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• This work evaluates PV contribution before and after hurricanes. • All hurricanes that made landfall in the U.S. from 2004–17 are considered. • PV generation during hurricanes is 18–60% of clear sky potential. • PV generation immediately after hurricanes is 46–100% of clear sky potential. Hurricanes are a major reason for outages in the U.S. electricity sector. These outages are largely caused by damaged transmission systems. As a distributed generator technology, solar PV has the potential to supply local loads while the transmission system is repaired. However, hurricanes mean significant cloud cover, which reduces the ability of PV to contribute as a generator. In this work we quantify the ability of PV to provide energy during 18 hurricanes that made landfall in the contiguous United States from 2004 to 2017. Based on simulations using resource data from the National Solar Radiation Database, we find that PV generation never goes to zero during daytime hours for any of the hurricanes, though its potential is considerably diminished. PV generation ranges from 18 to 60% of clear sky potential during hurricanes. After the hurricane departs, the solar resource increases considerably, with PV producing at 46–100% of clear sky potential for the 72 h following a hurricane. When coupled with storage, PV is able to supply some minimum level of energy for all hours both during and after the hurricane. The amount of load that can be supplied is a function of the size of the PV and storage, the amount of solar resource available, and the duration of the hurricane event. [ABSTRACT FROM AUTHOR]

• Stearic acid/palmitic acid showed highest charging rate compared to PureTemp68. • Stearic acid/palmitic acid exhibited higher discharging efficiency compared to PureTemp68. • Water charging efficiency of stearic acid/palmitic acid is higher compared to Paraffin wax. • Stearic acid/palmitic acid based system showed better performance without super-cooling behavior. A solar thermal water heating system using a custom-built latent heat storage tank with paraffin wax, puretemp68 and stearic acid/palmitic acid eutectic mixture based phase-change materials was designed, developed and its performance evaluated in real-time. The fully autonomous off-grid solar thermal water heating system was packaged by integrating solar thermal collector, phase change material tank, photovoltaic modules, operational controller, circulation pumps and battery, along with a data logger. A water-glycol with anti-freeze characteristics with efficient energy storage in cold weather was employed as heat transfer fluid for solar thermal energy harvesting for charging and discharging of phase change materials to heat the water tank. Solar charge-discharge and water charging results with phase change materials during May to October 2018 (Mesa, AZ 85212, USA) showed that the stearic acid/palmitic acid eutectic mixture outperformed the paraffin wax and exhibited comparable performance with puretemp68 storage system. The efficiency of water charging from stearic acid/palmitic acid (55%) is higher compared to that from paraffin wax (20%) and better than puretemp68 (45%). Even though, the paraffin wax melts quickly during charging, it exhibited super-cooling behavior during discharging, leading to incomplete discharge. The storage energy density of stearic acid/palmitic acid (∼0.48 MJ kg−1) is comparable to puretemp68 with uniform thermal energy distribution inside the storage container due to higher thermal conductivity and lower melting point. The solar thermal water heating system demonstration proved that the domestic hot water system using stearic acid/palmitic acid could be a practical solution for effectively harvesting solar thermal energy for rural areas. [ABSTRACT FROM AUTHOR]

Energy conservation continues to play a crucial role in social and economic development. With the remarkable increase in oil prices and exploring solutions for the replacement of fossil fuels, an ecofriendly energy resource has become the priority among more and more people. Keeping the intension for reducing the global warming impact and looking for alternative clean source of energy, solar energy applications such as solar thermal systems, solar water heating and cooling are becoming energy-efficient designs. One of the widely used applications of solar energy is solar water heating systems. Low-cost solar water heaters can cover the domestic needs for water in the range of 100-200 l per day. Solar water heating systems are generally more efficient and advantageous in hot areas. However, the application of solar water heating is still a challenge in winter and sub-zero conditions, having low solar irradiance. In such conditions, solar water heating system cannot produce enough energy, which drives a need for evaluating system component design and improves its performance during low ambient conditions. In this study, detailed design methods for solar water heater components are discussed for cold regions like North Dakota, USA. The type of system chosen in this study is natural circulation-based solar water heating system. The study will also compare the experimental data with previously conducted numerical analysis. [ABSTRACT FROM AUTHOR]

Background: The accessibility of reliable local solar resource data plays a critical role in the evaluation and development of any concentrating solar power (CSP) or photovoltaic (PV) project, impacting the areas of site selection, predicted output, and operational strategy. Currently available datasets for prediction of the local solar resource in south Louisiana rely exclusively on modeled data by various schemes. There is a significant need, therefore, to produce and report ground measured data to verify the various models under the specific and unique ambient conditions offered by the climate presented in south Louisiana. Methods: The University of Louisiana at Lafayette has been recording onsite high-fidelity solar resource measurements for the implementation into predictive models and for comparison with existing datasets and modeling resources. Industry standard instrumentation has been recording direct normal irradiance (DNI), diffuse horizontal irradiance (DHI), and global horizontal irradiance (GHI), as well as meteorological weather data since 2013. The measured data was then compared statistically to several available solar resource datasets for the geographic area under consideration. Results: Two years of high-fidelity solar resource measurements for a location in south Louisiana that were previously not available are presented. Collected data showed statistically good agreement with several existing datasets including those available from the National Solar Radiation Database (NSRDB). High variability in year-over-year monthly DNI due to cloud cover was prevalent, while a more consistent GHI level was observed. Conclusions: The analysis showed that the datasets presented can be utilized for predictive analysis on a monthly or yearly basis with good statistical correlation. High variability in year-over-year monthly DNI due to cloud cover was prevalent, with as much as a 70 % difference in monthly DNI values observed in the measured data. A more consistent GHI level was observed since the GHI is less susceptible to cloud cover transients. Collected data showed statistically good agreement with several existing datasets including those available from the NSRDB when forecasting was for monthly and yearly intervals. [ABSTRACT FROM AUTHOR]

Global solar radiation on horizontal surface is often the only radiation registered data available for a specific location. In this paper, values of solar irradiation are estimated and then compared to measured values, on a vertical south-facing surface, in Covilhã, Portugal using 14 different (kt, kd) correlation models. A very acceptable agreement between estimated and measured values is achieved. [ABSTRACT FROM AUTHOR]

Abstract: Space heating, primarily using fossil fuels, is a major component of US energy consumption. Seasonal solar thermal energy storage (SSTES) provides a method to store solar thermal energy collected in the summer to use for heating in the colder months. Solar collectors are used to heat a sand bed, which retains its thermal energy through the winter. That energy is then sent into the building via radiant floors for space heating use. A sand-based storage bed SSTES system for a new five story student housing complex at Virginia Commonwealth University is modeled using TRNSYS Version 16 software. A total of 15 simulations of various storage bed locations and configurations as well as building efficiencies are modeled to determine whether a system is feasible for an urban environment. Substantial energy savings are possible within the small footprint required by city lots. Up to 91% of energy for this large building can be provided by the most efficient SSTES system. [Copyright &y& Elsevier]

The article focuses on the move of the U.S. government to invest in the development of solar thermal power plants that will be obsolete before they generate a single kilowatt-hour of electricity for the nation. It discusses aspects of the Solar Vision Study (SVS), which creates a strategy to provide the nation with 10 to 20 percent of its electric energy from solar power by 2030. Also explored is the cost-effectiveness of solar photovoltaic (PV) compared to solar thermal.

Solar thermal is a viable technology that uses clean, renewable energy (the sun) to provide a primary heat source in homes. A combination of structural constraints and value-oriented motivators potentially influences solar thermal technology adoption. This study examines the extent to which solar thermal adoption correlates with structural or value-related factors through logistic regression modeling. Variables measuring socioeconomic circumstances, environmental concern, and ecological conditions are used to predict residential solar thermal technology adoption at the county level throughout the United States. This project provides insight regarding the role of structural and value-related factors, thus highlighting the significance of both structure and agency in explaining social change. [ABSTRACT FROM AUTHOR]

Abstract: This study investigates the potential changes in Solar Heat Gain Coefficient (SHGC) and Visible Transmittance (VT) ratings of vertical or tilted glazing systems that would result from a deliberate change in the reference spectrum used as Spectral Weighting Function (SWF). This SWF is necessary to evaluate broadband-average optical properties from their spectral values, and obtain the desired rating of such bulk properties. The SWFs currently specified by rating institutions in Europe and North America for SHGC and VT are now outdated, and their inadequacies are discussed. Six potential replacements, which have been recently adopted by ASTM are described, including three direct irradiance spectra and three global irradiance spectrum incident on tilted surfaces of various tilts (20°, 37° and 90°). Some of these spectra have been tailored for use in building energy applications, including Building-Integrated Photovoltaics (BIPV). The effect of tilt on the U-factor and hence SHGC of glazing systems used for skylights on roofs is discussed, using a representative dataset of 37 glazing system specimens. The spectral effects on SHGC induced by a change in the current North American SWF are also obtained for this dataset, and show small to moderate deviations from current ratings (−2% to +7% for windows, and −3% to +11% for skylights). The variations in VT are within ±2% for most glazing systems. To remove the current inconsistency in the SWFs used for SHGC and VT, it is recommended that a single SWF be used for both properties. For improved accuracy and reliance on active standards, it is also recommended that the SWF for SHGC and VT be either one of the two recent ASTM G197-08 global irradiance spectra, depending on application (incidence on a vertical surface for window applications, and incidence on a 20°-tilted surface for skylight applications). No change in colorimetric calculations (based on the D65 illuminant) is recommended, however. [Copyright &y& Elsevier]

Abstract: This work investigates the feasibility of renewable energy housing development in the U.S. using wind power and solar thermal systems to attain zero net energy consumption. The over all objective was to determine how the wind power and solar thermal system designs and economics differ with various climates, wind and solar resources, energy prices, and state incentives, such as net-metering. Five U.S. cities, one in each of the five climate zones, were selected for this study based on their potential for wind power. A zero net energy housing design tool was developed in order to analyze and compare various system designs. The energy performance and economics of the designs were compared for various sizes of housing development, for seven turbine models, and selected heating systems. The results suggest that while there are some economical options for wind powered zero net energy housing developments, they are generally more expensive (except in the warmest climate zone) than housing with natural gas heating. In all of the cases, the economies of scale for large-scale wind turbines gave more of an economic advantage than net-metering programs gave small- and medium-scale wind turbines. [Copyright &y& Elsevier]

Abstract: Solar thermal (ST) energy, using trough solar collectors, can be an environmentally friendly and economically competitive electric source for any part of the world (such as the USA) that includes large desert areas. Competitive ST involves trough solar collectors, which concentrate solar rays onto a flowing liquid able to sustain very high temperatures (⩾800°F) without exerting significant vapor pressure or decomposing. This allows the solar energy to be used to raise steam and drive turbines of electricity-generating plants directly, or to be harvested and stored as sensible heat in large underground ponds. The stored portion of the energy can be used instantaneously to meet variable power needs. This technology has been amply demonstrated by a 354MWe modular plant (consisting of 9 ST units) that has been running in the Mojave Desert for the past 20 years. For intermediate loads (50% of the US electricity requirement) ST energy is already competitive with any new power plant, including old-fashioned coal power plants equipped with scrubbers. ST energy, using trough solar collectors, can become a major technical, financial, and political development. [Copyright &y& Elsevier]

Solar Hot Water (SHW) systems that displace grid electricity are being considered for inclusion into installation and production credit programs. However, SHW systems normally have only energy production ratings, not power ratings, creating difficulties in including them into credit programs. Dave Menicucci, Sandia National Laboratories, USA describes the current issues surrounding this key area for solar thermal and presents a simple methodology that can estimate an effective power rating for SHW systems. [Copyright &y& Elsevier]

With levelized electricity costs (LEC) of 10–12 USCts/kWh the well-known SEGS (Solar Electric Generating Systems) plants in California are presently the most successful solar technology for electricity generation [Price and Cable (2001) Proc. ASME Int. Solar Energy Conf. Forum 2001]. The SEGS plants apply a two-circuit system, consisting of the collector circuit and the Rankine cycle of the power block. These two-circuits are connected via a heat exchanger. In the case of the Direct Steam Generation (DSG) in the collector field [Zarza et al. (2001) Proc. Solar Forum 2001, Washington], the two-circuit system turns into a single-circuit system, where the collector field is directly coupled to the power block. This renders a lower investment and higher process temperatures resulting in a higher system efficiency. Due to the lower investment and the higher efficiency a reduction of the LEC of 10% is expected when the DSG process is combined with improved components of the solar collectors [Zarza (2002) DISS Phase II Final Report, EU Contract No. JOR3-CT98-0277]. Within the European DISS (Direct Solar Steam) project the feasibility of the direct steam generation has been proven in more than 3700 operation hours. Steam conditions of 100 bar and 400 °C have been demonstrated. This paper presents the main scientific results of the DISS project that aims at the investigation and demonstration of the DSG process in parabolic troughs under real solar conditions. [Copyright &y& Elsevier]

The economics of two proposed solar thermal hybrid power generation systems (STHSs) have been evaluated. Each system consists of direct-steam-generation solar collectors, a steam accumulator and a gas turbine power generation system which uses steam as its working fluid. One (STHS-A) of the proposed systems emits CO2 generated by burning fuel, whereas the other (STHS-B) captures the CO2. Assuming that the systems are located in San Francisco, USA, where solar radiation energy is approximately the same as the global average, the levelized electricity costs (LECs) of the STHSs have been estimated considering future uncertainty of fuel cost and the capital cost of the solar collector. The LECs of combined cycle plants, which are considered to be one of the major thermal power generation systems in the near future, have also been estimated to evaluate the economics of the proposed systems. When fuel (methane) cost is 4.5 $/GJ, for example, the STHS-A has been estimated to be the most economical among the evaluated systems where the carbon tax is higher than a value in the range of 106–244 $/t-C, whereas the STHS-B is the most economical where the carbon tax is higher than a value between 368 and 475 $/t-C. [Copyright &y& Elsevier]

During 1973-1980, U.S. solar policy emphasized financial incentives to potential purchasers as the primary means of stimulating the introduction and spread of residential solar heating systems. This article examines the importance of nonfinancial factors in decisions to purchase residential solar heating systems during these early stages of market penetration and discusses the implications these factors have for policy design. Drawing upon research on the diffusion of innovations, on the effectiveness of income tax credits for solar heating systems, and on solar energy system purchasing decisions themselves, the argument is developed that nonfinancial factors such as system reliability, warranty protection, environmental concerns, adequate information about system costs and performance, and confidence in system suppliers and installers are at least as important as initial system cost to early purchasers. These considerations were not reflected in U.S. solar policy to the extent warranted. As a result, that policy failed to promote the balanced development of all elements essential to a viable residential solar heating industry and probably failed to alter the intentions of many prospective solar system purchasers. The reasons U.S. policymakers were relatively insensitive to nonfinancial factors are discussed and an alternative strategy for increasing the rate of market penetration of residential solar heating systems is offered. [ABSTRACT FROM AUTHOR]

• Annual average prices declined by $19–64/MWh between 2008 and 2017 in the United States. • Estimate counterfactual prices by changing a factor at a time in fundamental model. • Dominant driver of decline in average wholesale price is fall in natural gas prices. • Total impact of wind and solar on average prices is below $3/MWh. • Isolating the impact of individual factors is limited by non-linear interactions. Across multiple organized wholesale power markets in the United States, annual average prices declined by $19–64/MWh between 2008 and 2017 while retirements of thermal power plants accelerated. Several prominent changes over the last decade are often discussed as contributors to this decline in prices. These include growth in wind and solar, a reduction in the price of natural gas, and weakened load growth. Here we construct a fundamental supply curve model for each of seven organized wholesale market regions and use counterfactual simulations to assess the degree to which wind and solar—among other factors—have influenced wholesale electricity prices. We find that growth in wind and solar since 2008 reduced average annual wholesale electricity prices by less than $3/MWh. In contrast the decline in natural gas prices reduced wholesale prices by $7–53/MWh, depending on the region. This suggests that recent thermal-plant retirements in the U.S. are primarily due to low natural gas prices, not growth in wind and solar. Fully isolating the impact of individual factors, however, is limited by non-linear interactions between factors. [ABSTRACT FROM AUTHOR]

The multi-family residential building sector is the least energy efficient in the United States, thus allowing for ample opportunities for significant cost-effective energy and carbon savings. In the present study, we propose a district solar borehole thermal solar energy storage (BTES) system for both retrofit and new construction for a multi-family residence in the Midwestern United States, where the climate is moderately cold with very warm summers. Actual apartment interval power and water demand data was mined and used to estimate unit level hourly space and water heating demands, which was subsequently used to design a cost-optimal BTES system. Using a dynamic simulation model to predict the system performance over a 25-year period, a parametric study was conducted that varied the sizes of the BTES system and the solar collector array. A life-cycle cost analysis concluded that is it possible for an optimally-sized system to achieve an internal rate of return (IRR) of 11%, while reducing apartment-wide energy and carbon consumption by 46%. Both a stand-alone and solar-assisted ground-source heat pump system were designed and simulated for comparison to the BTES system, and found to be less economically favorable than the solar BTES system. Thus, the promise for district-scale adoption of BTES in multi-family residences is established, particularly for new buildings. • Multi-family dwellings have few options or incentives for improving energy efficiency. • A district BTES system utilizing solar heat was proposed for a multi-family dwelling. • Parametric system simulations used actual heating loads derived from utility data. • All heating and hot water loads can be met without the need of a heat pump. • A solar-BTES appears economically viable in a moderately cold climate. [ABSTRACT FROM AUTHOR]

Reflective roof membranes have been shown to lower air conditioning costs by reducing the influx of thermal energy through a roof assembly and into the building. However, there have been studies suggesting that reflective roofs in cold climates give rise to increased winter heating costs, due to the lack of absorption of solar thermal energy. Such studies could be used to justify continued use of dark, absorptive roof membranes even in areas that are striving to reduce urban heat island effects and/or lower contributions to global warming. In a prior modeling study, by this author and others, based on gas heat, it was found that reflective roofing provides net annual energy savings so long as air conditioning was used. Studies by others have suggested that when electric heat is used, the winter heating cost savings associated with non-reflective roofing outweigh summer air conditioning cost savings with reflective roofing. However, these studies did not take into account electric demand charges. Therefore, this present study modeled the energy efficiency of commercial buildings in order to compare the effect of gas versus electric heat with varying levels of demand charge included, on the net energy efficiency. Four different levels of demand charges were compared, along with three levels of solar reflectance for thirteen cities located throughout the US. In every studied case, when gas heat was assumed, net annual energy savings were predicted for reflective membranes. For electric heat, net energy savings were achieved in most cases even when demand charges were zero. In three northernmost cities, this was the case provided that demand charges exceeded a relatively small minimum. This finding suggests that reflective roofing provides for net energy efficiency improvements in most US cities and all cities when demand charges exceed USD 6.25 Therefore, efforts by cities to encourage reflective roofing as part of urban heat island effect mitigation programs should not be reduced. [ABSTRACT FROM AUTHOR]

To change an increasing trend of energy consumption, many counties have turned to solar thermal energy as a solution. Without greenhouse gas emissions, solar thermal power stations may play a vital role in the energy industry because they have a potential to produce electricity for 24 h per day. The goal of this study is to select solar thermal power stations from three regions (i.e., the United States, Spain and the other nations) throughout the world and to identify which region most efficiently produces solar thermal power energy. To measure their efficiencies, we use data envelopment analysis as a method to examine the performance of these power stations. Our empirical results show that the United States currently fields the most efficient solar thermal power stations. This study also finds that parabolic trough technology slightly outperforms the other two technologies (i.e., heliostat power tower and linear Fresnel reflector), but not at the level of statistical significance. In addition to the proposed efficiency assessment, we incorporate a new way of finding a possible existence of congestion. The phenomenon of congestion is separated into output-based and input-based occurrences. Output-based congestion implies a capacity limit (e.g., difficulties in transmission, voltage control and dispatch scheduling) in a grid network between generation and end users. Input-based congestion occurs when generators use "uncontrollable inputs" (e.g., sunlight hours). Renewable energy sources, such as solar thermal power, are indeed important for our future sustainability. However, this needs performance assessment on generation and transmission through which electricity generated by renewable energy is conveyed to end users. Such a holistic assessment, including both efficiency measurement and congestion identification, serves as a major component in evaluating and planning renewable energy generation. [ABSTRACT FROM AUTHOR]

The article offers information on the construction of an experimental atomic power plant at the Clinton Engineer Works at Oak Ridge, Tennessee. This development was made known through a press release on April 12, 1946. Unlike other power plants which were specifically designed for the production of plutonium, this one is designed to generate heat energy and the conversion of this kind of energy into electricity. The pile will be based on investigations which were conducted at the Metallurgical laboratory at the University of Chicago in Illinois under the tutelage of Farrington Daniels.

Focuses on low-temperature solar thermal system in the U.S. Potential of low-temperature solar thermal systems as an energy resource; Advantages over the use of fossil fuels.

The article focuses on concentrated solar power (CSP) plants. It states that CSP plants can generate solar power at 15 cents per kilowatt-hour. It mentions that solar heat can be stored in tanks filled with molten salt, allowing the CSP plant to continue generating electricity for up to six hours after sunset. It states that almost 300,000 homes in the southwestern U.S. are supplied power through CSP plants. George Douglas, spokesperson for the U.S. Department of Energy's National Renewable Energy Laboratory, said that CSP could meet a significant portion of energy needs and that CSP plants are planned for development in Arizona, California, Hawaii, and Florida.

The structural and thermal feasibility of a self-supporting sandwich panel for energy efficient residential roof applications is assessed. The assessment is limited to symmetric sandwich panels comprising two face sheets and an insulating core. Feasible panel designs are presented for loading conditions, corresponding to southern and northern climates in the United States. The base case panel is 5.5 m long for a nominal 4.6 m horizontal span and an 8/12 roof pitch. Face sheet materials considered are oriented strand board, steel, and fiber reinforced plastic. Core materials considered are expanded polystyrene, extruded polystyrene, polyurethane, and poly(vinyl-chloride) foams. A wide range of material options meet building code limits on deflection and weight and prevent face sheet fracture and buckling, and core shear failure. Panels are identified that have structural depths similar to conventional wood rafter construction. Shortening the overall panel length provides greater choice in the use of materials and decreases the required panel thickness. Suggestions for improved panel designs address uncertainty in the ability of the plastic core to withstand long term loading over the expected life of residential buildings. [ABSTRACT FROM AUTHOR]

Editorial. Comments on the significance of social, economic, and political needs on the solarthermal industrial processing in the United States. Benefits of solar energy; Consequence on the federal support to scientist and engineers; Recognition on the energy situation as a global threat.