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‣ Photovoltaic and wind energy systems monitoring and building energy management using ZigBee devices within a smart grid

Melício, Rui
Fonte: Energy (ELSEVIER) Publicador: Energy (ELSEVIER)
Tipo: Artigo de Revista Científica
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The actual electric grid was developed to offer electricity to the clients from centralized generation, so with large-scale distributed renewable generation there is an urgent need for a more flexible, reliable and smarter grid. The wireless technologies are becoming an important asset in the smart grid, particularly the ZigBee devices. These smart devices are gaining increased acceptance, not only for home and building automation, but also for energy management, efficiency optimization and metering services, being able to operate for long periods of time without maintenance needs. In this context, this paper provides new comprehensive field tests using open source tools with ZigBee technologies for monitoring photovoltaic and wind energy systems, and also for building energy management. Our experimental results demonstrate the proficiency of ZigBee devices applied in distributed renewable generation and smart metering systems.

‣ Net energy analysis in the Energy Research and Development Administration plan

Polenske, Karen R.
Fonte: MIT Energy Lab Publicador: MIT Energy Lab
Tipo: Trabalho em Andamento Formato: 5455418 bytes; application/pdf
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Report prepared for the M.I.T. Energy Laboratory and the Office of Technology Assessment

‣ How much do you know about energy? : a quiz from the Energy Lab

Energy Laboratory
Fonte: MIT Energy Laboratory Publicador: MIT Energy Laboratory
Tipo: Trabalho em Andamento Formato: 1821314 bytes; application/pdf
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‣ Planning and analysis for development and commercialization of photovoltaic energy conversion systems : final report

Massachusetts Institute of Technology Energy Laboratory in association with the Sloan School of Management and the Dept. of Urban Studies and Planning..
Fonte: MIT Energy Laboratory Publicador: MIT Energy Laboratory
Tipo: Relatório Formato: 2403444 bytes; application/pdf
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Near term consideration of development and commercialization requirements of photovoltaic power systems will increase the potential information generated during the experimental and field test phases of the photovoltaic technology development process. This report summarizes the research activities of the MIT Energy Laboratory Photovoltaics Project during its first year. The report discusses results of residential systems modeling, or market survey analysis and institutional analysis carried out in conjunction with the large scale photovoltaic field test at Mead, Nebraska, preliminary analysis of the social and environmental costs of photovoltaic power system development relative to conventional electrical power generation and the development of energy system R&D decision models. In addition, the report lists project reports and briefly discusses research work to be carried out in the second year of the project.; Prepared for the United States Dept. of Energy under Contract EX-76-A-01-2295, Task Order 37.

‣ Energy policies and their consequences after 25 years

Joskow, Paul L.
Fonte: MIT Center for Energy and Environmental Policy Research Publicador: MIT Center for Energy and Environmental Policy Research
Tipo: Trabalho em Andamento Formato: 41, [6] p
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Hans Landsberg and Sam Schurr each led research teams that produced two important energy futures policy studies that were published in 1979. The conclusions, policy recommendations, and energy demand, supply, and price forecasts contained in these studies are reviewed. Developments in U.S. energy policy over the last 25 years are discussed and compared with the recommendations contained in the two studies. The projections of energy demand, supply, and prices for 2000 contained in the studies is presented and compared to actual realizations. The nature, magnitudes, and reasons for the differences between the studies₂ forecasts and what actually emerged 25 years later are discussed. All things considered, the Landsberg and Schurr studies have stood the test of time very well.

‣ A residential energy demand system for Spain

Labandeira Villot, Xavier; Labeaga, José María; Rodriguez, Miguel A.
Fonte: MIT Center for Energy and Environmental Policy Research Publicador: MIT Center for Energy and Environmental Policy Research
Tipo: Trabalho em Andamento Formato: 37 p
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Sharp price fluctuations and increasing environmental and distributional concerns, among other issues, have led to a renewed academic interest in energy demand. In this paper we estimate, for the first time in Spain, an energy demand system with household microdata. In doing so, we tackle several econometric and data problems that are generally recognized to bias parameter estimates. This is obviously relevant, as obtaining correct price and income responses is essential if they may be used for assessing the economic consequences of hypothetical or real changes. With this objective, we combine data sources for a long time period and choose a demand system with flexible income and price responses. We also estimate the model in different sub-samples to capture varying responses to energy price changes by households living in rural, intermediate and urban areas. This constitutes a first attempt in the literature and it proved to be a very successful choice.

‣ Efficient bidding for hydro power plants in markets for energy and ancillary services

Perekhodtsev, Dmitri; Lave, Lester B.
Fonte: MIT Center for Energy and Environmental Policy Research Publicador: MIT Center for Energy and Environmental Policy Research
Tipo: Trabalho em Andamento Formato: 24 p
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In order to preserve stability of electricity supply generators must provide ancillary services in addition to energy production. Hydroelectric resources have significant ancillary service capability because of their dynamic flexibility. This paper suggests a solution for optimal bidding for hydro units operating in simultaneous markets for energy and ancillary services by estimating water shadow price from operating parameters of the hydro unit, expectations on prices of energy and ancillary services, and water availability. The model implications are illustrated on a numerical example of a hydro unit operating in markets of New York Independent System Operator. Participation in ancillary services market increases or decreases water shadow price depending on water availability. As a result of participation in ancillary services markets, a unit with water availability given by a capacity factor of 0.6 increases the value of existing generating capacity by 25% and nearly doubles the value of incremental generating capacity.

‣ Effects of airflow induction on heat transfer and energy consumption while freezing passion fruit pulp in stacked boxes

Fonte: International Energy Agency Publicador: International Energy Agency
Tipo: Artigo de Revista Científica
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The objectives of this work were to charac- terize the energy consumption and the heat transfer process by the determination of the convective heat transfer coefficient (h) of passion fruit pulp contained in high-density polyethylene (HDPE) boxes and frozen in two conditions: without and with airflow induction, which was achieved through the installation of obsta- cles. To determine the convective heat transfer coeffi- cients, HDPE boxes containing passion fruit pulp (contained in polyethylene bags) were interspersed with boxes containing metal tanks filled with low freezing point solutions. Three types of solutions were used: ethylene glycol, propylene glycol, and ethanol. The airflow induction under the stacks of passion fruit pulp provided higher h values than without airflow induction. The calculated average values and standard deviation were 6.340±0.87 W/m 2 °C, respectively, without air- flow induction and 8.419±1.39 W/m 2 °C with airflow induction. The average reduction of the freezing time was 25 % for the boxes located at the top and 20 % in the base of the stack. This proved that directing the airflow under the stacked product promoted more uniform and efficient heat transfer. The analysis of the electrical parameter measurements revealed an approximate de- crease of 16.7 % in energy consumption due to the reduction of the freezing time...

‣ Solar project cost report for Page Jackson Elementary School, Charles Town, West Virginia; Page Jackson Elementary School, Charles Town, West Virginia

Mueller Associates (Baltimore, Md.); United States -- Dept. of Energy; PRC Energy Analysis Company
Fonte: Dept. of Energy; National Technical Information Service; Dept. of Energy ( Washington ); National Technical Information Service ( Springfield, Va ) Publicador: Dept. of Energy; National Technical Information Service; Dept. of Energy ( Washington ); National Technical Information Service ( Springfield, Va )
Tipo: Artigo de Revista Científica Formato: 27 p. : 28 cm.
Publicado em //1979 Português
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MONTHLY CATALOG NUMBER: gp 80007826; National Solar Heating and Cooling Demonstration Program.; National Solar Data Program.; Jan. 19, 1979.; (Statement of Responsibility) prepared for Department of Energy, Office of Assistant Secretary for Conservation and Solar Applications, National Solar Heating and Cooling Demonstration Program.

‣ Energy and the economy (the economic impact of alternative energy supply-demand assumptions)

Kaufman, Alvin; Daly, Barbara; Farb, Warren E; Farb, Warren E. ( joint author ); Daly, Barbara ( joint author ); United States -- Congress. -- House. -- Committee on Interstate and Foreign Commerce. -- Subcommittee on Energy and Power; Library of Congress
Fonte: U.S. Govt. Print. Off.; U.S. Govt. Print. Off. ( Washington ) Publicador: U.S. Govt. Print. Off.; U.S. Govt. Print. Off. ( Washington )
Tipo: Artigo de Revista Científica Formato: v, 30 p. : ill. ; 24 cm.
Publicado em //1978 Português
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(Bibliography) Includes bibliographical references.; At head of title: 95th Congress, 2d session. Committee print 95-51.; CIS Microfiche Accession Numbers: CIS 78 H502-18; At head of title: 95th Congress, 2d session. Committee print. Committee print 95-51.; Issued Apr. 1978.; Reuse of record except for individual research requires license from LexisNexis Academic & Library Solutions.; (Statement of Responsibility) [by Alvin Kaufman, Warren E. Farb, and Barbara Daly] ; prepared at the request of John D. Dingell, Chairman, Subcommittee on Energy and Power, Committee on Interstate and Foreign Commerce, United States House of Representatives by the Congressional Research Service, Library of Congress.

‣ Assessment of integrated urban energy options

Pine, Gerald Dean
Fonte: MIT Energy Laboratory Publicador: MIT Energy Laboratory
Tipo: Relatório Formato: 8310651 bytes; application/pdf
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An initial comparison is carried out for the following residential space and water heating options: electric resistance heating, electrically- driven heat pumps, distribution of condenser temperature water combined with heat pumps to extract heat at the point of use, district heating via hot water from a combined heat-electric utility energy source, and individual gas furnaces. This comparison indicates that district heating is potentially competitive with conventional technologies for new urban areas. A more detailed analysis of the district heating option is undertaken to clarify its economics. Base case urban models, economic assumptions and distribution networks are defined and a computer program is developed to select optimum pipe sizes for the networks and to calculate life cycle costs. Cost optimization is carried out by considering thermal energy production costs as well as thermal conveyance costs. Because of the large number of variables entering into the cost determination, sensitivity analyses are performed to examine the effects of variations from base case assumptions. Variations in the installed pipe cost, interest rate, maintenance costs and degree of market penetra- tion are shown to have the greatest effect on energy cost. Pumping power and heat loss are found to be relatively insignificant cost items. Proper phasing of system inplementation with urban growth is shown to be very important. Initial use of temporary heat sources located near the loads coupled with implementation of only local piping networks is advantageous for present gas and oil prices if the urban growth occurs over a period of 15-30 years. There is shown to be an economically optimum time for conversion to a large centralized thermal energy source. Several potential institutional barriers to district heating system implementation are identified. These barriers will be more difficult to overcome than any technical or economic barriers...

‣ Factors affecting residential heating energy consumption

Donovan, John J.; Fischer, Walter P.
Fonte: MIT Energy Lab Publicador: MIT Energy Lab
Tipo: Trabalho em Andamento Formato: 3139071 bytes; application/pdf
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Twenty per cent of all energy consumed in New England and ten per cent of all energy consumed in the United States is consumed in home heating. This paper reports on an effort to ascertain the major factors affecting the consumption of home heating oil. Three general classes of factors are analyzed: (1) physical and occupant characteristics (number of rooms, number of occupants, number of stories, amount of insulation, income level, etc.); (2) external (price, shortage awareness, weather); and (3) behavioral and physical changes (change in temperature settings, change in insulation, change in oil burner, etc.). The study is based on four data series: (1) actual monthly home heating oil consumption data on 8000 suburban homeowners in suburban Boston; (2) questionnaire responses from 2000 homeowners on their homes' physical and occupant characteristics, as well as changes in physical and occu- pant behavioral characteristics between 1972 and 1975; (3) monthly weather data; and (4) heating oil price data. The data is associated with the years from 1972 through 1975, a period in which marked price changes, shortages, and behavioral changes occurred, hence providing an opportunity to study the effects of these various events. Three models are central to the study: Model I. A cross-sectional model that depicts consumption per degree-day as a function of physical and occupant characteristics of a home. Model II. A time series regression model that establishes consumption per degree-day as a function of price and consumer awareness of an energy shortage. Model III. A cross-sectional regression model that attempts to explain change in consumption per degree-day from one year to the next as a function of specific conservation actions such as temperature resetting...

‣ Policy review and analysis: Energy efficiency strategy for the Republic of South Africa

Rosenberg,Shirene A; Winkler,Harald
Fonte: Journal of Energy in Southern Africa Publicador: Journal of Energy in Southern Africa
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 Português
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This paper aims to draw attention to the complex landscape of translating policy into implementation actions. It underscores the disjuncture between a broad global response to climate change mitigation measures and the requirements for national action in this regard. Individual countries face this challenge of interpreting and translating the cross-cutting response measures into local action. Climate change mitigation and energy security are two themes that are growing in importance in terms of its contribution towards South Africa's developmental agenda, thereby requiring an understanding of how policies and strategies are geared towards supporting this developmental agenda, in a way that does not compromise existing or future growth and progress. An assessment of the implementation of the South African energy efficiency strategy, demonstrates that the translation of policy intent into implementation is not self evident and associated with a number of prerequisites. These do not merely relate to the competence or capacity of an institution to implement the policy, but to a complex interrelationship of a number of factors. This includes supporting legislation, institutional arrangements, sources of finance and the need for co-operative governance.

‣ Analysis of distributed energy resources for domestic electricity users

Raji,Atanda; Kahn,Mohamed Tariq
Fonte: Journal of Energy in Southern Africa Publicador: Journal of Energy in Southern Africa
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 Português
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After over a century with utilization of the benefits of economics of scale, power systems planning and development gets bigger and transmission grids have needed to transmit wide bringing the concept of onsite or close-to-load generation back. The turnaround strategy is prompted by market liberalization, transmission expansion constraints, related technology advancements, environmental pollution, health hazards, fossil fuel depletion, and climate change concerns. In the last decade, many countries have started the process of liberalisation of the electric systems, opening access to transmission and distribution grids.Technical feasibility analysis of a hybrid energy system for two types of geographical regions in South Africa using Homer is performed in this paper. Wind-PV hybrid systems are modelled as a micro-power system using Homer. The simulation results analyses conducted for a typical middle income earner electricity load profile for both a coaster and inlander domestic users of electricity showed that Wind-PV hybrid system is technically feasible and economical.

‣ A techno-economic model for optimising component sizing and energy dispatch strategy for PV-diesel-battery hybrid power systems

Hove,Tawanda; Tazvinga,Henerica
Fonte: Journal of Energy in Southern Africa Publicador: Journal of Energy in Southern Africa
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 Português
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This paper presents the development and application of a simple spreadsheet-based simulation model for sizing, energy performance evaluation and economic analysis of PV-diesel-battery power supply systems. The model is employed to generate a set of sizing curves that define the design space for hybrid systems using dimensionless generator component size variables, for a specified supply reliability and diesel energy dispatch strategy. The component size combination with the least unit cost of energy is selected among the many possible combinations satisfying a desired loss-of-load probability. Storage battery and diesel generator lifespan, as well as generator fuel efficiency, which depend on the operational loading stress of these components, are recognised as important variables in the economics of the system. The lifespan of the battery is premised to depend on the depth and rate of discharge of the operating cycles, while both the diesel generator lifespan and fuel efficiency are dependent on the degree and frequency of partial loading. The choice of diesel generator dispatch strategy was shown to be another important factor influencing the energy performance and economics of the system. The outputs of the model reveal several important sizing...

‣ Life cycle energy analysis of environmental management reports in the Japanese automotive industry: Learning from the Japanese experience

Mbohwa,C
Fonte: Journal of Energy in Southern Africa Publicador: Journal of Energy in Southern Africa
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2008 Português
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This paper discusses the assessment and comparison of the life cycle energy impacts of paper-based and electronic environmental reports in the Japanese automotive industry By January 2007, there were 129 031 ISO 14001 certified organisations and an additional 5389 certified to the European eco-management and audit scheme (EMAS). Energy use and the environmental burdens of environmental reporting by these companies, has grown and can no longer be ignored. Electronic systems are often portrayed as being more environmentally beneficial than traditional ones, for environmental reporting. However there are no known assessment methodologies that address this subject. This paper therefore creates a framework for analysing the two systems. Energy consumption models are developed within a life cycle assessment (LCA) framework and applied to the traditional and electronic systems respectively. A postal system model is developed for energy consumption in traditional mail distribution in Japan under six different scenarios. Data gaps in the Japanese automotive industry are compensated for by the use of justified assumption and sensitivity analysis of the variables concerned. Simulation results are analysed and some decision issues deciphered. A comparative analysis of electronic and traditional environmental reports identifies the necessary preconditions for reducing environmental burdens of the overall environmental management system (EMS).

‣ Energy models: Methods and characteristics

Neshat,Najmeh; Amin-Naseri,Mohammad Reza; Danesh,Farzaneh
Fonte: Journal of Energy in Southern Africa Publicador: Journal of Energy in Southern Africa
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2014 Português
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Given the importance of models in complicated problem solving, an inappropriate energy model can lead to inaccurate decisions and poor policy prescriptions. This paper aims at developing a decision support tool with which the selection of appropriate model characteristics can be facilitated for developing countries. Hence, it provides a comparative overview of different ways of energy models characterization and extracts the underlying relationships amongst them. Moreover, evolution of dynamic characteristics of energy models for developing countries is identified according to the previous studies on the developed and developing countries. To do this, it reviews the related literature and follows a systematic comparative approach to achieve its purposes. These findings are helpful in cases where model developers themselves are looking for appropriate characteristics in terms of certain purpose or situation.

‣ What contribution does the installation of solar water heaters make towards the alleviation of energy poverty in South Africa?

Wlokas,Holle Linnea
Fonte: Journal of Energy in Southern Africa Publicador: Journal of Energy in Southern Africa
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 Português
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The South African government has publicized plans to install one million solar water heaters in households throughout South Africa by the year 2014, with the goals of reducing strain on existing electricity resources, mitigating greenhouse gas emissions, creating employment and alleviating poverty. This paper examines two existing solar water heater installation projects with the aim of investigating the social contribution of the installation of solar water heaters in low-income households in South Africa. The Sustainable Urban Livelihoods approach (SULA) was adjusted to provide an analytical framework for the development of suitable indicators of social change in the context of renewable energies and energy poverty. Increases in household capital and the reduction of household vulnerability to shocks, stressors and seasonal variability as the result of solar water heater installation were investigated in projects in low-income housing developments in the cities of Cape Town and Port Elizabeth, South Africa. Data collected from paired household surveys (before and after installation) in over 600 households and qualitative information (Most Significant Change stories) show that the provision of a constant, cheap source of heated water contributed positively to the alleviation of energy poverty. Household capitals (categorised as Human...

‣ Technologies for recovery of energy from wastewaters: Applicability and potential in South Africa

Stafford,William; Cohen,Brett; Pather-Elias,Simisha; von Blottnitz,Harro; van Hille,Robert; Harrison,Sue T L; Burton,Stephanie G
Fonte: Journal of Energy in Southern Africa Publicador: Journal of Energy in Southern Africa
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 Português
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This study explored technologies for recovering energy from wastewater through production of bio-mass, combustion and gasification, generation of biogas, production of bioethanol, heat recovery and microbial fuel cells. A first order desktop analysis of the potential for applying these solutions to waste-waters in South Africa revealed that 3 200 to 9 000 MWth of energy has potential for recovery, equating to at most 7% of South Africa's current electrical power supply. Formal and informal animal husbandry, fruit and beverage industries and domestic blackwater were identified as wastewaters with the greatest potential for energy recovery. Of the reviewed technologies, anaerobic digestion shows applicability to the widest range of feedstocks. Net energy generated, reduction in pollution, and water reclamation are identified as the main benefits, but additional benefits such as certified emission reductions, fertiliser production and the production of secondary products may dictate the economic feasibility.

‣ Critical factors to be considered when planning the implementation of environmental improvements and energy saving

dos Santos,Juliane Barbosa; Jabbour,Charbel José Chiappetta
Fonte: Journal of Energy in Southern Africa Publicador: Journal of Energy in Southern Africa
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2013 Português
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To identify the critical success factors in the adoption of energy efficiency actions in Brazilian hospitals and describe their behaviour are the objectives of this paper. In order to achieve these goals, a literature review was performed on green management and energy efficiency. This was the basis to define the questions of the interview script applied to two hospitals located in the state of São Paulo, Brazil. The interview script application was complemented by secondary data and direct observation. The results showed that: a) the studied hospitals are embracing environmental management actions more often and, whenever possible, energy efficiency actions are taken as well; and b) in the cases analysed top management support, commitment with the environment, green process design and employee empowerment were some of the most relevant critical success factors to the accomplishment of energy efficiency actions. These findings may be of interest to emerging countries, including BRICS (Brazil, Russia, India, China and South Africa).