Assessment of the environment effects of constructing the Three Gorge Project on the Yangtze River
The Three Gorge Project is a multipurpose project with the primary function of flood control. Other functions include power and navigation and could include irrigation. A 200 m high concrete gravity dam, currently being considered, would be located in the lower reach of the famous Three Gorges of the Yangtze River in Hubei and Sichuan Provinces. The reservoir will store about 70 x 10 to the 9th cu m and extend upstream about 780 km. The proposed powerplant would have an installed capacity of 25,000 MW, consisting of twenty-five 1000-MW units. The Three Gorge Project, when constructed, would be the largest water resource project anywhere on earth. Beneficial effects include elimination of flooding along the middle and lower reaches of the Yangtze River, a substantial increase in much needed electric power for south and central China, and creation of a large body of water which could be used for aquaculture. Consideration is also being given to diverting water to the North China Plain, one of the most important agricultural areas of China. Major adverse impacts include relocation of more than 2 million people for the reservoir area; loss of habitat for many kinds of Yangtze River aquatic life, including themore » unique Chinese sturgeon; and the possibility of reducing nutrient input to the downstream and estuarine fisheries. The possibility of minimizing adverse effects seems high, if the potential environmental impacts are identified and means of mitigation are carried out. 22 references, 1 figure.« less
The World Bank's new environmental policy for dams and reservoirs.
Water development schemes are fraught with major environmental problems, especially in the tropics. However, where gains in conservation and use efficiency of energy and water have been substantial, then such schemes can often be more appropriate than alternatives, such as coal and nuclear. But this means that the environmental impacts of water development schemes must be prevented, mitigated or compensated for much more effectively than hitherto. The World Bank's new policy is designed to do just that.
A Critical Assessment on Functional Attributes and Degradation Mechanism of Membrane Electrode Assembly Components in Direct Methanol Fuel Cells
Direct methanol fuel cells (DMFC) are typically a subset of polymer electrolyte membrane fuel cells (PEMFC) that possess benefits such as fuel flexibility, reduction in plant balance, and benign operation. Due to their benefits, DMFCs could play a substantial role in the future, specifically in replacing Li-ion batteries for portable and military applications. However, the critical concern with DMFCs is the degradation and inadequate reliability that affect the overall value chain and can potentially impede the commercialization of DMFCs. As a consequence, a reliability assessment can provide more insight into a DMFC component’s attributes. The membrane electrode assembly (MEA) is the integral component of the DMFC stack. A comprehensive understanding of its functional attributes and degradation mechanism plays a significant role in its commercialization. The methanol crossover through the membrane, carbon monoxide poisoning, high anode polarization by methanol oxidation, and operating parameters such as temperature, humidity, and others are significant contributions to MEA degradation. In addition, inadequate reliability of the MEA impacts the failure mechanism of DMFC, resulting in poor efficiency. Consequently, this paper provides a comprehensive assessment of several factors leading to the MEA degradation mechanism in order to develop a holistic understanding.