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Solar Two

Description: Solar Two is a concentrating solar power plant that can supply electric power on demand to the local utility, Southern California Edison Company. It can do so because it operates not only during sunny parts of the day, but it can store enough thermal energy from the sun to operate during cloudy periods and after dark, for up to three hours, at its rated output of 10 megawatts (MW). For the first time ever, a utility scale solar power plant can supply electricity when the utility needs it most, to satisfy the energy requirements of its customers.
Date: April 1, 1998
Partner: UNT Libraries Government Documents Department

Technology Potential of Thermal Energy Storage (TES) Systems in Federal Facilities

Description: This document presents the findings of a technology market assessment for thermal energy storage (TES) in space cooling applications. The potential impact of TES in Federal facilities is modeled using the Federal building inventory with the appropriate climatic and energy cost data. In addition, this assessment identified acceptance issues and major obstacles through interviews with energy services companies (ESCOs), TES manufacturers, and Federal facility staff.
Date: July 31, 2001
Creator: Chvala, William D., Jr.
Partner: UNT Libraries Government Documents Department

Thermocline Thermal Storage Test for Large-Scale Solar Thermal Power Plants

Description: Solar thermal-to-electric power plants have been tested and investigated at Sandia National Laboratories (SNL) since the late 1970s, and thermal storage has always been an area of key study because it affords an economical method of delivering solar-electricity during non-daylight hours. This paper describes the design considerations of a new, single-tank, thermal storage system and details the benefits of employing this technology in large-scale (10MW to 100MW) solar thermal power plants. Since December 1999, solar engineers at Sandia National Laboratories' National Solar Thermal Test Facility (NSTTF) have designed and are constructing a thermal storage test called the thermocline system. This technology, which employs a single thermocline tank, has the potential to replace the traditional and more expensive two-tank storage systems. The thermocline tank approach uses a mixture of silica sand and quartzite rock to displace a significant portion of the volume in the tank. Then it is filled with the heat transfer fluid, a molten nitrate salt. A thermal gradient separates the hot and cold salt. Loading the tank with the combination of sand, rock, and molten salt instead of just molten salt dramatically reduces the system cost. The typical cost of the molten nitrate salt is $800 per ton versus the cost of the sand and rock portion at $70 per ton. Construction of the thermocline system will be completed in August 2000, and testing will run for two to three months. The testing results will be used to determine the economic viability of the single-tank (thermocline) storage technology for large-scale solar thermal power plants. Also discussed in this paper are the safety issues involving molten nitrate salts and other heat transfer fluids, such as synthetic heat transfer oils, and the impact of these issues on the system design.
Date: August 14, 2000
Creator: ST.LAURENT,STEVEN J.
Partner: UNT Libraries Government Documents Department

Performance of the Solar Two central receiver power plant

Description: Solar Two is a utility-led project to promote the commercialization of solar power towers by retrofitting the Solar One pilot plant from a water/steam-based system to a molten salt system. Solar Two is capable of producing 10 MW(e) net electricity with enough thermal storage capacity to operate the turbine for three hours after sunset. The plant was turned over to its operations and maintenance contractor in February 1998, marking transition from start-up to the test and evaluation phase. Solar Two has collected as much as 230 MWh thermal and generated as much as 72 MWh(e) gross electricity in one day. The plant has demonstrated dispatchability after dark, during clouds, and during sunshine hours. To date, Solar Two has collected thermal energy at a maximum rate of 39 MW(t) and generated gross electricity at a maximum rate of 11.1 MW(e). Important lessons have been learned in the areas of heat trace, valve selection, materials of construction, and steam generator design. Testing has begun in a number of areas relating to receiver performance, storage tank performance, salt chemistry, overnight thermal conditioning, electricity dispatching, performance monitoring and evaluation, availability tracking, and receiver controls.
Date: September 1, 1998
Creator: Prairie, M.R.; Pacheco, J.E.; Gilbert, R.L.; Reilly, H.E.; Speidel, P.J. & Kelly, B.D.
Partner: UNT Libraries Government Documents Department

Thermal Energy Storage for the Small Packaged Terminal Air Conditioning Unit. Quarterly progress report, February 2000

Description: To finalize the IceBear design for full-scale production, build two preproduction prototypes, and confirm cost projections for production and market analysis. The 5 tasks being carried out are: Task 1--Finalize thermal energy storage tank design; Task 2--Finalize internal heat exchanger; Task 3--Finalize refrigerant management and control components; Task 4--Preproduction prototype laboratory testing; and Task 5--Reporting.
Date: February 1, 2000
Partner: UNT Libraries Government Documents Department

Aquifer thermal energy storage. International symposium: Proceedings

Description: Aquifers have been used to store large quantities of thermal energy to supply process cooling, space cooling, space heating, and ventilation air preheating, and can be used with or without heat pumps. Aquifers are used as energy sinks and sources when supply and demand for energy do not coincide. Aquifer thermal energy storage may be used on a short-term or long-term basis; as the sole source of energy or as a partial storage; at a temperature useful for direct application or needing upgrade. The sources of energy used for aquifer storage are ambient air, usually cold winter air; waste or by-product energy; and renewable energy such as solar. The present technical, financial and environmental status of ATES is promising. Numerous projects are operating and under development in several countries. These projects are listed and results from Canada and elsewhere are used to illustrate the present status of ATES. Technical obstacles have been addressed and have largely been overcome. Cold storage in aquifers can be seen as a standard design option in the near future as it presently is in some countries. The cost-effectiveness of aquifer thermal energy storage is based on the capital cost avoidance of conventional chilling equipment and energy savings. ATES is one of many developments in energy efficient building technology and its success depends on relating it to important building market and environmental trends. This paper attempts to provide guidance for the future implementation of ATES. Individual projects have been processed separately for entry onto the Department of Energy databases.
Date: May 1, 1995
Partner: UNT Libraries Government Documents Department

Thermophysical properties and behavioral characteristics of phase-change materials

Description: The primary and near-term objective of the project is to compile a handbook of compounds and mixtures that melt in the range of 90 to 250/sup 0/C and which are suitable for isothermal heat storage. Organic compounds have been screened according to bulk price, thermal stability, and safety. Compounds were selected for further consideration if they cost less than $1.10/kg and if encyclopedia articles or handbooks indicated that they were reasonably stable chemically and were not toxic or otherwise hazardous. Of seven compounds thus selected, four (urea, phthalimide, adipic acid, phthalic anhydride) have been examined by DSC and other methods. The differential scanning calorimeter was used with two fairly well-characterized PCM's to test its applicability for rapidly evaluating thermal decomposition and supercooling. With Na/sub 2/SO/sub 4/ . 10H/sub 2/O, DSC data indicated (a) decrease in heat of transition with thermal cycling, and (b) considerable supercooling; with 3 to 6 percent borax added, supercooling was greatly lessened but not entirely eliminated. Measurements with paraffin wax showed that this material does not supercool nor does it degrade in thermal performance with cycling. The DSC results with these two materials confirmed (and extended) thermal performance characteristics obtained by other means. However, studies of supercooling in urea and in phthalimide suggested that DSC techniques may magnify the extent of supercooling at elevated temperatures.
Date: January 1, 1977
Creator: Cantor, S
Partner: UNT Libraries Government Documents Department

Third international workshop on ice storage for cooling applications

Description: The third international workshop on ice storage for cooling applications which was informal and interactive in nature, was open to persons interested in all ice-growing technologies and in ice storage, both seasonal and diurnal. Presentations were made on some 20 topics, ranging from freezers in Alaska to ice cooling of commercial jet aircraft. Workshop tours included visits to ice-storage systems at Commonwealth Edison's facilities in Bolingbrook and Des Plaines Valley, the A.C. Neilsen builing in Northbrook, and the new State of Illinois Center in Chicago. The first workshop in the present series considered the future of ice storage and predicted applications in the agricultural sector, desalinization, and commercial ice production. Progress has been rapid in the intervening two years, and an important topic at the third workshop was the possible use of ''warm ices'' (clathrate hydrates) for energy storage. This report consists primarily of abstracts of presentations made at the workshop. Persons wishing to obtain further information about particular papers should contact the speakers directly; speakers' addresses and telephone numbers are listed in this report.
Date: April 1, 1986
Creator: Gorski, A.J. (comp.)
Partner: UNT Libraries Government Documents Department

Commercialization of aquifer thermal energy storage technology

Description: Pacific Northwest Laboratory (PNL) conducted this study for the US Department of Energy's (DOE) Office of Energy Storage and Distribution. The purpose of the study was to develop and screen a list of potential entry market applications for aquifer thermal energy storage (ATES). Several initial screening criteria were used to identify promising ATES applications. These include the existence of an energy availability/usage mismatch, the existence of many similar applications or commercial sites, the ability to utilize proven technology, the type of location, market characteristics, the size of and access to capital investment, and the number of decision makers involved. The in-depth analysis identified several additional screening criteria to consider in the selection of an entry market application. This analysis revealed that the best initial applications for ATES are those where reliability is acceptable, and relatively high temperatures are allowable. Although chill storage was the primary focus of this study, applications that are good candidates for heat ATES were also of special interest. 11 refs., 3 tabs.
Date: September 1, 1989
Creator: Hattrup, M.P. & Weijo, R.O.
Partner: UNT Libraries Government Documents Department

Thermal energy storage for building heating and cooling applications. Quarterly progress report, April--June 1976

Description: This is the first in a series of quarterly progress reports covering activities at ORNL to develop thermal energy storage (TES) technology applicable to building heating and cooling. Studies to be carried out will emphasize latent heat storage in that sensible heat storage is held to be an essentially existing technology. Development of a time-dependent analytical model of a TES system charged with a phase-change material was started. A report on TES subsystems for application to solar energy sources is nearing completion. Studies into the physical chemistry of TES materials were initiated. Preliminary data were obtained on the melt-freeze cycle behavior and viscosities of sodium thiosulfate pentahydrate and a mixture of Glauber's salt and Borax; limited melt-freeze data were obtained on two paraffin waxes. A subcontract was signed with Monsanto Research Corporation for studies on form-stable crystalline polymer pellets for TES; subcontracts are being negotiated with four other organizations (Clemson University, Dow Chemical Company, Franklin Institute, and Suntek Research Associates). Review of 10 of 13 unsolicited proposals received was completed by the end of June 1976.
Date: November 1, 1976
Creator: Hoffman, H. W. & Kedl, R. J.
Partner: UNT Libraries Government Documents Department

Optimizing the design and operation of aquifer thermal energy systems

Description: The design of Aquifer Thermal Energy Storage (ATES) systems is complicated by significant uncertainties in ones ability to reliably predict the response of the aquifer to fluid and thermal fluxes. Overdesigning the system, to compensate for these uncertainties, reduces the potential economic and energy benefits of an ATES system. Underdesigning the system results in systems that fail to meet design targets. Unfortunately, standard aquifer characterization methods and hydrologic models do not provide adequate information to overcome these uncertainties. Thus, expensive full-scale tests are generally recommended to develop an adequate-understanding of the systems response. However, the standard engineering {open_quotes}design-build-operate{close_quotes} process is not. appropriate for ATES systems because an optimal design cannot be completed without some operational experience, i.e., field tests. A more adaptive engineering process is required. This engineering process should be flexible enough to allow the design to be adjusted during the operation, as monitoring data become available and as an understanding of the system response increases. Engineering approaches being developed for environmental restoration of contaminated soil and groundwater can be adapted to optimally design and operate ATES systems.
Date: November 1, 1994
Creator: Vail, L. W. & Jenne, E. A.
Partner: UNT Libraries Government Documents Department

Developing, testing, evaluating and optimizing solar heating systems. Project status report for October and November 1996

Description: This report describes progress on 3 projects: Integrated tank/heat exchanger modeling and experiments for solar thermal storage; Advanced residential solar domestic hot water systems; and Incident angle modifiers (IAMs) by the Monte Carlo method for cylindrical solar collectors. IAMs are used to correct for effects such as shading, back plane reflectance, inter-reflection, etc. Summaries are given for the first two projects; however, a full draft report is given for the third.
Date: January 1, 1997
Partner: UNT Libraries Government Documents Department

Applications of cogeneration with thermal energy storage technologies

Description: The Pacific Northwest Laboratory (PNL) leads the U.S. Department of Energy`s Thermal Energy Storage (TES) Program. The program focuses on developing TES for daily cycling (diurnal storage), annual cycling (seasonal storage), and utility-scale applications [utility thermal energy storage (UTES)]. Several of these storage technologies can be used in a new or an existing power generation facility to increase its efficiency and promote the use of the TES technology within the utility and the industrial sectors. The UTES project has included a study of both heat storage and cool storage systems for different utility-scale applications. The study reported here has shown that an oil/rock diurnal TES system, when integrated with a simple gas turbine cogeneration system, can produce on-peak power for $0.045 to $0.06 /kWh, while supplying a 24-hour process steam load. The molten salt storage system was found to be less suitable for simple as well as combined-cycle cogeneration applications. However, certain advanced TES concepts and storage media could substantially improve the performance and economic benefits. In related study of a chill TES system was evaluated for precooling gas turbine inlet air, which showed that an ice storage system could be used to effectively increase the peak generating capacity of gas turbines when operating in hot ambient conditions.
Date: March 1, 1995
Creator: Somasundaram, S.; Katipamula, S. & Williams, H.R.
Partner: UNT Libraries Government Documents Department

Automatic control of electric thermal storage (heat) under real-time pricing. Final report

Description: Real-time pricing (RTP) can be used by electric utilities as a control signal for responsive demand-side management (DSM) programs. Electric thermal storage (ETS) systems in buildings provide the inherent flexibility needed to take advantage of variations in prices. Under RTP, optimal performance for ETS operations is achieved under market conditions where reductions in customers` costs coincide with the lowering of the cost of service for electric utilities. The RTP signal conveys the time-varying actual marginal cost of the electric service to customers. The RTP rate is a combination of various cost components, including marginal generation fuel and maintenance costs, marginal costs of transmission and distribution losses, and marginal quality of supply and transmission costs. This report describes the results of an experiment in automatic control of heat storage systems under RTP during the winter seasons of 1989--90 and 1990--91.
Date: January 1, 1995
Creator: Daryanian, B.; Tabors, R.D. & Bohn, R.E.
Partner: UNT Libraries Government Documents Department

Ice slurry cooling research: Storage tank ice agglomeration and extraction

Description: A new facility has been built to conduct research and development on important issues related to implementing ice slurry cooling technology. Ongoing studies are generating important information on the factors that influence ice particle agglomeration in ice slurry storage tanks. The studies are also addressing the development of methods to minimize and monitor agglomeration and improve the efficiency and controllability of tank extraction of slurry for distribution to cooling loads. These engineering issues impede the utilization of the ice slurry cooling concept that has been under development by various groups.
Date: August 1, 1999
Creator: Kasza, K. & Hayashi, Kanetoshi
Partner: UNT Libraries Government Documents Department

Solar dynamic heat pipe development and endurance test. Monthly technical progress report number 6, 29 October--November 30, 1987

Description: The Space Station requires a high level of reliable electric power. The baseline approach is to utilize a hybrid system in which power is provided by photovoltaic arrays and by solar dynamic power conversion modules. The organic Rankine cycle (ORC) engine is one approach to solar dynamic conversion. The ORO provides the attributes of high efficiency at low temperature and compact simple designs utilizing conventional techniques and materials. The heat receiver is one area which must be addressed in applying the proven ORC to long life applications such as the Space Station. Heat pipes with integral thermal energy storage (TES) canisters and a toluene heater tube are the prime components of the heat receiver from the Phase B preliminary design. This contract is a task order type addressing the design, fabrication and testing of a full scale heat pipe. The contract was initiated on April 16, 1987. Sundstrand has specific responsibilities in each task. Los Alamos National Laboratory (LANL) in turn has the prime contract responsibility to NASA-LeRC.
Date: December 7, 1987
Creator: Parekh, M.B.
Partner: UNT Libraries Government Documents Department

Solar dynamic heat pipe development and endurance test. Monthly technical progress report number 5, 30 September--28 October, 1987

Description: The Space Station requires a high level of reliable electric power. The baseline approach is to utilize a hybrid system in which power is provided by photovoltaic arrays and by solar dynamic power conversion modules. The organic Rankine cycle (ORC) engine is one approach to solar dynamic conversion. The ORC provides the attributes of high efficiency at low temperature and compact simple designs utilizing conventional techniques and materials. The heat receiver is one area which must be addressed in applying the proven ORC to long life applications such as the Space Station. Heat pipes with integral thermal energy storage (TES) canisters and a toluene heater tube are the prime components of the heat receiver from the Phase B preliminary design. This contract is a task order type addressing the design, fabrication and testing of a full scale heat pipe. The contract was initiated on April 16, 1987. Sundstrand has specific responsibilities in each task. Los Alamos National Laboratory (LANL) in turn has the prime contract responsibility to NASA-LeRC.
Date: October 28, 1987
Creator: Parekh, M.B.
Partner: UNT Libraries Government Documents Department

Importance of energy efficiency in the design of the Process and Environmental Technology Laboratory (PETL) at Sandia National Laboratories, New Mexico (NM)

Description: As part of the design of the Process and Environmental Technology Laboratory (PETL) in FY97, an energy conservation report (ECR) was completed. The original energy baseline for the building, established in Title 1 design, was 595,000 BTU/sq. ft./yr, site energy use. Following the input of several reviewers and the incorporation of the various recommendations into the Title 2 design, the projected energy consumption was reduced to 341,000 BTU/sq. ft./yr. Of this reduction, it is estimated that about 150,000 BTU/sq. ft./yr resulted from inclusion of more energy efficient options into the design. The remaining reductions resulted from better accounting of energy consumption between Title 1 ECR and the final ECR. The energy efficient features selected by the outcome of the ECR were: (1) Energy Recovery system, with evaporative cooling assist, for the Exhaust/Make-up Air System; (2) Chilled Water Thermal Storage system; (3) Premium efficiency motors for large, year-round applications; (4) Variable frequency drives for all air handling fan motors; (4) Premium efficiency multiple boiler system; and (5) Lighting control system. The annual energy cost savings due to these measures will be about $165,000. The estimated annual energy savings are two million kWhrs electric, and 168,000 therms natural gas, the total of which is equivalent to 23,000 million BTUs per year. Put into the perspective of a typical office/light lab at SNL/NM, the annual energy savings is equal the consumption of a 125,000 square foot building. The reduced air emissions are approximately 2,500 tons annually.
Date: June 1, 1998
Creator: Wrons, R.
Partner: UNT Libraries Government Documents Department

Solar dynamic heat pipe development and endurance test. Monthly technical progress report number 4, August 28--September 29, 1987

Description: The Space Station requires a high level of reliable electric power. The baseline approach is to utilize a hybrid system in which power is provided by photovoltaic arrays and by solar dynamic power conversion modules. The organic Rankine cycle (ORC) engine is one approach to solar dynamic conversion. The ORC provides the attributes of high efficiency at low temperature and compact simple designs utilizing conventional techniques and materials. The heat receiver is one area which must be addressed in applying the proven ORC to long life applications such as the Space Station. Heat pipes with integral thermal energy storage (TES) canisters and a toluene heater tube are the prime components of the heat receiver from the Phase B preliminary design. This contract is a task order type addressing the design, fabrication and testing of a full scale heat pipe. The contract was initiated on April 16, 1987. Sundstrand has specific responsibilities in each task. Los Alamos National Laboratory (LANL) in turn has the prime contract responsibility to NASA-LeRC.
Date: September 29, 1987
Creator: Parekh, M.B.
Partner: UNT Libraries Government Documents Department

Solar power tower development: Recent experiences

Description: Recent experiences with the 10 MW{sub e} Solar Two and the 2.5 MW{sub t} TSA (Technology Program Solar Air Receiver) demonstration plants are reported. The heat transfer fluids used in these solar power towers are molten-nitrate salt and atmospheric air, respectively. Lessons learned and suggested technology improvements for next-generation plants are categorized according to subsystem. The next steps to be taken in the commercialization process for each these new power plant technologies is also presented.
Date: December 1, 1996
Creator: Tyner, C.; Kolb, G. & Prairie, M.
Partner: UNT Libraries Government Documents Department

Ice slurry cooling research: Microscale study of ice particles characteristics, role of freezing point depressant, and influence on slurry fluidity

Description: The influences of freezing-point-depressants on ice slurry characteristics in the form of ice slurry fluidity and on the microscale ice particle features are studied. The results identify microscale features of ice particles such as surface roughness that greatly influence slurry fluidity that are altered favorably by the use of a freezing point depressant. The engineering of a workable and efficient ice slurry cooling system depends very strongly on the characteristics of the individual ice particles in the slurry and, in turn, on the method of ice production. Findings from this study provide guidance on the fluidity and handleability of slurry produced by several methods currently under development and already many achieved.
Date: May 3, 2000
Creator: Hayashi, K. & Kasza, K.
Partner: UNT Libraries Government Documents Department

Tomorrow`s energy today for cities and counties - keep it cool with thermal energy storage

Description: Cool thermal energy storage (TES) is described as a means for electric utilities to provide electricity from off-peak times, particularly in the summer when air-conditioning accounts for 50% or more of electricity consumption. Cool TES uses off-peak power to provide cooling capacity by extracting heat from a storage medium such as ice or other phase change material. A refrigeration system may may be utilized at night to provide a reservoir of cold material. During the day, the reservoir is tapped to provide cooling capacity. The advantages of TES are discussed.
Date: July 1, 1995
Partner: UNT Libraries Government Documents Department

Site-specific investigations of aquifer thermal energy storage for space and process cooling

Description: The Pacific Northwest Laboratory (PNL) has completed three preliminary site-specific feasibility studies that investigated using aquifer thermal energy storage (ATES) to reduce space and process cooling costs. Chilled water stored in an ATES system could be used to meet all or part of the process and/or space cooling loads at the three facilities investigated. The work was sponsored by the US Department of Energy's (DOE) Office of Energy Management. The ultimate goal of DOE's Thermal Energy Storage Program is to successfully transfer ATES technology to industrial and commercial sectors. The primary objective of this study was to identify prospective sites and determine the technical and economic feasibility of implementing chill ATES technology. A secondary objective was to identify site-specific factors promoting or inhibiting the application of chill ATES technology so that other potentially attractive sites could be more easily identified and evaluated. A preliminary investigation of the feasibility of commercializing chill ATES in automotive assembly facilities was completed. The results suggested that automotive assembly facilities was completed. The results suggested that automotive assembly facilities represent a good entry market for chill ATES, if the system is cost-effective. As a result, this study was undertaken to identify and evaluate prospective chill ATES applications in the automotive industry. The balance of the report contains two main sections. Section 2.0 describes the site identification process. Site feasibility is addressed in Section 3.0. Overall study conclusions and recommendations are than presented in Section 4.0.
Date: August 1, 1991
Creator: Brown, D R; Hattrup, M P & Watts, R L
Partner: UNT Libraries Government Documents Department

Summary of seasonal thermal energy storage field test projects in the United States

Description: Seasonal thermal energy storage (STES) involves storage of available heat or chill for distribution at a later time to meet thermal loads. STES can reduce energy consumption, peak energy demand, and emissions of carbon dioxide to the atmosphere over conventional systems. It is estimated that full-scale application of STES would provide 2% to 4% of total energy needs in the United States. One STES technology, aquifer thermal energy storage (ATES), has been determined to be the most cost-effective option in the United States when site conditions enable its use. ATES has been analyzed in the laboratory and investigated in the field in the United States since the program was established at Pacific Northwest Laboratory (PNL) in 1979. Two field test facilities (FTFs), one for heating ATES at the University of Minnesota and the other for cooling ATES at the University of Alabama, have been primary testing grounds for US ATES research. Computer models have been developed to analyze the complex thermal and fluid dynamics. Extensive monitoring of FTFs has provided verification of and refinements to the computer models. The areas of geochemistry and microbiology have been explored as they apply to the aquifer environment. In general, the two FTFs have been successful in demonstrating the steps needed to make an ATES system operational.
Date: July 1, 1989
Creator: Johnson, B.K.
Partner: UNT Libraries Government Documents Department