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At least 289 records · Page 16

Wireless Power Transmission Options for Space Solar Power

Space Solar Power (SSP), combined with Wireless Power Transmission (WPT), offers the far-term potential to solve major energy problems on Earth. In this presentation, two basic WPT options, using radio waves an d light waves, are considered for both long-term and near-term SSP applications. In the long-term, we aspire to beam energy to Earth from geostationary Earth orbit (GEO), or even further distances in space. Accordingly, radio- and light- wave WPT options are compared through a wide range of criteria, each showing certain strengths. In the near-term, we plan to beam power over more moderate distances, but still stretch the limits of today's technology. For the near-term, a 100 kWe-class "Power Plug" Satellite and a 10 kWe-class Lunar Polar Solar Power outpost are considered as the first steps in using these WPT options for SSP. By using SSP and WPT technology in nearterm space science and exploration missions, we gain experience needed for sound decisions in designing and developing larger systems to send power from Space to Earth.

Henley, Mark↗

Wireless Power Transmission Options for Space Solar Power

Space Solar Power (SSP), combined with Wireless Power Transmission (WPT), offers the far-term potential to solve major energy problems on Earth. In the long-term, we aspire to beam energy to Earth from geostationary Earth orbit (GEO), or even further distances in space. In the near-term, we can beam power over more moderate distances, but still stretch the limits of today s technology. In recent studies, a 100 kWe-class "Power Plug" Satellite and a 10 kWe-class Lunar Polar Solar Power outpost have been considered as the first steps in using these WPT options for SSP. Our current assessments include consideration of orbits, wavelengths, and structural designs to meet commercial, civilian government, and military needs. Notional transmitter and receiver sizes are considered for use in supplying 5 to 15 MW of power. In the longer term, lunar or asteroidal material can be used. By using SSP and WPT technology for near-term missions, we gain experience needed for sound decisions in designing and developing larger systems to send power from space to Earth.

Potter, Seth↗

Wireless Power Transmission Options for Space Solar Power

Space Solar Power (SSP), combined with Wireless Power Transmission (WPT), offers the far-term potential to solve major energy problems on Earth. In the long term, we aspire to beam energy to Earth from geostationary Earth orbit (GEO), or even further distances in space. In the near term, we can beam power over more moderate distances, but still stretch the limits of today s technology. In recent studies, a 100 kWe-class "Power Plug" Satellite and a 10 kWe-class Lunar Polar Solar Power outpost have been considered as the first steps in using these WPT options for SSP. Our current assessments include consideration of orbits, wavelengths, and structural designs to meet commercial, civilian government, and military needs. Notional transmitter and receiver sizes are considered for use in supplying 5 to 40 MW of power. In the longer term, lunar or asteroidal material can be used. By using SSP and WPT technology for near-term missions, we gain experience needed for sound decisions in designing and developing larger systems to send power from space to Earth.

Potter, Seth↗

Beam combining of high-power terahertz lasers with semiconductor metasurface gratings

Spectral beam combining (SBC) of an array of single-mode lasers has the potential for realizing a chip-scale electrically tunable multispectral laser source without any moving parts and with emission at closely spaced discrete frequencies. Here, we demonstrate SBC of an array of single-mode THz quantum-cascade lasers (QCLs) with small frequency spacing. Semiconductor-based metasurface THz blazed gratings are developed for integration with QCLs in a compact cryocooler setup. Single-lobed beams of four QCLs emitting around 3.2 THz and spectrally separated by ~14 GHz are combined to achieve collinear propagation of spatially overlapped and collimated beams in the far field with ≲ 0.1° of pointing error. Peak optical power in the range 50–100 mW is detected from each of the QCLs after combining. The dense frequency spacing in our method provides a pathway to incorporate tens of QCLs on a chip to realize a high-power discretely tunable THz laser source for applications in THz spectroscopy.

Jia, Fei [Lehigh Univ., Bethlehem, PA (United Stat↗

Grid oscillators

Loading a two-dimensional grid with active devices offers a means of combining the power of solid-state oscillators in the microwave and millimeter-wave range. The grid structure allows a large number of negative resistance devices to be combined. This approach is attractive because the active devices do not require an external locking signal, and the combining is done in free space. In addition, the loaded grid is a planar structure amenable to monolithic integration. Measurements on a 25-MESFET grid at 9.7 GHz show power-combining and frequency-locking without an external locking signal, with an ERP of 37 W. Experimental far-field patterns agree with theoretical results obtained using reciprocity.

Popovic, Zorana B.↗

Co-design optimization of combined heat and power-based microgrids

With the emergent need for clean and reliable energy resources, hybrid energy systems, such as the microgrid, are widely adopted in the United States. A microgrid can consist of various distributed energy resources, for instance, combined heat and power (CHP) systems. Here, the CHP module is a distributed cogeneration technology that produces electricity and recaptures heat generated as a by-product. It is an energy-efficient technology converting heat that would otherwise be wasted to valuable thermal energy. For an optimal system configuration, this study develops a novel co-design optimization framework for CHP-based cogeneration microgrids. The framework provides the stakeholder with a method to optimize investments and attain resilient operations. The proposed co-design framework has a mixed integer programming (MIP) model that outputs decisions for both plant designs and operating controls. The microgrid considered in this study contains six components: the CHP, boiler, heat recovery unit, thermal storage system, power storage system, and photovoltaic plant. After solving the MIP model, the optimal design parameters of each component can be found to minimize the total installation cost of all components in the microgrid. Furthermore, the online costs from energy production, operation, maintenance, machine startup, and disruption-induced unsatisfied loads are minimized by solving the optimal control decisions for operations. Case studies based on designing a CHP-based microgrid with empirical data are conducted. Moreover, we consider both nominal and disruptive operational scenarios to validate the performance of the proposed co-design framework in terms of a cost-effective, resilient system.

42 ENGINEERING↗

Direct conversion of light to radio frequency energy

A description is presented of the test results obtained with the latest models of the phototron. The phototron was conceived as a replacement for the high voltage solar cell-high power klystron combination for the solar power satellite concept. Physically, the phototron is a cylindrical evacuated glass tube with a photocathode, two grids, and a reflector electrode in a planar configuration. The phototron can be operated either in a biased mode where a low voltage is used to accelerate the electron beam produced by the photocathode or in an unbiased mode referred to as self-oscillation. The device is easily modulated by light input or voltage to broadcast in AM or FM. The range of operation of the present test model phototrons is from 2 to 200 MHz.

Freeman, J. W.↗

X-Band, 17-Watt Solid-State Power Amplifier

An advanced solid-state power amplifier that can generate an output power of as much as 17 W at a design operating frequency of 8.4 GHz has been designed and constructed as a smaller, lighter, less expensive alternative to traveling-wave-tube X-band amplifiers and to prior solid-state X-band power amplifiers of equivalent output power. This amplifier comprises a monolithic microwave integrated circuit (MMIC) amplifier module and a power-converter module integrated into a compact package (see Figure 1). The amplifier module contains an input variable-gain amplifier (VGA), an intermediate driver stage, a final power stage, and input and output power monitors (see Figure 2). The VGA and the driver amplifier are 0.5-m GaAs-based metal semiconductor field-effect transistors (MESFETs). The final power stage contains four parallel high-efficiency, GaAs-based pseudomorphic high-electron-mobility transistors (PHEMTs). The gain of the VGA is voltage-variable over a range of 10 to 24 dB. To provide for temperature compensation of the overall amplifier gain, the gain-control voltage is generated by an operational-amplifier circuit that includes a resistor/thermistor temperature-sensing network. The driver amplifier provides a gain of 14 dB to an output power of 27 dBm to drive the four parallel output PHEMTs, each of which is nominally capable of putting out as much as 5 W. The driver output is sent to the input terminals of the four parallel PHEMTs through microstrip power dividers; the outputs of these PHEMTs are combined by microstrip power combiners (which are similar to the microstrip power dividers) to obtain the final output power of 17 W.

Mittskus, Anthony↗

Techno-Economic Analysis of Greenfield Geothermal Hybrid Power Plants using a Solar or Natural Gas Steam Topping Cycle

The relatively low generation costs associated with wind, solar photovoltaic (PV), and natural-gas power plants make it challenging for geothermal power plants to produce and sell the power that has the reliability and sustainability characteristics that are greatly needed in U.S. power markets. This is especially true for geothermal resources with low-to-medium temperatures, which results in relatively low-thermal efficiency and generation costs that are higher than those for wind, solar PV, and natural gas. This analysis evaluates solar thermal- and natural-gas combustion waste heat recovery-based topping cycle hybridization of geothermal binary power plants. This approach provides several benefits that may allow geothermal power plants to generate power at more competitive costs. First, the addition of solar thermal energy or natural-gas combustion waste heat input to a geothermal power plant provides additional heat input that can be converted to electrical power. Second, the temperature level of the heat obtained from concentrating solar collectors or natural-gas combustion exhaust is higher than that of geothermal heat, which provides opportunities for improving the efficiency of the conversion of thermal energy to electrical power. Third, the ease with which solar thermal systems integrate with energy storage and the flexibility of natural gas means power generation can occur during peak demand periods. The hybrid cycles are compared to equivalently sized, co-located, independent geothermal, concentrating solar, and/or natural-gas power plants. The hybrid cycle tends to produce slightly more power than the standalone plants combined. However, the hybrid plant Levelized Cost of Energy (LCOE) is slightly higher than the LCOE of the combined standalone power plants for each of the case study locations investigated. Using the steam-topping cycle, organic Rankine cycle (ORC)-bottoming cycle hybrid plant design to combine a solar thermal resource and low- temperature geothermal resource (<120 degrees C) leads to a hybrid plant with a lower LCOE than a standalone geothermal-only system. Thus, hybrid plants may enable the economic development of geothermal resources in locations with low geothermal resource temperatures. However, in areas with higher geothermal resource temperatures (>120 degrees C), the geothermal-only plant has a lower LCOE than the hybrid cycle and thus could be developed without the need for solar heat addition. iv A geothermal-natural-gas reciprocating engine hybrid plant was evaluated for an Elk Hills, California case study location. The Elk Hills case study analysis indicates that when the natural-gas engine operates for more than 12 hours per day the hybrid plant can produce power at an LCOE lower than a standalone geothermal plant, and comparable to that of the standalone natural-gas reciprocating engine, while also reducing the carbon intensity of the power generated relative to the standalone natural-gas engine. This may represent a scenario in which the hybrid plant provides an opportunity for the deployment of a low-temperature geothermal resource that otherwise may have an LCOE too high to develop and operate as a standalone resource, while also reducing the carbon intensity of natural-gas generation sources. A "triple-hybrid" plant that combines natural gas, solar thermal, thermal energy storage, and geothermal was also investigated. A natural-gas combustion turbine (NGCT) is added to the geothermal-solar hybrid such that the hot exhaust gas from the gas turbine provides an alternative source of heat to the steam turbine of the hybrid cycle. Analysis results suggest that the triple-hybrid plant has a significantly higher energy generation and revenue than a standalone NGCT or the original geothermal-solar hybrid. The triple-hybrid design benefits most from using a smaller solar field so that the solar energy can be dispatched at the most valuable times available. The triple-hybrid plant also has a lower LCOE than the standalone NGCT. The triple-hybrid plant was evaluated making simple assumptions about the dispatch profile of the gas cycle, and more nuanced and realistic dispatching schedules should be analyzed in future work.

15 GEOTHERMAL ENERGY↗

Ka-Band Waveguide Hybrid Divider with Unequal and Arbitrary Power Output Ratio

One or more embodiments of the present invention describe an apparatus and method to combine unequal powers. The apparatus includes a first input port, a second input port, and a combiner. The first input port is operably connected to a first power amplifier and is configured to receive a first power from the first power amplifier. The second input port is operably connected to a second power amplifier and is configured to receive a second power from the second power amplifier. The combiner is configured to simultaneously receive the first power from the first input port and the second power from the second input port. The combiner is also configured to combine the first power and second power to produce a maximized power. The first power and second power are unequal.

Simons, Rainee N.↗

Studies of an extensively axisymmetric rocket based combined cycle (RBCC) engine powered single-stage-to-orbit (SSTO) vehicle

The present comparative performance study has established that rocket-based combined cycle (RBCC) propulsion systems, when incorporated by essentially axisymmetric SSTO launch vehicle configurations whose conical forebody maximizes both capture-area ratio and total capture area, are capable of furnishing payload-delivery capabilities superior to those of most multistage, all-rocket launchers. Airbreathing thrust augmentation in the rocket-ejector mode of an RBCC powerplant is noted to make a major contribution to final payload capability, by comparison to nonair-augmented rocket engine propulsion systems.

Foster, Richard W.↗

Nuclear powered Mars cargo transport mission utilizing advanced ion propulsion

Nuclear-powered ion propulsion technology was combined with detailed trajectory analysis to determine propulsion system and trajectory options for an unmanned cargo mission to Mars in support of manned Mars missions. A total of 96 mission scenarios were identified by combining two power levels, two propellants, four values of specific impulse per propellant, three starting altitudes, and two starting velocities. Sixty of these scenarios were selected for a detailed trajectory analysis; a complete propulsion system study was then conducted for 20 of these trajectories. Trip times ranged from 344 days for a xenon propulsion system operating at 300 kW total power and starting from lunar orbit with escape velocity, to 770 days for an argon propulsion system operating at 300 kW total power and starting from nuclear start orbit with circular velocity. Trip times for the 3 MW cases studied ranged from 356 to 413 days. Payload masses ranged from 5700 to 12,300 kg for the 300 kW power level, and from 72,200 to 81,500 kg for the 3 MW power level.

Galecki, Diane L.↗

Nuclear powered Mars cargo transport mission utilizing advanced ion propulsion

Nuclear-powered ion propulsion technology was combined with detailed trajectory analysis to determine propulsion system and trajectory options for an unmanned cargo mission to Mars in support of manned Mars missions. A total of 96 mission scenarios were identified by combining two power levels, two propellants, four values of specific impulse per propellant, three starting altitudes, and two starting velocities. Sixty of these scenarios were selected for a detailed trajectory analysis; a complete propulsion system study was then conducted for 20 of these trajectories. Trip times ranged from 344 days for a xenon propulsion system operating at 300 kW total power and starting from lunar orbit with escape velocity, to 770 days for an argon propulsion system operating at 300 kW total power and starting from nuclear start orbit with circualr velocity. Trip times for the 3 MW cases studied ranged from 356 kW to 413 days. Payload masses ranged from 5700 to 12,300 kg for the 300 kW power level, and from 72,200 to 81, 500 kg for the 3 MW power level.

Galecki, Diane L.↗

2.1.3.404 - WEC Array Power Management and Output Simulation Tool

An array of wave energy converter (WEC) devices has variations in power output due to the chaotic nature of the waves. Eliminating or mitigating the power fluctuations is important for reducing the integration impacts of WEC plants in both distribution and transmission grids, and in standalone isolated power systems. Reduced variability of WEC-generated power in combination with energy storage or power management control at each WEC and at the array level will help increasing hosting capacity of distribution feeders for this type of variable renewable generation, and minimization of electric losses. To reduce risks and risk perception, gain key stakeholder acceptance, and enable developers to design effective and compatible energy plants with arrays of WEC devices, it requires the use of modeling tools to simulate the resource environment, device dynamics, utility power system response, as well as the development of an interface for an array controller. The project will create a publicly accessible numerical modeling framework to empower the wave energy sector to design projects of various scales (kW-100s MW), which are optimized on a plant performance basis and are compatible with different power systems and wave conditions. The framework will integrate with WEC-Sim, a wave environment model (SWAN-FUNWAVE), as well as established relevant electrical analysis tools, to model the grid system and interconnection, and optimize power output and power management for the WEC array.

POWER TRANSMISSION AND DISTRIBUTION,TIDAL AND WAVE↗

The spectrum and pulses of 1E 2259+586 from ASCA and BBXRT observations

The 7 s X-ray pulsator 1E 2259+586 was observed for approximately 1 day in 1993 with the Advanced Satellite for Cosmology and Astrophysics (ASCA). Observations were also obtained with Broad Band X-ray Telescope (BBXRT) in 1990 a few months after Ginga had observed 1E 2259+586 to be brighter than normal and the BBXRT data show 1E 2259+586 to be at an intermediate brightness level. By contrast, the ASCA data appear to have been obtained during a more common lower luminosity state. The pulse profiles we obtain are consistent with a connection between flux and pulse shape reported from Ginga data, and the pulsator continues to spin down. We use our high spectral resolution data to search for cyclotron lines in the spectrum that were claimed from observations made with other satellites. We find that the ASCA spectra of 1E 2259+586 cannot be satisfactorily fitted with either a single power law or a combination of two power laws, and that significant residuals occur around 1.5 and 5 keV. However, a combination of a power law and blackbody gives a good fit over the entire ASCA energy band with no evidence of spectral features. We have reanalyzed a Ginga LAC spectrum and find that this is also significantly better fitted by this two-component spectrum than a single power law. A possible explanation for such a two-component spectrum is that the blackbody emission comes from a neutron star and that the power-law component comes, at least in part, from a surrounding nebula. As there has, so far, no direct evidence that 1E 2259+586 is a binary system we consider whether there are other plausible mechanisms that might power the observed X-ray emission.

Corbet, R. H. D.↗