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Energies, Volume 3, Issue 7 (July 2010), Pages 1335-1422

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Research

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Open AccessArticle Metamaterial Electromagnetic Superabsorber with Arbitrary Geometries
Energies 2010, 3(7), 1335-1343; doi:10.3390/en3071335
Received: 25 May 2010 / Revised: 23 June 2010 / Accepted: 28 June 2010 / Published: 29 June 2010
Cited by 6 | PDF Full-text (547 KB) | HTML Full-text | XML Full-text
Abstract
The electromagnetic superabsorber that has larger absorption cross section than its real size may be a novel photothermal device with improved solar energy conversion rates. Based on a transformation optical approach, the material parameters for a two-dimensional (2D) metamaterial-assisted electromagnetic superabsorber with arbitrary
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The electromagnetic superabsorber that has larger absorption cross section than its real size may be a novel photothermal device with improved solar energy conversion rates. Based on a transformation optical approach, the material parameters for a two-dimensional (2D) metamaterial-assisted electromagnetic superabsorber with arbitrary geometries are derived and validated by numerical simulation. We find that for the given geometry size, the absorption cross section of the superabsorber using nonlinear transformation is larger than that using linear transformation. These transformations can also be specialized to the designing the N-sided regular polygonal superabsorber just by changing the contour equation. All theoretical and numerical results validate the material parameters for the 2D electromagnetic superabsorber we have developed. Full article
Open AccessArticle Gasification of Biochar from Empty Fruit Bunch in a Fluidized Bed Reactor
Energies 2010, 3(7), 1344-1352; doi:10.3390/en3071344
Received: 6 May 2010 / Accepted: 31 May 2010 / Published: 2 July 2010
Cited by 15 | PDF Full-text (193 KB) | HTML Full-text | XML Full-text
Abstract
A biochar produced from empty fruit bunches (EFB) was gasified in a fluidized bed using air to determine gas yield, overall carbon conversion, gas quality, and composition as a function of temperature. The experiment was conducted in the temperature range of 500–850 °C.
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A biochar produced from empty fruit bunches (EFB) was gasified in a fluidized bed using air to determine gas yield, overall carbon conversion, gas quality, and composition as a function of temperature. The experiment was conducted in the temperature range of 500–850 °C. It was observed that biochar has the potential to replace coal as a gasification agent in power plants. Hydrogen gas from biochar was also optimized during the experiment. High temperatures favor H2 and CO formation. There was an increase of H2 over the temperature range from 500–850 °C from 5.53% to 27.97% (v/v), with a heating value of 30 kJ/g. The C conversion in the same temperature range increased from 76% to 84%. Therefore, there are great prospects for the use of biochar from EFB as an alternative fuel in power plants, as a renewable energy providing an alternative path to biofuels. Results from this work enable us to better understand syn gas production under high treatment temperatures. Full article
Open AccessArticle Electricity Self-Generation Costs for Industrial Companies in Cameroon
Energies 2010, 3(7), 1353-1368; doi:10.3390/en3071353
Received: 27 May 2010 / Accepted: 8 June 2010 / Published: 5 July 2010
Cited by 4 | PDF Full-text (310 KB) | HTML Full-text | XML Full-text
Abstract
Industrial production in developing countries (DC) is frequently perturbed by electric energy supply difficulties. To overcome this problem, generators are used in self-generation of energy, but this leads to an increase of electricity-related expenses. This article assesses the impact of electricity self-generation on
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Industrial production in developing countries (DC) is frequently perturbed by electric energy supply difficulties. To overcome this problem, generators are used in self-generation of energy, but this leads to an increase of electricity-related expenses. This article assesses the impact of electricity self-generation on Cameroonian industrial companies. The model described in this article is based on data collected through a survey of a representative sample of industrial companies and from numerous previous thematic and statistical studies. The results of our analyses show that expenses related to electricity in industrial companies in Cameroon have increased five times due to electricity rationing and untimely power cuts. The article also suggests some solutions to improve the electricity self-generation capacity of industrial companies. Full article
Figures

Open AccessArticle Co-Fuelling of Peat with Meat and Bone Meal in a Pilot Scale Bubbling Bed Reactor
Energies 2010, 3(7), 1369-1382; doi:10.3390/en3071369
Received: 5 June 2010 / Accepted: 2 July 2010 / Published: 8 July 2010
Cited by 5 | PDF Full-text (310 KB) | HTML Full-text | XML Full-text
Abstract
Co-combustion performance trials of Meat and Bone Meal (MBM) and peat were conducted using a bubbling fluidized bed (BFB) reactor. In the combustion performance trials the effects of the co-combustion of MBM and peat on flue gas emissions, bed fluidization, ash agglomeration tendency
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Co-combustion performance trials of Meat and Bone Meal (MBM) and peat were conducted using a bubbling fluidized bed (BFB) reactor. In the combustion performance trials the effects of the co-combustion of MBM and peat on flue gas emissions, bed fluidization, ash agglomeration tendency in the bed and the composition and quality of the ash were studied. MBM was mixed with peat at 6 levels between 15% and 100%. Emissions were predominantly below regulatory limits. CO concentrations in the flue gas only exceeded the 100 mg/m3 limit upon combustion of pure MBM. SO2 emissions were found to be over the limit of 50 mg/m3, while in all trials NOx emissions were below the limit of 300 mg/m3. The HCl content of the flue gases was found to vary near the limit of 30 mg/m3. VOCs however were within their limits. The problem of bed agglomeration was avoided when the bed temperature was about 850 °C and only 20% MBM was co-combusted. This study indicates that a pilot scale BFB reactor can, under optimum conditions, be operated within emission limits when MBM is used as a co-fuel with peat. This can provide a basis for further scale-up development work in industrial scale BFB applications. Full article

Review

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Open AccessReview Coastal and Offshore Wind Energy Generation: Is It Environmentally Benign?
Energies 2010, 3(7), 1383-1422; doi:10.3390/en3071383
Received: 15 June 2010 / Accepted: 6 July 2010 / Published: 20 July 2010
Cited by 27 | PDF Full-text (804 KB) | HTML Full-text | XML Full-text
Abstract
Offshore and coastal wind power is one of the fastest growing industries in many areas, especially those with shallow coastal regions due to the preferable generation conditions available in the regions. As with any expanding industry, there are concerns regarding the potential environmental
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Offshore and coastal wind power is one of the fastest growing industries in many areas, especially those with shallow coastal regions due to the preferable generation conditions available in the regions. As with any expanding industry, there are concerns regarding the potential environmental effects which may be caused by the installation of the offshore wind turbines and their associated infrastructure, including substations and subsea cables. These include the potential impacts on the biological, physical and human environments. This review discusses in detail the potential impacts arising from offshore wind farm construction, and how these may be quantified and addressed through the use of conceptual models. It concludes that while not environmentally benign, the environmental impacts are minor and can be mitigated through good siting practices. In addition, it suggests that there are opportunities for environmental benefits through habitat creation and conservation protection areas. Full article
(This article belongs to the Special Issue Wind Energy)

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