a nation), downstream production (meaning both direct and indirect emissions caused by the production activities of a nation), and consumption (meaning both direct and indirect emissions caused by final consumption of goods and services in a nation). Results show that nations function differently within global supply chains. Developed nations usually have larger consumption-based emissions than up- and downstream production-based emissions. India, South Korea, and Taiwan have larger downstream production-based emissions than their upstream production- and consumption-based emissions. Developed nations (e.g., United States, Japan, and Germany) are in part responsible for mercury emissions of developing nations (e.g., China, India, and Indonesia). Our findings indicate that global mercury abatement should focus on multiple stages of global supply chains. We propose three initiatives for global mercury abatement, comprising the establishment of mercury control technologies of upstream producers, productivity improvement of downstream producers, and behavior optimization of final consumers.

Urban Metabolism in China Achieving Dematerialization and Decarbonization in Suzhou

Urban metabolism is a critical component of urban sustainability. On the basis of the driving force−pressure−state−response (DPSR) model and using material flow analysis, this article proposes a framework for sustainable urban management and policy assessment. A case study city in China, Suzhou, illustrates this framework. The results show that resource consumption (excluding water), water consumption, and waste generation (excluding carbon dioxide) in Suzhou after implementation of proposed policies will be 14% lower than 2005 levels, 4.5% higher, and 28.9% higher, respectively, in 2015. Carbon dioxide (CO) emissions in Suzhou will increase by 71.0% in 2015 over 2005 levels, whereas carbon intensity (CO emissions per unit of gross domestic product) will decrease by 44.9%. Future pollution control in Suzhou should pay more attention to pollution from vehicles. In addition, goals for relative dematerialization of energy and decarbonization in Suzhou will be achieved before absolute ones are. In the short term, the urban metabolism of Suzhou in 2015 may meet corresponding urban objectives. In the longer term, however, reducing the citys resource demand and waste generation will pose challenges for the sustainability of Suzhou.

Comparing urban solid waste recycling from the viewpoint of urban metabolism based on physical input-output model: A case of Suzhou in China

Investigating impacts of urban solid waste recycling on urban metabolism contributes to sustainable urban solid waste management and urban sustainability. Using a physical input-output model and scenario analysis, urban metabolism of Suzhou in 2015 is predicted and impacts of four categories of solid waste recycling on urban metabolism are illustrated: scrap tire recycling, food waste recycling, fly ash recycling and sludge recycling. Sludge recycling has positive effects on reducing all material flows. Thus, sludge recycling for biogas is regarded as an accepted method. Moreover, technical levels of scrap tire recycling and food waste recycling should be improved to produce positive effects on reducing more material flows. Fly ash recycling for cement production has negative effects on reducing all material flows except solid wastes. Thus, other fly ash utilization methods should be exploited. In addition, the utilization and treatment of secondary wastes from food waste recycling and sludge recycling should be concerned.

Unintended consequences of bioethanol feedstock choice in China.

Economic, energy, and environmental impacts of 11 types of bioethanol feedstock in China were evaluated using a mixed-unit input-output life cycle assessment model. Corn grain and wheat grain had higher negative economic, energy, and environmental impacts. Sweet sorghum, cassava, sugar beet, and sugarcane showed better economic performance but increasing negative energy and environmental impacts. Cellulose-based feedstocks in general showed positive economic, energy, and environmental performance; but may lead to increasing negative impacts on freshwater use, global warming, toxicity, and aquatic ecotoxicity. Sugarcane-based bioethanol had the potential to provide positive economic, energy, and environmental impacts in China. Scrap paper-derived ethanol could also become promising under significant government support.

Waste oil derived biofuels in China bring brightness for global GHG mitigation

This study proposed a novel way for global greenhouse gas reduction through reusing Chinas waste oil to produce biofuels. Life cycle greenhouse gas mitigation potential of aviation bio-kerosene and biodiesel derived from Chinas waste oil in 2010 was equivalent to approximately 28.8% and 14.7% of mitigation achievements on fossil-based CO2 emissions by Annex B countries of the Kyoto Protocol in the period of 1990-2008, respectively. Chinas potential of producing biodiesel from waste oil in 2010 was equivalent to approximately 7.4% of Chinas fossil-based diesel usage in terms of energy. Potential of aviation bio-kerosene derived from waste oil could provide about 43.5% of Chinas aviation fuel demand in terms of energy. Sectors key to waste oil generation are identified from both production and consumption perspectives. Measures such as technology innovation, government supervision for waste oil collection and financial subsidies should be introduced to solve bottlenecks.

Comparisons of four categories of waste recycling in China's paper industry based on physical input-output life-cycle assessment model

Waste recycling for paper production is an important component of waste management. This study constructs a physical input-output life-cycle assessment (PIO-LCA) model. The PIO-LCA model is used to investigate environmental impacts of four categories of waste recycling in Chinas paper industry: crop straws, bagasse, textile wastes and scrap paper. Crop straw recycling and wood utilization for paper production have small total intensity of environmental impacts. Moreover, environmental impacts reduction of crop straw recycling and wood utilization benefits the most from technology development. Thus, using crop straws and wood (including wood wastes) for paper production should be promoted. Technology development has small effects on environmental impacts reduction of bagasse recycling, textile waste recycling and scrap paper recycling. In addition, bagasse recycling and textile waste recycling have big total intensity of environmental impacts. Thus, the development of bagasse recycling and textile waste recycling should be properly limited. Other pathways for reusing bagasse and textile wastes should be explored and evaluated. Moreover, imports of scrap paper should be encouraged to reduce large indirect impacts of scrap paper recycling on domestic environment.