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All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Upgrade fo the CMS Hadron Outer Calorimeter with SIPMs

The CMS Hadron Outer Calorimeter (HO) is undergoing an upgrade to replace the existing photodetectors (HPDs) with SIPMs. The chosen device is the Hamamatsu 3 x 3mm 50 {mu}m pitch MPPC. The system has been developed to be a 'drop-in' replacement of the HPDs. A complete control system of bias voltage generation, leakage current monitoring, temperature monitoring, and temperature control using solid state Peltier coolers has been developed and tested. 108 channels of the system have been installed into CMS and operated for more than 2 years. The complete system of about 2200 channels is in production and will be installed in the next LHC long shutdown scheduled for 2013. The CMS central calorimeter consists of a detector inside the solenoidal magnet, HB, and a component outside the magnet, the Outer Hadron Calorimeter, HO [1]. The HO is installed inside the magnet flux return yoke and provides for typically 3{lambda} of additional absorber to the calorimetric measurement. The outer calorimeter is composed of one or more layers of scintillator with wavelength shifting fiber readout into photodetectors. Figure 1 (a) shows the schematic layout of the calorimeters in CMS and shows the location of the HO scintillator layers. The front end electronics are placed inside the CMS detector, close to the scintillators. Figure 1(b) shows a photograph of the scintillators. Note the four wavelength shifting fibers per tile. The tile size creates a projective tower with the HB. Currently the photodetector used is the HPD but for performance and operational reasons it is desired to upgrade these with SIPMs. The CMS HCAL group has developed a drop-in replacement for the HPD using SIPMs. SIPMs are very suitable for this application because of several factors: The radiation levels are modest with a lifetime expected fluence of less than 5*10{sup 11} neutrons (E > 100 KeV) per cm{sup 2}. The energy flux into HO is small, the rate of larger energy depositions is low, and the required dynamic range is modest. The HO is in the return magnetic field of up to 2KG and the photodetector needs to operate in that environment. Finally, the available physical volume for the photodetectors is small.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Drought impacts on photosynthesis, isoprene emission and atmospheric formaldehyde in a mid-latitude forest

Isoprene plays a critical role in air quality and climate. Photosynthesis (gross primary productivity, GPP) and formaldehyde (HCHO) are both related to isoprene emission at large spatiotemporal scales, but neither is a perfect proxy. Here we apply multiple satellite products and site-level measurements to examine the impact of water deficit on the three interlinked variables at the Missouri Ozarks site during a 20-day mild dryness stress in summer 2011 and a 3-month severe drought in summer 2012. Isoprene emission shows opposite responses to the short- and long-term droughts, while GPP was substantially reduced in both cases. In 2012, both remote-sensed solar-induced fluorescence (SIF) and satellite HCHO column qualitatively capture reductions in flux-derived GPP and isoprene emission, respectively, on weekly to monthly time scales, but with muted responses. For instance, as flux-derived GPP approaches zero in late summer 2012, SIF drops by 29–33% (July) and 19–27% (August) relative to year 2011. A possible explanation is that electron transport and photosystem activity are maintained to a certain extent under the drought stress. Similarly, flux tower isoprene emissions in July 2012 are 54% lower than July 2011, while the relative reductions in July for 3 independent satellite-derived HCHO data products are 27%, 12% and 6%, respectively. Finally, we attribute the muted HCHO response to a photochemical feedback whereby reduced isoprene emission increases the oxidation capacity available to generate HCHO from other volatile organic compound sources. Satellite SIF offers a potential alternative indirect method to monitor isoprene variability at large spatiotemporal scales from space, although further research is needed under different environmental conditions and regions. Our analysis indicates that fairly moderate reductions in satellite SIF and HCHO column may imply severe drought conditions at the surface.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

Three-dimensional MHD simulation of the Caltech plasma jet experiment: first results

Magnetic fields are believed to play an essential role in astrophysical jets with observations suggesting the presence of helical magnetic fields. Here, we present three-dimensional (3D) ideal MHD simulations of the Caltech plasma jet experiment using a magnetic tower scenario as the baseline model. Magnetic fields consist of an initially localized dipole-like poloidal component and a toroidal component that is continuously being injected into the domain. This flux injection mimics the poloidal currents driven by the anode-cathode voltage drop in the experiment. The injected toroidal field stretches the poloidal fields to large distances, while forming a collimated jet along with several other key features. Detailed comparisons between 3D MHD simulations and experimental measurements provide a comprehensive description of the interplay among magnetic force, pressure, and flow effects. In particular, we delineate both the jet structure and the transition process that converts the injected magnetic energy to other forms. With suitably chosen parameters that are derived from experiments, the jet in the simulation agrees quantitatively with the experimental jet in terms of magnetic/kinetic/inertial energy, total poloidal current, voltage, jet radius, and jet propagation velocity. Specifically, the jet velocity in the simulation is proportional to the poloidal current divided by the square root of the jet density, in agreement with both the experiment and analytical theory. This work provides a new and quantitative method for relating experiments, numerical simulations, and astrophysical observation, and demonstrates the possibility of using terrestrial laboratory experiments to study astrophysical jets.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

On the Path to SunShot: Advancing Concentrating Solar Power Technology Performance and Dispatchability.

Since the SunShot Vision Study (DOE 2012) was published, global deployment of concentrating solar power (CSP) has increased threefold to nearly 4,500 MW, with a similar threefold increase in operational capacity to 1,650 MW within the United States. Growth in U.S. CSP capacity has primarily been driven by policy support at the state and federal levels. State-driven renewable portfolio standards (RPSs), combined with a 30% federal investment tax credit (ITC) and federal loan guarantees, provided the opportunity for CSP developers to kick-start construction of CSP plants throughout the Southwest. Figure ES-1 demonstrates that deployment and private- and public-sector research and development have led to dramatic cost reductions that have placed CSP well on the path to reaching the U.S. Department of Energy’s SunShot Initiative goal of 6 cents/kWh by 2020. In comparing the estimated capital costs from the SunShot Vision Study and the current analysis, we find that parabolic trough solar-field costs have fallen more rapidly than predicted, although the drop in solar-field costs was offset by the additional costs of moving from a wet-cooled power block in 2010 to a more expensive dry-cooled power block in 2015. The predicted 2015 decline in tower costs was in line with expectations, primarily driven by reduced heliostat costs. Figure ES-1 shows the reduction in levelized cost of electricity (LCOE) for both parabolic trough and tower systems, in addition to the projected 2020 SunShot target.

14 SOLAR ENERGY↗
DOE OSTI2016

On the Path to SunShot: Advancing Concentrating Solar Power Technology, Performance, and Dispatchability

Since the SunShot Vision Study (DOE 2012) was published, global deployment of concentrating solar power (CSP) has increased threefold to nearly 4,500 MW, with a similar threefold increase in operational capacity to 1,650 MW within the United States. Growth in U.S. CSP capacity has primarily been driven by policy support at the state and federal levels. State-driven renewable portfolio standards (RPSs), combined with a 30% federal investment tax credit (ITC) and federal loan guarantees, provided the opportunity for CSP developers to kick-start construction of CSP plants throughout the Southwest. Figure ES-1 demonstrates that deployment and private- and public-sector research and development have led to dramatic cost reductions that have placed CSP well on the path to reaching the U.S. Department of Energy’s SunShot Initiative goal of 6 cents/kWh by 2020. In comparing the estimated capital costs from the SunShot Vision Study and the current analysis, we find that parabolic trough solar-field costs have fallen more rapidly than predicted, although the drop in solar-field costs was offset by the additional costs of moving from a wet-cooled power block in 2010 to a more expensive dry-cooled power block in 2015. The predicted 2015 decline in tower costs was in line with expectations, primarily driven by reduced heliostat costs. Figure ES-1 shows the reduction in levelized cost of electricity (LCOE) for both parabolic trough and tower systems, in addition to the projected 2020 SunShot target.

14 SOLAR ENERGY↗
DOE OSTI2019

Dispatch optimization of concentrating solar power with utility-scale photovoltaics

Concentrating solar power (CSP) tower technologies capture thermal radiation from the sun utilizing a field of solar-tracking heliostats. When paired with inexpensive thermal energy storage (TES), CSP technologies can dispatch electricity during peak-market-priced hours, day or night. The cost of utility-scale photovoltaic (PV) systems has dropped significantly in the last decade, resulting in inexpensive energy production during daylight hours. The hybridization of PV and CSP with TES systems has the potential to provide continuous and stable energy production at a lower cost than a PV or CSP system alone. Hybrid systems are gaining popularity in international markets as a means to increase renewable energy portfolios across the world. Typically, CSP-PV hybrid systems have been evaluated using either monthly averages of hourly PV production or scheduling algorithms that neglect the time-of-production value of electricity in the market. To more accurately evaluate a CSP-PV-battery hybrid design, we develop a profit-maximizing mixed-integer linear program ($\mathcal{H}$) that determines a dispatch schedule for the individual sub-systems with a sub-hourly time fidelity. We introduce the mathematical formulation of such a model and show that it is computationally expensive to solve. To improve model tractability and reduce solution times, we offer techniques that: (1) reduce the problem size, (2) tighten the linear programming relaxation of ($\mathcal{H}$) via reformulation and the introduction of cuts, and (3) implement an optimization-based heuristic (that can yield initial feasible solutions for (($\mathcal{H}$) and, at any rate, yields near-optimal solutions). Applying these solution techniques results in a 79% improvement in solve time, on average, for our 48-h instances of (($\mathcal{H}$); corresponding solution times for an annual model run decrease by as much as 93%, where such a run consists of solving 365 instances of (($\mathcal{H}$), retaining only the first 24 h' worth of the solution, and sliding the time window forward 24 h. We present annual system metrics for two locations and two markets that inform design practices for hybrid systems and lay the groundwork for a more exhaustive policy analysis. A comparison of alternative hybrid systems to the CSP-only system reflects that hybrid models can almost double capacity factors while resulting in a 30% improvement related to various economic metrics.

14 SOLAR ENERGY↗
DOE OSTI2010

Experimental study on corrugated cross-flow air-cooled plate heat exchangers

Experimental study on cross-flow air-cooled plate heat exchangers (PHEs) was performed. The two prototype PHEs were manufactured in a stack of single-wave plates and double-wave plates in parallel. Cooling air flows through the PHEs in a crosswise direction against internal cooling water. The heat exchanger aims to substitute open-loop cooling towers with closed-loop water circulation, which guarantees cleanliness and compactness. In this study, the prototype PHEs were tested in a laboratory scale experiments. From the tests, double-wave PHE shows approximately 50% enhanced heat transfer performance compared to single-wave PHE. However, double-wave PHE costs 30% additional pressure drop. For commercialization, a wide channel design for air flow would be essential for reliable performance. (author)

42 ENGINEERING↗
DOE OSTI2022

Cost Update: Commercial and Advanced Heliostat Collectors

The research team performed a detailed bottom-up manufacturing cost estimate for 2 heliostat designs: i) a commercially available design, the Stellio; and ii) an advanced heliostat design, the Drop-C. The Drop-C is designed and developed by Solar Dynamics (SD) of the United States, whilst the Stellio has been developed primarily by Schlaich Bergermann Und Partner, Sonne Gmbh (sbp) of Germany. The Stellio heliostat has been deployed at commercial scale and is being used at the Hami CSP 50-megawatt electric (MW e ) power tower plant in China. For each design, this includes all components for manufacturing and assembly in a manufacturing facility (e.g., struts and frame) using Design for Manufacturing and Assembly (DFMA), and the purchased parts (e.g., mirrors, control systems, and drives). The field-assembly and construction activities are also considered to determine the installed cost of the modelled solar fields.

14 SOLAR ENERGY↗
DOE OSTI2018

2017 Wind Technologies Market Report

The U.S. Department of Energy (DOE)’s Wind Technologies Market Report provides an annual overview of trends in the U.S. wind power market. Highlights of this year’s report include: -Wind power capacity additions continued at a rapid pace in 2017: $11 billion was invested in new wind power plants in 2017. In 2017, wind energy contributed 6.3% of the nation’s electricity supply, more than 10% of total electricity generation in fourteen states, and more than 30% in four of those states—Iowa, Kansas, Oklahoma, and South Dakota. -Bigger turbines are enhancing wind project performance: Increased blade lengths have dramatically increased wind project capacity factors, one measure of project performance, and taller towers appear to be on the horizon. The average 2017 capacity factor among projects built from 2014 through 2016 was 42%, compared to an average of 31.5% among projects built from 2004 to 2011 and 23.5% among projects built from 1998 to 2001. -Low wind turbine pricing continues to push down installed project costs: Wind turbine prices have fallen from their highs in 2008 to $750–$950/kW. Overall, the average installed cost of wind projects in 2017 was $1,610/kW, down $795/kW from the peak in 2009 and 2010. -Wind energy prices remain low: After topping out at 7¢/kWh for power purchase agreements (PPAs) executed in 2009, the national average price of wind PPAs has dropped to around 2¢/kWh—though this nationwide average is dominated by projects that hail from the lowest-priced Interior region of the country (such as Oklahoma, Nebraska, Kansas). These prices, which are possible in part due to federal tax support, compare favorably to the projected future fuel costs of gas-fired generation. -The domestic supply chain for wind equipment is diverse: Wind sector employment reached a new high of more than 105,000 full-time workers at the end of 2017. For wind projects recently installed in the U.S., domestically manufactured content is highest for nacelle assembly (>90%), towers (70-90%), and blades and hubs (50-70%), but is much lower (<20%) for most components internal to the turbine. -Continued strong growth in wind capacity is anticipated in the near term: With federal tax incentives still available, various forecasts for the domestic market show expected wind power capacity additions of 8,000 to 11,000 MW/year from 2018 to 2020, with market contraction anticipated beginning in 2021 as those tax incentives are phased out.

17 WIND ENERGY↗
DOE OSTI2017

Thermosyphon Cooler Hybrid System for Water Savings in an Energy-Efficient HPC Data Center: Modeling and Installation: Preprint

The Thermosyphon Cooler Hybrid System (TCHS) integrates the control of a dry heat rejection device, the thermosyphon cooler (TSC), with an open cooling tower. A combination of equipment and controls, this new heat rejection system embraces the 'smart use of water,' using evaporative cooling when it is most advantageous and then saving water and modulating toward increased dry sensible cooling as system operations and ambient weather conditions permit. Innovative fan control strategies ensure the most economical balance between water savings and parasitic fan energy. The unique low-pressure-drop design of the TSC allows water to be cooled directly by the TSC evaporator without risk of bursting tubes in subfreezing ambient conditions. Johnson Controls partnered with the National Renewable Energy Laboratory (NREL) and Sandia National Laboratories to deploy the TSC as a test bed at NREL's high-performance computing (HPC) data center in the first half of 2016. Located in NREL's Energy Systems Integration Facility (ESIF), this HPC data center has achieved an annualized average power usage effectiveness rating of 1.06 or better since 2012. Warm-water liquid cooling is used to capture heat generated by computer systems direct to water; that waste heat is either reused as the primary heat source in the ESIF building or rejected using evaporative cooling. This data center is the single largest source of water and power demand on the NREL campus, using about 7,600 m3 (2.0 million gal) of water during the past year with an hourly average IT load of nearly 1 MW (3.4 million Btu/h) -- so dramatically reducing water use while continuing efficient data center operations is of significant interest. Because Sandia's climate is similar to NREL's, this new heat rejection system being deployed at NREL has gained interest at Sandia. Sandia's data centers utilize an hourly average of 8.5 MW (29 million Btu/h) and are also one of the largest consumers of water on Sandia's site. In addition to describing the installation of the TSC and its integration into the ESIF, this paper focuses on the full heat rejection system simulation program used for hourly analysis of the energy and water consumption of the complete system under varying operating scenarios. A follow-up paper will detail the test results. The evaluation of the TSC's performance at NREL will also determine a path forward at Sandia for possible deployment in a large-scale system not only for data center use but also possibly site wide.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

2018 Wind Technologies Market Report

The U.S. Department of Energy (DOE)’s Wind Technologies Market Report provides an annual overview of trends in the U.S. wind power market. Highlights of this year’s report include: ~Wind power capacity additions continued at a robust pace in 2018: $11 billion was invested in new wind power plants in 2018. In 2018, wind energy contributed 6.5% of the nation’s electricity supply, more than 10% of total electricity generation in fourteen states, and more than 30% in three of those states—Kansas, Iowa, and Oklahoma. 232 gigawatts of wind are seeking transmission interconnection, 2% of which represents proposed wind plants paired with storage. ~Bigger turbines are enhancing wind project performance: Increased blade lengths have dramatically increased wind project capacity factors, one measure of project performance, and taller towers are on the horizon. The average 2018 capacity factor among projects built from 2014 through 2017 was 42%, compared to an average of 31% among projects built from 2004 to 2011 and 24% among projects built from 1998 to 2001. Low wind turbine pricing continues to push down installed project costs: Wind turbine prices have fallen to $700–$900/kW. The average installed cost of wind projects in 2018 was $1,470/kW, down 40 percent since the peak in 2009 and 2010. ~Wind energy prices are at historical lows: After topping out at 7¢/kWh for power purchase agreements (PPAs) executed in 2009, the national average price of wind PPAs has dropped to below 2¢/kWh—though this nationwide average is dominated by projects that hail from the lowest-priced Interior region of the country. These prices, which are possible in part due to federal tax support, compare favorably to the projected future fuel costs of gas-fired generation. Solar PPA prices have declined precipitously, pressuring wind’s competitive position. ~The grid-system value of wind has declined over the last decade, but rebounded over the last two years. The value of wind in wholesale power markets is impacted by the location of wind plants, their hourly output profiles, and how those characteristics correlate with real-time electricity prices and capacity markets. The market value of wind in 2018 was the lowest in the Southwest Power Pool and Texas (average of $17/MWh and $18/MWh, respectively) whereas the highest-value market was New England (at $41/MWh). Wind energy prices are generally competitive with these value estimates. ~The domestic supply chain for wind equipment is diverse: For wind projects recently installed in the U.S., domestically manufactured content is highest for nacelle assembly (>90%), towers (75-90%), and blades and hubs (50-70%), but is much lower (<20%) for most components internal to the nacelle. Wind sector employment reached a new high of more than 114,000 full-time workers at the end of 2018. ~Continued strong growth in wind capacity is anticipated in the near term: With federal tax incentives still available, various forecasts for the domestic market show expected wind power capacity additions of 9,000-12,000 MW in 2019 and 11,000-15,000 in 2020, with market contraction anticipated beginning in 2021 as those tax incentives are phased out.

17 WIND ENERGY↗
NASA NTRS1992

Static and dynamic strain energy release rates in toughened thermosetting composite laminates

In this work, the static and dynamic fracture properties of several thermosetting resin based composite laminates are presented. Two classes of materials are explored. These are homogeneous, thermosetting resins and toughened, multi-phase, thermosetting resin systems. Multi-phase resin materials have shown enhancement over homogenous materials with respect to damage resistance. The development of new dynamic tests are presented for composite laminates based on Width Tapered Double Cantilevered Beam (WTDCB) for Mode 1 fracture and the End Notched Flexure (ENF) specimen. The WTDCB sample was loaded via a low inertia, pneumatic cylinder to produce rapid cross-head displacements. A high rate, piezo-electric load cell and an accelerometer were mounted on the specimen. A digital oscilloscope was used for data acquisition. Typical static and dynamic load versus displacement plots are presented. The ENF specimen was impacted in three point bending with an instrumented impact tower. Fracture initiation and propagation energies under static and dynamic conditions were determined analytically and experimentally. The test results for Mode 1 fracture are relatively insensitive to strain rate effects for the laminates tested in this study. The test results from Mode 2 fracture indicate that the toughened systems provide superior fracture initiation and higher resistance to propagation under dynamic conditions. While the static fracture properties of the homogeneous systems may be relatively high, the apparent Mode 2 dynamic critical strain energy release rate drops significantly. The results indicate that static Mode 2 fracture testing is inadequate for determining the fracture performance of composite structures subjected to conditions such as low velocity impact. A good correlation between the basic Mode 2 dynamic fracture properties and the performance is a combined material/structural Compression After Impact (CAI) test is found. These results underscore the importance of examining rate-dependent behavior for determining the longevity of structures manufactured from composite materials.

Cairns, Douglas S.↗
DOE OSTI2014

Sensitivity of vegetation indices and gross primary production of tallgrass prairie to severe drought

Drought affects vegetation photosynthesis and growth.Many studies have used the normalized difference vegetation index (NDVI), which is calculated as the normalized ratio between near infrared and red spectral bands in satellite images, to evaluate the response of vegetation to drought. In this study, we examined the impacts of drought on three vegetation indices (NDVI, enhanced vegetation index, EVI, and land surface water index, LSWI) and CO2 flux from three tallgrass prairie eddy flux tower sites in the U.S. Gross primary production (GPP) was also modeled using a satellite-based Vegetation Photosynthesis Model (VPM), and the modeled GPP (GPPVPM) was compared with the GPP (GPPEC) derived from eddy covariance measurements. Precipitation at two sites in Oklahoma was 30% below the historical mean in both years of the study period (2005–2006), while the site in Illinois did not experience drought in the 2005–2007 study period. The EVI explained the seasonal dynamics of GPP better than did NDVI. The LSWI dropped below zero during severe droughts in the growing season, showing its potential to track drought. The result shows that GPP was more sensitive to drought than were vegetation indices, and EVI and LSWI were more sensitive than NDVI. We developed a modified function (Wscalar), calculated as a function of LSWI, to account for the effect of severe droughts on GPP in VPM. The GPPVPM from the modified VPM accounted for the rapid reduction in GPP during severe droughts and the seasonal dynamics of GPPVPM agreed reasonably well with GPPEC. Our analysis shows that 8-day averaged values (temperature, vapor-pressure deficit) do not reflect the short-term extreme climate events well, suggesting that satellite based models may need to be run at daily or hourly scales, especially under unfavorable climatic conditions.

Drought↗
DOE OSTI2012

Technology to Facilitate the Use of Impaired Waters in Cooling Towers

The project goal was to develop an effective silica removal technology and couple that with existing electro-dialysis reversal (EDR) technology to achieve a cost effective treatment for impaired waters to allow for their use in the cooling towers of coal fired power plants. A quantitative target of the program was a 50% reduction in the fresh water withdrawal at a levelized cost of water of $3.90/Kgal. Over the course of the program, a new molybdenum-modified alumina was developed that significantly outperforms existing alumina materials in silica removal both kinetically and thermodynamically. The Langmuir capacity is 0.11g silica/g adsorbent. Moreover, a low cost recycle/regeneration process was discovered to allow for multiple recycles with minimal loss in activity. On the lab scale, five runs were carried out with no drop in performance between the second and fifth run in ability to absorb the silica from water. The Mo-modified alumina was successfully prepared on a multiple kilogram scale and a bench scale model column was used to remove 100 ppm of silica from 400 liters of simulated impaired water. Significant water savings would result from such a process and the regeneration process could be further optimized to reduce water requirements. Current barriers to implementation are the base cost of the adsorbent material and the fine powder form that would lead to back pressure on a large column. If mesoporous materials become more commonly used in other areas and the price drops from volume and process improvements, then our material would also lower in price because the amount of molybdenum needed is low and no additional processing is required. There may well be engineering solutions to the fine powder issue; in a simple concept experiment, we were able to pelletize our material with Boehmite, but lost performance due to a dramatic decrease in surface area.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2021

Land-Based Wind Market Report: 2021 Edition

The U.S. Department of Energy's 2021 edition of its land-based wind market report provides an overview of key trends in the U.S. wind power market, with a focus on 2020. You can find a report, data file and presentation on the Files tab, below. Additionally, several data visualizations are available on the Visualizations tab. Highlights of this year’s update include: -Wind comprises a growing share of electricity supply: U.S. wind power capacity grew at a record pace in 2020, with 25 billion dollars invested in 16.8 GW of capacity. Wind energy output rose to account for more than 8% of the entire nation’s electricity supply, and is more than 20% in 10 states. At least 209 GW of wind are seeking transmission interconnection; 61 GW of this capacity are offshore wind and 13 GW are hybrid plants that pair wind with storage or PV. -Wind project performance has increased over time: The average capacity factor among recently built projects was over 40%, considerably higher than projects built earlier. The highest capacity factors are seen in the interior ‘wind belt’ of the country. -Turbines continue to get larger: Improved plant performance has been driven by larger turbines mounted on taller towers and featuring longer blades. In 2010, no turbines employed blades that were 115 meters in diameter or larger, but in 2020, 91% of newly installed turbines featured such rotors. Proposed projects indicate that total turbine height will continue to rise. -Low wind turbine pricing has pushed down installed project costs over the last decade: Wind turbine prices are averaging 775–850 dollars/kW. The average installed cost of wind projects in 2020 was 1,460 dollars/kW, down more than 40% since the peak in 2010, though stable for the last three years. The lowest costs were found in Texas and the (non-ISO) West. -Wind energy prices remain low, around 20 dollars/MWh in the interior of the country: After topping out at 70 dollars/MWh for power purchase agreements (PPAs) executed in 2009, the national average price of wind PPAs has dropped. In the interior ‘wind belt’ of the country, recent pricing is around 20 dollars/MWh. In the West and East, prices tend to average 30 dollars/MWh or more. These prices, which are possible in part due to federal tax support, fall below the projected future fuel costs of gas-fired generation. -Wind PPA prices are often attractive compared to wind’s grid-system market value: The value of wind in wholesale power markets is affected by the location of wind plants, their hourly output profiles, and how those characteristics correlate with real-time electricity prices and capacity markets. The market value of wind declined in 2020, following natural gas prices lower and averaging under 15 dolalrs/MWh in ERCOT, MISO, NYISO and SPP; higher values were seen in CAISO, ISO-NE and PJM. -The average levelized cost of wind energy is down to 33 dollars/MWh: Levelized costs, which exclude the impacts of federal tax incentives, vary across time and geography, but the national average stood at 33 dollars/MWh in 2020—down substantially historically, though consistent with the previous two years. Levelized costs were lowest in ERCOT, SPP, and the (non-ISO) West. -The health and climate benefits of wind in 2020 were larger than its grid-system value, and the combination of all three far exceeds the current levelized cost of wind: Wind generation reduces power-sector emissions of carbon dioxide, nitrogen oxides, and sulfur dioxide. These reductions, in turn, provide public health and climate benefits that vary regionally, but together are economically valued at an average of 76 dollars/MWh-wind nationwide in 2020. -The domestic supply chain for wind equipment is diverse: For wind projects recently installed in the U.S., domestically manufactured content is highest for nacelle assembly (>85%), towers (60-75%), and blades and hubs (30-50%), but is much lower for most components internal to the nacelle.

17 WIND ENERGY↗
DOE OSTI2021

Evaluation of external tubular configurations for a high-temperature chloride molten salt solar receiver operating above 700°C

Next-generation concentrating solar power (CSP) tower technologies target operating temperatures exceeding 700°C to increase the thermal-to-electric conversion efficiency. Molten chloride salts are one possible alternative to current commercial molten nitrate salts to enable the higher operating temperature. This paper analyzes the predicted optical, thermal-fluids, and structural performance of traditional external tubular solar receiver configurations applied with a chloride salt heat transfer fluid (HTF) and inlet/outlet temperatures of 500°C/735°C, and considers sensitivity analysis and optimization relative to receiver sizing, tube sizing, number of panels, flow circuit configurations, and solar flux concentration under constraints on internal velocity, pressure drop, wall thickness, and required creep-fatigue lifetime. The high temperature conditions increase the significance of inelastic deformation mechanisms such as creep relative to that expected in commercial 565°C nitrate salt designs. High-temperature creep and creep-fatigue damage in the metal alloy tubes are the key factors that limit allowable solar flux concentration and achievable receiver thermal efficiency at the near-800°C wall temperature conditions. For a traditional external cylindrical receiver configuration, the design parameters and conditions capable of satisfying all constraints produced, at best, a design point receiver efficiency of 78.2%, or 80.5% when excluding receiver intercept efficiency. Variation in the optimal receiver performance relative to uncertainty in the binding maximum velocity, minimum wall thickness, and minimum lifetime constraints is presented.

14 SOLAR ENERGY↗
DOE OSTI2020

Litter Production of Oak-Hickory Forest at Missouri Ozark (MOFLUX) Site: 2003-2022

This dataset contains measurements of litter production at the second-growth upland oak-hickory forest at the Missouri Ozark AmeriFlux (MOFLUX) site. The MOFLUX site is located in the University of Missouri Baskett Forest situated in the Ozark Border Region of central Missouri, USA, and is part of the AmeriFlux network (site ID: US-MOz). During 2003, 24 circular vegetation plots (each 0.08 hectares) were established in the MOFLUX forest. The plots were situated 50 meters apart on 5 linear transects radiating out from the flux tower base in southeast, south, southwest, west, and northwest directions—there were 5 plots per transect except for the northwest one, which had only 4 due to the presence of a small pond at the terminus (Fig. 1). Litter measurements were initiated in October 2003 and continue to the present. Data through 2022 are reported in this dataset. On each plot, two subplots were established for the collection of litter. Subplots were setup using a stratified random design to ensure the collectors were not immediately adjacent to one another. Litter collectors were usually emptied at monthly intervals, or less during the autumn leaf drop. Samples were dried to constant mass and then sorted before determining the dry mass of leaf, vegetative and woody litter. These litter data have been valuable in modeling efforts to examine the impacts of intensifying moisture extremes (i.e., moisture excess and deficit conditions) on soil carbon cycling. More recent data will be added periodically with no changes to previously released data or the format and structure of the data file. This dataset contains one data file in comma separate (.csv) format. Additional metadata are provided: one data dictionary and a file-level metadata file in comma separate (.csv) format and a user guide in PDF (*.pdf) format.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

2016 Wind Technologies Market Report

The U.S. Department of Energy (DOE)’s Wind Technologies Market Report provides an annual overview of trends in the U.S. wind power market. You can find the report, a presentation, and a data file on the Files tab, below. Additionally, several data visualizations are available in the Data Visualizations tab. Highlights of this year’s report include: -Wind power additions continued at a rapid clip in 2016: $13 billion was invested in new wind power plants in 2016. In 2016, wind energy contributed 5.6% of the nation’s electricity supply, more than 10% of total electricity generation in fourteen states, and 29% to 37% in three of those states—Iowa, South Dakota, and Kansas. -Bigger turbines are enhancing wind project performance: Increased blade lengths, in particular, have dramatically increased wind project capacity factors, one measure of project performance. For example, the average 2016 capacity factor among projects built in 2014 and 2015 was 42.6%, compared to an average of 32.1% among projects built from 2004 to 2011 and 25.4% among projects built from 1998 to 2001. -Low wind turbine pricing continues to push down installed project costs: Wind turbine prices have fallen from their highs in 2008, to $800–$1,100/kW. Overall, the average installed cost of wind projects in 2016 was $1,590/kW, down $780/kW from the peak in 2009 and 2010. -Wind energy prices remain low: After topping out at nearly 7¢/kWh for power purchase agreements (PPAs) executed in 2009, the national average price of wind PPAs has dropped to around 2¢/kWh—though this nationwide average is dominated by projects that hail from the lowest-priced Interior region of the country (such as Texas, Iowa, Oklahoma). These prices, which are possible in part due to federal tax support, compare favorably to the projected future fuel costs of gas-fired generation. -The supply chain continued to adjust to swings in domestic demand for wind equipment: Wind sector employment reached a new high of more than 101,000 full-time workers at the end of 2016. For wind projects recently installed in the U.S., domestically manufactured content is highest for nacelle assembly (>90%), towers (65-80%), and blades and hubs (50-70%), but is much lower (<20%) for most components internal to the turbine. -Continued strong growth in wind capacity is anticipated in the near term: With federal tax incentives still available, though declining, various forecasts for the domestic market show expected wind power capacity additions averaging more than 9,000 MW/year from 2017 to 2020.

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