Large Amounts Of Electric Power Research Articles

MMC as nonlinear vector current source for grid connection of wave energy generation

Modular multilevel converter (MMC) is a type of electronic converter currently used as voltage source in real HVDC transmission systems. This paper presents, as an alternative, a control system designed to operate an MMC as a nonlinear vector current source (NLVCS). From the design point of view, it features advantages such as constant switching frequency, robustness against grid parameters changes and that the algorithm is entirely designed from space vectors. From the application point of view, the main advantages are its fast dynamic response combined with its capability to handle large amounts of electric power. Together, these two features allow the MMC to deal with highly variable renewable energies.To show the advantages of the proposed control system, it has been chosen a very demanding application: wave energy. In this type of applications, the random nature of the sea produces large and fast variations of the generated power, that enters the DC link and that the grid side converter has to handle very fast, injecting it into the grid in order to maintain the DC voltage constant.The capability of the NLVCS for MMC to handle the energy generated has been tested in two different wave energy applications. Firstly, on a single wave energy converter (WEC), a point absorber. This case is characterized by smaller and faster power changes. Secondly, on a wave farm made up of 200 WECs connected to the grid through an MMC. This case is characterized by much larger but smoother power changes.Wave farms, WECs and MMC are large and sophisticated facilities or devices that are almost impossible to gather in the same laboratory. Consequently, the features of the new control system for MMC and the advantages that provide in the connection of wave energy power plants and point absorbers to the grid has been simulated using detailed models.The results demonstrated the capability of the MMC operating as NLVCS to deal with the fast and random power changes present in renewable energy sources.

Kaji Eksperimen lengkungan Sudu Turbin Angin Savonius Tipe-U

Wind energy sources in coastal areas of Indonesia are generally one of the potential renewable energy sources (renewable energy resources) that are abundant, environmentally friendly and renewable. Savonius wind turbines can produce relatively high torque even at low wind speeds. Because it is very well developed to produce electrical energy. To get a large amount of electrical power, a large turbine construction is also needed which also requires a large amount of money, of course. For this reason, the dimensions of this wind turbine construction need to be developed, known as aspect ratio (Ar). Ar which has been studied is the cross section of the blade, as well as other values. Whereas the arch depth or blade length of type U is still likely to be studied. Therefore it is necessary to do research on type U blade arcs to get more power than before. Experimental method by making a prototype savonius type U wind turbine with 2 blades. The parameters varied only in terms of the ratio of arc length and blade cross section, other parameters followed the previous study. The expected experimental results get the aspect ratio (Ar) of the best blade in capturing wind energy and producing large electrical power.

Energy efficient design of membrane processes by use of entropy production minimization

To minimize entropy production means to reduce the lost work in a process, and to optimize the use of energy resources. Due to the need for re-compression, membrane units for separation of CO2 from natural gas require large amounts of electrical power. We show that this power requirement can be reduced by controlling the permeation process so that the entropy production is minimum. With the use of optimal control theory, we develop in this work a detailed and robust method to minimize the entropy production of a membrane unit for separation of CO2 from natural gas, by control of the partial and total pressures on the permeate side. Moreover, we show how the continuous optimal results can serve as ideal limits for the practical design. A three-step permeate pressure that approximates the optimum reduces both the entropy production and the compressor power, when the permeate gas is re-compressed.

Deployable Techniques for Small Satellites

A deployable structure serves an important function in small satellites as their performance is improved steadily. Larger deployable solar array paddles are expected as the satellite requires a larger amount of electric power. The synthetic aperture radar (SAR) system for small satellites requires a deployable antenna. Various deployable membrane structures have been proposed for the deorbit of micro/nanosatellites in low Earth orbit. The actuators and devices for a deployable structure continue to progress along with the development of a deployable structure. The hold-release mechanism has been becoming smaller and simpler. The shape control devices are actively researched for a high-precision deployable structure. There are several requirements imposed on the deployable structures, e.g., low cost, lightweight, small volume in stored configuration, reliable deployment, large aperture in deployed configuration, and accuracy/repeatability of a deployed shape. Dedicated efforts are made to satisfy these requirements in research and development of a deployable structure/device. This paper provides an overview of the past and current research and development of a deployable structure for small satellites.

Toyota unveils Sora fuel cell bus, Fine-Comfort Ride saloon

Toyota Motor Corporation unveiled two fuel cell concept vehicles at the recent Tokyo Motor Show in Japan. Toyota plans to begin sales of a commercial model based on the Sora fuel cell bus (FC Bus) concept in 2018. The company also launched the Fine-Comfort Ride premium saloon, which employs a flexible layout and offers a large amount of electric power.

Engineering simulated evolution for integrated power optimization in data centers

Cloud computing has evolved as the next-generation platform for hosting applications ranging from engineering to sciences, and from social networking to media content delivery. The numerous data centers, employed to provide cloud services, consume large amounts of electrical power, both for their functioning and their cooling. Improving power efficiency, that is, decreasing the total power consumed, has become an increasingly important task for many data centers for reasons such as cost, infrastructural limits, and mitigating negative environmental impact. Power management is a challenging optimization problem due to the scale of modern data centers. Most published work focuses on power management in computing nodes and the cooling facility in an isolated manner. In this paper, we use a combination of server consolidation and thermal management to optimize the total power consumed by the computing nodes and the cooling facility. We describe the engineering of an evolutionary non-deterministic iterative heuristic known as simulated evolution to find the best location for each virtual machine (VM) in a data center based on computational power and data center heat recirculation model to optimize total power consumption. A “goodness” function which is related to the target objectives of the problem is defined. It guides the moves and helps traverse the search space using artificial intelligence. In the process of evolution, VMs with high goodness value have a smaller probability of getting perturbed, while those with lower goodness value may be reallocated via a compound move. Results are compared with those published in previous studies, and it is found that the proposed approach is efficient both in terms of solution quality and computational time.

(Invited) Development of a Superionic Conductor for High Power All-Solid-State Battery

Batteries has been widely used as energy source of mobile electronic devices and considered to be promising for large scale energy storage for electric vehicle and smart power grid due to their high energy density. Although high power density is required to regulate a large amount of electric power, the highest energy density battery, such as lithium ion batteries, generally offer lower power density than supercapacitors, because of slow ionic transport under the charge-discharge reactions. As the high rate capabilities of solid-state electrodes were confirmed, the rate determining steps that prevent their high power densities might be the ion transport in liquid electrolyte and/or at the liquid-solid interface. At high current condition, a concentration gradient is produced due to slow diffusion both of anions and cations of the electrolyte salts in solution, and lithium near the electrode region is consumed by the electrode reaction, this is well known as a solution phase diffusion limitation. In addition, reaction kinetics at the interface of liquid electrolyte / solid electrode is slow because of the (de-)solvation reactions of lithium ion that derives from a strong interaction between lithium ion and solvents. Since issues preventing the lithium ion batteries to be high power derive from the fundamental properties of liquid electrolyte, our strategy for high energy and power is to fabricate an energy storage device with solid electrolyte instead of liquids. Although the solidification of electrolyte has been investigated over the past few decades, none of the high power secondary systems have been actually realized. Low ionic conductivity of solid electrolytes (10-5 ~ 10-3 S/cm; three to one order of magnitude of lower than those of liquid electrolytes) causes high ohmic resistivity, resulting in poor electrochemical performance; none of the all-solid-state battery systems could operate at the high current density region where solution phase limitation occurs in lithium ion battery systems, therefore, the advantage of solid configurations have not been clarified experimentally. In this study, we reported a superionic conductor of Li9.54Si1.74P1.44S11.7Cl0.3 the materials group, Li10GeP2S12. It exhibits the ionic conductivity of 25 mS cm-1 at room temperature. The wide three dimensional distributed lithium in the framework of this crystal has been clarified using careful structural analysis using neutron diffraction technique. Such a high ionically conducting solid may improve the power characteristics of the all-solid-state battery. Therefore, here we clarify the rate characteristics of an all-solid-state battery using the developed solid electrolyte and compare the performance with that of a lithium-ion battery with a standard liquid organic electrolyte of 1M LiPF6 in EC:DEC. The rate capability of all-solid-state batteries was superior to that of lithium ion battery using liquid electrolyte although the configuration of batteries were same for each systems except for electrolytes. The results of high rate capability of all-solid-state battery could be summarized as below: (Low temperature) A significant difference in the discharge profiles of the solid-state and liquid electrolyte systems was evident; while the all-solid-state battery exhibited large charge-discharge capacity at current densities of 0.03 mA cm-2, large voltage drops were observed for the liquid electrolyte battery. (Room temperature) Differences in rate characteristics between the solid-state and lithium ion batteries are clearly indicated by the rate dependence of the discharge capacities. Discharge capacity of the liquid electrolyte battery decreased rapidly at a current density of 30 mA cm-2 (45 C), although no differences in discharge capacities of the solid-state and liquid electrolyte batteries were found in the low current density region of 0.06 mA cm-2 (0.09 C) to 20 mA cm-2 (30 C). (High temperature) The performance of lithium ion battery and all-solid-state battery were evaluated at high temperature 100 °C. The lithium ion battery could not function due to thermal instability of the LiPF6-based liquid electrolyte19. In contrast, the present all-solid-state battery exhibits the excellent performance at high temperature owing to good thermal stability of solid electrolyte. The advantages of the all-solid-state battery are discussed using electrochemical evaluation techniques: (1) simple lithium transfer at the electrode / electrolyte interface with low activation energy that reduces the charge-transfer resistance at low temperatures. (2) High lithium concentration and high lithium-ion transport number prevent a concentration gradient under high rate current conditions, promoting a high rate performance. (3) Thermal stability of solid electrolyte allows to exhibit ultrahigh rate discharging performance at high temperature where lithium ion battery could not be operated. These results showed the experimental evidence of high power in an all-solid-state battery.

Greenhouse gas emission estimate in sugarcane irrigation in Brazil: is it possible to reduce it, and still increase crop yield?

Irrigation increases sugarcane yield, especially in areas under restricted rainfall conditions. However, few studies have been carried out on the environmental impacts of this activity, mainly regarding greenhouse gas (GHG) emissions. Therefore, the aim of this study was to estimate the environmental impacts of sugarcane irrigation, contemplating GHG emissions at different production scenarios. For that, biomass production was simulated under rainfed conditions and different irrigation systems, comparing six Brazilian regions (Ribeirão Preto – SP; Araçatuba – SP; Paracatu – MG; Itumbiara – GO; Paranaíba – MS; and Petrolina – PE). After gathered, GHG emission estimates of each scenario were confronted with sugarcane production data. The results were expressed in “carbon (C) footprint” (kg CO2eq t−1). For all evaluated regions, irrigation intensifies and encumbers environmentally the agricultural practices by increasing GHG emissions (∼7447.0 kg CO2eq ha−1 yr−1) compared with rainfed condition (∼2154.6 kg CO2eq ha−1 yr−1). Irrigation systems require a large amount of electric power, diesel and other inputs such as synthetic nitrogen fertilizers. Surprisingly, this situation can change substantially if C footprint is considered. We observed that irrigated areas had a decrease C footprint of up to 59% (33.0 kg CO2eq t−1) against rainfed ones, as observed in Petrolina scenario. In other regions, C footprint reductions ranged from 23% (7.1 kg CO2eq t−1) in Ribeirão Preto to 37% (13.9 kg CO2eq t−1) in Paracatu. Thus, irrigated agriculture impact could be explored in terms of C footprint, which depends on regional biomass production as well as irrigation system efficiency towards a better water use.

Impacts of Data Centres on the Environment

In the present era, the concept of virtualization is very common due to the advent of ICT. The data centers are the building blocks of IT business organizations providing the capabilities of centralized repository for storage, management, networking and dissemination of data. Continuous growth and demand in computational power endorsed for the creation of high scale data centers, requires very large amount of electrical power which acquires high operational cost and emission of carbon dioxide. These data centers not only consume a tremendous amount of energy but are riddled with IT inefficiencies and ill effects to the environment. This paper assesses to aggregate different impacts from different data centers, and so on. The future will bring increasing pressure for Data Center managers to use less electricity, buy “greener” equipment and take increased responsibility for the responsible management of e waste Power, Pollution and the Internet (2013).

Characterization and fate of polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in soils and sediments at the Portsmouth Gaseous Diffusion Plant, Ohio

The U.S. Department of Energy Portsmouth Gaseous Diffusion Plant is in the early stages of decommissioning and decontamination. During operations, the site drew a large amount of electric power and had multiple large switchyards on site. These are a source of polychlorinated biphenyls (PCB) contamination to both on-site and off-site streams. Some soil remediation has been completed in the main switchyard. During 2011 and 2012, fifteen sites were sampled at the surface (<10cm) and subsurface (20–30cm) to characterize the extent of PCB contamination, to identify weathering and migration of PCB contamination and to explore potential polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) contamination due to transformer fires and explosions in the 1950s and 1960s. Stagnant sites tended to exhibit more migration of contamination to deeper sediments than sites with fast-moving waters, and the highest concentrations were found at the bottom of a settling pond. A signature set of five dioxin-like PCBs were consistently found across the site with higher concentrations in carbon rich surface sediments. PCB concentrations had a significant inverse correlation with clay content, suggesting that PCBs did not bind to clays at this site. Remediation has reduced PCB concentrations throughout the site compared to levels found in previous studies and long-term upkeep of sediment lagoons is necessary to retain PCB and dioxin-rich sediments. The flow regimen, organic carbon and clay content play a very important role in the fate of PCBs in the environment at the surface as well as downward migration.

Wireless Power Transmission via Sheet Medium Using Automatic Phase Adjustments of Multiple Inputs

SUMMARYWireless power transmission via a sheet medium is a novel physical form of communication that utilizes a surface as a medium to provide both data and power transmission services. To efficiently transmit a relatively large amount of electric power (several watts), we have developed a wireless power transmission system via sheet medium that concentrates electric power on a specific spot by using phase control of multiple inputs. However, to find the optimal phases of the multiple inputs that let the microwave energy converge on a specific spot in the sheet medium, prior knowledge of the device's position and a preliminary experiment measuring the output power are needed. In the field of wireless communication, it is known that the retrodirective array scheme can efficiently transmit power in a self‐phasing manner, which uses pilot signals sent by client devices. In this paper, we apply the retrodirective array scheme to our wireless power transmission system via a sheet medium, and propose a power transmission scheme using the phase‐adjusted power transmission inputs. To confirm the effectiveness of the proposed scheme, we evaluate its performance by computer simulation and real‐world measurement. Both results show that the proposed scheme can achieve retrodirectivity over wireless power transmission via a sheet medium.

圧縮型柔軟発電デバイスを用いた波エネルギー発電技術の開発

A way of energy harvesting from ocean power, e.g. tide, current wave, breaking wave and vortex, has been developed using a Flexible Piezoelectric Device (FPED) consisting of a Poly Vinylidene Fluoride, an elastic material such as rubber, silicon and resin, in our previous works. A compressed type of the FPED has been proposed to convert wave power into electric power in this study. The compressed type having a porous resin with a roughness elastic material can generate a high voltage. The electric power is increasing with wave height and the horizontal momentum due to wave breaking phenomena could produce a large amount of electric power.

Energy-Efficient Redundant Execution of Processes in a Fault-Tolerant Cluster of Servers

This paper investigates into fault tolerance of cluster of servers and their energy efficiency to realize a reliable and energy aware server cluster system. A client issues a request to one server in a server cluster and the server sends a reply to the client in information systems. Once the server stops by fault, the client does not receive a reply of the request. Even if the request is performed on another server on detection of fault of the server, some QoS requirements like response time may not be satisfied. Hence, each request has to be redundantly performed on multiple servers to be tolerant of server faults. The redundant power consumption laxity-based (RPCLB) algorithm is discussed where multiple servers are selected to redundantly and energy-efficiently perform a request process in our previous studies. Since each application process is redundantly performed on more than one server, the larger amount of electric power is consumed. In this paper, we propose a novel and improved RPCLB (IRPCLB) algorithm to reduce the power consumption of servers, where once a process successfully terminates on one server, meaningless redundant processes are forced to terminate on the other servers. In the evaluation, we show the total power consumption of servers and total execution time of processes are reduced in homogeneous and heterogeneous types of clusters by the IRPCLB algorithm than the RPCLB and RR algorithms.

Analysis of energy efficiency and productivity in dry process in PCB manufacturing

Generally, the cleaning process in printed circuit board (PCB) manufacturing consists of prewash, wash, rinse, and drying stages. The prewash stage rinses off the gross contaminants from the board before the wash stage. In the wash stage, spray bar and nozzle assembly is used to remove all remaining contaminants. An anti-dragout section exists between the wash and the rinse stages. The use of an air in this section helps prevent any liquid dragout from the wash to the rinse tank. Some cleaners also have a wet isolation that provides further rinsing off the wash water from the PCB. As the last stage of the cleaning process, at drying stage, high temperature and high pressure air is used to get rid of the remaining moist thoroughly. By the way, it is known that the dry process consumes a moderately large amount of electric power since high temperature and high pressure air are required in this stage. However, if the due date of a certain PCB product is not too much tight, it would be not necessary to increase the temperature and pressure to proceed with drying. Thus, in this research, after collecting the experimental data and modeling the situations with appropriate statistical models, we develop a heuristic approach to the dry process in order to find optimal operating condition which minimizes the energy consumption while meeting the due dates of the ordered products as exactly as possible. Through the heuristic algorithm, that is, interchange-crossover algorithm, we provide an optimal (or near optimal) operating condition which can minimize both the total energy consumption and total penalty cost incurred by earliness and tardiness at the same time. The performance of the other approach is also investigated and compared to that of the developed heuristic approach.

Increasing Cloud Usage: A Shift towards Green Clouds

Cloud computing is being adopted widely and usage of internet services is increasing day by day, which gives rise to built large scale data centers. In cloud computing, a lot of research has been done on energy saving programs for reducing the energy consumption of large scale data centers. As large scale data centers consumes large amount of electrical power which affects the operating cost, performance as well as environment. This paper surveys the different energy saving techniques in network, protocols, algorithms and hardware infrastructure for energy- efficient operations.

The Hydrogen Issue

Hydrogen is often proposed as the fuel of the future, but the transformation from the present fossil fuel economy to a hydrogen economy will need the solution of numerous complex scientific and technological issues, which will require several decades to be accomplished. Hydrogen is not an alternative fuel, but an energy carrier that has to be produced by using energy, starting from hydrogen-rich compounds. Production from gasoline or natural gas does not offer any advantage over the direct use of such fuels. Production from coal by gasification techniques with capture and sequestration of CO₂ could be an interim solution. Water splitting by artificial photosynthesis, photobiological methods based on algae, and high temperatures obtained by nuclear or concentrated solar power plants are promising approaches, but still far from practical applications. In the next decades, the development of the hydrogen economy will most likely rely on water electrolysis by using enormous amounts of electric power, which in its turn has to be generated. Producing electricity by burning fossil fuels, of course, cannot be a rational solution. Hydroelectric power can give but a very modest contribution. Therefore, it will be necessary to generate large amounts of electric power by nuclear energy of by renewable energies. A hydrogen economy based on nuclear electricity would imply the construction of thousands of fission reactors, thereby magnifying all the problems related to the use of nuclear energy (e.g., safe disposal of radioactive waste, nuclear proliferation, plant decommissioning, uranium shortage). In principle, wind, photovoltaic, and concentrated solar power have the potential to produce enormous amounts of electric power, but, except for wind, such technologies are too underdeveloped and expensive to tackle such a big task in a short period of time. A full development of a hydrogen economy needs also improvement in hydrogen storage, transportation and distribution. Hydrogen and electricity can be easily interconverted by electrolysis and fuel cells, and which of these two energy carriers will prevail, particularly in the crucial field of road vehicle powering, will depend on the solutions found for their peculiar drawbacks, namely storage for electricity and transportation and distribution for hydrogen. There is little doubt that power production by renewable energies, energy storage by hydrogen, and electric power transportation and distribution by smart electric grids will play an essential role in phasing out fossil fuels.

Electrical Insulation Characteristics of a High-${\rm T}_{\rm c}$ Superconducting DC Cable

A high temperature superconducting (HTS) DC cable is ideal for transmitting large amount of electrical power over a long distance. However, it must be designed to operate reliably within the constraints of the electrical systems. Therefore, a study of the electrical insulation is important to develop a HTS DC cable because it is operated in a cryogenic high voltage environment. This paper discusses the dielectric constructions of the cable and summarizes the experiment results on the DC and impulse dielectric characteristics of the insulation material, in sheet form and mini-model cable configuration. This shows how to design such insulation to be operated reliably. These studies are essential for the insulation design of a HTS DC cable operating in cryogenic environment.

Superconducting Lines for the Transmission of Large Amounts of Electrical Power Over Great Distances: Garwin–Matisoo Revisited Forty Years Later

In 1966, following a decade of discovery and development on A15 compounds, Richard Garwin and Juri Matisoo [1], two research staff members then in the IBM Research Division, submitted for publication a paper examining the prospect to employ one of the most promising of these materials, Nb3Sn, in a cable system for transmission of electricity. The scale of their proposal was truly enormous -100 GW (+/100 kV at 500 kA direct current) over a distance of 1000 km, the entire length refrigerated by liquid helium. At the time, such a cable would have been capable of carrying half the entire electric power generated in the United States, and about one-tenth today. This paper will revisit their vision in the context of the subsequent discovery of high temperature superconductivity twenty years later, and the now emerging availability of long lengths of high performance wire and tape for operation in the 20-80 K range. Whereas the scenario set by Garwin and Matisoo addressed the one-way transmission of electricity from remote coal and nuclear generation multi-plant farms to large population centers, we will extend their picture to include two-way transmission on a diurnal or longer period to take advantage of regional electricity pricing and production which has resulted from the deregulation of generation. We conclude that the advent of high temperature superconductivity substantially extends and brings closer both the technical and economic feasibility of Garwin and Matisoo's dream. However, we note, as did they, the caveat that whether it is desirable or necessary is another matter entirely. We believe this question will be decided in the affirmative as societal demands continue to increase for the clean, reliable and ecologically gentle delivery of large amounts of electric power, a need that was foreseen but not as overriding forty years ago as it is now.

Proposal of utilization of nuclear spent fuels for gamma cells

Abstract Large amounts of nuclear spent fuel are generated in nuclear power plants every year and stored in fuel storage facilities for 20–30 years until reprocessing. However, the spent fuel still has residual energies, such as high-temperature heat energy and high-intensity gamma radioactivity. We have examined the characteristics of solar cells exposed to gamma radiation for the development of gamma cells utilizing nuclear spent fuel. We used a highly intense 60Co gamma source as a suitable substitute for spent fuel due to safety concerns and convenience. Two representative types of solar cells, amorphous and crystalline cells, were examined and the current and voltage generated by each type were measured. In general, solar cells are largely insensitive to gamma radiation because the radiation passes through solar cells without imparting all of its energy. In order to enhance the sensitivity to radiation, the solar cells were coupled to CsI(Tl), NaI(Tl) and plastic scintillators. We confirmed the following characteristics: (1) amorphous solar cells coupled to a CsI(Tl) scintillator are able to generate a large amount of electric power, compared to crystal-type solar cells, (2) amorphous cells exhibit a good linear response to high-intensity gamma radiation and generate electric power almost in proportion to the volume of the scintillator used, (3) the generated electric power is independent of the incident angle of the gamma rays and the amount of power is determined only by the volume of the scintillator used. The electric power generated by a single solar cell is very small, but a large amount of electric power can be obtained by arranging many solar cells in stacks and combining their induced current or voltage and by operating the cells all day, as they are not affected by weather conditions. We concluded that gamma cells utilizing the gamma radiation of nuclear spent fuel can be expected to be useful for electric power generation in the near future.

Intensive energy density thermoelectric energy conversion system by using FGM compliant pads

In order to provide increasingly large amounts of electrical power to space and terrestrial systems with a sufficient reliability at a reasonable cost, thermoelectric energy conversion system by using Functionally Graded Material (FGM) compliant pads has been focused. To achieve high thermal energy density in thermoelectric (TE) power conversion systems, conductively coupling the TE module to the hot and cold heat exchangers is the most effective configuration. This is accomplished by two sets of FGM compliant pads. This design strategy provides (1) a high flux, direct conduction path to heat source and heat sink, (2) the structural flexibility to protect the cell from high stress due to thermal expansion, (3) an extended durability by a simple FGM structure, and (4) manufacturing cost reduction by spark plasma sintering. High thermal energy density of more than twice as much as conventional conduction coupling TE generator is expected. TE energy conversion systems combined with FGM compliant pads for space and terrestrial design options are proposed in this paper.