Lixiao Zhang

Emergy evaluation and economic analysis of three wetland fish farming systems in Nansi Lake area, China.

Emergy and economic methods were used to evaluate and compare three fish production models, i.e., cage fish farming system, pond intensive fish rearing system and semi-natural extensive pond fish rearing system, in Nansi Lake area in China in the year 2007. The goal of this study was to understand the benefits and driving forces of selected fish production models from ecological and economic points of view. The study considered input structure, production efficiency, environmental impacts, economic viability and sustainability. Results show that the main difference among the three production systems was the emergy cost for fish feed associated with their feeding system, i.e., feeding on natural biomass such as plankton and grass or on commercial feedstock. As indicated by EYR, ELR and ESI, it can be clearly shown that the intensive production model with commercial feed is not a sustainable pattern. However, the point is that more environmentally sound patterns do not seem able to provide a competitive net profit in the short run. The intensive pond fish farming system had a net profit of 2.57E+03

Input-output modeling for urban energy consumption in Beijing : dynamics and comparison

/ha, much higher than 1.27E+03

Environmental life cycle assessment of a small hydropower plant in China

/ha for cage fish farming system and slightly higher than 2.37E+03

High Resolution Carbon Dioxide Emission Gridded Data for China Derived from Point Sources

/ha for semi-natural fish farming system. With regard to the drivers of local farmers decisions, the accessibility of land for the required use and investment ability determine the farmers choice of the production model and the scale of operation, while other factors seem to have little effect. Theoretically, the development of environmentally sustainable production patterns, namely water and land conservation measures, greener feed as well as low waste systems is urgently needed, to keep production activities within the carrying capacity of ecosystems. Coupled emergy and economic analyses can provide better insight into the environmental and economic benefits of fish production systems and help solve the problems encountered during policy making.

Influences of Urban Expansion on Urban Heat Island in Beijing during 1989–2010

Input-output analysis has been proven to be a powerful instrument for estimating embodied (direct plus indirect) energy usage through economic sectors. Using 9 economic input-output tables of years 1987, 1990, 1992, 1995, 1997, 2000, 2002, 2005, and 2007, this paper analyzes energy flows for the entire city of Beijing and its 30 economic sectors, respectively. Results show that the embodied energy consumption of Beijing increased from 38.85 million tonnes of coal equivalent (Mtce) to 206.2 Mtce over the past twenty years of rapid urbanization; the share of indirect energy consumption in total energy consumption increased from 48% to 76%, suggesting the transition of Beijing from a production-based and manufacturing-dominated economy to a consumption-based and service-dominated economy. Real estate development has shown to be a major driving factor of the growth in indirect energy consumption. The boom and bust of construction activities have been strongly correlated with the increase and decrease of system-side indirect energy consumption. Traditional heavy industries remain the most energy-intensive sectors in the economy. However, the transportation and service sectors have contributed most to the rapid increase in overall energy consumption. The analyses in this paper demonstrate that a system-wide approach such as that based on input-output model can be a useful tool for robust energy policy making.

Analysis of Resource and Emission Impacts: An Emergy-Based Multiple Spatial Scale Framework for Urban Ecological and Economic Evaluation

PurposeSmall hydropower (SHP) in China has experienced soring development in the past two decades and has been assigned ambitious development goals recently, while its environmental performance remains unclear. This study is intended to provide a comprehensive assessment of the environmental impacts of SHP plants in China, to compare the results with its counterparts in other countries, and to identify the key factors in the mitigation of negative consequences.MethodsA life cycle assessment of a SHP plant in Guizhou Province of China was conducted in a cradle-to-grave manner following the ISO 14040 guidelines. The functional unit is defined as 1xa0MWh of net electricity produced by the plant. The CML 2001 method was applied to characterize the environmental impacts. The environmental impact categories considered in this study included global warming (GWP), abiotic depletion (ADP), acidification (AP), freshwater aquatic ecotoxicity (FAETP), human toxicity (HTP), and photochemical ozone creation (POCP). Further contribution analyses and sensitivity analysis was performed to identify the key contributors to each impact category during the life cycle of the plant.Results and discussionFor the case plant, the considered impacts are caused primarily by the construction stage. As for the materials and energy inputs, cement, steel, and electricity are the three dominating ones for the overall environmental impacts. Compared with SHP plants in other countries, the plant performs similar to the MW scale plants in Thailand and Japan but worse than the plant in Switzerland. Further comparison of life cycle inventories (LCIs) revealed that the quality of hydro-energy resources and acquisition of indigenous equipment technology is essential to their environmental performance. The results of the sensitivity analysis suggested that the amount of construction materials and energy consumption as well as the plant output influences its environmental performance significantly.Conclusionsxa0and recommendationsThe construction stage of the SHP plant is the most important source of environmental impacts. To minimize the impacts of this stage, optimization of the structural design and application of new construction materials and good construction practices is recommended. In addition, determining suitable installed capacity and advancing equipment technologies to ensure the optimal output is also crucial to improve the environmental performance of SHP plants in China, regarding the current serious problem of unstable operation.

Evaluating the impact of odors from the 1955 landfills in China using a bottom-up approach.

A high spatial resolution carbon dioxide (CO2) emission map of China is proving to be essential for Chinas carbon cycle research and carbon reduction strategies given the current low quality of CO2 emission data and the inconsistencies in data quality between different regions. Ten km resolution CO2 emission gridded data has been built up for China based on point emission sources and other supporting data. The predominance of emissions from industrial point sources (84% of total emissions) in China supports the use of bottom-up methodology. The resultant emission map is informative and proved to be more spatially accurate than the EDGAR data. Spatial distribution of CO2 emissions in China is highly unbalanced and has positive spatial autocorrelation. The spatial pattern is mainly influenced by key cities and key regions, i.e., the Jing-Jin-Ji region, the Yangtze River delta region, and the Pearl River delta region. The emission map indicated that the supervision of 1% of total land could enable the management of about 70% of emissions in China.

Extended exergy analysis of urban socioeconomic system: a case study of Beijing, 1996-2006

Beijing has experienced rapid urbanization and associated urban heat island (UHI) effects. This study aimed at analyzing the impact of urban form on UHI in Beijing using TM/ETM images between 1989 and 2010. Spatial analysis was proposed to explore the relationships between area, compactness ratio, the gravity centers of urban land, and UHI. The UHI in Beijing spatially represented a “NE-SW” spindle. The land surface temperature (LST) was higher in south than in north. Urban Heat Island Ratio Index (URI) was well interrelated with urban land area in different zones. Under the similar urban land area condition, UHI and compactness ratio of urban land were in positive correlation. The moving direction of the UHI gravity center was basically in agreement with urban land sprawl. The encroachment of urban land on suburban land is the leading source of UHI effect. The results suggest that urban design based on urban form would be effective for regulating the thermal environment.

Cost of non-renewable energy in production of wood pellets in China

Abstract: The development of the complex and multi-dimensional urban socio-economic system creates impacts on natural capital and human capital, which range from a local to a global scale. An emergy-based multiple spatial scale analysis framework and a rigorous accounting method that can quantify the values of human-made and natural capital losses were proposed in this study. With the intent of comparing the trajectory of Beijing over time, the characteristics of the interface between different scales are considered to explain the resource trade and the impacts of emissions. In addition, our improved determination of emergy analysis and acceptable management options that are in agreement with Beijing’s overall sustainability strategy were examined. The results showed that Beijing’s economy was closely correlated with the consumption of nonrenewable resources and exerted rising pressure on the environment. Of the total emergy use by the economic system, the imported nonrenewable resources from other provinces contribute the most, and the multi-scale environmental impacts of waterborne and airborne pollution continued to increase from 1999 to 2006. Given the inputs structure, Beijing was chiefly making greater profits by shifting resources from other provinces in China and transferring the emissions outside. The results of our study should enable urban policy planners to better understand the multi-scale policy planning and development design of an urban ecological economic system.

Urban Ecosystem Health Assessment and Its Application in Management: A Multi-Scale Perspective

Landfill odors have created a major concern for the Chinese public. Based on the combination of a first order decay (FOD) model and a ground-level point source Gaussian dispersion model, the impacts from odors emitted from the 1955 landfills in China are evaluated in this paper. Our bottom-up approach uses basic data related to each landfill to achieve a more accurate and comprehensive understanding of impact of landfill odors. Results reveal that the average radius of impact of landfill odors in China is 796xa0m, while most landfills (46.85%) are within the range of 400-1000xa0m, in line with the results from previous studies. The total land area impacted by odors has reached 837,476xa0ha, accounting for 0.09% of Chinas land territory. Guangdong and Sichuan provinces have the largest land areas impacted by odors, while Tibet Autonomous Region and Tianjin Municipality have the smallest. According to the CALPUFF (California Puff) model and an analysis of social big data, the overall uncertainty of our calculation of the range of odor impacts is roughlyxa0-32.88% to 32.67%. This type of study is essential for gaining an accurate and detailed estimation of the affected human population and will prove valuable for addressing the current Not In My Back Yard (NIMBY) challenge in China.