Showing papers on "Efficient energy use published in 2011"

Demand Side Management: Demand Response, Intelligent Energy Systems, and Smart Loads

Abstract: Energy management means to optimize one of the most complex and important technical creations that we know: the energy system. While there is plenty of experience in optimizing energy generation and distribution, it is the demand side that receives increasing attention by research and industry. Demand Side Management (DSM) is a portfolio of measures to improve the energy system at the side of consumption. It ranges from improving energy efficiency by using better materials, over smart energy tariffs with incentives for certain consumption patterns, up to sophisticated real-time control of distributed energy resources. This paper gives an overview and a taxonomy for DSM, analyzes the various types of DSM, and gives an outlook on the latest demonstration projects in this domain.

Magnetic materials and devices for the 21st century: Stronger, lighter, and more energy efficient

Abstract: A new energy paradigm, consisting of greater reliance on renewable energy sources and increased concern for energy effi ciency in the total energy lifecycle, has accelerated research into energy-related technologies. Due to their ubiquity, magnetic materials play an important role in improving the effi ciency and performance of devices in electric power generation, conditioning, conversion, transportation, and other energy-use sectors of the economy. This review focuses on the state-of-the-art hard and soft magnets and magnetocaloric materials, with an emphasis on their optimization for energy applications. Specifi cally, the impact of hard magnets on electric motor and transportation technologies, of soft magnetic materials on electricity generation and conversion technologies, and of magnetocaloric materials for refrigeration technologies, are discussed. The synthesis, characterization, and property evaluation of the materials, with an emphasis on structure‐property relationships, are discussed in the context of their respective markets, as well as their potential impact on energy effi ciency. Finally, considering future bottlenecks in raw materials, options for the recycling of rare-earth intermetallics for hard magnets will be discussed.

How much energy is needed to run a wireless network

Abstract: In order to quantify the energy efficiency of a wireless network, the power consumption of the entire system needs to be captured. In this article, the necessary extensions with respect to existing performance evaluation frameworks are discussed. The most important addenda of the proposed energy efficiency evaluation framework (E3F) are a sophisticated power model for various base station types, as well as large-scale long-term traffic models. The BS power model maps the RF output power radiated at the antenna elements to the total supply power of a BS site. The proposed traffic model emulates the spatial distribution of the traffic demands over large geographical regions, including urban and rural areas, as well as temporal variations between peak and off-peak hours. Finally, the E3F is applied to quantify the energy efficiency of the downlink of a 3GPP LTE radio access network.

Materials used as PCM in thermal energy storage in buildings: A review

Abstract: In recent years the use of thermal energy storage with phase change materials has become a topic with a lot of interest within the research community, but also within architects and engineers. Many publications have appeared, and several books, but the information is disseminated and not very much organised. This paper shows a review of the latest publications on the use of phase change materials (PCM) in buildings. The paper compiles information about the requirements of the use of this technology, classification of materials, materials available and problems and possible solutions on the application of such materials in buildings.

Green Cellular Networks: A Survey, Some Research Issues and Challenges

Abstract: Energy efficiency in cellular networks is a growing concern for cellular operators to not only maintain profitability, but also to reduce the overall environment effects. This emerging trend of achieving energy efficiency in cellular networks is motivating the standardization authorities and network operators to continuously explore future technologies in order to bring improvements in the entire network infrastructure. In this article, we present a brief survey of methods to improve the power efficiency of cellular networks, explore some research issues and challenges and suggest some techniques to enable an energy efficient or "green" cellular network. Since base stations consume a maximum portion of the total energy used in a cellular system, we will first provide a comprehensive survey on techniques to obtain energy savings in base stations. Next, we discuss how heterogenous network deployment based on micro, pico and femtocells can be used to achieve this goal. Since cognitive radio and cooperative relaying are undisputed future technologies in this regard, we propose a research vision to make these technologies more energy efficient. Lastly, we explore some broader perspectives in realizing a "green" cellular network technology.

Fundamental trade-offs on green wireless networks

Abstract: Traditional mobile wireless network mainly design focuses on ubiquitous access and large capacity. However, as energy saving and environmental protection become global demands and inevitable trends, wireless researchers and engineers need to shift their focus to energy-efficiency-oriented design, that is, green radio. In this article, we propose a framework for green radio research and integrate the fundamental issues that are currently scattered. The skeleton of the framework consists of four fundamental tradeoffs: deployment efficiency-energy efficiency, spectrum efficiency-energy efficiency, bandwidth-power, and delay-power. With the help of the four fundamental trade-offs, we demonstrate that key network performance/cost indicators are all strung together.

Fundamental Tradeoffs on Green Wireless Networks

Abstract: Traditional design of mobile wireless networks mainly focuses on ubiquitous access and large capacity. However, as energy saving and environmental protection become a global demand and inevitable trend, wireless researchers and engineers need to shift their focus to energy-efficiency oriented design, that is, green radio. In this paper, we propose a framework for green radio research and integrate the fundamental issues that are currently scattered. The skeleton of the framework consists of four fundamental tradeoffs: deployment efficiency - energy efficiency tradeoff, spectrum efficiency - energy efficiency tradeoff, bandwidth - power tradeoff, and delay - power tradeoff. With the help of the four fundamental tradeoffs, we demonstrate that key network performance/cost indicators are all stringed together.

Passive building energy savings: A review of building envelope components

Abstract: A significant portion of the total primary energy is consumed by today's buildings in developed countries In many of these buildings, the energy consumption can be significantly reduced by adopting energy efficiency strategies Due to environmental concerns and the high cost of energy in recent years there has been a renewed interest in building energy efficiency This article strives to make an exhaustive technical review of the building envelope components and respective improvements from an energy efficiency perspective Different types of energy efficient walls such as Trombe walls, ventilated walls, and glazed walls are discussed Performance of different fenestration technologies including aerogel, vacuum glazing and frames are presented Advances in energy efficient roofs including the contemporary green roofs, photovoltaic roofs, radiant-transmittive barrier and evaporative roof cooling systems are discussed Various types of thermal insulation materials are enumerated along with selection criteria of these materials The effects of thermal mass and phase change material on building cooling/heating loads and peak loads are discussed Application of thermal mass as an energy saving method is more effective in places where the outside ambient air temperature differences between the days and nights are high Air tightness and infiltration of building envelopes are discussed as they play a crucial role in the energy consumption of a building Energy efficiency approaches sometimes might not require additional capital investment For example, a holistic energy efficient building design approach can reduce the size of mechanical systems compensating the additional cost of energy efficiency features

The future of microprocessors

Abstract: Energy efficiency is the new fundamental limiter of processor performance, way beyond numbers of processors.

A Review of Piezoelectric Energy Harvesting Based on Vibration

Abstract: This paper reviews energy harvesting technology from mechanical vibration. Recent advances on ultralow power portable electronic devices and wireless sensor network require limitless battery life for better performance. People searched for permanent portable power sources for advanced electronic devices. Energy is everywhere around us and the most important part in energy harvesting is energy transducer. Piezoelectric materials have high energy conversion ability from mechanical vibration. A great amount of researches have been conducted to develop simple and efficient energy harvesting devices from vibration by using piezoelectric materials. Representative piezoelectric materials can be categorized into piezoceramics and piezopolymers. This paper reviews key ideas and performances of the reported piezoelectric energy harvesting from vibration. Various types of vibration devices, piezoelectric materials and mathematical modeling of vibrational energy harvestings are reviewed.

U.S. Department of Energy Commercial Reference Building Models of the National Building Stock

Abstract: The U.S. Department of Energy (DOE) Building Technologies Program has set the aggressive goal of producing marketable net-zero energy buildings by 2025. This goal will require collaboration between the DOE laboratories and the building industry. We developed standard or reference energy models for the most common commercial buildings to serve as starting points for energy efficiency research. These models represent fairly realistic buildings and typical construction practices. Fifteen commercial building types and one multifamily residential building were determined by consensus between DOE, the National Renewable Energy Laboratory, Pacific Northwest National Laboratory, and Lawrence Berkeley National Laboratory, and represent approximately two-thirds of the commercial building stock.

A review on solar energy use in industries

Abstract: Presently, solar energy conversion is widely used to generate heat and produce electricity A comparative study on the world energy consumption released by International Energy Agency (IEA) shows that in 2050, solar array installations will supply around 45% of energy demand in the world It was found that solar thermal is getting remarkable popularity in industrial applications Solar thermal is an alternative to generate electricity, process chemicals or even space heating It can be used in food, non-metallic, textile, building, chemical or even business related industries On the other hand, solar electricity is wildly applied in telecommunication, agricultural, water desalination and building industry to operate lights, pumps, engines, fans, refrigerators and water heaters It is very important to apply solar energy for a wide variety of applications and provide energy solutions by modifying the energy proportion, improving energy stability, increasing energy sustainability, conversion reduction and hence enhance the system efficiency The present work aimed to study the solar energy systems utilization in industrial applications and looked into the industrial applications which are more compatible to be integrated with solar energy systems

Green radio: radio techniques to enable energy-efficient wireless networks

Abstract: Recent analysis by manufacturers and network operators has shown that current wireless networks are not very energy efficient, particularly the base stations by which terminals access services from the network. In response to this observation the Mobile Virtual Centre of Excellence (VCE) Green Radio project was established in 2009 to establish how significant energy savings may be obtained in future wireless systems. This article discusses the technical background to the project and discusses models of current energy consumption in base station devices. It also describes some of the most promising research directions in reducing the energy consumption of future base stations.

Energy-efficient wireless communications: tutorial, survey, and open issues

Abstract: With explosive growth of high-data-rate applications, more and more energy is consumed in wireless networks to guarantee quality of service. Therefore, energy-efficient communications have been paid increasing attention under the background of limited energy resource and environmental- friendly transmission behaviors. In this article, basic concepts of energy-efficient communications are first introduced and then existing fundamental works and advanced techniques for energy efficiency are summarized, including information-theoretic analysis, OFDMA networks, MIMO techniques, relay transmission, and resource allocation for signaling. Some valuable topics in energy-efficient design are also identified for future research.

A Taxonomy and Survey of Energy-Efficient Data Centers and Cloud Computing Systems

Abstract: Traditionally, the development of computing systems has been focused on performance improvements driven by the demand of applications from consumer, scientific, and business domains. However, the ever-increasing energy consumption of computing systems has started to limit further performance growth due to overwhelming electricity bills and carbon dioxide footprints. Therefore, the goal of the computer system design has been shifted to power and energy efficiency. To identify open challenges in the area and facilitate future advancements, it is essential to synthesize and classify the research on power- and energy-efficient design conducted to date. In this study, we discuss causes and problems of high power/energy consumption, and present a taxonomy of energy-efficient design of computing systems covering the hardware, operating system, virtualization, and data center levels. We survey various key works in the area and map them onto our taxonomy to guide future design and development efforts. This chapter concludes with a discussion on advancements identified in energy-efficient computing and our vision for future research directions.

Energy Efficiency in the Future Internet: A Survey of Existing Approaches and Trends in Energy-Aware Fixed Network Infrastructures

Abstract: The concept of energy-efficient networking has begun to spread in the past few years, gaining increasing popularity. Besides the widespread sensitivity to ecological issues, such interest also stems from economic needs, since both energy costs and electrical requirements of telcos' and Internet Service Providers' infrastructures around the world show a continuously growing trend. In this respect, a common opinion among networking researchers is that the sole introduction of low consumption silicon technologies may not be enough to effectively curb energy requirements. Thus, for disruptively boosting the network energy efficiency, these hardware enhancements must be integrated with ad-hoc mechanisms that explicitly manage energy saving, by exploiting network-specific features. This paper aims at providing a twofold contribution to green networking. At first, we explore current perspectives in power consumption for next generation networks. Secondly, we provide a detailed survey on emerging technologies, projects, and work-in-progress standards, which can be adopted in networks and related infrastructures in order to reduce their carbon footprint. The considered approaches range from energy saving techniques for networked hosts, to technologies and mechanisms for designing next-generation and energy-aware networks and networking equipment.

Material efficiency: A white paper

Abstract: For most materials used to provide buildings, infrastructure, equipment and products, global stocks are still sufficient to meet anticipated demand, but the environmental impacts of materials production and processing, particularly those related to energy, are rapidly becoming critical. These impacts can be ameliorated to some extent by the ongoing pursuit of efficiencies within existing processes, but demand is anticipated to double in the next 40 years, and this will lead to an unacceptable increase in overall impacts unless the total requirement for material production and processing is reduced. This is the goal of material efficiency, and this paper aims to stimulate interest in the area. Four major strategies for reducing material demand through material efficiency are discussed: longer-lasting products; modularisation and remanufacturing; component re-use; designing products with less material. In industrialised nations, these strategies have had little attention, because of economic, regulatory and social barriers, which are each examined. However, evidence from waste management and the pursuit of energy efficiency suggests that these barriers might be overcome, and an outline of potential mechanisms for change is given. In bringing together insights into material efficiency from a wide range of disciplines, the paper presents a set of 20 open questions for future work.

A review on energy saving strategies in industrial sector

Abstract: An industrial sector uses more energy than any other end-use sectors and currently this sector is consuming about 37% of the world's total delivered energy. Energy is consumed in the industrial sector by a diverse group of industries including manufacturing, agriculture, mining, and construction and for a wide range of activities, such as processing and assembly, space conditioning, and lighting. This paper presents a comprehensive literature review about industrial energy saving by management, technologies and policies. Latest literatures in terms of thesis (MS and PhD), journal articles, conference proceedings, web materials, reports, books, handbooks on industrial energy management, policies and energy savings strategies have been compiled. Energy saving by management including energy audit, training programs and housekeeping beside some energy management practices in the world has been reviewed. Energy saving technologies, such as use of high efficiency motors (HEMs), variable speed drives (VSDs), economizers, leak prevention and reducing pressure drop has been reviewed. Based on energy saving technologies results, it has been found that in the industrial sectors, a sizeable amount of electric energy, emissions and utility bill can be saved using these technologies. Payback periods for different energy savings measures have been identified and found to be economically viable in most cases. Finally, various energy-saving policies for few selected countries were reviewed.

Development of phase change materials based microencapsulated technology for buildings: a review

Abstract: Thermal energy storage (TES) systems using phase change material (PCM) have been recognized as one of the most advanced energy technologies in enhancing the energy efficiency and sustainability of buildings. Now the research is focus on suitable method to incorporate PCMs with building. There are several methods to use phase change materials (PCMs) in thermal energy storage (TES) for different applications. Microencapsulation is one of the well known and advanced technologies for better utilization of PCMs with building parts, such as, wall, roof and floor besides, within the building materials. Phase change materials based microencapsulation for latent heat thermal storage (LHTS) systems for building application offers a challenging option to be employed as effective thermal energy storage and a retrieval device. Since the particular interest in using microencapsulation PCMs for concrete and wall/wallboards, the specific research efforts on both subjects are reviewed separately. This paper presents an overview of the previous research work on microencapsulation technology for thermal energy storage incorporating the phase change materials (PCMs) in the building applications, along with few useful conclusive remarks concluded from the available literature.

Clean energy new deal for a sustainable world: from non-CO2 generating energy sources to greener electrochemical storage devices

Abstract: The fundamental challenge of the 21st century that mankind has to face is definitely energy supply, its storage and conversion in a way that necessarily protects the environment. For 250 years, the tremendous development of humanity has been founded on the harnessing of fossil fuels (coal, crude oil then natural gas) as primary energy due to their high energy density values and the easiness of access. However, this global pattern of energy supply and use is unsustainable. Global warming and finite fossil-fuel supplies call for a radical change in the energy mix to favour renewable energy sources. Without being exhaustive, we tackle in this article the tricky energy question and associated environmental issues as personally perceived. The eminent role of electric energy produced from decarbonized sources in a future sustainable economy is particularly highlighted as well as the issues of its needed storage. The possible and foreseen hindrances of electrochemical energy storage devices, focusing on the lithium-ion technology, are presented in parallel with the possible pathways to make such a technology greener in synergy with the rise of a biomass-based industry.

Toward dynamic energy-efficient operation of cellular network infrastructure

Abstract: The operation of cellular network infrastructure incurs significant electrical energy consumption. From the perspective of cellular network operators, reducing this consumption is not only a matter of showing environmental responsibility, but also of substantially reducing their operational expenditure. We discuss how dynamic operation of cellular base stations, in which redundant base stations are switched off during periods of low traffic such as at night, can provide significant energy savings. We quantitatively estimate these potential savings through a first-order analysis based on real cellular traffic traces and information regarding base station locations in a part of Manchester, United Kingdom. We also discuss a number of open issues pertinent to implementing such energy-efficient dynamic base station operation schemes, such as various approaches to ensure coverage, and interoperator coordination.

Predicted vs. Actual Energy Performance of Non-Domestic Buildings

Abstract: With the increasing demand for more energy efficient buildings, the construction industry is faced with the challenge to ensure that the energy efficiency predicted during the design is realised once a building is in use. There is, however, significant evidence to suggest that buildings are not performing as well as expected and initiatives such as PROBE and CarbonBuzz aim to illustrate the extent of this so called "Performance Gap". This paper discusses the underlying causes of discrepancies between detailed energy modelling predictions and in-use performance of occupied buildings (after the twelve month liability period). Many of the causal factors relate to the use of unrealistic input parameters regarding occupancy behaviour and facilities management in building energy models. In turn, this is associated with the lack of feedback to designers once a building has been constructed and occupied. This paper aims to demonstrate how knowledge acquired from Post-Occupancy Evaluation (POE) can be used to produce more accurate energy performance models. A case study focused specifically on lighting, small power and catering equipment in a high density office building is presented. Results show that by combining monitored data with predictive energy modelling, it was possible to increase the accuracy of the model to within 3% of actual electricity consumption values. Future work will seek to use detailed POE data to develop a set of evidence based benchmarks for energy consumption in office buildings. It is envisioned that these benchmarks will inform designers on the impact of occupancy and management on the actual energy consumption of buildings. Moreover, it should enable the use of more realistic input parameters in energy models, bringing the predicted figures closer to reality.

A critical review on energy use and savings in the cement industries

Abstract: The cement sub-sector consumes approximately 12–15% of total industrial energy use. Therefore, a state of art review on the energy use and savings is necessary to identify energy wastage so that necessary measures could be implemented to reduce energy consumption in this sub-sector. In this paper energy use at different sections of cement industries, specific energy consumption, types of energy use, details of cement manufacturing processes, various energy savings measures were reviewed and presented. Various energy savings measures were critically analyzed considering amount of energy that can be saved along with the implementation cost. Amount of CO2 reduction has been presented along with the payback period for different energy savings measures as well. This study complied a comprehensive literature on the cement industries in terms of Thesis (MS and PhD), peer reviewed journals papers, conference proceedings, books, reports, websites. It has been observed that China producing major share of global cement production. Coal contribute major share of fuel used in cement industries. However, along with conventional fuels, industries are moving towards the use of alternative fuels to reduce environmental pollution. It was reported that cement industries are moving from wet process to dry process as it consume less energy compared to wet process.

Base Station Operation and User Association Mechanisms for Energy-Delay Tradeoffs in Green Cellular Networks

Abstract: Energy-efficiency, one of the major design goals in wireless cellular networks, has received much attention lately, due to increased awareness of environmental and economic issues for network operators. In this paper, we develop a theoretical framework for BS energy saving that encompasses dynamic BS operation and the related problem of user association together. Specifically, we formulate a total cost minimization that allows for a flexible tradeoff between flow-level performance and energy consumption. For the user association problem, we propose an optimal energy-efficient user association policy and further present a distributed implementation with provable convergence. For the BS operation problem (i.e., BS switching on/off), which is a challenging combinatorial problem, we propose simple greedy-on and greedy-off algorithms that are inspired by the mathematical background of submodularity maximization problem. Moreover, we propose other heuristic algorithms based on the distances between BSs or the utilizations of BSs that do not impose any additional signaling overhead and thus are easy to implement in practice. Extensive simulations under various practical configurations demonstrate that the proposed user association and BS operation algorithms can significantly reduce energy consumption.

Reverse electrowetting as a new approach to high-power energy harvesting

Abstract: High-power mechanical energy harvesting could be an alternative to batteries, but efficient energy conversion technology has been missing. Here, a novel mechanical-to-electrical energy conversion method is described that is based on reverse electrowetting and is uniquely suited for high-power energy harvesting.