Hybridizing a geothermal power plant with concentrating solar power and thermal storage to increase power generation and dispatchability

Castro, J. Ramon; Mungas, Greg; Kramer, Nick; King, J. E.; Turchi, Craig; McTigue, Joshua D.

doi:10.1016/j.apenergy.2018.07.064

Cited by 71 publications

(34 citation statements)

References 30 publications

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“…Therefore, it would be more appropriate to undertake further LCOE analysis of other conventional technologies (such as PV arrays with BES, and stand-alone CSP and geothermal plants) using the same assumptions and techniques, to evaluate how the proposed hybrid system compares. Recent work on a hybrid solar-geothermal plant (using double-flash) technology undertook such analysis and indicated that the hybrid system was preferable to PV+BES and to stand-alone CSP plants [11]. Similar conclusions were obtained by Zhou et al for a binary cycle with a steam topping cycle [19].…”

Section: Further Workmentioning

confidence: 54%

“…The quantity of HTF is also reduced and thereby reduces system costs (HTF is the most expensive component in two-tank liquid storage). A previous study indicated that packed beds may be less than half the cost of two-tank liquid storage [11]. However, packed beds have complicated transient behavior and require detailed models to accurately assess the appropriate size and cost.…”

Section: Integrating Thermal Storage With Solar-field Sizing In the Gmentioning

confidence: 99%

“…Further analysis is required to determine whether this cost is feasible. Previous research indicates that values in the range 30-50 $/kWhth are realistic for two-tank liquid storage [11]. Costs could potentially be reduced by using alternative technologies, such as a single tank with a thermocline or solid baffle, or a packed bed.…”

Section: Further Workmentioning

confidence: 99%

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Solar-Driven Steam Topping Cycle for a Binary Geothermal Power Plant

McTigue

Kincaid

Wendt

et al. 2018

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Executive SummaryGreater deployment of moderate-temperature geothermal binary power plants (GBPPs) and concentrating solar power (CSP) can be limited in some markets by their respective generation characteristics and/or levelized cost of electricity (LCOE). Worldwide, both geothermal power and CSP are under intense pressure from the rapidly dropping cost of solar photovoltaic (PV) and wind energy. In the United States, there is further pressure from the ongoing era of low natural gas prices. CSP can generate high-temperature thermal energy that enables high cycle efficiency and low-cost thermal storage systems, and GBPP can produce baseload power generation. Hybridization may take advantage of technical merits of both technologies to produce energy at a levelized cost of energy (LCOE) competitive in the future energy market. New approaches that can lower the LCOE of both geothermal power and concentrating solar can therefore help to increase adoption of both technologies.In this technical report, we explore several methods of combining heat generated by a concentrating solar field with an existing geothermal binary power plant. The Raft River geothermal power plant in southern Idaho operates below its rated capacity because the reservoir is unable to deliver the design flow and temperature of geothermal energy. The GBPP is a twopressure cycle with independent high-pressure and low-pressure isopentane turbines. Solar heat may be added in several ways to this cycle and we perform a screening study and then more detailed calculations for several configurations, including:1. Geothermal production brine directly heated by solar energy; 2. A fraction of geothermal brine extracted from some part of the binary plant, heated with solar energy, and mixed with the production fluids; and3. The addition of a steam topping cycle, the hot exit flow of which is used to:a. Heat brine, as in points 1 and 2, and b. Vaporize the binary-cycle working fluid after the fluid has been preheated by the geothermal brine.The initial screening study was performed on a large number of different cycle configurations at a single operating condition. Subsequently, a more detailed study investigated annual cost and performance. Both the screening study (using one set of modeling software) and the detailed analysis (using another software package) were calibrated against one or more aspects of the Raft River operating condition. The combined results of the screening and detailed study are shown in Table A (although the results from one model should not be compared to those of the other). vii This report is available at no cost from the National Renewable Energy Laboratory at www.nrel.gov/publications.Table A: Comparison of different hybrid plant configurations from the screening study and detailed study. '-' indicates that the configuration was not studied. Design-Point Cycle EfficiencyAnnual Efficiency Cycle and DescriptionScreening StudyDetailed Study Detailed StudyTwo solar steam turbines: Use high-temperature solar steam in two turbines, which...

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Section: Further Workmentioning

confidence: 54%

Section: Integrating Thermal Storage With Solar-field Sizing In the Gmentioning

confidence: 99%

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Solar-Driven Steam Topping Cycle for a Binary Geothermal Power Plant

McTigue

Kincaid

Wendt

et al. 2018

Self Cite

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“…Another study [20] examined the exergetic efficiency of a multigenerational system that would produce electric power, space heating, hot water, air-conditioning and heat for industrial use. A more recent study by McTigue et al [21] used concentrated solar power for a hybrid solar-geothermal power plant that generates dispatchable power and uses a flashing system. It must be noted that a geothermal unit supplemented with both PV and thermal solar (conventional solar power) is in operation in Stillwater, Nevada, USA [22].…”

Section: Introductionmentioning

confidence: 99%

A Geothermal-Solar Hybrid Power Plant with Thermal Energy Storage

Bokelman¹,

Michaelides²,

Michaelides

2020

Energies

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The concept of a geothermal-solar power plant is proposed that provides dispatchable power to the local electricity grid. The power plant generates significantly more power in the late afternoon and early evening hours of the summer, when air-conditioning use is high and peak power is demanded. The unit operates in two modes: a) as a binary geothermal power plant utilizing a subcritical Organic Rankine Cycle; and b) as a hybrid geothermal-solar power plant utilizing a supercritical cycle with solar-supplied superheat. Thermal storage allows for continuous power generation in the early evening hours. The switch to the second mode and the addition of solar energy into the cycle increases the electric power generated by a large factor—2 to 9 times—during peak power demand at a higher efficiency (16.8%). The constant supply of geothermal brine and heat storage in molten salts enables this power plant to produce dispatchable power in its two modes of operation with an exergetic efficiency higher than 30%.

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“…The high processing temperature complicates the fabrication with the high risk in thermal decomposition of PCMs and chemical reaction between different components [23]. A variety of PCMs with different melting temperatures are generally required to match various operating temperature ranges in the utilization of solar heat and industrial waste heat or their gradient utilization for realizing high-efficiency thermal storage [24]. Furthermore, combination of composite PCMs with different melting temperatures can form a multi-layered thermal storage device, which is helpful to reducing grade loss of the stored heat (exergy loss) and increasing the operating time [25].…”

Section: Introductionmentioning

confidence: 99%