Showing papers on "Renewable energy published in 2005"
TL;DR: Developing solar cells that are based on the sensitization of mesoscopic oxide films by dyes or quantum dots, and the examples for the first outdoor application of such solar cells will be provided.
Abstract: The quality of human life depends to a large degree on the availability of energy. This is threatened unless renewable energy resources can be developed in the near future. Chemistry is expected to make important contributions to identify environmentally friendly solutions of the energy problem. One attractive strategy discussed in this Forum Article is the development of solar cells that are based on the sensitization of mesoscopic oxide films by dyes or quantum dots. These systems have already reached conversion efficiencies exceeding 11%. The underlying fundamental processes of light harvesting by the sensitizer, heterogeneous electron transfer from the electronically excited chromophore into the conduction band of the semiconductor oxide, and percolative migration of the injected electrons through the mesoporous film to the collector electrode will be described below in detail. A number of research topics will also be discussed, and the examples for the first outdoor application of such solar cells wi...
3,214 citations
TL;DR: In this article, the authors focus on the generation of electricity from clean and renewable sources, and show that wind energy has become the world's fastest growing energy source, and that renewable energy is the most promising energy source.
Abstract: As environmental concerns have focussed attention on the generation of electricity from clean and renewable sources, wind energy has become the world's fastest growing energy source. The authors dr ...
2,878 citations
15 Dec 2005
TL;DR: The U.S. Department of Energy and the United States Department of Agriculture have both strongly committed to expanding the role of biomass as an energy source as mentioned in this paper, and they support biomass fuels and products as a way to reduce the need for oil and gas imports; to support the growth of agriculture, forestry, and rural economies; and to foster major new domestic industries making a variety of fuels, chemicals, and other products.
Abstract: The U.S. Department of Energy (DOE) and the U.S. Department of Agriculture (USDA) are both strongly committed to expanding the role of biomass as an energy source. In particular, they support biomass fuels and products as a way to reduce the need for oil and gas imports; to support the growth of agriculture, forestry, and rural economies; and to foster major new domestic industries--biorefineries--making a variety of fuels, chemicals, and other products. As part of this effort, the Biomass R&D Technical Advisory Committee, a panel established by the Congress to guide the future direction of federally funded biomass R&D, envisioned a 30 percent replacement of the current U.S. petroleum consumption with biofuels by 2030. Biomass--all plant and plant-derived materials including animal manure, not just starch, sugar, oil crops already used for food and energy--has great potential to provide renewable energy for America's future. Biomass recently surpassed hydropower as the largest domestic source of renewable energy and currently provides over 3 percent of the total energy consumption in the United States. In addition to the many benefits common to renewable energy, biomass is particularly attractive because it is the only current renewable source of liquid transportation fuel. This, of course, makes it invaluable in reducing oil imports--one of our most pressing energy needs. A key question, however, is how large a role could biomass play in responding to the nation's energy demands. Assuming that economic and financial policies and advances in conversion technologies make biomass fuels and products more economically viable, could the biorefinery industry be large enough to have a significant impact on energy supply and oil imports? Any and all contributions are certainly needed, but would the biomass potential be sufficiently large to justify the necessary capital replacements in the fuels and automobile sectors? The purpose of this report is to determine whether the land resources of the United States are capable of producing a sustainable supply of biomass sufficient to displace 30 percent or more of the country's present petroleum consumption--the goal set by the Advisory Committee in their vision for biomass technologies. Accomplishing this goal would require approximately 1 billion dry tons of biomass feedstock per year.
2,637 citations
TL;DR: A whirlwind survey of energy harvesting can be found in this article, where the authors present a survey of recent advances in energy harvesting, spanning historic and current developments in sensor networks and mobile devices.
Abstract: Energy harvesting has grown from long-established concepts into devices for powering ubiquitously deployed sensor networks and mobile electronics. Systems can scavenge power from human activity or derive limited energy from ambient heat, light, radio, or vibrations. Ongoing power management developments enable battery-powered electronics to live longer. Such advances include dynamic optimization of voltage and clock rate, hybrid analog-digital designs, and clever wake-up procedures that keep the electronics mostly inactive. Exploiting renewable energy resources in the device's environment, however, offers a power source limited by the device's physical survival rather than an adjunct energy store. Energy harvesting's true legacy dates to the water wheel and windmill, and credible approaches that scavenge energy from waste heat or vibration have been around for many decades. Nonetheless, the field has encountered renewed interest as low-power electronics, wireless standards, and miniaturization conspire to populate the world with sensor networks and mobile devices. This article presents a whirlwind survey through energy harvesting, spanning historic and current developments.
2,497 citations
TL;DR: In this article, the authors examine the systems and processes needed to tap energy in vehicles and implement V2G and quantitatively compare today's light vehicle fleet with the electric power system.
2,022 citations
TL;DR: In this paper, the potential applications of renewable energy sources to replace fossil fuel combustion as the prime energy sources in various countries, and discusses problems associated with biomass combustion in boiler power systems.
973 citations
TL;DR: In this article, the authors present a review of various systems that use renewable energy sources for desalination, including solar collectors, photovoltaics, solar ponds and geothermal energy.
949 citations
TL;DR: In this article, the use of an electrolyzer for peak shaving is discussed, as well as grid independent and grid assisted hydrogen generation, and integrated systems where electrolytically generated hydrogen is stored and then via fuel cell converted back to electricity when needed.
871 citations
TL;DR: In this paper, the authors explore the reasons for and technical challenges associated with co-combustion of biomass and coal in boilers designed for coal (mainly pulverized coal) combustion.
572 citations
TL;DR: In this paper, the authors deal with hydrogen energy as a clean energy carrier, discuss the key role of hydrogen energy technologies and systems, and compare hydrogen with other energy forms, and discuss energy strategies that incorporate hydrogen energy.
Abstract: This article deals with hydrogen energy as a clean energy carrier, discusses the key role of hydrogen energy technologies and systems, and compares hydrogen with other energy forms. Energy strategies that incorporate hydrogen are considered, and the importance of hydrogen energy in achieving a sustainable energy system is discussed. Exergetic, environmental, sustainability and other perspectives are considered.
544 citations
TL;DR: In this article, a simple method of formulating load profile (SMLP) for UK domestic buildings has been presented in which domestic space heating load profile for different types of houses have been produced using thermal dynamic model which has been developed using thermal resistant network method.
TL;DR: In this article, a pre-feasibility study of using hybrid energy systems with hydrogen as an energy carrier for applications in Newfoundland, Canada is explained, and various renewable and non-renewable energy sources, energy storage methods and their applicability in terms of cost and performance are discussed.
TL;DR: In this paper, the authors compare the benefits and environmental impacts of ethanol fuel, in Brazil and in the United States, using the ecological footprint tool developed by Wackernagel and Rees.
Abstract: The major contributor to global warming is considered to be the high levels of greenhouse gas emissions, especially carbon dioxide (CO2), caused by the burning of fossil fuel. Thus, to mitigate CO2 emissions, renewable energy sources such as ethanol have been seen as a promising alternative to fossil fuel consumption. Brazil was the world's first nation to run a large-scale program for using ethanol as fuel. Eventually, the United States also developed large-scale production of ethanol. In this study, we compare the benefits and environmental impacts of ethanol fuel, in Brazil and in the United States, using the ecological footprint tool developed by Wackernagel and Rees. We applied the STELLA model to gauge possible outcomes as a function of variations in the ethanol production scenario.
TL;DR: In this article, the attitudes towards wind power among the electricity consumers as well as the foundations of these attitudes were analyzed based on a postal survey that was sent out to 1000 Swedish house owners.
21 Apr 2005
TL;DR: A recent report of the Basic Energy Sciences Workshop on Solar Energy Utilization identifies the key scientific challenges and research directions that will enable efficient and economic use of the solar resource to provide a significant fraction of global primary energy by the mid-21st century as mentioned in this paper.
Abstract: This report of the Basic Energy Sciences Workshop on Solar Energy Utilization identifies the key scientific challenges and research directions that will enable efficient and economic use of the solar resource to provide a significant fraction of global primary energy by the mid 21st century. The report reflects the collective output of the workshop attendees, which included 200 scientists representing academia, national laboratories, and industry in the United States and abroad, and the U.S. Department of Energy’s Office of Basic Energy Sciences and Office of Energy Efficiency and Renewable Energy.
Solar energy conversion systems fall into three categories according to their primary energy product: solar electricity, solar fuels, and solar thermal systems. Each of the three generic approaches to exploiting the solar resource has untapped capability well beyond its present usage. Workshop participants considered the potential of all three approaches, as well as the potential of hybrid systems that integrate key components of individual technologies into novel cross-disciplinary paradigms.
TL;DR: In this paper, a review demonstrates that offshore renewable energy developments will have direct and, potentially, indirect consequences for coastal ecology, with these effects occurring at different scales, with the significance of any effects is likely to depend on the natural disturbance regime and the stability and resilience of the communities.
Abstract: Summary
1Global-scale environmental degradation and its links with non-renewable fossil fuels have led to an increasing interest in generating electricity from renewable energy resources. Much of this interest centres on offshore renewable energy developments (ORED). The large scale of proposed ORED will add to the existing human pressures on coastal ecosystems, therefore any ecological costs and benefits must be determined.
2The current pressures on coastal ecology set the context within which the potential impacts (both positive and negative) of offshore renewable energy generation are discussed.
3The number of published peer-review articles relating to renewable energy has increased dramatically since 1991. Significantly, only a small proportion of these articles relate to environmental impacts and none considers coastal ecology.
4Actual or potential environmental impact can occur during construction, operation and/or decommissioning of ORED.
5Construction and decommissioning are likely to cause significant physical disturbance to the local environment. There are both short- and long-term implications for the local biological communities. The significance of any effects is likely to depend on the natural disturbance regime and the stability and resilience of the communities.
6During day-to-day operation, underwater noise, emission of electromagnetic fields and collision or avoidance with the energy structures represent further potential impacts on coastal species, particularly large predators. The wider ecological implications of any direct and indirect effects are discussed.
7Synthesis and applications. This review demonstrates that offshore renewable energy developments will have direct and, potentially, indirect consequences for coastal ecology, with these effects occurring at different scales. Ecologists should be involved throughout all the phases of an ORED to ensure that appropriate assessments of the interaction of single and multiple developments with the coastal environment are undertaken.
TL;DR: In this paper, the authors present a review of hydrogen energy technologies, namely technologies for hydrogen production, storage, distribution, and utilization, in parallel with possibilities to use hydrogen to enhance wind power competitiveness.
09 May 2005
TL;DR: The essence of the natural gas infrastructure for supplying the ever-increasing number of gas-powered units is discussed and security-constrained unit commitment is used to analyze the short-time impact of natural gas prices on power generation scheduling.
Abstract: The restructuring of electricity has introduced new risks associated with the security of natural gas infrastructure on a significantly large scale, which entails changes in physical capabilities of pipelines, operational procedures, sensors and communications, contracting (supply and transportation), and tariffs. This paper will discuss the essence of the natural gas infrastructure for supplying the ever-increasing number of gas-powered units and use security-constrained unit commitment to analyze the short-time impact of natural gas prices on power generation scheduling. The paper analyzes the impact of natural gas infrastructure contingencies on the operation of electric power systems. Furthermore, the paper examines the impact of renewable sources of energy such as pumped-storage units and photovoltaic/battery systems on power system security by reducing the dependence of electricity infrastructure on the natural gas infrastructure. A modified IEEE 118-bus with 12 combined-cycle units is presented for analyzing the gas/electric interdependency.
TL;DR: In this article, a knee of the cost curve exists between 15% and 20% goals for 2020 in the central case, and higher natural gas prices lower the cost of greater reliance on renewables.
TL;DR: In this article, a hybrid power system using many wind turbine generators in isolated small islands is proposed. But the system can supply high quality power using an aqua electrolyzer, fuel cell, renewable energy and diesel generator.
Abstract: A hybrid power system uses many wind turbine generators in isolated small islands. The output power of wind turbine generators is mostly fluctuating and has an effect on system frequency. In order to solve this problem, we propose a new power system using renewable energy in small, isolated islands. The system can supply high-quality power using an aqua electrolyzer, fuel cell, renewable energy, and diesel generator. The generated hydrogen by an aqua electrolyzer is used as fuel for a fuel cell. The simulation results are given to demonstrate the availability of the proposed system in this paper.
01 Jan 2005
TL;DR: In this article, the potential for the exploitation of renewable energy sources is underused in the Community at present and it is therefore necessary to ensure that this potential is better exploited within the framework of the internal electricity market.
Abstract: (1) The potential for the exploitation of renewable energy sources is underused in the Community at present. The Community recognises the need to promote renewable energy sources as a priority measure given that their exploitation contributes to environmental protection and sustainable development. In addition this can also create local employment, have a positive impact on social cohesion, contribute to security of supply and make it possible to meet Kyoto targets more quickly. It is therefore necessary to ensure that this potential is better exploited within the framework of the internal electricity market.
TL;DR: In this paper, the authors explored the key factors at play in the 12 States in which a substantial amount of wind energy capacity has been developed or planned, including policy drivers such as Renewable Portfolio Standards (RPS), Federal and State financial incentives; as well as market drivers, such as consumer demand for green power, natural gas price volatility, and wholesale market rules.
TL;DR: In this paper, the main challenges in the development of materials for solar-hydrogen are discussed and discussed in detail, such as defect disorder, electronic structure and related semiconducting properties, on the impact of interfaces on photo-electrochemical properties.
TL;DR: In this paper, the authors consider the efficient use of primary energy sources, which can be used for hydrogen production, by a consideration of four key measures, which reflect the ability of different sources and processing routes to meet underlying needs and the practical demands of energy on a large scale.
TL;DR: In this paper, the authors compared direct input energy and indirect energy in per hectare in cotton production and compare with input costs, and concluded that large farms were more successful in energy productivity, use efficiency and economic performance.
TL;DR: In this paper, the authors evaluated the energy, environmental, and economic performance of willow biomass production and conversion to electricity using life cycle modeling methods and found that the net energy ratio (electricity generated/life cycle fossil fuel consumed) for willow ranges from 10 to 13 for direct firing and gasification processes.
Abstract: Short-rotation woody crops (SRWC) along with other woody biomass feedstocks will play a significant role in a more secure and sustainable energy future for the United States and around the world. In temperate regions, shrub willows are being developed as a SRWC because of their potential for high biomass production in short time periods, ease of vegetative propagation, broad genetic base, and ability to resprout after multiple harvests. Understanding and working with willow's biology is important for the agricultural and economic success of the system. The energy, environmental, and economic performance of willow biomass production and conversion to electricity is evaluated using life cycle modeling methods. The net energy ratio (electricity generated/life cycle fossil fuel consumed) for willow ranges from 10 to 13 for direct firing and gasification processes. Reductions of 70 to 98 percent (compared to U.S. grid generated electricity) in greenhouse gas emissions as well as NOx, SO2, and particulate emiss...
TL;DR: In this article, the authors discuss the transmission challenges of Denmark, Spain, Germany and Ireland with increasing wind capacity, and the impact of high levels of wind generation on system stability.
Abstract: The European Union has committed to reduce the equivalent carbon dioxide emissions by 8% of the 1990 level by the end of 2012. To meet the objective, the member states have financially encouraged the development of renewable energy especially wind power. Locally, this results in some of the highest wind power penetration levels in the world. This paper discusses the transmission challenges of Denmark, Spain, Germany and Ireland. With increasing wind capacity, the transmission system operators (TSOs) became concerned about the impact of high levels of wind generation on system stability. The integration of wind power has been hampered by the lack of suitable dynamic models for use in transient stability programs. The number of different turbine technologies used increased the complexity of the modeling problems.
TL;DR: In this article, the technical performance and energy requirements for production and transportation of a stand-alone photovoltaic (PV)-battery system at different operating conditions are presented.
TL;DR: The predicted size of the global energy market and the constraints of global warming upon it are reviewed, before detailing the complex set of biochemical pathways that underlie the photosynthetic process and how they could be modified for improved biohydrogen production.
Abstract: Solar energy capture, conversion into chemical energy and biopolymers by photoautotrophic organisms, is the basis for almost all life on Earth. A broad range of organisms have developed complex molecular machinery for the efficient conversion of sunlight to chemical energy over the past 3 billion years, which to the present day has not been matched by any man-made technologies. Chlorophyll photochemistry within photosystem II (PSII) drives the water-splitting reaction efficiently at room temperature, in contrast with the thermal dissociation reaction that requires a temperature of ca. 1550 K. The successful elucidation of the high-resolution structure of PSII, and in particular the structure of its Mn4Ca cluster (K. N. Ferreira, T. M. Iverson, K. Maghlaoui, J. Barber and S. Iwata, Science, 2004, 303, 1831–1838, ) provides an invaluable blueprint for designing solar powered biotechnologies for the future. This knowledge, combined with new molecular genetic tools, fully sequenced genomes, and an ever increasing knowledge base of physiological processes of oxygenic phototrophs has inspired scientists from many countries to develop new biotechnological strategies to produce renewable CO2-neutral energy from sunlight. This review focuses particularly on the potential of use of cyanobacteria and microalgae for biohydrogen production. Specifically this article reviews the predicted size of the global energy market and the constraints of global warming upon it, before detailing the complex set of biochemical pathways that underlie the photosynthetic process and how they could be modified for improved biohydrogen production.
Book•
03 Aug 2005
TL;DR: The third edition of the classic text highlights advances in this vital area, which are proceeding at an unprecedented pace, allowing everyone interested in this burgeoning field to keep up with the latest developments in diverse topics from solar cooling to renewable energy storage.
Abstract: With energy sustainability and security at the forefront of public discourse worldwide, there is a pressing need to foster an understanding of clean, safe alternative energy sources such as solar and wind power. Aldo da Rosa's highly respected and comprehensive resource fulfills this need; it has provided thousands of engineers, scientists, students and professionals alike with a thorough grounding in the scientific principles underlying the complex world of renewable energy technologies. This new third edition of the classic text highlights advances in this vital area, which are proceeding at an unprecedented pace, allowing everyone interested in this burgeoning field to keep up with the latest developments in diverse topics from solar cooling to renewable energy storage. It illuminates the basic principles behind all key renewable power sources - solar, wind, biomass, hydropower & fuel cells; connects scientific theory with practical implementation through physical examples; end-of-chapter questions help readers apply their knowledge; and written by one of the world's foremost experts in renewable energy, drawing from his decades of experience in academia and industry. New to this edition: all new chapter on pivotal renewable energy storage technologies; now includes discussion of power grid and transmission issues; expanded coverage of Hydropower and advances in PV cells; new and improved figures and additional end-of-chapter problems.