Showing papers on "Efficient energy use published in 2006"
TL;DR: Solar energy is by far the largest exploitable resource, providing more energy in 1 hour to the earth than all of the energy consumed by humans in an entire year, and if solar energy is to be a major primary energy source, it must be stored and dispatched on demand to the end user.
Abstract: Global energy consumption is projected to increase, even in the face of substantial declines in energy intensity, at least 2-fold by midcentury relative to the present because of population and economic growth. This demand could be met, in principle, from fossil energy resources, particularly coal. However, the cumulative nature of CO2 emissions in the atmosphere demands that holding atmospheric CO2 levels to even twice their preanthropogenic values by midcentury will require invention, development, and deployment of schemes for carbon-neutral energy production on a scale commensurate with, or larger than, the entire present-day energy supply from all sources combined. Among renewable energy resources, solar energy is by far the largest exploitable resource, providing more energy in 1 hour to the earth than all of the energy consumed by humans in an entire year. In view of the intermittency of insolation, if solar energy is to be a major primary energy source, it must be stored and dispatched on demand to the end user. An especially attractive approach is to store solar-converted energy in the form of chemical bonds, i.e., in a photosynthetic process at a year-round average efficiency significantly higher than current plants or algae, to reduce land-area requirements. Scientific challenges involved with this process include schemes to capture and convert solar energy and then store the energy in the form of chemical bonds, producing oxygen from water and a reduced fuel such as hydrogen, methane, methanol, or other hydrocarbon species.
7,076 citations
TL;DR: In this article, the authors analyzed energy efficiency of 29 administrative regions in China for the period 1995-2002 with a newly introduced index, the index of total-factor energy efficiency (TFEE), which divides the target energy input by the actual energy input.
1,151 citations
TL;DR: A new distributed energy-efficient clustering scheme for heterogeneous wireless sensor networks, which is called DEEC, is proposed and evaluated, which achieves longer lifetime and more effective messages than current important clustering protocols in heterogeneous environments.
1,131 citations
TL;DR: In this paper, the authors compared redox flow systems in the light of characteristics such as open circuit potential, power density, energy efficiency, and charge-discharge behavior, and highlighted areas for further research.
1,054 citations
TL;DR: This article presents a survey of data-aggregation algorithms in wireless sensor networks and compares and contrast different algorithms on the basis of performance measures such as lifetime, latency, and data accuracy.
Abstract: Wireless sensor networks consist of sensor nodes with sensing and com- munication capabilities. We focus on data-aggregation problems in energy- constrained sensor networks. The main goal of data-aggregation algorithms is to gather and aggregate data in an energy efficient manner so that net- work lifetime is enhanced. In this article we present a survey of data-aggre- gation algorithms in wireless sensor networks. We compare and contrast different algorithms on the basis of performance measures such as lifetime, latency, and data accuracy. We conclude with possible future research directions.
943 citations
TL;DR: In this article, the authors present an overview of state-of-the-art naphtha cracking technologies and show that up to 20% savings on the current average process energy use are possible.
822 citations
TL;DR: This article surveys recent contributions addressing energy-efficient coverage problems in the context of static wireless sensor networks, and presents various coverage formulations, their assumptions, as well as an overview of the solutions proposed.
584 citations
TL;DR: An analytical model is presented to understand the key performance metrics such as data transfer, latency to the destination, and power and shows that this approach can provide substantial savings in energy as compared to the traditional ad-hoc network approach.
Abstract: We analyze an architecture based on mobility to address the problem of energy efficient data collection in a sensor network. Our approach exploits mobile nodes present in the sensor field as forwarding agents. As a mobile node moves in close proximity to sensors, data is transferred to the mobile node for later depositing at the destination. We present an analytical model to understand the key performance metrics such as data transfer, latency to the destination, and power. Parameters for our model include: sensor buffer size, data generation rate, radio characteristics, and mobility patterns of mobile nodes. Through simulation we verify our model and show that our approach can provide substantial savings in energy as compared to the traditional ad-hoc network approach.
552 citations
TL;DR: The design and implementation of a complete running system, called VigilNet, for energy-efficient surveillance, which allows a group of cooperating sensor devices to detect and track the positions of moving vehicles in an energy- efficient and stealthy manner is described.
Abstract: This article describes one of the major efforts in the sensor network community to build an integrated sensor network system for surveillance missions. The focus of this effort is to acquire and verify information about enemy capabilities and positions of hostile targets. Such missions often involve a high element of risk for human personnel and require a high degree of stealthiness. Hence, the ability to deploy unmanned surveillance missions, by using wireless sensor networks, is of great practical importance for the military. Because of the energy constraints of sensor devices, such systems necessitate an energy-aware design to ensure the longevity of surveillance missions. Solutions proposed recently for this type of system show promising results through simulations. However, the simplified assumptions they make about the system in the simulator often do not hold well in practice, and energy consumption is narrowly accounted for within a single protocol. In this article, we describe the design and implementation of a complete running system, called VigilNet, for energy-efficient surveillance. The VigilNet allows a group of cooperating sensor devices to detect and track the positions of moving vehicles in an energy-efficient and stealthy manner. We evaluate VigilNet middleware components and integrated system extensively on a network of 70 MICA2 motes. Our results show that our surveillance strategy is adaptable and achieves a significant extension of network lifetime. Finally, we share lessons learned in building such an integrated sensor system.
550 citations
28 Jun 2006
TL;DR: It is demonstrated that the introduction of a second parallel network can increase performance while improving efficiency, and different strategies for distributing traffic over the subnetworks are evaluated.
Abstract: We develop detailed area and energy models for on-chip interconnection networks and describe tradeoffs in the design of efficient networks for tiled chip multiprocessors. Using these detailed models we investigate how aspects of the network architecture including topology, channel width, routing strategy, and buffer size affect performance and impact area and energy efficiency. We simulate the performance of a variety of on-chip networks designed for tiled chip multiprocessors implemented in an advanced VLSI process and compare area and energy efficiencies estimated from our models. We demonstrate that the introduction of a second parallel network can increase performance while improving efficiency, and evaluate different strategies for distributing traffic over the subnetworks. Drawing on insights from our analysis, we present a concentrated mesh topology with replicated subnetworks and express channels which provides a 24% improvement in area efficiency and a 48% improvement in energy efficiency over other networks evaluated in this study.
547 citations
TL;DR: In this article, the authors provide an up-to-date review of the various cogeneration technologies suitable for residential applications, and consider the various technologies available and under development for residential, i.e. single-family (single-family) buildings.
Abstract: There is a growing potential for the use of micro-cogeneration systems in the residential sector because they have the ability to produce both useful thermal energy and electricity from a single source of fuel such as oil or natural gas. In cogeneration systems, the efficiency of energy conversion increases to over 80% as compared to an average of 30–35% for conventional fossil fuel fired electricity generation systems. This increase in energy efficiency can result in lower costs and reduction in greenhouse gas emissions when compared to the conventional methods of generating heat and electricity separately. Cogeneration systems and equipment suitable for residential and small-scale commercial applications like hospitals, hotels or institutional buildings are available, and many new systems are under development. These products are used or aimed for meeting the electrical and thermal demands of a building for space and domestic hot water heating, and potentially, absorption cooling. The aim of this paper is to provide an up-to-date review of the various cogeneration technologies suitable for residential applications. The paper considers the various technologies available and under development for residential, i.e. single-family (
07 May 2006
TL;DR: A set of energy minimization benchmarks, which are used to compare the solution quality and running time of several common energy minimizations algorithms, as well as a general-purpose software interface that allows vision researchers to easily switch between optimization methods with minimal overhead.
Abstract: One of the most exciting advances in early vision has been the development of efficient energy minimization algorithms. Many early vision tasks require labeling each pixel with some quantity such as depth or texture. While many such problems can be elegantly expressed in the language of Markov Random Fields (MRF's), the resulting energy minimization problems were widely viewed as intractable. Recently, algorithms such as graph cuts and loopy belief propagation (LBP) have proven to be very powerful: for example, such methods form the basis for almost all the top-performing stereo methods. Unfortunately, most papers define their own energy function, which is minimized with a specific algorithm of their choice. As a result, the tradeoffs among different energy minimization algorithms are not well understood. In this paper we describe a set of energy minimization benchmarks, which we use to compare the solution quality and running time of several common energy minimization algorithms. We investigate three promising recent methods—graph cuts, LBP, and tree-reweighted message passing—as well as the well-known older iterated conditional modes (ICM) algorithm. Our benchmark problems are drawn from published energy functions used for stereo, image stitching and interactive segmentation. We also provide a general-purpose software interface that allows vision researchers to easily switch between optimization methods with minimal overhead. We expect that the availability of our benchmarks and interface will make it significantly easier for vision researchers to adopt the best method for their specific problems. Benchmarks, code, results and images are available at http://vision.middlebury.edu/MRF.
TL;DR: In this article, the authors reviewed energy intensity trends for the major OECD nations since 1973, considering how much of the overall reduction in E/GDP was due to energy efficiency improvement and how much due to structural change, and the bulk of the energy efficiency policies and programs adopted in Japan, United States, and Western Europe, commenting on their effectiveness and energy savings impacts where possible.
TL;DR: The United States Department of Energy has established three centers of excellence for hydrogen storage materials development as mentioned in this paper, focusing on complex metal hydrides that can be regenerated onboard a vehicle, chemical hydride that require off-board reprocessing, and carbon-based storage materials.
TL;DR: In this article, the authors argue that a more effective CO 2 policy is to concentrate on shifting to non-fossil fuels, like renewables, subsidized through a carbon tax.
01 Jan 2006
TL;DR: In this article, the authors used the Controls Advanced Research Turbine (CART) as a model for this article's research, which is located in Golden, Colorado, at the U.S. National Renewable Energy Laboratory's National Wind Technology Center.
Abstract: 1066-033X/06/$20.00©2006IEEE W ind energy is the fastest-growing energy source in the world, with worldwide wind-generation capacity tripling in the five years leading up to 2004 [1]. Because wind turbines are large, flexible structures operating in noisy environments, they present a myriad of control problems that, if solved, could reduce the cost of wind energy. In contrast to constantspeed turbines (see “Wind Turbine Development and Types of Turbines”), variable-speed wind turbines are designed to follow wind-speed variations in low winds to maximize aerodynamic efficiency. Standard control laws [2] require that complex aerodynamic properties be well known so that the variable-speed turbine can maximize energy capture; in practice, uncertainties limit the efficient energy capture of a variable-speed turbine. The turbine used as a model for this article’s research is the Controls Advanced Research Turbine (CART) pictured in Figure 1. CART is located in Golden, Colorado, at the U.S. National Renewable Energy Laboratory’s National Wind Technology Center (see “The National Renewable Energy Laboratory and National Wind Technology Center”). A modern utility-scale wind turbine, as shown in Figure 2, has several levels of control systems. On the uppermost level, a supervisory controller monitors the turbine and wind resource to determine when the wind speed is sufficient to start up the turbine and when, due to high winds, the turbine must be shut down for safety. This type of control is the discrete if-then variety. On the middle level is turbine control, which includes generator torque control, blade pitch control, and yaw control. Generator torque control, performed using the power electronics, determines how much torque is extracted from the turbine, specifically, the high-speed shaft. The extracted torque opposes the aerodynamic torque provided by the wind and, thus, indirectly regulates the turbine speed. Depending on the pitch actuators and type of generator and power electronics, blade pitch control and generator torque control can operate quickly relative to the rotor-speed time constant. STANDARD AND ADAPTIVE TECHNIQUES FOR MAXIMIZING ENERGY CAPTURE
TL;DR: The results show that with judicious choice of design parameters the virtual MIMO technique can be made to provide significant energy and delay efficiencies, even after allowing for additional training overheads.
Abstract: An energy-efficient virtual multiple-input multiple-output (MIMO)-based communication architecture is proposed for distributed and cooperative wireless sensor networks. Assuming a space-time block coding (STBC) based MIMO system, the energy and delay efficiencies of the proposed scheme are derived using semi-analytic techniques. The dependence of these efficiency values on physical channel propagation parameters, fading coherence time and the amount of required training is also investigated. The results show that with judicious choice of design parameters the virtual MIMO technique can be made to provide significant energy and delay efficiencies, even after allowing for additional training overheads.
TL;DR: In this paper, material choice may affect both embodied energy and recycling potential in one of the most energy efficient apartment-type housing projects in Sweden (calculated energy for operation is 45 kWh/m(2) floor area per year).
TL;DR: In this article, the authors compared several candidate technologies that span the range from well developed to conceptual and compared their energy efficiency at a lower temperature range than the other alternatives, including high-temperature steam electrolysis (HTSE) coupled with an advanced gas reactor cooled by supercritical CO2 (S-CO2) and equipped with a supercritical co-product power conversion cycle.
TL;DR: In this paper, the authors investigate the existence and importance of different barriers to the implementation of energy efficiency measures in the Swedish non-energy intensive manufacturing industry and highlight a number of factors that inhibit the degree of implementation.
04 Sep 2006
TL;DR: In this article, the authors presented a new wireless sensor network routing protocol based on the Ant Colony Optimization metaheuristic, which is studied by simulation for several Wireless Sensor Network scenarios and the results clearly show that it minimises communication load and maximises energy savings.
Abstract: Wireless Sensor Networks are characterized by having specific requirements such as limited energy availability, low memory and reduced processing power. On the other hand, these networks have enormous potential applicability, e.g., habitat monitoring, medical care, military surveillance or traffic control. Many protocols have been developed for Wireless Sensor Networks that try to overcome the constraints that characterize this type of networks. Ant-based routing protocols can add a significant contribution to assist in the maximisation of the network lifetime, but this is only possible by means of an adaptable and balanced algorithm that takes into account the Wireless Sensor Networks main restrictions. This paper presents a new Wireless Sensor Network routing protocol, which is based on the Ant Colony Optimization metaheuristic. The protocol was studied by simulation for several Wireless Sensor Network scenarios and the results clearly show that it minimises communication load and maximises energy savings.
TL;DR: In this article, a new dynamic model and design methodology for an FC and ultracapacitor-based energy source for stand-alone residential applications has been developed using MATLAB, Simulink and SimPowerSystems environments based on the mathematical and dynamic electrical models developed for the proposed system.
Abstract: The available power generated from a fuel cell (FC) power plant may not be sufficient to meet sustained load demands, especially during peak demand or transient events encountered in stationary power plant applications. An ultracapacitor (UC) bank can supply a large burst of power, but it cannot store a significant amount of energy. The combined use of FC and UC has the potential for better energy efficiency, reducing the cost of FC technology, and improved fuel usage. In this paper, we present an FC that operates in parallel with a UC bank. A new dynamic model and design methodology for an FCand UC-based energy source for stand-alone residential applications has been developed. Simulation results are presented using MATLAB, Simulink, and SimPowerSystems environments based on the mathematical and dynamic electrical models developed for the proposed system
TL;DR: In this article, the authors empirically quantified the marginal costs of energy efficiency investments (i.e., additional insulation, improved window systems, ventilation and heating systems and architectural concepts).
TL;DR: In this article, the authors examined some classical indicators which are often found in national and international energy studies in the 1970s and 1980s and described the recent developments in using the index decomposition analysis to give an economy-wide composite energy efficiency index based on a bottom-up approach.
TL;DR: In this paper, the authors tried to assess the impact of a change in energy consumption on income and vice versa in G-7 countries and uncover Granger causality relation between energy consumption and income in all countries.
30 Nov 2006
TL;DR: In this paper the energy needs of a hydrogen economy are quantified and it is shown that only 20%-25% of the source energy needed to synthesized hydrogen from natural compounds can be recovered for end use by efficient fuel cells.
Abstract: The establishment of a sustainable energy future is one of the most pressing tasks of mankind. With the exhaustion of fossil resources the energy economy will change from a chemical to an electrical base. This transition is one of physics, not one of politics. It must be based on proven technology and existing engineering experience. The transition process will take many years and should start soon. Unfortunately, politics seems to listen to the advice of visionaries and lobby groups. Many of their qualitative arguments are not based on facts and physics. A secure sustainable energy future cannot be based on hype and activism, but has to be built on solid grounds of established science and engineering. In this paper the energy needs of a hydrogen economy are quantified. Only 20%-25% of the source energy needed to synthesized hydrogen from natural compounds can be recovered for end use by efficient fuel cells. Because of the high energy losses within a hydrogen economy the synthetic energy carrier cannot compete with electricity. As the fundamental laws of physics cannot be chanced by research, politics or investments, a hydrogen economy will never make sense
TL;DR: In this paper, the authors review literature on several types of energy efficiency policies: appliance standards, financial incentive programs, information and voluntary programs, and management of government energy use and provide a brief synopsis of the relevant programs, along with available existing estimates of energy savings, costs, and cost-effectiveness at a national level.
Abstract: ▪ Abstract We review literature on several types of energy efficiency policies: appliance standards, financial incentive programs, information and voluntary programs, and management of government energy use. For each, we provide a brief synopsis of the relevant programs, along with available existing estimates of energy savings, costs, and cost-effectiveness at a national level. The literature examining these estimates points to potential issues in determining the energy savings and costs, but recent evidence suggests that techniques for measuring both have improved. Taken together, the literature identifies up to four quads of energy savings annually from these programs—at least half of which is attributable to appliance standards and utility-based demand-side management, with possible additional energy savings from the U.S. Department of Energy's (DOE's) ENERGY STAR, Climate Challenge, and Section 1605b voluntary programs to reduce carbon dioxide (CO2) emissions. Related reductions in CO2 and criteria a...
TL;DR: In this article, the authors presented a Life Cycle Energy Analysis of bioethanol (from sugar beet or wheat) and bioETBE systems in France, and the energy used throughout was calculated.
31 Oct 2006
TL;DR: It is shown that run-time dynamic linking is an effective method for reprogramming even resource constrained wireless sensor nodes, and a combination of native code and virtual machine code provide good energy efficiency.
Abstract: From experience with wireless sensor networks it has become apparent that dynamic reprogramming of the sensor nodes is a useful feature. The resource constraints in terms of energy, memory, and processing power make sensor network reprogramming a challenging task. Many different mechanisms for reprogramming sensor nodes have been developed ranging from full image replacement to virtual machines.We have implemented an in-situ run-time dynamic linker and loader that use the standard ELF object file format. We show that run-time dynamic linking is an effective method for reprogramming even resource constrained wireless sensor nodes. To evaluate our dynamic linking mechanism we have implemented an application-specific virtual machine and a Java virtual machine and compare the energy cost of the different linking and execution models. We measure the energy consumption and execution time overhead on real hardware to quantify the energy costs for dynamic linkin.Our results suggest that while in general the overhead of a virtual machine is high, a combination of native code and virtual machine code provide good energy efficiency. Dynamic run-time linking can be used to update the native code, even in heterogeneous networks.
TL;DR: The role of non-renewable and renewable sources of energy in the current Five-Fuel Diversification Strategy energy mix is discussed in this paper, and the implementation of energy efficiency program in Malaysia.