Gregory Kolb

Sandia National Laboratories · National Solar Thermal Test Facility

Greg Kolb was a systems engineer at Sandia National Laboratories from 1978 to 2011. Most of that time was devoted to the R&D of large concentrating solar power (CSP) plants, including projects that significantly reduced the operating costs at the 150 MW Kramer Junction solar trough plant, as well as the construction and operation of the 10 MW Solar...

This chapter provides key highlights of the Concentrating Solar Power Best Practices Study, published in 2020 by the National Renewable Energy Laboratory (Mehos et al., 2020). Focusing on parabolic trough and central receiver concentrating solar power (CSP) plants, the study gathered, categorized, and ranked issues encountered by a group of stakeho...

There are currently 90 operational CSP plants of 10 MW or larger located throughout the world, primarily in Spain, U.S., MENA region, South Africa, and China. In 2018, the U.S. Department of Energy (DOE) funded Solar Dynamics, under subcontract to NREL, to investigate and document lessons learned and best practices associated with the construction,...

The primary objective of this Concentrating Solar Power Best Practices Study is to publish best practices and lessons learned from the engineering, construction, commissioning, operations, and maintenance of existing concentrating solar power (CSP) parabolic trough and power tower systems. To accomplish this objective, information was solicited fro...

https://www.osti.gov/scitech/servlets/purl/1106681

Various technologies described herein pertain to evaluating a beam reflected by a heliostat. A portable target that has an array of sensors mounted thereupon is configured to capture the beam reflected by the heliostat. The sensors in the array output measured values indicative of a characteristic of the beam reflected by the heliostat. Moreover, a...

A suction-recirculation device is described for stabilizing the flow of a curtain of blackened heat absorption particles falling blackened particles falling inside of a solar receiver with an open aperture. External winds entering the receiver can destabilize the flow and cause particle loss through the aperture. This device prevents particle loss...

Due to the high capacity of solar thermal power plants (50 MWel and more) and large required investment, concentrating solar power (CSP) projects are subject to an extensive project development process. Predicting the energy yield of a CSP plant is a crucial task in this process. Mathematical models predicting the system’s energy yield are required...

Direct-absorption solid particle receivers are theoretically capable of yielding temperatures in excess of 1000°C, which enables higher efficiency power cycles and lower thermal storage costs. This paper presents rigorous CFD simulations of alternative solid particle receiver designs with recirculation to help identify optimal configurations that m...

A study was performed to compare the annual performance of 50 MW(e) Andasol-like trough plants that employ either a 2-tank or a thermocline-type molten-salt thermal storage system. TRNSYS software was used to create the plant models and to perform the annual simulations. The annual performance of each plant was found to be nearly identical in the b...

Probabilistic modeling of concentrating solar power technologies provides important information regarding uncertainties and sensitivities not available from deterministic models. Benefits of using probabilistic models include quantification of uncertainties inherent in the system and characterization of their impact on system performance and econom...

Hydrogen demand has already significantly increased due to the industry needs. Mature technologies based on fossil fuels are not satisfactory due to greenhouse gas concerns. In response, a range of advanced processes are being developed throughout the world. Within the "International Energy Agency - Hydrogen Implementing Agreement - Task 25", a mu...

Since completion of the Solar Two molten-salt power tower demonstration in 1999, the solar industry has been developing initial commercial-scale projects that are 3 to 14 times larger. Like Solar Two, these initial plants will power subcritical steam-Rankine cycles using molten salt with a temperature of 565 C. The main question explored in this st...

The collector aperture and diameter of the receiver of a parabolic trough were studied to investigate the relative impacts of parasitic pressure drop, heat losses, and heat flux intercepted by the receiver tube. The configuration of an LS-2 parabolic trough was used as the baseline, and the size of the HCE and collector aperture were parametrically...

NREL's Solar Advisor Model (SAM) is employed to estimate the current and future costs for parabolic trough and molten salt power towers in the US market. Future troughs are assumed to achieve higher field temperatures via the successful deployment of low melting-point, molten-salt heat transfer fluids by 2015-2020. Similarly, it is assumed that mol...

Recent studies in the United States suggest that parabolic trough levelized energy costs (LECs) can be reduced 10-15% through integration of a large salt energy storage system coupled with the direct heating of molten salt in the solar field. While noteworthy, this relatively small predicted improvement may not justify the increased technical risks...

A method for applying probabilistic models to concentrating solar thermal power plants is described in this paper. Benefits of using probabilistic models include quantification of uncertainties inherent in the system and characterization of their impact on system performance and economics. Sensitivity studies using stepwise regression analysis can...

Through the International Energy Agency organisation, CEA proposed to the Hydrogen Implement Agreement (HIA) Executive Committee that an expert group be set up to address the definition of the high temperature hydrogen production processes running either with a solar or a nuclear heat source. This project was accepted and referenced as Task No 25....

Several studies predict an economic benefit of using nitrate-based salts instead of the current synthetic oil within a solar parabolic trough field. However, the expected economic benefit can only be realized if the reliability and optical performance of the salt trough system is comparable to today's oil trough. Of primary concern is whether a sal...

A prototype direct absorption central receiver, called the solid particle receiver (SPR), was built and evaluated on-sun at power levels up to 2.5 MW(th) at Sandia National Laboratories in Albuquerque, NM. The SPR consists of a 6 m tall cavity through which spherical sintered bauxite particles are dropped and directly heated with concentrated solar...

The solid particle receiver (SPR) is a direct absorption central receiver that can provide a solar interface with thermal storage for thermo-chemical hydrogen production processes requiring heat input at temperatures up to 1000°C. In operation, a curtain made up of approximately 697μm ceramic particles is dropped within the receiver cavity and dire...

Concentrating solar power (CSP) technologies continue to mature and are being deployed worldwide. Power towers will likely play an essential role in the future development of CSP due to their potential to provide dispatchable solar electricity at a low cost. This Power Tower Technology Roadmap has been developed by the U.S. Department of Energy (DO...

Concentrating solar power (CSP) technologies continue to mature and are being deployed worldwide. Power towers will likely play an essential role in the future development of CSP due to their potential to provide dispatchable solar electricity at a low cost. This Power Tower Technology Roadmap has been developed by the U.S. Department of Energy (DO...

The solid particle receiver (SPR) is a direct absorption receiver in which solar energy heats a curtain of falling ceramic particle to a temperature in excess of 1000 °C. A small scale test platform was built to investigate particle flow properties. The curtain was comprised of approximately 697 μm ceramic particles that were dropped within the rec...

The wind conditions affect the performance of a solid particle solar receiver (SPSR) by convection heat transfer through the existing open aperture. Aerowindows have the potential of increasing the efficiency of an SPSR. In the present paper, the wind effect on the performance of an SPSR is investigated numerically with and without the protection o...

Solid particle receivers have the potential to provide high-temperature heat for advanced power cycles, thermochemical processes, and thermal storage via direct particle absorption of concentrated solar energy. This paper presents two different models to evaluate the performance of these systems. One model is a detailed computational fluid dynamics...

Recent studies in the United States suggest that parabolic trough levelized energy costs (LEC) can be reduced 10-to-15% through integration of a large salt energy storage system coupled with the direct heating of molten salt in the solar field. While noteworthy, this relatively small predicted improvement may not justify the increased technical ris...

A prototype direct absorption central receiver, called the solid particle receiver (SPR), was recently built and tested on-sun at Sandia National Laboratories. The SPR consists of a 6 m tall cavity through which a 1 m wide curtain of spherical ceramic particles is dropped and directly heated with concentrated solar energy. The focus of this current...

Solar power towers can be used to make hydrogen on a large scale. Electrolyzers could be used to convert solar electricity produced by the power tower to hydrogen, but this process is relatively inefficient. Rather, efficiency can be much improved if solar heat is directly converted to hydrogen via a thermochemical process. In the research summariz...

Power towers are capable of producing solar- generated electricity and hydrogen on a large scale. Heliostats are the most important cost element of a solar power tower plant. Since they constitute ~50% to the capital cost of the plant it is important to reduce the cost of heliostats as much as possible to improve the economic viability of power tow...

Power towers are capable of producing solar-generated electricity and hydrogen on a large scale. Heliostats are the most important cost element of a solar power tower plant. Since they constitute â 50% of the capital cost of the plant it is important to reduce heliostat cost as much as possible to improve the economic performance of power towers. I...

Solar thermo-chemical processes often require high temperatures that can be achieved by direct absorption of solar energy. The solid particle solar receiver can be used to heat ceramic particles that may serve as a heat transfer and storage medium or as a substrate on which chemical reaction may be performed directly. Using solid particles enclosed...

The solid particle receiver (SPR) is a direct absorption central receiver that can provide a solar interface with thermal storage for thermochemical hydrogen production processes requiring heat input at temperatures up to 1000 C. In operation, a curtain consisting of ∼690 μm ceramic particles is dropped within the receiver cavity and directly illum...

The 1 MW Saguaro solar parabolic trough power plant began operation in December 2005. The plant will initially operate without an energy storage system. However, recent studies predict a thermocline-type storage should be the most cost-effective storage concept for solar parabolic troughs power plants. If such a system can be successfully demonstra...

The goals of the DOD-solar study were to identify potentially economic solar-energy projects on specific military bases and to define the necessary steps to install solar projects in the near term. Five classes of mature solar technologies were investigated: crystalline photovoltaics, solar hot water, transpired collectors (solar wall), pool heater...

Solar Two was a collaborative, cost-shared project between 11 U. S. industry and utility partners and the U. S. Department of Energy to validate molten-salt power tower technology. The Solar Two plant, located east of Barstow, CA, comprised 1926 heliostats, a receiver, a thermal storage system, a steam generation system, and steam-turbine power blo...

This report utilizes the results of the Solar Two project, as well as continuing technology development, to update the technical and economic status of molten-salt power towers. The report starts with an overview of power tower technology, including the progression from Solar One to the Solar Two project. This discussion is followed by a review of...

Solar power towers, based on molten salt technology, have been the subject of extensive research and development since the late 1970s. In the mid 1980s, small experimental plants were successfully fielded in the USA and France that demonstrated the feasibility of the concept at a 1 to 2 MW{sub e} scale. Systems analyses indicate this technology wil...

This report describes the results of a six-year, $6.3 million project to reduce operation and maintenance (O&M) costs at power plants employing concentrating solar power (CSP) technology. Sandia National Laboratories teamed with KJC Operating Company to implement the O&M Improvement Program. O&M technologies developed during the course of the progr...

In October, 1995, the concept of the START Mission (START stands for Solar Thermal Analysis, Review and Training) was developed. The goal of these Missions is to help nations in the above mentioned regions develop a rational approach to the deployment of solar thermal electric systems within their country. Each Mission means the concentrated joint...

Research and development activities sponsored by countries within the International Energy Agency's solar thermal working group, SolarPACES (Solar Power and Chemical Energy Systems), have helped reduce the cost of solar thermal systems to one-fifth that of the early pilot plants. Continued technological improvements are currently being proven in ne...

At the request of USA sponsors Spencer Management Associates (SMA) and Sun♦Lab, China's Center for Renewable Energy Development and former Ministry of Electric Power conducted an initial appraisal of the issues involved with developing China's first solar thermal electric power plant in the sunbelt regions of Tibet or Xinjiang provinces. The apprai...

Several hybrid and solar-only configurations for molten-salt power towers were evaluated with a simple economic model, appropriate for screening analysis. The solar-specific aspects of these plants were highlighted. In general, hybrid power towers were shown to be economically superior to solar-only plants with the same field size. Furthermore, the...

Solar thermal power is produced by three types of concentrating systems, which utilize parabolic troughs, dishes, and heliostats as the solar concentrators. These systems are at various levels of development and commercialization in the United States and in Europe. The U.S. Industry is currently developing these systems for export at the end of thi...

Solar power towers offer the only source of utility-scale solar electricity with cost-effective thermal energy storage. This is achieved most effectively using molten nitrate salt as the energy storage and heat transfer medium. Other options exist, e.g., liquid sodium or air with ceramic storage, but are either less developed, less efficient, or mo...

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...

The five Solar Electric Generating Systems (SEGS) at Kramer Junction, California, now have nearly 30 years of cumulative operating experience. These 30 MW plants employ parabolic trough technology originally deployed by LUZ International in the late 1980`s and are now managed, operated and maintained by the Kramer Junction Company. In this paper, S...

A SEGS LS-2 parabolic trough solar collector was tested to determine the collector efficiency and thermal losses with two types of receiver selective coatings, combined with three different receiver configurations: glass envelope with either vacuum or air in the receiver annulus, and glass envelope removed from the receiver. As expected, collector...

This article is a look at the status of solar thermal power plant design and application. The topics of the article include US DOE involvement, trough-electric systems as a current alternative to conventional electric power production, and central receiver systems and dish/Stirling systems as alternatives to fossil-fuel power plants within the next...

This paper presents the results of a reliability analysis for a solar central receiver power plant that employs a salt-in-tube receiver. Because reliability data for a number of critical plant components have only recently been collected, this is the first time a credible analysis can be performed. This type of power plant will be built by a consor...

The Solar One Pilot Plant successfully demonstrated the feasibility of generating electricity with a solar central receiver power plant. During the six years the plant was operated, a great deal of data was collected relating to the efficiency and availability of the plant's various systems. This paper summarizes these statistics and compares them...

A control algorithm is proposed for a molten-salt solar central receiver in a cylindrical configuration. The algorithm simultaneously regulates the receiver outlet temperature and limits thermal-fatigue damage of the receiver tubes to acceptable levels. The algorithm is similar to one that was successfully tested for a receiver in a cavity configur...

For 15 years, the United States Department of Energy has worked with industry, both utilities and manufacturers, to develop the technology of solar central receiver power plants. In this type of plant, sunlight is concentrated by a field of sun-tracking mirrors, called heliostats, onto a centrally located receiver. The solar energy is collected in...

Treating carbon fibers with solar flux was thought to improve the oxidation resistance of carbon fibers. This report examines the empirical evidence.

Currently, over 90% of the world's large-scale solar electric energy is generated with concentrating solar thermal power plants. Such plants have the potential to meet many of the world's future energy needs. Research efforts are generally focused on generating electricity, though a variety of other applications are being pursued. Today, the techno...

The 10-MW{sub e} Solar One Pilot Plant was the world's largest solar central receiver power plant. During its power production years it delivered over 37,000 MWhrs (net) to the utility grid. In this type of electric power generating plant, large sun-tracking mirrors called heliostats reflect and concentrate sunlight onto a receiver mounted on top a...

The cost and performance of treating materials with a solar furnace were compared to similar treatment with high-intensity electric-arc lamps. Qualitative results indicate that because of the long focal length of the solar furnace, it is capable of performing much dirtier materials processing tasks than the arc lamp. Quantitative results indicate t...

The Direct Absorption Receiver (DAR) concept was proposed in the mid-1970s as an alternative advanced receiver concept to simplify and reduce the cost of solar central receiver systems. Rather than flowing through tubes exposed to the concentrated solar flux, the heat absorbing fluid (molten nitrate salt) would flow in a thin film down a flat, near...

This paper presents the results of a reliability analysis for a solar central receiver power plant that employs a salt-in-tube receiver. Because reliability data for a number of critical plant components have only recently been collected, this is the first time a credible analysis can be performed. The power plant design analyzed was similar to the...

The Solar One Pilot Plant successfully demonstrated the feasibility of solar central receiver power plants. During its operating years many data were collected regarding the efficiency and availability of the various plant systems. The author summarizes these statistics and compares them with goals developed by the Department of Energy. On the basi...

A dynamic simulation model of the solar subsystem of a molten-salt-in-tube central receiver power plant was constructed. It consists of 132 ordinary differential equations and is programmed in the system simulation language. The model was validated with experimental data obtained at the Central Receiver Test Facility and was shown to accurately pre...

Solar One is the world's largest central receiver power plant. During the last 4 years the plant availability was 80%, 83%, and 96%, respectively, during hours of sunshine. This reliability is considered to be excellent considering the plant is a first-of-a-kind facility and because it has been subjected to daily cyclic service. In this paper we pr...

The SOLERGY computer code is a valuable tool for the commercialization of solar central receiver power plants. SOLERGY predicts the annual energy produced by a plant and can be used in design optimization studies to evaluate alternative plant designs or operating strategies. This report validates SOLERGY by comparing its prediction of annual energy...

The molton salt thermal storage system located at the Central Receiver Test Facility (CRTF) was recently subjected to thermal performance tests. The system is composed of a hot storage tank containing molten nitrate salt at a temperature of 1050 F and a cold tank containing 550 F salt with associated valves and controls. It is rated at 7 MWht and w...

The Solar Two Project was a United States Department of Energy sponsored project operated from 1996 to 1999 to demonstrate the coupling of a solar power tower with a molten nitrate salt as a heat transfer media and for thermal storage. Over all, the Solar Two Project was very successful; however many operational challenges were encountered. In this...

The Interim Reliability Evaluation Program (IREP) was designed to develop and implement improved methods of PRA systems analysis. The methods were used to analyze four plants, two PWRs and two BWRs (Arkansas Nuclear One Unit 1, Calvert Cliffs Unit 1, Browns Ferry Unit 1 and Millstone Unit 1). This paper presents a review of the methodology improvem...

The power production phase at Solar One spanned three years from August 1, 1984 through July 31, 1987. In that period the plant achieved an average availability, during hours of sunshine, of 81.7%. This report presents the frequencies and causes of the plant outages that occurred. The eleven most important causes composed 75% of the total outage ti...

In this report, a sensitivity analysis was performed to evaluate the effect that three operations and control room improvements have on the core melt frequency estimated for the Arkansas Nuclear One-Unit 1 (ANO-1) nuclear power plant. The three improvements evaluated were (1) installation of a safety parameter display system, (2) installation of a...

The Central Receiver Test Facility was designed and constructed to serve as a test-bed for advanced solar receiver system concepts. In its current configuration, it consists of a 5 MW solar receiver (2 adjacent panels of 18 passes - 6 tubes per pass) through which molten salt is circulated. The heated salt is pumped to thermal storage from which it...

The concept of a photovoltaic central receiver system has existed for about ten years, but was not seriously considered because of the high cost and marginal quality of the PV cells. Recent breakthroughs in PV cell efficiency and quality coupled with the design of low-cost heliostats has justified reconsideration of the concept. An economic analysi...

A screening analysis was performed to identify concentrating solar power (CSP) concepts that produce hydrogen with the highest efficiency. Several CSP concepts were identified that have the potential to be much more efficient than today's low-temperature electrolysis technology. They combine a central receiver or dish with either a thermochemical c...

A suction-recirculation device for stabilizing the flow of a curtain of blackened heat absorption particles falling inside of a solar receiver with an open aperture. The curtain of particles absorbs the concentrated heat from a solar mirror array reflected up to the receiver on a solar power tower. External winds entering the receiver at an oblique...

Arizona Public Service (APS) is currently installing new power facilities to generate a portion of its electricity from solar resources that will satisfy its obligation under the Arizona Environmental Portfolio Standard (EPS). During FY04, APS began construction on a 1-MWe parabolic trough concentrating solar power plant. This plant represents the...

Thesis (M.S. - Nuclear Engineering)--University of Arizona. Includes bibliographical references.