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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

3D characterization of a Great Basin geothermal system: Astor Pass, NV

The Great Basin exhibits both anomalously high heat flow (~75±5 mWm-2) and active faulting and extension resulting in robust geothermal activity. There are ~430 known geothermal systems in the Great Basin, with evidence suggesting that undiscovered blind geothermal systems may actually represent the majority of geothermal activity. These systems employ discrete fault intersection/interaction areas as conduits for geothermal circulation. Recent studies show that steeply dipping normal faults with step-overs, fault intersections, accommodation zones, horse-tailing fault terminations and transtensional pull-aparts are the most prominent structural controls of Great Basin geothermal systems. These fault geometries produce sub-vertical zones of high fault and fracture density that act as fluid flow conduits. Structurally controlled fluid flow conduits are further enhanced when critically stressed with respect to the ambient stress conditions. The Astor Pass blind geothermal system, northwestern Nevada, lies along the boundary between the Basin and Range to the east and the Walker Lane to the west. Along this boundary, strain is transferred from dextral shear in the Walker Lane to west-northwest directed extension in the Basin and Range. As such, the Astor Pass area lies in a transtensional setting consisting of both northwest-striking, left-stepping dextral faults and more northerly striking normal faults. The Astor Pass tufa tower implies the presence of a blind geothermal system. Previous studies suggest that deposition of the Astor Pass tufa was controlled by the intersection of a northwest-striking dextral normal fault and north-northwest striking normal fault. Subsequent drilling (to ~1200 m) has revealed fluid temperatures of ~94°C, confirming the presence of a blind geothermal system at Astor Pass. Expanding upon previous work and employing additional detailed geologic mapping, interpretation of 2D seismic reflection data and analysis of well cuttings, a 3-dimensional geologic model of the Astor Pass blind geothermal system was constructed. The 3D structural framework indicates that the Pleistocene tufa is associated with three discrete fault zones whose intersections plunge moderately to steeply NW-NNW. These critically stressed fault intersections act as conduits for upwelling geothermal fluids.

15 GEOTHERMAL ENERGY↗
DOE OSTI2013

STRUCTURAL CONTROLS OF THE EMERSON PASS GEOTHERMAL SYSTEM, NORTHWESTERN NEVADA: CHARACTERIZATION OF A "BLIND" SYSTEM

The Pyramid Lake area is favorable for geothermal development due to the tectonic setting of the region. The Walker Lane belt, a dextral shear zone that accommodates ~20% relative motion between the Pacific and North American plates, terminates northwestward in northeast California. NW-directed dextral shear is transferred to WNW extension accommodated by N-to -NNE striking normal faults of the Basin and Range. As a consequence, enhanced dilation occurs on favorably oriented faults generating high geothermal potential in the northwestern Great Basin. The NW-striking right-lateral Pyramid Lake fault, a major structure of the northern Walker Lane, terminates at the southern end of Pyramid Lake and transfers strain to the NNE-striking down to the west Lake Range fault, resulting in high geothermal potential. Known geothermal systems in the area have not been developed due to cultural considerations of the Pyramid Lake Paiute Tribe. Therefore, exploration has been focused on discovering blind geothermal systems elsewhere on the reservation by identifying structurally favorable settings and indicators of past geothermal activity. One promising area is the northeast end of Pyramid Lake, where a broad left step between the west-dipping range-bounding faults of the Lake and Fox Ranges has led to the formation of a broad, faulted relay ramp. Furthermore, tufa mounds, mineralized veins, and altered Miocene rocks occur proximal to a thermal anomaly discovered by a 2-m shallow temperature survey at the north end of the step-over in Emerson Pass. Detailed geologic mapping has revealed a system of mainly NNE-striking down to the west normal faults. However, there are three notable exceptions to this generality, including 1) a prominent NW-striking apparent right-lateral fault, 2) a NW-striking down to the south fault which juxtaposes the base of the mid-Miocene Pyramid sequence against younger late Tertiary sedimentary rocks, and 3) a NNE-striking down to the east normal fault, which accommodates motion such that the Mesozoic Nightingale sequence is juxtaposed with late Tertiary sedimentary rocks. The NW dextral fault, the NNE-down to east fault, and several NNE-down to the west faults intersect roughly at the thermal anomaly in Emerson Pass. This suggests that fault intersections locally control upwelling of geothermal fluids within the step-over. Based on this assumption, it is proposed that the area near Buckbrush Springs be investigated further for geothermal potential. At this location, a NNE-down to the west normal fault, with >1 km of offset, intersects a NW-striking down to the south fault at a small left step in the NNE fault. Further studies will include collection of available kinematic indicators near the shallow thermal anomaly in Emerson Pass, geothermometry on Buckbrush Spring, and possibly drilling of temperature gradient wells in Emerson Pass and at Buckbrush Spring.

15 GEOTHERMAL ENERGY↗
DOE OSTI2013

NEAR-SURFACE GEOPHYSICAL CHARACTERIZATION OF A HOLOCENE FAULT CONDUCIVE TO GEOTHERMAL FLOW NEAR PYRAMID LAKE, NEVADA

Linear deposits of calcium carbonate tufa columns mark recent faults that cut 11 ka Lake Lahontan sediments at Astor Pass, north of Pyramid Lake, Nevada. Throughout the Great Basin, faults appear to control the location of geothermal resources by providing pathways for fluid migration. Reservoir-depth (greater than 1 km) seismic imaging at Astor Pass reveals a fault that projects to one of the lines of tufa columns at the surface. The presence of the tufa deposits suggests this fault carried warm geothermal waters through the lakebed clay sediments in recent time. The warm fluids deposited the tufa when they hit cold Lake Lahontan water at the lakebed. Lake Lahontan covered this location 11 ka to a depth of at least 60 m. In collaboration with the Pyramid Lake Paiute Tribe, an Applied Geophysics class at UNR investigated the near-surface geophysical characteristics of this fault. The survey at and near the tufa columns comprises near-surface Pwave seismic reflection and refraction, electrical resistivity tomography, nearsurface refraction microtremor arrays, nine near-surface direct-current resistivity soundings, magnetic surveys, and gravity surveys. The refraction microtremor results show shear velocities near tufa and faults to be marginally lower, compared to Vs away from the faults. Overall, the 30-m depth-averaged shear velocities are low, less than 300 m/s, consistent with the lakebed clay deposits. These results indicate that no seismically fast (> 500 m/s) tufa deposits are present below the surface at or near the tufa columns. Vs30 averages were for example 274 ± 13 m/s on the fault, 287 ± 2 m/s at 150 m east of the fault, and 290 ± 15 m/s at 150 m west of the fault. The P-velocity refraction optimization results similarly indicate a lack of high-velocity tufa buried below the surface in the Lahontan sediments, reinforcing the idea that all tufa was deposited above the lakebed surface. The seismic results provide a negative test of the hypothesis that deposition of the lakebeds in the Quaternary buried and preserved older tufa columns within the section. Near-surface Wenner arrays with a-spacings up to 30 m show a higher resistivity near the faults, and tufa, than away from the faults. Resistivity averages within a few meters of the surface were 33 ± 17 ohm-m on the fault, 13 ± 3 ohm-m east of the fault, and 9 ± 3 ohm-m west of the fault. It is possible that the geothermal waters are fresher, and more resistive, than waters held in the lakebed clays. Water samples from more than 1 km depth in exploration wells have a TDS of 2500 p.p.m., nearly drinking-water quality. The relatively resistive water, perhaps localized by greater permeability along the fault, could explain the higher resistivity measured near the fault. The results show that there is no high-velocity, high-resistivity tufa along the faults below the surface, so we are unable to use buried tufa to locate the faults that may promote geothermal upwelling in this area. We further hypothesize that as sedimentation buried the tufa during the Quaternary, warm geothermal waters re-dissolved it, and re-precipitated it in the cold lake-bottom water.

15 GEOTHERMAL ENERGY↗
DOE OSTI2014

Solar Radiometric Data Quality Assessment of SIRS, SKYRAD and GNDRAD Measurements (Poster)

Solar radiation is the driving force for the earth's weather and climate. Understanding the elements of this dynamic energy balance requires accurate measurements of broadband solar irradiance. Since the mid-1990's the ARM Program has deployed pyrheliometers and pyranometers for the measurement of direct normal irradiance (DNI), global horizontal irradiance (GHI), diffuse horizontal irradiance (DHI), and upwelling shortwave (US) radiation at permanent and mobile field research sites. This poster summarizes the basis for assessing the broadband solar radiation data available from the SIRS, SKYRAD, and GNDRAD measurement systems and provides examples of data inspections.

14 SOLAR ENERGY↗
DOE OSTI2018

Characterization of a Low-Cost Multiparameter Sensor for Solar Resource Applications

Low-cost, multiparameter sensing and measurement devices enable cost-effective monitoring of the functional, operational reliability, efficiency, and resiliency of the electric grid. The National Renewable Research Laboratory (NREL) Solar Radiation Research Laboratory (SRRL), in collaboration with Arable Labs, Inc., deployed Arable Lab's Mark multiparameter sensor system. The device measures the downwelling and upwelling shortwave solar resource and longwave radiation, humidity, air temperature, and ground temperature. The system is also equipped with six downward-and upward-facing narrowband spectrometer channels that measure spectral radiation and surface spectral reflectance. This study describes the shortwave calibration, characterization, and validation of measurement accuracy of this instrument by comparison with existing instruments that are part of NREL-SRRL's Baseline Measurement System.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2018

Characterization of a Low-Cost Multi-Parameter Sensor for Resource Applications: Preprint

Low-cost multi-parameter sensing and measurement devices enable cost-effective monitoring of the functional, operational reliability, efficiency, and resiliency of the electrical grid. The National Renewable Research Laboratory (NREL) Solar Radiation Research Laboratory (SRRL), in collaboration with Arable Labs Inc., deployed Arable Lab's Mark multi-parameter sensor system. The unique suite of system sensors measures the down-welling and upwelling shortwave solar resource and longwave radiation, humidity, air temperature, and ground temperature. This study describes the shortwave calibration, characteriza-tion, and validation of measurement accuracy of this instrument by comparison with existing instruments that are part of NREL-SRRL's Baseline Measurement System.

14 SOLAR ENERGY↗
DOE OSTI2018

Discovery and analysis of a blind geothermal system in southeastern Gabbs Valley, Western Nevada

This study assessed the potential for high-temperature (≥130°C) blind geothermal systems in southeastern Gabbs Valley by employing a geothermal play fairway analysis approach involving integration of geologic, geophysical, and geochemical datasets. Gabbs Valley is a complex, tectonically active basin within the Great Basin on the boundary between the transtensional central Walker Lane domain and extensional Basin and Range province. The termination of the Petrified Springs fault, a major dextral fault of the central Walker Lane, in an array of normal faults indicates that southeastern Gabbs Valley occupies a displacement transfer zone, which is a favorable structural setting for geothermal activity. The displacement transfer zone is a structurally complicated area with many faults of varying geometries, kinematics, and ages. A substantial northwest-trending gravity high within the south-central part of southeastern Gabbs Valley is produced from offsets along concealed northwest-striking dextral-normal faults that intersect strands of north-northeast-to east-northeast-striking normal faults. This area of tightly spaced faults and fault intersections is a particularly favorable structural setting within the broader-scale displacement transfer zone. Multiple lines of direct and indirect evidence suggest the presence of a relatively high-temperature (≥130°C) blind geothermal system in this area, including collocated intersecting gravity gradients, magnetic-low, low-resistivity, and 2-m temperature anomaly. Potentially related, water samples from agricultural wells ~7 km northwest of the 2-m anomaly yield geothermometers indicating subsurface fluid temperatures of 130-140°C. Six temperature-gradient holes were drilled to target the extent of the shallow-temperature and geophysical anomalies to define the geothermal system in southeastern Gabbs Valley. Two wells contained high temperatures exceeding boiling with bottom-hole temperatures ii of 114.5°C and 124.9°C, respectively, and the remaining wells displayed elevated to background temperatures ranging from 79.2°C to 28.7°C. The observed temperature gradients for the two hottest drill holes necessitate drill-hole intercepts of convecting hydrothermal fluids. The 2-m survey is spatially and thermally consistent with the temperature-gradient holes and constrains the core of upflow at a shallow depth interval (<250m) to an area <0.5-1 km west-southwest of the hottest drill hole. The zone of inferred upwelling occupies the area corresponding to the center of the magnetic-low. This project has several significant implications. The newly discovered blind geothermal system in southeastern Gabbs Valley may be capable of supporting a binary-type geothermal power plant. This detailed study provides an initial validation of the play fairway approach to geothermal exploration. It also demonstrates both the broad applicability of the play fairway exploration strategy and the large untapped potential for commercial-grade blind geothermal systems in many of the basins in the Great Basin region.

15 GEOTHERMAL ENERGY↗
DOE OSTI2013

mfr3m (b1)

The multifilter radiometer (MFR) is simply the head from a multifilter rotating shadowband radiometer (MFRSR) mounted on a tower pointing at the surface. Like the MFRSR, it has six narrowband channels (415, 500, 615, 673, 870, and 940 nm) and one broadband channel. Pointing the head at the surface provides spectral measurements of reflected irradiance. Measurements are taken every 20 seconds, with no averaging performed.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2012

mfraaf (a0)

The multifilter radiometer (MFR) is simply the head from a multifilter rotating shadowband radiometer (MFRSR) mounted on a tower pointing at the surface. Like the MFRSR, it has six narrowband channels (415, 500, 615, 673, 870, and 940 nm) and one broadband channel. Pointing the head at the surface provides spectral measurements of reflected irradiance. Measurements are taken every 20 seconds, with no averaging performed.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2012

mfraaf (b1)

The multifilter radiometer (MFR) is simply the head from a multifilter rotating shadowband radiometer (MFRSR) mounted on a tower pointing at the surface. Like the MFRSR, it has six narrowband channels (415, 500, 615, 673, 870, and 940 nm) and one broadband channel. Pointing the head at the surface provides spectral measurements of reflected irradiance. Measurements are taken every 20 seconds, with no averaging performed.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

NGEE Arctic Tram: Radiation and Environmental Measurements over Low- and High-Centered Polygon Vegetation Communities, Barrow, Alaska, 2014-2017

These data were generated from an observational platform (Tram), an automated cart carrying a suite of radiation and remote sensing instruments running on 68 meters of elevated track 1 to 1.5 meters above the surface of the vegetation communities of low- and high-centered polygon ground. The Tram is in the footprint of the NGEE Arctic/AmeriFlux eddy covariance flux tower (US-NGB) at the Barrow Environmental Observatory, Barrow, Alaska, and operated before, during, and after the growing seasons of 2014-2017. Dataset includes one user guide (*.pdf) with final and raw *.csv data files. The Next-Generation Ecosystem Experiments: Arctic (NGEE Arctic), was a research effort to reduce uncertainty in Earth System Models by developing a predictive understanding of carbon-rich Arctic ecosystems and feedbacks to climate. NGEE Arctic was supported by the Department of Energy's Office of Biological and Environmental Research. The NGEE Arctic project had two field research sites: 1) located within the Arctic polygonal tundra coastal region on the Barrow Environmental Observatory (BEO) and the North Slope near Utqiagvik (Barrow), Alaska and 2) multiple areas on the discontinuous permafrost region of the Seward Peninsula north of Nome, Alaska. Through observations, experiments, and synthesis with existing datasets, NGEE Arctic provided an enhanced knowledge base for multi-scale modeling and contributed to improved process representation at global pan-Arctic scales within the Department of Energy's Earth system Model (the Energy Exascale Earth System Model, or E3SM), and specifically within the E3SM Land Model component (ELM).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2013

Cloud Properties and Radiative Heating Rates for TWP

A cloud properties and radiative heating rates dataset is presented where cloud properties retrieved using lidar and radar observations are input into a radiative transfer model to compute radiative fluxes and heating rates at three ARM sites located in the Tropical Western Pacific (TWP) region. The cloud properties retrieval is a conditional retrieval that applies various retrieval techniques depending on the available data, that is if lidar, radar or both instruments detect cloud. This Combined Remote Sensor Retrieval Algorithm (CombRet) produces vertical profiles of liquid or ice water content (LWC or IWC), droplet effective radius (re), ice crystal generalized effective size (Dge), cloud phase, and cloud boundaries. The algorithm was compared with 3 other independent algorithms to help estimate the uncertainty in the cloud properties, fluxes, and heating rates (Comstock et al. 2013). The dataset is provided at 2 min temporal and 90 m vertical resolution. The current dataset is applied to time periods when the MMCR (Millimeter Cloud Radar) version of the ARSCL (Active Remotely-Sensed Cloud Locations) Value Added Product (VAP) is available. The MERGESONDE VAP is utilized where temperature and humidity profiles are required. Future additions to this dataset will utilize the new KAZR instrument and its associated VAPs.

54 ENVIRONMENTAL SCIENCES↗