A simple method for partitioning total solar radiation into diffuse/direct components in the United States

Solar radiation is a major sustainable and clean energy resource, and use of solar radiation is expected to increase. The utilization efficiency of solar energy varies with the relative proportions of the direct and diffuse components that compose total solar radiation and with the slope and aspect of the irradiated surface. The purpose of this paper is to develop a simple method for estimating diffuse and direct solar radiation at sites with observation of only total solar radiation. An existing model for estimating diffuse radiation, i.e., a linear relationship between the diffuse fraction (the ratio of diffuse radiation to total solar radiation) and the clearness index (the ratio of total solar radiation to extraterrestrial radiation), is applied to 7 sites across the continental United States with observations of diffuse and total radiation. The linear model shows good monthly performance. The model parameters (slope and interception) show a strong seasonal pattern that exhibits small variation across the 7 sites; therefore, the average values of the two monthly parameters may be used for estimating diffuse radiation for other locations with observations of total radiation.     

Prediction of diffuse solar radiation using satellite data

In the project of the solar systems, the values of the solar radiation of a region must be known. The global solar radiation measurements are performed by the Turkish Meteorological Service in Turkey, while the diffuse solar radiation measurements are unavailable. In this study, some new models for predicting the monthly average daily diffuse solar radiation on a horizontal surface for Erzincan, Turkey are developed using satellite data. The evaluation of the models is carried out with the statistical analysis methods of mean bias error (MBE), root mean square error (RMSE) and correlation coefficient (r). The results are proved that the correlation equations obtained in here can be used to forecast diffuse solar radiation reasonably well.     

Comparative assessment of solar photovoltaic panels based on metal-derived hazardous waste,resource depletion,and toxicity potentials

Solar photovoltaic (PV) cells are used to resolve energy security and climate change problems. Although PV panels have long physical lifetimes, they would be eventually replaced by new ones with higher energy efficiency and then changed to waste. Depending on the types of PV cells, waste PV panels have different environmental impact potentials due to different contents of substances. This study assesses and compares hazardous waste, resource depletion, and toxicity potentials from metals in three types of PV modules (i.e., polycrystalline silicon (Si), amorphous Si, and CIGS (copper/indium/gallium/di-selenite) PVs) on per-watt electricity generation basis. Hazardous waste potentials are examined by using metal leachability tests, and resource depletion and toxicity potentials are evaluated by using life cycle impact assessment methods. The polycrystalline Si and CIGS PVs have hazardous waste potentials due to lead (Pb) and cadmium/selenium, respectively, whereas the amorphous Si PV does not. The polycrystalline Si PV has the highest resource depletion potential due primarily to silver; the CIGS PV has the next highest due primarily to selenium; and the amorphous Si PV had the lowest, which is derived primarily from tin and copper. For toxicity potentials, overall the amorphous Si PV had lower potentials, derived primarily from barium/copper/nickel/zinc, than the polycrystalline Si and CIGS PVs of which the toxicity potentials were primarily form copper/lead/nickel/silver and copper/mercury/molybdenum/nickel/silver, respectively. Therefore, waste polycrystalline Si and CIGS PV panels should be recycled and managed with priority, and PV technology development needs to be directed to amorphous Si PV from the material perspective.     

生物质能源及发电技术研究

随着能源消耗和环境污染之间矛盾的加剧,使得人类需要寻找一些相对比较清洁的可再生能源。生物质能源由于其数量巨大,环境污染小,并具有可再生性,成为目前比较好的选择之一。生物质能发电是生物质能利用的主要方式之一。介绍了生物质能的特点及利用转化方式,重点讲述了直接燃烧发电技术、气化发电技术以及生物质燃料电池技术,最后根据我国国情指出了生物质能利用的主要问题及几点建议。对我国生物质能发电的发展提供了技术参考和技术支持。     

Histopathology of cerebro neuronal cells in freshwater snail Bellamya bengalensis: impact on respiratory physiology,by acute poisoning of mercuric and zinc chloride

Mercuric (Hg) and zinc (Zn) chloride toxicity was investigated in cerebroneuronal cells and gills of Bellamya bengalensis using sublethal concentrations under lab conditions. Freshwater snail B. bengalensis was exposed to mean LC₅₀ concentration (1.56 ppm and 12.7 ppm) of Hg and Zn chloride, respectively. Bioaccumulation of Hg and Zn was observed in nervous and gill tissue in proportion to the time of exposure. Respiratory mechanisms and rate of oxygen consumption was depleted by both metals. Histopathological alterations in cerebro neuronal cells (giant, large, medium, and small) and gill filamental epithelia were apparent in Hg and Zn-exposed snails. Histopathology demonstrated increased cytoplasmic basophilia, extreme indentation of plasma membrane, karyolitic and eccentric nuclei, nuclear envelope with irregular size, and shrunken appearance of cerebroneuronal cells. Histologically, gill filamental epithelia showed hypertrophy, enlarged ciliated margins reduced length of cilia, nuclear dilations, thickening of basal lamina, and hemocytic accumulations in induced cells and severe loss of goblet mucus cells at the tip. Histopathology was accompanied by dysfunctioning cilia with decreased rate of respiration. Overall, neuronal impairment with damaged gill filament produced improper gaseous exchange leading to sluggish movement.     

Renewable electricity policies,heterogeneity, and cost effectiveness

Renewable electricity policies promote investment in renewable electricity generators and have become increasingly common around the world. Because of intermittency and the composition of other generators in the power system, the value of certain renewable – particularly wind and solar – varies across locations and technologies. This paper investigates the implications of this heterogeneity for the cost effectiveness of renewable electricity policies. A simple model of the power system shows that renewable electricity policies cause different investment mixes. Policies also differ according to their effect on electricity prices, and both factors cause the cost effectiveness to vary across policies. We use a detailed, long-run planning model that accounts for intermittency on an hourly basis to compare the cost effectiveness for a range of policies and alternative parameter assumptions. The differences in cost effectiveness are economically significant, where broader policies, such as an emissions price, outperform renewable electricity policies.     

Evaluation of the potential of harvesting heat energy from asphalt pavements

The potential of harvesting heat energy from asphalt pavement using a piping network with fluid flowing through it needs to be evaluated before spending a significant amount of time on planning details of design and construction. The key factors involved in this evaluation include the temperature of the pavement at the depth at which the system is being considered, as well as the temperature of the fluid used for harvesting the heat energy. Costs include those required for the system such as pumps and pipes, and cost of energy required for pumping. Taking all of the factors into consideration, a macro-enabled spreadsheet has been developed that allows the user to input air temperature data as well as pipe location and cost parameters. The end results are data on flow rate versus yearly savings and payback period. From these data, a user can easily determine whether the payback period is reasonable or not and could also evaluate the effect of the different parameters on the payback period. Examples of the results of analysis for different cities in four different parts of the USA and Singapore and Chennai, India, are presented. The payback period shows a good relationship with the latitude of the location – the period increases with an increase in latitude. The public domain location from where the spreadsheet can be downloaded is provided.