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Space-based solar power SBSP is the concept of collecting solar power in outer space and distributing it to Earth, distribution electrical paper powe study thesis. Potential advantages of collecting solar energy in space include a higher collection distribution electrical paper powe study thesis and a longer collection period due to the lack of a diffusing atmosphereand the possibility of placing a solar collector in an orbiting location where there is no night, distribution electrical paper powe study thesis.
Space-based solar power systems convert sunlight to microwaves outside the atmosphere, avoiding these losses and the downtime due to the Earth's rotationbut at great cost due to the expense of launching material into orbit.
SBSP is considered a form of sustainable or green energyrenewable energyand is occasionally considered among climate engineering proposals. It is attractive to those seeking large-scale solutions to anthropogenic climate change or fossil fuel depletion such as peak oil. Various SBSP proposals have been researched since the early s, [1] [2] but none are economically viable with present-day space launch infrastructure.
Some technologists speculate that this may change in the distant future if an off-world industrial base were to be developed that could manufacture solar power satellites out of asteroids or lunar material, or if radical new space launch technologies other than rocketry should become available in the future. Besides the cost of implementing such a system, SBSP also introduces several technological hurdles, including the problem of transmitting energy from orbit to Earth's surface for use.
Since wires extending from Earth's surface to an orbiting satellite are neither practical nor feasible with current technology, SBSP designs generally include the use of some manner of wireless power transmission with its concomitant conversion inefficiencies, as well as land use concerns for the necessary antenna stations to receive the energy at Earth's surface. The collecting satellite would convert solar energy into electrical energy on board, powering a microwave transmitter or laser emitter, and transmit this energy to a collector or microwave rectenna on Earth's surface.
Contrary to appearances of SBSP in popular novels and video games, most designs propose beam energy densities that are not harmful if human beings were to be inadvertently exposed, such as if a transmitting satellite's beam were to wander off-course. But the vast size of the receiving antennas that would be necessary would still require large blocks of land near the end users to be procured and dedicated to this purpose.
The service life of space-based collectors in the face of challenges from long-term exposure to the space environment, including degradation from radiation and micrometeoroid damage, could also become a concern for SBSP. SBSP is being actively pursued by Japan, China, [3] Russia, India, the United Kingdom [4] and the US.
InJapan passed its Basic Space Law which established space solar power as a national goal [5] and JAXA has a roadmap to commercial SBSP. Inthe China Academy for Space Technology CAST showcased their roadmap at the International Space Development Conference.
In FebruaryScience and Technology Daily 科技日报, Keji Ribaothe official newspaper of the Ministry of Science and Technology of the People's Republic of Chinareported that construction of a testing base had started in Chongqing's Bishan District. CAST vice-president Li Ming was quoted as saying China expects to be the first nation to build a working space solar power station with practical value. Chinese scientists were reported as planning to launch several small- and medium-sized space power stations between and In May the US Naval Research Laboratory conducted its first test of solar power generation in a satellite.
Inscience fiction writer Isaac Asimov published the science fiction short story " Reason ", in which a space station transmits energy collected from the Sun to various planets using microwave beams. The SBSP concept, originally known as satellite solar-power system SSPSwas first described in November patent number 3, for his method of transmitting power over long distances distribution electrical paper powe study thesis. from an SPS to Earth's surface using microwaves from a very large distribution electrical paper powe study thesis up to one square kilometer on the satellite to a much larger one, now known as a rectennaon the ground.
Glaser then was a vice president at Arthur D. LittleInc. NASA signed a contract with ADL to lead four other companies in a broader study in They found that, while the concept had several major problems — chiefly the expense of putting the required materials in orbit and the lack of experience on projects of this scale in space — it showed enough promise to merit further investigation and research.
Between andthe Congress authorized the Department of Energy DoE and NASA to jointly investigate the concept. They organized the Satellite Power System Concept Development and Evaluation Program.
They include:. The project was not continued with the change in administrations after the US Federal elections. The Office of Technology Assessment concluded that "Too little is currently known about the technical, distribution electrical paper powe study thesis, economic, and environmental aspects of SPS to make a sound decision whether to proceed with its development and deployment. In addition, without further research distribution electrical paper powe study thesis SPS demonstration or systems-engineering verification program would be a high-risk venture.
InNASA conducted its "Fresh Look" study to examine the modern state of SBSP feasibility. In assessing "What has changed" since the DOE study, NASA asserted that the "US National Space Policy now calls for NASA to make significant investments in technology not a particular vehicle to drive the costs of ETO [Earth to Orbit] transportation down dramatically. This is, of course, an absolute requirement of space solar power.
Conversely, Pete Worden of NASA claimed that space-based solar is about five orders of magnitude more expensive than solar power from the Arizona desert, with a major cost being the transportation of materials to orbit. Worden referred to possible solutions as speculative, and which would not be available for decades at the earliest. On November 2,China proposed space collaboration with India that mentioned SBSP, "may be Space-based Solar Power initiative so that both India and China can work for long term association with proper funding along with other willing space faring nations to bring space solar power to earth.
InNASA's Space Solar Power Exploratory Research and Technology program SERT was initiated for the following purposes:. SERT went about developing a solar power satellite SPS concept for a future gigawatt space power system, to provide electrical power by converting the Sun's energy and beaming it to Earth's surface, and provided a conceptual development path that would utilize current technologies, distribution electrical paper powe study thesis.
SERT proposed an inflatable photovoltaic gossamer structure with concentrator lenses or solar heat engines to convert sunlight into electricity, distribution electrical paper powe study thesis. The program looked both at systems in sun-synchronous orbit and geosynchronous orbit. Some of SERT's conclusions:. The May IEEE Spectrum magazine carried a lengthy article "It's Always Sunny in Space" by Susumu Sasaki.
JAXA announced on 12 March that they wirelessly beamed 1. This is the standard plan for this type of power. The SBSP concept is attractive because space has several major advantages over the Earth's surface for the collection of solar power:.
Space-based solar power essentially consists of three elements: [2]. The space-based portion will not need to support itself against gravity other than relatively weak tidal stresses. It needs no protection from terrestrial wind or weather, but will have to cope with space hazards such as micrometeors and solar flares. Two basic methods of conversion have been studied: photovoltaic PV and solar dynamic SD, distribution electrical paper powe study thesis.
Most analyses of SBSP have focused on photovoltaic conversion using solar cells that directly convert sunlight into electricity.
Solar dynamic uses mirrors to concentrate light on a boiler. The use of solar dynamic could reduce mass per watt. Wireless power transmission was proposed early on as a means to transfer energy from collection to the Earth's surface, using either microwave or laser radiation at a variety of frequencies. William C. Brown demonstrated induring Walter Cronkite 's CBS News program, a microwave-powered model helicopter that received all the power it needed for flight from a microwave beam.
Between andBill Brown was technical director of a JPL Raytheon program that beamed 30 kW of power over a distance of 1 mile 1. Microwave power transmission of tens of kilowatts has been well proven by existing tests at Goldstone in California [54] [55] [56] and Grand Bassin on Reunion Island More recently, microwave power transmission has been demonstrated, in conjunction with solar energy capture, distribution electrical paper powe study thesis, between a mountain top in Maui and the island of Hawaii 92 miles awayby a team under John C.
It includes an introduction to SPS, current research and future prospects. Laser power beaming was envisioned by some at NASA as a stepping stone to further industrialization of space. In the s, researchers at NASA worked on the potential use of lasers for space-to-space power beaming, focusing primarily on the distribution electrical paper powe study thesis of a solar-powered laser. Indistribution electrical paper powe study thesis, it was suggested that power could also be usefully beamed by laser from Earth to space.
Inthe SELENE project SpacE Laser ENErgy had begun, which included the study of laser power beaming for supplying power to a lunar base. The SELENE program was a two-year research effort, but the cost of taking the concept to operational status was too high, and the official project ended in before reaching a space-based demonstration.
Inthe use of an Earth-based laser to power an electric thruster for space propulsion was proposed by Grant Logan, with technical details worked out in He proposed using diamond solar cells operating at degrees [ clarification needed ] to convert ultraviolet laser light. The main advantage of locating a space power station in geostationary orbit is that the antenna geometry stays constant, and so keeping the antennas lined up is simpler.
Another advantage is that nearly continuous power transmission is immediately available as soon as the first space power station is placed in orbit, LEO requires several satellites before they are producing nearly continuous power. Power beaming from geostationary orbit by microwaves carries the difficulty that the required 'optical aperture' sizes are very large. For example, distribution electrical paper powe study thesis, the NASA SPS study required a 1-km diameter transmitting antenna, and a 10 km diameter receiving rectenna, for a microwave beam at 2.
These sizes can be somewhat decreased by using shorter wavelengths, although they have increased atmospheric absorption and even potential beam blockage by rain or water droplets. Because of the thinned array curseit is not possible to make a narrower beam by combining the beams of several smaller satellites, distribution electrical paper powe study thesis. The large size of the transmitting distribution electrical paper powe study thesis receiving antennas means that the minimum practical power level for an SPS will necessarily be high; small SPS systems will be possible, but uneconomic.
A collection of LEO Low Earth Orbit space power stations has been proposed as a precursor to GEO Geostationary Orbit space-based solar power. The Earth-based rectenna would likely consist of many short dipole antennas connected via diodes. Rectennas would likely be several kilometers across.
A laser SBSP could also power a base or vehicles on the surface of the Moon or Mars, saving on mass costs to land the power source. A spacecraft or another satellite could also be powered by the same means. In a report presented to NASA on space solar power, the author mentions another potential use for the technology behind space solar power could be for distribution electrical paper powe study thesis electric propulsion systems that could be used for interplanetary human exploration missions.
One problem for the SBSP concept is the cost of space launches and the amount of material that would need to be launched. Much of the material launched need not be delivered to its eventual orbit immediately, distribution electrical paper powe study thesis, which raises the possibility that high efficiency but slower engines could move SPS material from LEO to GEO at an acceptable cost.
Examples include ion thrusters or nuclear propulsion. To give an idea of distribution electrical paper powe study thesis scale of the problem, assuming a solar panel mass of 20 kg per kilowatt without considering the mass of the supporting structure, antenna, or any significant mass reduction of any focusing mirrors a 4 GW power station would weigh about 80, metric tons[69] all of which would, in current circumstances, be launched from the Earth.
Beyond the mass of the panels, overhead including boosting to the desired orbit and stationkeeping must be distribution electrical paper powe study thesis. To these costs must be added the environmental impact of heavy space launch missions, if such costs are to be used in comparison to earth-based energy production.
Gerard O'Neillnoting the problem of high launch costs in the early s, proposed building the SPS's in orbit with materials from the Moon. This s proposal assumed the then-advertised future launch costing of NASA's space shuttle.
This approach would require substantial up front capital investment to establish mass drivers on the Moon. Inwhen it became obvious NASA's launch cost estimates for the space shuttle were grossly optimistic, O'Neill et al. published another route to manufacturing using lunar materials with much lower startup costs. The high net energy gain of this proposal derives from the Moon's much shallower gravitational well. Having a relatively cheap per pound source of raw materials from space would lessen the concern for low mass designs and result in a different sort of SPS being built.
The low cost per pound of lunar materials in O'Neill's vision would be supported by using lunar material to manufacture more facilities in orbit than just solar power satellites. Advanced techniques for launching from the Moon may reduce the cost of building a solar power satellite from lunar materials. Some proposed techniques include the lunar mass driver and the lunar space elevatorfirst described by Jerome Pearson, distribution electrical paper powe study thesis.
Single line diagram in Hindi -- भाग-1 -- Transmission and Distribution of Electrical Power
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