Search

The article features a discussion on wind power. Wind power does not require further research and development before initial large-scale deployment unlike other solar-related processes. Wind power generating electricity on a large scale could contribute substantially to the national energy needs. Large wind-electric machines could be designed and built now that would provide the operating experience and the data for dependable cost analyses needed before large numbers of these machines would be deployed. An example of a wind-electric machine is the Smith-Putnam machine which was built and largely financed by a turbine firm, the S. Morgan Smith Company of Pennsylvania, with the participation of various firms and experts.

This work presents a systematic method for analysis and optimization of specific energy production (SEP) of pressure retarded osmosis (PRO) systems employing single-stage configuration as well as multistage design with interstage hydro-turbines. It is shown that the SEP normalized by the draw solution feed osmotic pressure increases with the number of stages as well as a dimensionless parameter [ABSTRACT FROM AUTHOR]

In this paper, different types of zero head or run of the river scheme micro hydro turbines with their design methodologies have been discussed. These are considered to be ideal for hydropower production with very low head (VLH) differences between 0.5 and 5 m. Punjab has a total low-head hydel potential of 600- 1000 MW on canals and barrages. Already developed technologies are much costly and are suitable for large potential sites only. For sites with low potential need is to develop a novel technology that can be manufactured locally to use this potential. These small resources, if exploited efficiently, can contribute to overcome the short fall of electricity in rural areas of the province of Punjab. A design of Undershot Hydrostatic Pressure Converter (U-HPC) for a specific site in Punjab has been also been presented. [ABSTRACT FROM AUTHOR]

Various factors exist that cause torsional interaction, such as subsynchronous resonance and switching effects following electrical disturbances. In particular, successive circuit-breaker operation may amplify the turbine-generator shaft torque under unsuccessful reclosing conditions. Thus, in this paper, we carried out transient stability analysis using the integral square error method and derived the relationship between the shaft torque amplitude and reclosing time through analysis of a 2-degree of freedom system under reclosing into permanent fault condition. In addition, we proposed a novel reclosing algorithm with consideration of transient stability and shaft torque amplitude. The performance of the proposed reclosing method was verified in actual 154 kV and 345 kV Korean study systems using the Electromagnetic Transient Program. [ABSTRACT FROM PUBLISHER]

To improve the power generation efficiency, the parameters matching analysis method for the downhole generator with asymmetric turbine is established on basis of the experimental design theory, response surface methodology and orthogonal experimental design. Firstly, according to the theoretical analysis, the computational domain model is built by the three-dimensional modeling software. Based on the calculation results by Computational Fluid Dynamics (CFD), the blade parameters of stator and rotor which affect the objective function a lot are screened out by the single-factor experimental design. Then, to get the optimal design results, these parameters are analyzed and determined by the Box-Behnken design and response surface methodology. Once the approximation model of objective function is constructed, the interplay between these parameters is discussed in this paper. Furthermore, the secondary factors are analyzed to obtain the more reasonable matching by orthogonal experimental method. Finally, the experimental study is conducted on the optimal design point of the new asymmetric turbine. The results show that CFD simulations are in good accordance with the calculations based on response surface method. The relative error of experimental value is smaller compared with the predictive value, and the trends of performance curves are almost the same. What's more, the efficiency of new asymmetric turbine increases by 10 % after optimizing matching. It declares that the design method based on Box-Behnken and the orthogonal design experiments can be used in the matching analysis of asymmetric turbine's parameters. The research in this paper provides reliable guidance in turbine blade design and technological parameters optimizing. [ABSTRACT FROM AUTHOR]

The hydrokinetic energy conversion system has capabilities to supply inevitable and secured power which is obtained from free stream like ocean, river, and man-made channel etc. So far, researchers have done different work on resource availability, design parameter, electricity generation cost, reactivity of plant, its impact on environmental separately. In this paper an attempt is made to review the technology, performance, design optimization, reliability, techno-economic analysis and environmental impact of the hydrokinetic energy conversion systems altogether to establish the relationship between the above said aspects towards the viability of power project. After conducting these reviews it has become clear that in order to avoid cavitation, coefficient of pressure should be less than cavitation coefficient especially at leading edge of hydrokinetic turbine blade. Moreover, to avoid stall and separation, angle of attack should be kept as less as possible. By implementing hydrofoil blade profile, performance of the hydrokinetic turbine can be improved. Sometimes, implementation of double blade hydrofoil may be beneficial and increase the coefficient of lift more than that of the single blade hydrofoil. Apart from the above considerations it is to be noted that deployment of turbine near bed level should be avoided as it brings down available power, increase hydrodynamic loading, turbulence level, and fouling by sediments. Moreover to increase the performance arm and end plate can be incorporated in hydrokinetic turbine design. It is also observed that hybrid conversion system is also viable in order to reduce power generation cost. This paper will help researchers to identify areas of design parameter of hydrokinetic turbine that need to improve and encourage the project developer, funding and financial institution, policy maker or government officials, and local community, to provide knowledge about hydrokinetic energy conversion system for executing the project and compete with the existing market. [ABSTRACT FROM AUTHOR]

The current prevailing idea of tidal energy conversion is that it is presumed uneconomical to extract power from tidal flows of less than 2 m/s. As a result, there are a limited number of locations where energy from tidal flows can be exploited worldwide. Increasing the operating range of tidal energy devices to enable the extraction of useful power from low-velocity tidal flows would make tidal energy conversion possible in many more places around the world and greatly increase the potential global generating capacity. This paper presents a novel approach in extracting power from low tidal flows using vertical arrays of reduced diameter turbines. This has the effect of reducing the cut-in speed, increasing the operating range of the tidal energy device as well as the advantage of a lower cost, modular design, which addresses the issue of economical extraction at low flow rates. An assessment of the tidal energy resource around Hong Kong has been conducted for the preliminary stages of an ongoing tidal energy research project. The gathered data have been used to demonstrate the effectiveness of the presented concept in the Hong Kong region and other areas of low-velocity tidal flows. It has been demonstrated that a power increase of 40% is attainable from a vertical array of reduced diameter turbines when compared to a single, large-diameter device with the same frontal area. With the additional advantages of reduced cost of fabrication, installation, and maintenance from using smaller-diameter, modular tidal turbines, the concept is highly important to the advancement of global tidal power generation. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Large arrays of tidal turbines are critical to realise the potential of tidal current power. This study is a systematic exploration of large tidal array optimisation in channels with numerically modelled array layouts in 2-D. Crucially, flow along channels is driven by head loss leading to significantly more realistic results than previous models which assume constant velocity. The 2-D adaptive mesh approach bridges the gap between large- and small-scale array models. Hundreds of layouts and turbine tunings have been simulated using LES of turbulent flow in tidally reversing currents to explore channel-scale optimisation and tuning of large arrays. Simulations show that total power capture increases as rows are added to the array although there are diminishing returns on additional turbines. Each turbine in 1 (7), optimally blocked row in a small channel captures 2.5 × ( 0.5 × ) the power of an isolated turbine. There is an optimum blockage for maximum power per turbine which decreases linearly from 1.0 as the number of rows increases. As array size increases individual turbine wakes become less important than stepped head loss across each row. Free-stream velocity reduces linearly with total power capture, with the gradient increasing with channel size. [ABSTRACT FROM AUTHOR]

Our work presents the original mathematical model, which can be determined on the basis of the actual profits from electricity production in pumped storage hydropower plants (PSHP). The derived relationship was obtained by the dimensional analysis of the relevant physical parameters describing the production of energy. The main purpose of this paper is to prove whether a dimensional analysis can be a useful tool to describe the economic aspect of the phenomenon, as proved by its worth when examining technical phenomena. The mathematical model has been derived for PSHP Ružín in Slovakia, but its validity, based on the similarity theory, can be extended to any pumping power plant that works with the influx of water into the upper storage reservoir, and/or without the feed, respectively. The article discusses the effects of various parameters on the operating profit for the turbine operations and the costs associated with the pumping operation. [ABSTRACT FROM AUTHOR]

The article focuses on the use of natural gas for electric power generation as well as needed research and development to further improve existing natural gas combustion turbine technology. Topics discussed include the demand for natural gas-based electricity in 2013 according to the U.S. Energy Information Administration, factors that will influence the use of natural gas for electric power generation and the state of natural gas turbine technology in 2015.

There are two popular practical models of synchronous generators used in power system simulation, both based on Park equations, defined as assumedAand assumedBrespectively, according to the different assumptions. To study the influence of the different models on the first swing stability calculation precision, the physical essence of the two assumptions are revealed in theory, and it is obtained that assumedAtakes account of the mutual leakage flux linkage between field and damping windings and neglects the self-leakage flux linkage of damping winding, the opposite of assumedB. Taking a 300-MW turbine generator as an example, first swing stability limits calculated by two practical models are compared; simulation results are verified by the time-step finite-element model. The influence of line reactance and excitation system on first swing stability limits is studied. Results show that the first swing stability limit calculated by the practical model with assumedAis closer to the result of the time-step finite-element model, since assumedAtakes account of the larger mutual leakage flux linkage. Therefore, the practical model with assumedAis more accurate. The result provides reasonable reference to select synchronous generator models in power system simulation. [ABSTRACT FROM PUBLISHER]

Abstract: Achieving the economic and viability of power generation from wave energy requires design and development of new and improved machinery. This paper displays the design of an improved impulse turbine using a systematic method, which combines two powerful design tools, i.e. Pugh concept analysis and 3DCAD environment. Using this approach allows the user to combine the strength of Pugh’s method and the design space, allowing the concept selection process to be streamlined. This brings new concept in the mechanical design field, which is inline with the technological trends prevalent in the industry. The capabilities of the proposed approach is applied in a case study that considers impulse turbine wave energy extraction optimum design. The latter was arrived at by combining and/or refining the alternatives as the process develops. Furthermore, the optimum design has been tested for structural performance using structural analysis integrated within the 3DCAD environment. The results show a moderate design stress which would relax the manufacturing technique, and yet with a good safety factor. [Copyright &y& Elsevier]

Abstract: In this work, combustion turbine inlet air cooling (CTIAC) systems are analyzed from an economic outlook, their effects on the global performance parameters and the economic results of the power plant. The study has been carried out on a combined cogeneration system, composed of a General Electric PG 6541 gas turbine and a heat recovery steam generator. The work has been divided into three parts. First, a revision of the present CTIAC technologies is shown, their effects on power plant performance and evaluation of the associated investment and maintenance costs. In a second phase of the work, the cogeneration plant was modelled with the objective of evaluating the power increase and the effects on the generated steam and the thermal oil. The cogeneration power plant model was developed, departing from the recorded operational data of the plant in 2005 and the gas turbine model offered by General Electric, to take into consideration that, in 2000, the gas turbine had been remodelled and the original performance curves should be corrected. The final objective of this model was to express the power plant main variables as a function of the gas turbine intake temperature, pressure and relative humidity. Finally, this model was applied to analyze the economic interest of different intake cooling systems, in different operative ranges and with different cooling capacities. [Copyright &y& Elsevier]

This paper presents exergy analysis of a conceptualized combined cogeneration plant that employs pressurized oxygen blown coal gasifier and high-temperature, high-pressure solid oxide fuel cell (SOFC) in the topping cycle and a bottoming steam cogeneration cycle. Useful heat is supplied by the pass-out steam from the steam turbine and also by the steam raised separately in an evaporator placed in the heat recovery steam generator (HRSG). Exergy analysis shows that major part of plant exergy destruction takes place in gasifier and SOFC while considerable losses are also attributed to gas cooler, combustion chamber and HRSG. Exergy losses are found to decrease with increasing pressure ratio across the gas turbine for all of these components except the gas cooler. The fuel cell operating temperature influences the performance of the equipment placed downstream of SOFC. Copyright © 2005 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Installation of wind-turbine blades on monopile-type offshore wind turbines is a demanding task. Typically, a jack-up crane vessel is used, and blades are individually lifted from the vessel deck and docked with the preinstalled hub. During the process of mating, large relative motions are developed between the hub and root due to combined effects of wind-generated blade-root responses and wave-generated monopile vibrations. This can cause impact loads at the blade root and induce severe damages at the blade-root connection. Such events are highly likely to cause the failure of the mating task, while affecting the subsequent activities, and thus require competent planning. The purpose of this paper is to present a probabilistic response-based methodology for estimating the allowable sea states for planning a wind-turbine blade-mating task, considering impact risks with the hub as the hazardous event. A case study is presented where the installation system consisting of blade-lift and monopile system are modelled using multibody formulations. Time-domain analyses are carried out for various sea states, and impact velocities between root and hub are analyzed. Finally, an extreme value analysis using the Gumbel fitting of response parameters is performed and limiting sea state curves are obtained by comparing characteristic extreme responses with allowable values. It is found that the limiting sea states for blade-root mating tasks are low for aligned wind–wave conditions, and further increase with increased wind–wave misalignment. The results of the study also show that the parameter T p is essential for estimating limiting sea states given that this parameter significantly influences monopile vibrations during the blade-root mating task. Overall, the findings of the study can be used for a safer and more cost-effective mating of wind-turbine blades. [ABSTRACT FROM AUTHOR]

The article presents turbines designed by Alexander Gorlov for producing electricity from river currents that will be installed on Merrimack River in Massachusetts in 2004. It is one of the many proposed devices in development that could extract power from water with minimal environmental damage. But this patented prototype has gained international interest and funds after collaborating with Verdant Power, GCK Technology and Massachusetts Renewable Energy Trust. These turbines can work in shallower waters better than conventional turbines, so this technology can bring hydropower to places where dams could not be built.

Reports on the issues concerning the limits placed on wind turbine viability. Arguments for scaling rotors; Contribution of developmental cost on wind turbine viability; Impact of wind turbine design on its viability.

Points out the implications of serious design faults in gas turbines that are used in generating power in the United Kingdom. Reasons for the occurrence of design faults; Key to successful machine manufacturing and designing; Information on the worst design failures.