Showing papers on "Solar power published in 2010"

Solar Water Splitting Cells

Abstract: Energy harvested directly from sunlight offers a desirable approach toward fulfilling, with minimal environmental impact, the need for clean energy. Solar energy is a decentralized and inexhaustible natural resource, with the magnitude of the available solar power striking the earth’s surface at any one instant equal to 130 million 500 MW power plants.1 However, several important goals need to be met to fully utilize solar energy for the global energy demand. First, the means for solar energy conversion, storage, and distribution should be environmentally benign, i.e. protecting ecosystems instead of steadily weakening them. The next important goal is to provide a stable, constant energy flux. Due to the daily and seasonal variability in renewable energy sources such as sunlight, energy harvested from the sun needs to be efficiently converted into chemical fuel that can be stored, transported, and used upon demand. The biggest challenge is whether or not these goals can be met in a costeffective way on the terawatt scale.2

The Catalytic Valorization of Lignin for the Production of Renewable Chemicals

Abstract: Biomass is an important feedstock for the renewable production of fuels, chemicals, and energy. As of 2005, over 3% of the total energy consumption in the United States was supplied by biomass, and it recently surpassed hydroelectric energy as the largest domestic source of renewable energy. Similarly, the European Union received 66.1% of its renewable energy from biomass, which thus surpassed the total combined contribution from hydropower, wind power, geothermal energy, and solar power. In addition to energy, the production of chemicals from biomass is also essential; indeed, the only renewable source of liquid transportation fuels is currently obtained from biomass.

Renewable Energy Policies and Technological Innovation: Evidence Based on Patent Counts

Abstract: This paper examines the effect of environmental policies on technological innovation in the specific case of renewable energy. The analysis is conducted using patent data on a panel of 25 countries over the period 1978–2003. We find that public policy plays a significant role in determining patent applications. Different types of policy instruments are effective for different renewable energy sources. Broad-based policies, such as tradable energy certificates, are more likely to induce innovation on technologies that are close to competitive with fossil fuels. More targeted subsidies, such as feed-in tariffs, are needed to induce innovation on more costly energy technologies, such as solar power.

State of the art on high-temperature thermal energy storage for power generation. Part 2—Case studies

Abstract: Power generation systems are attracting a lot of interest from researchers and companies. Storage is becoming a component with high importance to ensure system reliability and economic profitability. A few experiences of storage components have taken place until the moment in solar power plants, most of them as research initiatives. In this paper, real experiences with active storage systems and passive storage systems are compiled, giving detailed information of advantages and disadvantages of each one. Also, a summary of different technologies and materials used in solar power plants with thermal storage systems existing in the world is presented.

Multi-electron reaction materials for high energy density batteries

Abstract: The need for high energy density batteries becomes increasingly important for the development of new and clean energy technologies, such as electric vehicles and electrical storage from wind and solar power. The search for new energetic materials of primary and secondary batteries with higher energy density has been highlighted in recent years. This review surveys recent advances in the research field of high energy density electrode materials with focus on multi-electron reaction chemistry of light-weight elements and compounds. In the first section, we briefly introduce the basic strategies for enhancement of the energy density of primary batteries based on multi-electron reactions. The following sections present overviews of typical electrode materials with multi-electron chemistry and their secondary battery applications in aqueous and non-aqueous electrolytes. Finally, the challenges and ongoing research strategies of these novel electrode materials and battery systems for high density energy storage and conversion are discussed.

The Value of Concentrating Solar Power and Thermal Energy Storage

Abstract: This paper examines the value of concentrating solar power (CSP) and thermal energy storage (TES) in a number of regions in the southwestern United States. Our analysis shows that TES can increase the value of CSP by allowing more thermal energy from a CSP plant's solar field to be used, allowing a CSP plant to accommodate a larger solar field, and by allowing CSP generation to be shifted to hours with higher energy prices. We analyze the sensitivity of this value to a number of factors, including the optimization period, price and solar forecasting, ancillary service sales, and dry cooling of the CSP plant, and also estimate the capacity value of a CSP plant with TES. We further discuss the value of CSP plants and TES net of capital costs.

Keeping the Energy Debate Clean: How Do We Supply the World's Energy Needs?

Abstract: We take a fresh look at the major nonrenewable and renewable energy sources and examine their long-term viability, scalability, and the sustainability of the resources that they use. We achieve this by asking what would happen if each energy source was a single supply of power for the world, as a gedanken experiment. From this perspective, a solar hydrogen economy emerges as a dominant solution to the world's energy needs. If we globally tap sunlight over only 1% of the incident area at only an energy conversion efficiency of 1%, it is simple to show that this meets our current world energy consumption. As 9% of the planet surface area is taken up by desert and efficiencies well over 1% are possible, in practice, this opens up many exciting future opportunities. Specifically, we find solar thermal collection via parabolic reflectors - where focussed sunlight heats steam to about 600?C to drive a turbine - is the best available technology for generating electricity. For static power storage, to provide electricity at night, there are a number of viable options that are discussed. For mobile power storage, such as for fueling vehicles, we argue the case for both liquid and gaseous hydrogen for use in internal combustion engines. We outline a number of reasons why semiconductor solar cells and hydrogen fuel cells do not appear to scale up for a global solution. We adopt an approach that envisions exploiting massive economy of scale by establishing large arrays of solar collectors in hot desert regions of the world. For nonrenewable sources we argue that we cannot wait for them to be exhausted - we need to start conserving them imminently. What is often forgotten in the energy debate is that oil, natural gas, and coal are not only used as energy sources, but we also rely on them for embodying many crucial physical products. It is this fact that requires us to develop a solar hydrogen platform with urgency. It is argued that a solar future is unavoidable, as ultimately humankind has no other choice.

Implications of Wide-Area Geographic Diversity for Short- Term Variability of Solar Power

Abstract: LBNL-3884E E RNEST O RLANDO L AWRENCE B ERKELEY N ATIONAL L ABORATORY Implications of Wide-Area Geographic Diversity for Short- Term Variability of Solar Power Andrew Mills and Ryan Wiser Environmental Energy Technologies Division September 2010 Download from http://eetd.lbl.gov/EA/EMP The work described in this paper was funded by the U.S. Department of Energy (Office of Energy Efficiency and Renewable Energy and Office of Electricity Delivery and Energy Reliability) under Contract No. DE-AC02-05CH11231.

Carbon Nanotubes for Photoconversion and Electrical Energy Storage

Abstract: The majority of the world energy consumption is derived from fossil fuels. The conversion reactions required for retrieving energy from carbon resources result in the production of green house gases and subsequent global warming effects. Furthermore, the United States (U.S.) consumption of petroleum vastly exceeds its production, with the majority of the petroleum being consumed in the transportation sector. The severe environmental impacts of a petroleum-based society coupled with increasing dependency on foreign fuels dictates that alternative renewable energy resources be developed and implemented. The U.S. Department of Energy’s (DOE’s) Office of Energy Efficiency and Renewable Energy1,2 and the Office of Basic Energy Sciences3 are currently promoting the need both to rely on solar energy and also to implement efficient methods for electrical energy storage. However, significant scientific advancement is still required for the practical and safe deployment of both of these technologies. A detailed discussion of the benefits of transitioning to a solar-powered energy economy as well as the technical hurdles faced for the development of electrical energy storage systems, with a focus on vehicle technologies, is provided here. Many next-generation photovoltaic (PV) and electrical energy storage devices, such as Li-ion batteries and electrochemical capacitors, will be advanced as a result of new developments in nanotechnology. Carbon nanotubes (CNTs) have been widely studied since their discovery in 1991.4 CNTs have highly unique electronic, mechanical, catalytic, adsorption, and transport properties, making them interesting for a variety of applications.5-13 This review focuses on how both carbon multiwall nanotubes (MWNTs) and single-wall nanotubes (SWNTs) may be employed to improve upon state-of-the art photoconversion and electrical energy storage technologies.

Prototype implementation of ambient RF energy harvesting wireless sensor networks

Abstract: Energy harvesting is a key technique that can be used to overcome the barriers that prevent the real world deployment of wireless sensor networks (WSNs). In particular, solar energy harvesting has been commonly used to overcome this barrier. However, it should be noted that WSNs operating on solar power suffer form energy shortage during nighttimes. Therefore, to solve this problem, we exploit the use of TV broadcasts airwaves as energy sources to power wireless sensor nodes. We measured the output of a rectenna continuously for 7 days; from the results of this measurement, we showed that Radio Frequency (RF) energy can always be harvested. We developed an RF energy harvesting WSN prototype to show the effectiveness of RF energy harvesting for the usage of a WSN. We also proposed a duty cycle determination method for our system, and verified the validity of this method by implementing our system. This RF energy harvesting method is effective in a long period measurement application that do not require high power consumption.

An Efficient Wind–Photovoltaic Hybrid Generation System Using Doubly Excited Permanent-Magnet Brushless Machine

Abstract: With ever-increasing concerns on energy issues, the development of renewable energy sources is becoming more and more attractive. This paper first reviews both the wind power and photovoltaic (PV) power generation techniques and their maximum-power-point tracking (MPPT) methods. Then, a new stand-alone wind-PV hybrid generation system is proposed for application to remote and isolated areas. For the wind power generation branch, a new doubly excited permanent-magnet brushless machine is used to capture the maximum wind power by using online flux control. For the PV power generation branch, a single-ended primary inductance converter is adopted to harness the maximum solar power by tuning the duty cycle. The experimental results confirm that the proposed hybrid generation system can provide high efficiency with the use of MPPT.

Green Nanotechnology: Solutions for Sustainability and Energy in the Built Environment

Abstract: Green Nanotechnology: Introduction and Invitation What Is Nanotechnology? What Is Green Nanotechnology? Some Basic Issues in Nanoscience Nanoscience, Dimensionality, and Thin Films Outdoing Nature in Exploiting Complexity Energy Supply and Demand Energy and Development References In Harmony with the Environment: Nature's Energy Flows and Desired Materials Properties Global Energy Flows Radiation in Our Ambience: An Overview Interaction Between Radiation and Materials Beam and Diffuse Radiation Hemispherical Absorptance Solar and Daylighting Performance Parameters Thermal Radiation and Spectral Properties of the Atmosphere Dynamical Environmental Properties Materials for Optimized Use of the Spectral, Directional, and Dynamical Properties of Solar Energy and Sky Radiation Thermal and Density Gradients in the Atmosphere and Oceans Performance of Energy Systems: Thermodynamics and Value References Optical Materials Science for Green Nanotechnology: The Basics Light and Nanostructures Spectral Properties of Uniform Materials Plasmonic Materials in General Materials for Electron-Based Plasmonics: Mirrors for Visible and Infrared Light Ionic-Based Materials with Narrow-Band Infrared Properties Generic Classes of Spectrally Selective Materials Thin Films for Controlling Spectral Properties and Local Light Intensities Nanoparticle Optics Optical Homogenization of Nanocomposites Surface Plasmon Resonances in Films, Particles, and "Rectennas" Temporary "Storage" of Light at Resonances and in Evanescent Fields References Visual Indoors-Outdoors Contact and Daylighting: Windows General Introduction Spectral Selectivity: The Potential in Energy Efficiency Spectral Selectivity of Noble-Metal-Based Films Spectral Selectivity of Oxide-Semiconductor-Based Films Spectral Selectivity: Novel Developments for Films and Foils Optimized Angular Properties: The Energy Efficiency That Is Possible Angular Selectivity of Films with Inclined Columnar Nanostructures Chromogenics: The Energy Efficiency That Is Possible Photochromics Thermochromics Electrochromics References Electric Lighting and Daylighting: Luminaires Lighting: Past, Present, and Future Daylighting Technology: The "Cool" Option Dielectric Mirrors Based on Nanostructure Luminescent Solar Concentrators for Daylighting and Solar Power Light Diffusing Transmitting Materials Advanced Electronic Lighting Concepts References Heat and Electricity: Solar Collectors and Solar Cells Solar Thermal Materials and Devices Photovoltaic Materials and Devices References Coolness: High-Albedo Surfaces and Sky Cooling Devices Two Cooling Strategies City Heating, Global Cooling, and Summer Blackouts High-Albedo Paints for Cool Buildings Sky Cooling to Subambient Temperatures Water Condensation Using Sky Cooling A Role for Cooling and Waste Heat in Electric Power Generation Electronic Cooling and Nanotechnology Whither Cooling? References Supporting Nanotechnologies: Air Sensing and Cleaning, Thermal Insulation and Electrical Storage Air Quality and Air Sensing Photocatalysis for Cleaning Thermal Insulation with Nanomaterials Green Energy Storage References Conclusions: Nanotechnologies for a Sustainable Future Energy and the Future New Technologies and Growing Uptake of Proven Technologies Towards a "Nanoworld" References Appendix 1: Thin Film Deposition Appendix 2: Abbreviations, Acronyms, and Symbols Index

Solar electricity prospects in Oman using GIS-based solar radiation maps

Abstract: This paper discusses solar power prospects in Oman. First, the geographic and topographic information about Oman are presented. The methodology of producing solar radiation maps using GIS tools is then discussed. The results obtained show very high potential of solar radiation over all the lands of Oman during the whole year. A slope analysis has allowed calculating the yearly electricity generation potential for different Concentrated Solar Power (CSP) technologies such as the parabolic trough, parabolic dish, tower, and concentrated PV. For instance if only 10% of the land of Oman with a slope less than 1% is considered an exploitable land for the parabolic trough CSP technology, then the total calculated potential of yearly electricity generation would be about 7.6 million GWh, which is many multiples of (680 times) the current generation supply in Oman which was about 11,189 GWh in 2007.

Parabolic Trough Reference Plant for Cost Modeling with the Solar Advisor Model (SAM)

Abstract: This report describes a component-based cost model developed for parabolic trough solar power plants. The cost model was developed by the National Renewable Energy Laboratory (NREL), assisted by WorleyParsons Group Inc., for use with NREL's Solar Advisor Model (SAM). This report includes an overview and explanation of the model, two summary contract reports from WorleyParsons, and an Excel spreadsheet for use with SAM. The cost study uses a reference plant with a 100-MWe capacity and six hours of thermal energy storage. Wet-cooling and dry-cooling configurations are considered. The spreadsheet includes capital and operating cost by component to allow users to estimate the impact of changes in component costs.

Analytical Approach for Well-Being Assessment of Small Autonomous Power Systems With Solar and Wind Energy Sources

Abstract: This paper presents a systematic analytical approach for the well-being assessment of small autonomous power systems (SAPSs) with wind and solar energy sources. The proposed technique accounts for the uncertainties associated with solar irradiance, wind speed, demand, and outages of various generating units. The impact of wind power fluctuation on the system stability is also assessed by limiting the wind power dispatch to a certain percentage of system load. Well-being assessment and production costing simulation for SAPS are performed using proposed analytical approach and Monte Carlo simulation (MCS) method, and then, obtained results are compared in terms of accuracy and computational time. The comparison shows that the developed technique requires less computational time than MCS method, with reasonable accuracy, and thus, validates the usefulness of proposed analytical method. The impact of renewable energy penetration on a SAPS is also analyzed using the proposed method.

Systems for cost-effective concentration and utilization of solar energy

Abstract: The present invention is primarily directed to cost-effective systems for using large reflective elements that track the sun on two axes to concentrate solar energy onto a receiver that can convert the sun's optical energy to a form usable for extensive displacement of combustion of fossil fuels. The structures of the tracker frame, tracking mechanism and tracker supports are co-optimized with the optical elements and the receiver for high efficiency, low cost, and ease of assembly, making moderate and large-scale implementations cost-competitive with fossil fuels for peak power, and. with suitable storage, for base-load power and dispatchable peaking power in sunny locations. Improvement to small-tracker two-axis systems and one-axis tracking systems that focus in two dimensions are also included, as are improvements in systems for space-based solar power.