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Abstract: Constructed wetlands (CW) are a clean and environmentally friendly alternative to conventional wastewater treatment methods, namely in the removal of the nutrients responsible for the eutrophication of receiving water bodies, as is the case of phosphorus compounds. The materials used as CW filling can directly contribute to the removal of phosphorus compounds from wastewater, but with the operating time they tend to become saturated and treatment efficiency decreases. In order to evaluate the viability of producing an energy crop in phosphorus-saturated CW, sugarcane growth was monitored in two pilot-scale CW filled with two different expanded clay aggregates used for 10 years in wastewater treatment. This paper presents the results obtained during the first year of plant development in the plant-cane cycle. Morphologic aspects of sugarcane growth, such as height and average diameter of stems, average leaf area and number of new sprouts, have been monitored. The results obtained are comparable with those cited in the literature for traditional cultivation. Dry biomass productivity of 26.6 ton per hectare per year can be achieved. Estimated sucrose productivity can reach 13.5 ton per hectare per year, and related bioethanol production potential can be between 2.4 and 7.6 cubic meters per hectare per year, depending on the CW filter media used. It is concluded that the cultivation of sugarcane in CW allows to extend the life of these systems by reusing fillers, and simultaneously is an alternative to produce bioethanol raw-material without the use of scarce resources such as arable land, fresh water and plant nutrients. Keywords: Bioethanol, expanded clay, phosphorous removal, sustainability, wastewater treatment. |
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Abstract: Various alternative renewable energy sources have been proposed and implemented. These energy sources, which generally do not rely on fossil fuel, are distinguished from the traditional large scale energy projects in a number of ways. On the other hand, the circumstances surrounding renewable energy sources currently under use are characterized by their small size and scale and their economic impacts are generally local. For example, wind mills based electric power generation uses locally available wind currents and geothermal power generation uses locally available geothermal heat sources. Similarly, solar power generation uses solar power available in the local regions. These imply that the economic impacts of most renewable energy sources currently in use are local. We estimate our model using cross-sectional data of regional economies measured at the prefecture level in Japan. This will allow us to estimate the impacts of certain government policy variables at the regional level as well. One hypothesis we consider in this paper is that while solar power is still negligible in terms of its impact on Japan’s national economy, it has some economic impacts on the economies of the regions where they are located. Keywords: Local renewable energy generation, regional economies, regional income and employment. |
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Abstract: Measurement of elemental carbon (EC) and black carbon (BC) aerosols was carried out using AE-31, 7 channel aethalometer at Kathmandu and Biratnagar; two mega cities of Nepal, for five months, January to May 2011 to study its temporal and spatial variation. Total solar radiation was also monitored using Kipp and Zonen CMP 6 pyranometer. Monthly concentration variation for EC and BC was distinct in both study sites. At Biratnagar, monthly EC concentration varies from 3.3 -20.7 µg /m3 while in Kathmandu it varies between 6.0-13.7 µg /m3. Similarly, BC monthly concentration ranges from 3.3 -20.1 µg /m3 and 7.0-14.9 µg /m3 respectively. It was found that both EC and BC were highest during January in both the sites and it decreases gradually. Monthly average solar radiation shows a maximum value in May and minimum in January. A distinct anti-correlation between monthly average carbonaceous aerosols and total solar radiation was observed. Moreover, there was a pronounced diurnal variation of both carbonaceous aerosols EC and BC in the sites with two high peaks one in the morning at about 9:00 and another at late evening 20:00 local time with minimum concentration in the afternoon. The nature of peaks were different at two sites. Biratnagar shows a larger evening peak while Kathmandu shows in the morning inferring heavy domestic and industrial fuel consuming activities in evening and morning respectively. In addition to this, daily and monthly concentration of EC was more than BC at Biratnagar reflecting slightly more biomass fuel consumption than fossil fuel for domestic, industrial and other urban activities. In contrast to this, Kathmandu shows more domination of fossil fuel than biofuel because of reverse order concentration of carbonaceous aerosols. Total solar radiation also shows apparent diurnal variation in both sites with the highest value at around noon time. Keywords: Carbonaceous aerosol, Black carbon, Elemental carbon, Aethalometer, Total solar radiation. |
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Abstract: This paper discusses the evolution of various energy resources, their reserves, and usages for policy makers and energy experts. It finds that there is a huge supply-side deficit to meet the demand of the 7 billion people in today’s world. To meet this huge energy needs, alternative energy sources are investigated and suggestions are made to address energy crises in Bangladesh and global contexts. The author argues that with the advancement of technology, a completely new nuclear meaning thorium reactors, small modular reactors, and novel solar technologies can offer potential alternatives to meet the needs of mankind. In addition, developing cost-effective carbon capture storage devices to catch carbon at its generating sources, energy storage devices, and energy culture model can be explored. The search for alternative technologies and energy culture require robust discussion, cooperation, and investment in clean energy sources. The paper concludes with a discussion of future energy policy and appropriate action plans to adopt emerging alternative technologies as per the promises made at the Paris Climate Change Accord COP21. Keywords: Energy resources, Alternative technology, Energy culture model, Energy Cooperation. |
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Abstract: Reversible reaction couples of hydrogenation and dehydrogenation of organic compounds e.g. methylcyclohexane and toluene, or 2-propanol and acetone, are described in terms of hydrogen supplier to fuel cells, which will satisfy our demands of combined heat and power at various compact sizes. Carbon supported nano-sized metal particles, wetted with the liquid substrate in a reactor, was used for conversion of organic hydrides into hydrogen and organic compounds, being separable by distillation. Vigorous nucleate boiling is important for heat transfer as well as for irreversible bubble evolution, leading hydrogen to the vapor phase. Once the bubble is broken at the interface, catalytic hydrogenation will be prohibited, because gaseous hydrogen is unable to dissolve into the boiling liquid. Catalytic dehydrogenation under superheated liquid-film conditions can thus convert low-quality heats into hydrogen energy. Keywords: Dehydrogenation catalyst, Organic hydride, Superheated liquid-film.Download Full Article |