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An artist's depiction of a solar satellite, which could send energy wirelessly to a space vessel or planetary surface.

A solar power satellite, or SPS or Powersat, as originally proposed would be a satellite built in high Earth orbit that uses microwave power transmission to beam solar power to a very large antenna on Earth. Advantages of placing the solar collectors in space include the unobstructed view of the Sun, unaffected by the day/night cycle, weather, or seasons^[1]. It is a renewable energy source, zero emission, and generates no waste. However, the costs of construction are very high, and SPS will not be able to compete with conventional sources (at current energy prices) unless at least one of the following conditions is met: Image File history File links Sustainable_development. ... Image File history File links Download high resolution version (1024x768, 191 KB)The Sun Tower in Vancouver, British Columbia. ... Image File history File links Download high resolution version (1024x768, 191 KB)The Sun Tower in Vancouver, British Columbia. ... It has been suggested that Power beaming be merged into this article or section. ... For other uses, see Satellite (disambiguation). ... Highly Elliptical Orbit (HEO) (often incorrectly referred to as the Molniya orbit after the former Soviet communications satellite network which used a HEO orbit) is a satelite orbit characterized by a relatively low-altitude perigee and an extremely high-altitude apogee. ... This article does not cite any references or sources. ... Solar power from a parabolic reflector. ... A yagi antenna Most simply, an antenna is an electronic component designed to send or receive radio waves. ... A laundromat in California with solar collectors on the roof. ... Sol redirects here. ... Renewable energy effectively utilizes natural resources such as sunlight, wind, tides and geothermal heat, which are naturally replenished. ... Zero emission refers to an engine, motor, or other energy source, that emits no waste products that pollutes the environment or disrupts the climate. ... The following articles relate to the price of energy: Energy crisis The Price of Oil and The Economy Hubbert peak theory (peak oil) Energy economics Electricity market Categories: | ...

• Low launch costs can be achieved
• A space-based manufacturing industry develops that is capable of building solar power satellites in orbit, using off-Earth materials
• Conventional energy costs increase
• A determination is made that the disadvantages of fossil fuel use are so large they must be substantially replaced.

In addition such a system could potentially have advantages to a nation in terms of national self-sufficiency and some reduction in levels of conflict, military spending, and loss of life. Two bodies with a slight difference in mass orbiting around a common barycenter. ... The following articles relate to the price of energy: Energy crisis The price of oil and the economy Hubbert peak theory (peak oil) Energy economics Electricity market Categories: | ... Global warming refers to the increase in the average temperature of the Earths near-surface air and oceans in recent decades and its projected continuation. ... Fossil fuels or mineral fuels are hydrocarbons found within the top layer of the earth’s crust. ...

History

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An artist's concept of a solar power satellite, 1976. (NASA)

The SPS concept was first described in November 1968 ^[2]. At first it was regarded as impractical due to the lack of a workable method of sending power collected down to the Earth's surface. This changed in 1973 when Peter Glaser was granted U.S. patent number 3,781,647 ^[3] for his method of transmitting power to aver long distances (eg, from an SPS to the Earth's surface) using microwaves from a, perhaps square kilometer, antenna on the satellite to a much larger one on the ground, which came to be known as a rectenna.[1] Image File history File links Broom_icon. ... Prose is writing distinguished from poetry by its greater variety of rhythm and its closer resemblance to the patterns of everyday speech. ... Image File history File links Size of this preview: 755 × 600 pixel Image in higher resolution (3020 × 2400 pixel, file size: 6. ... Image File history File links Size of this preview: 755 × 600 pixel Image in higher resolution (3020 × 2400 pixel, file size: 6. ... Dr. Peter Glaser, creator of the Solar Power Satellite concept Photo courtesy National Space Society Dr. Peter Glaser, Vice President, Advanced Technology (retired), was associated with Arthur D. Little, Inc. ... This article is about the type of Electromagnetic radiation. ... A rectenna is a rectifying antenna, a special type of antenna that is used to directly convert microwave energy into DC electricity. ...

Glaser then worked at Arthur D. Little, Inc., as a vice-president. NASA became interested and signed a contract with ADL to lead four other companies in a broader study in 1974. 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 ^[1]. Arthur D. Little, Inc. ...

During the period from 1978 - 1981 the US Congress authorized DOE and NASA to jointly investigate. They organized the Satellite Power System Concept Development and Evaluation Program ^[4][5]. The study remains the most extensive performed to date. Several reports were published addressing various issues, together investigating most of the possible problems with such an engineering project. They include: Doe is the term used for the females of various species of animal, including: some species of deer rabbits In job and classified ads, DOE is an acronym for Depending On Experience and usually indicated in pay rates. ... This article is about the American space agency. ...

• Resource Requirements (Critical Materials, Energy, and Land)^[6]
• Financial/Management Scenarios^[7][8]
• Public Acceptance^[9]
• State and Local Regulations as Applied to Satellite Power System Microwave Receiving Antenna Facilities^[10]
• Student Participation^[11]
• Potential of Laser for SPS Power Transmission^[12]
• International Agreements^[13][14]
• Centralization/Decentralization^[15]
• Mapping of Exclusion Areas For Rectenna Sites^[16]
• Economic and Demographic Issues Related to Deployment^[17]
• Some Questions and Answers^[18]
• Meteorological Effects on Laser Beam Propagation and Direct Solar Pumped Lasers^[19]
• Public Outreach Experiment^[20]
• Power Transmission and Reception Technical Summary and Assessment ^[21]
• Space Transportation^[22]
• Office of Technology Assessment^[23]

After these studies were published, there was no follow up work and the concept dwindled. The DOE study conclusions were critical of the project's possibilities. Confusing press reports widely reported that the concept had been demonstrated to be infeasible ^[24].

More recently, the SPS concept has again become interesting, due to increased energy demand, increased costs, and emission implications, and starting in 1997 with the NASA "Fresh Look"^[25] however funding is still minimal.

In 2007, the US Department of Defense expressed interest in the concept^[26].

At some cost point, the high initial costs of an SPS project will become favourable due to the low-cost delivery of power. By some estimates, this has already happened in some locations, as a result of the widely varying costs of electricity which sometimes approach (or even exceed) this point. In addition, continued advances in material science and space transport continue to whittle away at the startup cost of an SPS.^[27]

Description

The SPS essentially consists of three parts: Image File history File links Download high-resolution version (2024x1320, 718 KB)http://www. ... Image File history File links Download high-resolution version (2024x1320, 718 KB)http://www. ...

1. a solar collector, typically made up of solar cells
2. a microwave antenna on the satellite, aimed at Earth
3. one or more paired, and much larger, antennas (rectennas) on the Earth's surface

A solar cell, made from a monocrystalline silicon wafer A solar cell or photovoltaic cell is a device that converts light energy into electrical energy. ...

Spacecraft design

In many ways, the SPS is a simpler conceptual design than most power generation systems previously proposed. The simple aspects include the physical structure required to hold the SPS together and to align it orthogonally to the Sun. This will be considerably lighter than any similar structure on Earth since it will be in a zero-g, vacuum environment and will not need to support itself against a gravity field and needs no protection from terrestrial wind or weather. Itaipu Dam is a hydroelectric generating station Electricity generation is the first process in the delivery of electricity to consumers. ... In mathematics, orthogonal is synonymous with perpendicular when used as a simple adjective that is not part of any longer phrase with a standard definition. ... Zero G is the pseudonym of an elite hacker rumored to be female and a child prodigy of MIT. Zero G emerged in the late 1990s. ... Look up Vacuum in Wiktionary, the free dictionary. ...

Solar photons will be converted to electricity aboard the SPS spacecraft, and that electricity will be fed to an array of Klystron tubes which will generate the microwave beam. In physics, the photon (from Greek φως, phōs, meaning light) is the quantum of the electromagnetic field; for instance, light. ... Electricity (from New Latin ēlectricus, amberlike) is a general term for a variety of phenomena resulting from the presence and flow of electric charge. ... The Space Shuttle Discovery as seen from the International Space Station. ... Reflex klystron Type 2K25 or 723 A/B. The threaded adjustment rod on the right side allows the position of the reflector to be adjusted (by compressing the reflex cavity), and thus the natural resonant frequency of the device. ...

Solar energy conversion (Photons to DC)

Two methods of converting photons to electricity have been studied, Solar Dynamic (SD) and Photovoltaic (PV). Solar thermal energy is a technology for harnessing solar energy for practical applications from solar heating to electrical power generation. ... A solar cell, a form of photovoltaic cell, is a device that uses the photoelectric effect to generate electricity from light, thus generating solar power (energy). ...

SD uses a heat engine to drive a piston or a turbine which connects to a generator or dynamo. Two heat cycles for Solar Dynamic are thought to be reasonable for this: Brayton Cycle or Stirling Cycle. Solar Dynamic systems typically use a large reflector to focus sunlight to a high concentration to achieve a high temperature so the heat engine can operate at very high efficiency. ^[28] A heat engine is a physical or theoretical device that converts thermal energy to mechanical output. ... For the use of the term in optics, see piston (optics). ... A Siemens steam turbine with the case opened. ... This article is about machines that produce electricity. ... Dynamo, or Dinamo, may refer to: Dynamo, an electrical generator Dynamo (sports society) of the Soviet Union Operation Dynamo, the 1940 mass evacuation at Dunkirk Dynamo, the rock band based in Belfast Dynamo theory, a theory relating to magnetic fields of celestial bodies Dynamo Open Air, annual heavy metal music... The Brayton cycle is a constant-pressure cycle named after George Brayton (1830–1892), the American engineer who developed it. ... The Stirling engine is a type of hot air engine, invented in 1816 by the Rev. ... A reflector can mean one of several things: a reflecting telescope a device or a part of an antenna that reflects radio waves a device that causes reflection, for example, a mirror or a retroreflector a 1981 album by Pablo Cruise In LAPACK the term reflector with the types block... Look up focus in Wiktionary, the free dictionary. ... For other uses, see Temperature (disambiguation). ...

PV uses semiconductors (e.g., Silicon or Gallium Arsenide) to directly convert sunlight photons into electric potential. These are commonly known as “Solar cells”, and will likely be rather different from the glass panel protected semiconductors in familiar panels in current use. They will, for reasons of weight, probably be built onto membranes. A semiconductor is a material that is an insulator at very low temperature, but which has a sizable electrical conductivity at room temperature. ... Not to be confused with Silicone. ... This article is about the chemical compound. ... This article does not cite any references or sources. ... A solar cell, a form of photovoltaic cell, is a device that uses the photoelectric effect to generate electricity from light, thus generating solar power (energy). ...

Comparison of PV versus SD

The main problems with PV are that PV cells are relatively expensive, and require a relatively large area to be acceptable. In addition, being semiconductors, the PV panels will require a reasonably large amount of energy to produce. PV can refer to // Periventricular nucleus of the hypothalamus Poliovirus Pathovar, a classification scheme for bacteria The product of pressure and volume, such as in the ideal gas equation PV=nRT The present value of money. ...

SD has a much more severe pointing requirement than PV because most proposed designs require accurate and stable optical focus. If a PV array drifts off a few degrees, the power being produced will drop a few percent. But, if a SD array drifts off a few degrees, the power produced will drop off very quickly to zero, or near to it. An image that is partially in focus, but mostly out of focus in varying degrees. ...

Currently, PV cells weigh between 0.5kg/kW^[29] and 10kg/kW depending on design. SD designs also vary but most seem to be heavier per kW produced than PV cells and thus this pushes up launch costs.

Lifetime

The lifetime of a PV based SPS is limited mainly by the ionizing radiation from the radiation belts and the Sun. Without some method of protection, this is likely to cause the cells to continuously degrade by about a percent or two per year. Deterioration is likely to be more rapid during periods of high exposure to energetic protons from solar particle events^[30]. If some practical protection can be designed, this also might be reducible. Radiation hazard symbol. ... Van Allen belts The Van Allen radiation belt is a torus of energetic charged particles around Earth, trapped by Earths magnetic field. ...

Lifetimes for SD based SPS designs will be limited by structural and mechanical considerations, such as micrometeorite impact, metal fatigue of turbine blades, wear of sliding surfaces (although this might be avoidable by hydrostatic bearings or magnetic bearings), and degradation or loss off lubricants and working fluids in vacuum and from temperature extremes. As well, the mirror surface will degrade from both radiation^{[citation needed]} and particles, but such mirrors can be designed simply, so that replacement is practical. This article is about a computer game. ... In materials science, wear is the erosion of material from a solid surface by the action of another solid. ... Fluid bearings, also called fluid dynamic bearings or hydrostatic or gas bearings, are bearings which support load on a thin layer of liquid or gas. ... A magnetic bearing is a bearing which supports a load using magnetic levitation. ... A lubricant (colloquially, lube) is a substance introduced between two moving surfaces to reduce the friction and wear between them. ... A subset of the phases of matter, fluids include liquids and gases, plasmas and, to some extent, plastic solids. ... Look up Vacuum in Wiktionary, the free dictionary. ...

In either case, another advantage of the SPS design is that waste heat is re-radiated back into space, instead of warming the adjacent local biosphere as with conventional sources; thus thermal efficiency will not be in itself an important design parameter except insofar as it affects the power/weight ratio and hence pushes up launch costs. (For example SD may require larger radiators if a lower efficiency is obtained). Earth based power handling systems must always be carefully designed, for both economic and purely engineering reasons, with thermal efficiency in mind. Waste heat is the by-product heat of machines and technical processes for which no useful application is found. ... For other uses, see Biosphere (disambiguation). ...

Energy payback

Clearly for a system (including manufacture, launch and deployment) to provide net power it must repay the energy needed to construct it. For current silicon PV panels the energy needs are relatively high, and typically several years of deployment in a terrestrial environment is needed to recover this energy.^{[31][32][31][33]} With SPS net energy received on the ground is higher (more or less necessarily so, for the system to be worth deploying), so this energy payback period would be somewhat reduced; however SD, being made of conventional materials, are more similar to conventional powerstations and are likely to be less energy intensive and would be expected to give quicker energy breakeven, depending on construction technology.

Power Transmission (DC to photons)

Wireless power transmission was early proposed to transfer energy from collection to the Earth's surface. The power could be transmitted as either microwave or laser radiation at a variety of frequencies depending on system design. Whatever choice is made, the transmitting radiation would have to be non-ionizing to avoid potential disturbances either ecologically or biologically if it is to reach the Earth's surface. This established an upper bound for the frequency used, as energy per photon, and so the ability to cause ionization, increases with frequency. Ionization of biological materials doesn't begin until ultraviolet or higher frequencies so most radio frequencies will be acceptable for this. Wireless energy transfer is wireless transfer of electromagnetic energy via electromagnetic induction. ...

As well, to minimize the sizes of the antennas used, the wavelength should be small (and frequency correspondingly high) since antenna efficiency increases as antenna size increases. But, higher radio frequencies are typically more absorbed in the atmosphere than lower radio frequencies.

For these reasons, 2.45 GHz has been proposed as being the most reasonable compromise. However, that frequency results in large antenna sizes at the GEO distance. A loitering stratospheric airship has been proposed to receive higher frequencies (or even laser beams), converting them to something like 2.45GHz for retransmission to the ground. The proposal has not been as carefully evaluated for engineering plausibility as other aspects of SPS design.

Spacecraft sizing

The sizing will be dominated by the distance from Earth to geostationary orbit (22,300 miles, 35,700 km), the chosen wavelength of the microwaves, and the laws of physics, specifically the Rayleigh Criterion or Diffraction limit, used in standard RF (Radio Frequency) antenna design. Geostationary orbit A geostationary orbit (GEO) is a geosynchronous orbit directly above the Earths equator (0° latitude), with orbital eccentricity of zero. ... Resolving power is the ability of a microscope or telescope to measure the angular separation of images that are close together. ... The intensity pattern formed on a screen by diffraction from a square aperture Diffraction refers to various phenomena associated with wave propagation, such as the bending, spreading and interference of waves passing by an object or aperture that disrupts the wave. ... RF may mean: RF, the IATA code for Florida West International Airways RF, NYSE ticker symbol for Regions Financial Corporation Royalty free Rf or RF may stand for: Radio frequency Volumetric flow rate/rate of flow (Rf) RF connectors, electrical connectors designed to work at radio frequencies Red Faction, a... It has been suggested that this article or section be merged with Radio waves. ... A Yagi-Uda beam antenna Short Wave Curtain Antenna (Moosbrunn, Austria) A building rooftop supporting numerous dish and sectored mobile telecommunications antennas (Doncaster, Victoria, Australia) An antenna is a transducer designed to transmit or receive radio waves which are a class of electromagnetic waves. ...

For best efficiency, the satellite antenna should be circular and about 1 kilometers in diameter or larger; the ground antenna (rectenna) should be elliptical and around 14 kilometers by 10 kilometers. Smaller antennas would result in increased losses to diffraction/sidelobes. For the desired (23mW/cm²) microwave intensity ^[34] these antennas could transfer between 5 and 10 gigawatts of power. To be most cost effective, the system needs to operate at maximum capacity. And, to collect and convert that much power, the satellite would need between 50 and 100 square kilometers of collector area (if readily available ~14% efficient monocrystalline silicon solar cells were deployed). State of the art (currently, quite expensive, triple junction gallium arsenide) solar cells with a maximum efficiency of 40.7% ^[35] could reduce the necessary collector area by two thirds, but would not necessarily give overall lower costs. In either cases, the SPS's structure would be kilometers wide, making it larger than most man-made structures here on Earth. While almost certainly not beyond current engineering capabilities, building structures of this size in orbit has not yet been attempted. U.S. military MILSTAR communications satellite A communications satellite (sometimes abbreviated to comsat) is an artificial satellite stationed in space for the purposes of telecommunications using radio at microwave frequencies. ... A circular may be: the adjective form of circle an advertisement which is circulated a Pastoral letter, Encyclic, or Papal bull that is circulated between churches a circular argument is a term for a type of logical fallacy where the very thing that is trying to be proved is assumed... A kilometre (American spelling: kilometer) (symbol: km) is a unit of length equal to 1000 metres (from the Greek words khilia = thousand and metro = count/measure). ... DIAMETER is a computer networking protocol for AAA (Authentication, Authorization and Accounting). ... A rectenna is a rectifying antenna, a special type of antenna that is used to directly convert microwave energy into DC electricity. ... Elliptical may refer to: Ellipse: a shape and mathematical construct Elliptical trainer: an exercise machine This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... The intensity pattern formed on a screen by diffraction from a square aperture Diffraction refers to various phenomena associated with wave propagation, such as the bending, spreading and interference of waves passing by an object or aperture that disrupts the wave. ... In antenna engineering, the parts of the radiation pattern that are not the main lobe. ... 1000000000 Watts ... A solar cell, made from a monocrystalline silicon wafer A solar cell or photovoltaic cell is a device that converts light energy into electrical energy. ... A solar cell, made from a monocrystalline silicon wafer A solar cell or photovoltaic cell is a device that converts light energy into electrical energy. ...

LEO/MEO instead of GEO

A LEO system of space power stations has been proposed as a precursor to GEO space power beaming system(s)^[36]. There would be advantages, (much shorter path length allowing smaller antenna sizes, lower cost to orbit) and disadvantages (constantly changing antenna geometries, increased debris collision difficulties, etc). It might be possible to deploy LEO systems sooner than GEO because the antenna development would take less time. Ultimately, because full engineering feasibility studies have not been conducted, it is not known whether this would be an improvement over a GEO installation.

Earth based infrastructure

The Earth-based receiver antenna (or rectenna) is a critical part of the original SPS concept. It would probably consist of many short dipole antennas, connected via diodes. Microwaves broadcast from the SPS will be received in the dipoles with about 85% efficiency^[37]. With a conventional microwave antenna, the reception efficiency is still better, but the cost and complexity is also considerably greater, almost certainly prohibitively so. Rectennas would be multiple kilometers across. Crops and farm animals may be raised underneath a rectenna, as the thin wires used for support and for the dipoles will only slightly reduce sunlight, so such a rectenna would not as expensive in terms of land use as might be supposed. A rectenna is a rectifying antenna, a special type of antenna that is used to directly convert microwave energy into DC electricity. ... The Earths magnetic field, which is approximately a dipole. ... Closeup of the image below, showing the square shaped semiconductor crystal various semiconductor diodes, below a bridge rectifier Structure of a vacuum tube diode In electronics, a diode is a two-terminal component, almost always one that has electrical properties which vary depending on the direction of flow of charge...

Advantages of an SPS

The SPS concept is attractive because space has several major advantages over the Earth's surface for the collection of solar power. There is no air in space, so the collecting surfaces would receive much more intense sunlight, unaffected by weather. In geostationary orbit, an SPS would be illuminated over 99% of the time. The SPS would be in Earth's shadow on only a few days at the spring and fall equinoxes; and even then for a maximum of an hour and a half late at night^{[citation needed]} when power demands are at their lowest^{[citation needed]}. This allows the power generation system to avoid the expensive storage facilities (eg, lakes behind dams, oil storage tanks, etc) necessary in many Earth-based power generation systems. Additionally, an SPS will avoid entirely the polluting consequences of fossil fuel systems, the ecological problems resulting from many renewable or low impact power generation systems (eg, dams). Geostationary orbit A geostationary orbit (GEO) is a geosynchronous orbit directly above the Earths equator (0° latitude), with orbital eccentricity of zero. ... For other uses, see Equinox (disambiguation). ...

More long-term, the potential amount of power production is enormous. If power stations can be placed outside Earth orbit, the upper limit is vastly higher still. In the extreme, such arrangements are called Dyson spheres. A cut-away diagram of an idealized Dyson shell—a variant on Dysons original concept—1 AU in radius. ...

Problems

Launch costs

Without doubt, the most obvious problem for the SPS concept is the currently immense cost of space launches. Current rates on the Space Shuttle run between $3,000 and $5,000 per pound ($6,600/kg and $11,000/kg) to low Earth orbit, depending on whose numbers are used. Calculations show that launch costs of less than about $180-225 per pound ($400-500/kg) to LEO (Low Earth orbit) seem to be necessary. NASAs Space Shuttle, officially called Space Transportation System (STS), is the United States governments current manned launch vehicle. ... A low Earth orbit (LEO) is an orbit in which objects such as satellites are below intermediate circular orbit (ICO) and far below geostationary orbit, but typically around 350 - 1400 km above the Earths surface. ...

However, economies of scale for expendable vehicles could give rather large reductions in launch cost for this kind of launched mass. Thousands of rocket launches could very well reduce the costs by ten to twenty times, using standard costing models. This puts the economics of an SPS design into the practicable range.^[38] Reusable vehicles could quite conceivably attack the launch problem as well, but are not a well developed technology. The increase in output from Q to Q2 causes a decrease in the average cost of each unit from C to C1. ...

Much of the material launched need not be delivered to its eventual orbit immediately, which raises the possibility that high efficiency (but slower) engines could move SPS material from LEO to GEO at acceptable cost. Examples include ion thrusters or nuclear propulsion. They might even be designed to be reusable. An ion engine test This article focuses on electrostatic ion thrusters - for a more general description, refer to electric propulsion. ... Nuclear propulsion can include a wide variety of methods, the commonality of which is the use of some form of nuclear reaction as their primary power source. ...

Power beaming from geostationary orbit by microwaves has the difficulty that the required 'optical aperture' sizes are very large. For example, the 1978 NASA SPS study required a 1-km diameter transmitting antenna, and a 10 km diameter receiving rectenna, for a microwave beam at 2.45 GHz. 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 curse, it is not possible to make a narrower beam by combining the beams of several smaller satellites. The large size of the transmitting and receiving antennas means that the minimum practical power level for a SSPS will necessarily be high; small SPS systems will be possible, but uneconomic. Geostationary orbit A geostationary orbit (GEO) is a geosynchronous orbit directly above the Earths equator (0° latitude), with orbital eccentricity of zero. ... The thinned array curse (sometimes, sparse array curse) is a theorem in electromagnetic theory of transmitters. ...

To give an idea of the scale of the problem, assuming an (arbitrary, as no space ready design has been adequately tested) 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 80,000 metric tons, all of which would, in current circumstances, be launched from the Earth. Very lightweight designs could likely achieve 1 kg/kW,^[39], meaning 4000 metric tons for the solar panels for the same 4 GW capacity station. This would be the equivalent of between 40 and 80 HLLV launches to send the material to low earth orbit, where it would likely be converted into subassembly solar arrays, which then could use high efficiency ion-engine style rockets to (slowly) reach GEO (Geostationary orbit). With an estimated serial launch cost for shuttle-based HLLVs of $500 million to $800 million, total launch costs would range between $20 billion (low cost HLLV, low weight panels) and $320 billion ('expensive' HLLV, heavier panels). Economies of scale on such a large launch program could be as high as 90% (if a learning factor of 30% could be achieved for each doubling of production) over the cost of a single launch today. On addition, there would be the cost of an assembly area in LEO (which could be spread over several power satellites), and probably one or more smaller one(s) in GEO. The costs of these supporting efforts would also contribute to total costs. Geostationary orbit A geostationary orbit (GEO) is a geosynchronous orbit directly above the Earths equator (0° latitude), with orbital eccentricity of zero. ...

So how much money could an SPS be expected to make? For every one gigawatt rating, current SPS designs will generate 8.75 terawatt-hours of electricity per year, or 175 TW•h over a twenty year lifetime. With current market prices of $0.22 per kW•h (UK, January 2006) and an SPS's ability to send its energy to places of greatest demand (depending on rectenna siting issues), this would equate to $1.93 billion per year or $38.6 billion over its lifetime. The example 4 GW 'economy' SPS above could therefore generate in excess of $154 billion over its lifetime. Assuming facilities are available, it may turn out to be substantially cheaper to recast on-site steel in GEO, than to launch it from Earth. If true, then the initial launch cost could be spread over multiple SPS lifespans. The terawatt hour (TW·h) is a unit for measuring energy. ...

Extraterrestrial Materials

Gerard O'Neill, noting the problem of high launch costs in the early 1970s, proposed building the SPS's in orbit with materials from the Moon.^[40] Launch costs from the Moon are about 100 times lower than from Earth, due to the lower gravity. This 1970s 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. Gerard Kitchen ONeill (1927 - 1992) was a U.S. physicist and space pioneer. ... This article is about Earths moon. ... Gravity is a force of attraction that acts between bodies that have mass. ... A mass driver for lunar launch (artists conception) A mass driver or electromagnetic catapult is a method of spacecraft propulsion that would use a linear motor to accelerate payloads up to high speeds. ...

Nevertheless, on 30 April 1979, the Final Report ("Lunar Resources Utilization for Space Construction") by General Dynamics' Convair Division, under NASA contract NAS9-15560, concluded that use of lunar resources would be cheaper than terrestrial materials for a system of as few as thirty Solar Power Satellites of 10GW capacity each.^[41] is the 120th day of the year (121st in leap years) in the Gregorian calendar. ... Also: 1979 by Smashing Pumpkins. ...

In 1980, when 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 ^[42] This 1980s SPS concept relied less on human presence in space and more on partially self-replicating systems on the lunar surface under telepresence control of workers stationed on Earth. Again, this proposal suffers from the current lack of such automated systems, on Earth much less on the Moon. Telepresence refers to a set of technologies which allow a person to feel as if they were present, to give the appearance that they were present, or to have an effect, at a location other than their true location. ...

Asteroid mining has also been seriously considered. A NASA design study^[43]evaluated a 10,000 ton mining vehicle (to be assembled in orbit) that would return a 500,000 ton asteroid 'fragment' to geostationary orbit. Only about 3000 tons of the mining ship would be traditional aerospace-grade payload. The rest would be reaction mass for the mass-driver engine; which could be arranged to be the spent rocket stages used to launch the payload. Assuming, likely unrealistically, that 100% of the returned asteroid was useful, and that the asteroid miner itself couldn't be reused, that represents nearly a 95% reduction in launch costs. However, the true merits of such a method would depend on a thorough mineral survey of the candidate asteroids; thus far, we have only estimates of their composition. There has been no such survey. Once built, NASA's CEV should be capable of beginning such a survey, Congressional money and imagination permitting. 433 Eros is a stony asteroid in a near-Earth orbit Raw resources and minerals could be mined from an asteroid in space using a variety of methods. ... CEV with lunar lander CEV during a landing on earth CEV rocket, the Crew Launch Vehicle (CLV) (right) along side the heavy-lift Cargo Launch Vehicle (CaLV) rocket. ...

Space Elevator

More recently the SPS concept has been suggested as a use for a space elevator. The elevator would make construction of an SPS considerably less expensive, possibly making them competitive with conventional sources. However it appears unlikely that even recent advances in materials science, namely carbon nanotubes, can reduce the price of construction of the elevator enough in the short term. That is, even if a space elevator is ever possible. A space elevator would consist of a cable anchored to the Earths surface, reaching into space. ... 3D model of three types of single-walled carbon nanotubes. ...

Safety

The use of microwave transmission of power has been the most controversial issue in considering any SPS design, but any thought that anything which strays into the beam's path will be incinerated is an extreme misconception. Consider that quite similar microwave relay beams have long been in use by telecommunications companies world wide without such problems. This article does not cite any references or sources. ...

At the earth's surface, a suggested microwave beam would have a maximum intensity, at its center, of 23 mW/cm2 (less than l/4 the solar irradiation constant), and an intensity of less than 1 mW/cm2 outside of the rectenna fenceline^[34] (10 mW/cm2 is the current United States maximum microwave exposure standard). At present, per OSHA, ^[44], the workplace exposure limit (10 mW/sq. cm.) is expressed in voluntary language and has been ruled unenforceable for Federal OSHA enforcement. If you are searching for the organization, click OSHA. Osha (Ligusticum porteri) is a perennial herb used for its medicinal properties. ...

The beam's most intense section (more or less, at its center) is far below dangerous levels even for an exposure which is prolonged indefinitely. ^[45] Furthermore, exposure to the center of the beam can easily be controlled on the ground (eg, via fencing), and typical aircraft flying through the beam provide passengers with a protective shell metal (ie, a Faraday Cage), which will intercept the microwaves. Other aircraft (balloons, ultra-light, etc) can avoid exposure by observing airflight control spaces, as is currently done for military and other controlled airspace. Over 95% of the beam energy will fall on the rectenna. The remaining microwave energy will be absorbed and dispersed well within standards currently imposed upon microwave emissions around the world.^[46] Entrance to a Faraday room A Faraday cage or Faraday shield is an enclosure formed by conducting material, or by a mesh of such material. ... For other uses, see Balloon (disambiguation). ...

The microwave beam intensity at ground level in the center of the beam would be designed and physically built into the system; simply, the transmitter would be too far away and too small to be able to increase the intensity to unsafe "death ray" levels, even in principle.

In addition, a design constraint is that the microwave beam must not be so intense as to avoid injury to wildlife, particularly birds. Experiments with deliberate microwave irradiation at reasonable levels have failed to show negative effects even over multiple generations. ^[47]

Some have suggested locating rectennas offshore ^[48][49], but this presents serious problems, including corrosion, mechanical stresses, biological contamination, ...

A commonly proposed approach to ensuring fail-safe beam targeting is to use a retrodirective phased array antenna/rectenna. A "pilot" microwave beam emitted from the center of the rectenna on the ground establishes a phase front at the transmitting antenna. There, circuits in each of the antenna's subarrays compare the pilot beam's phase front with an internal clock phase to control the phase of the outgoing signal. This forces the transmitted beam to be centered precisely on the rectenna and to have a high degree of phase uniformity; if the pilot beam is lost for any reason (if the transmitting antenna is turned away from the rectenna, for example) the phase control value fails and the microwave power beam is automatically defocused.^[50] Such a system would be physically incapable of focusing its power beam anywhere that did not have a pilot beam transmitter. For the ultrasonic and medical imaging application, see phased array ultrasonics. ...

It is important for system efficiency that as much of the microwave radiation as possible be focused on the rectenna. Outside of the rectenna, microwave intensities would rapidly decrease, so nearby towns or other human activity should be completely unaffected.^[50]

The long-term effects of beaming power through the ionosphere in the form of microwaves has yet to be studied, but nothing has been suggested which might lead to any significant effect.

Defending solar power satellites

Solar power satellites would normally be at a high orbit that is difficult to reach, and hence attack.

However, it has been suggested that a large enough quantity of granular material placed in a retrograde orbit at the geostationary altitude could theoretically completely destroy these kinds of system and render that orbit useless for generations.

Whether this is a realistic attack scenario is arguable, and in any case at the present time there is only a small list of countries with the necessary launch capability to do this, such an attack would probably be considered an act of war, and conventional power generators are more easily attacked.

SPS's economic feasibility

Current energy price landscape

In order to be competitive on a purely economic level, an SPS must cost no more than existing supplies. This may be difficult, especially if it is deployed for North America, where energy costs have been relatively low. It must cost less to deploy, or operate for a very long period of time, or offer other advantages. Many proponents have suggested that the lifetime is effectively infinite, but normal maintenance and replacement of less durable components makes this unlikely. Satellites do not, in our now-extensive experience, last forever.

Current prices for electricity on the public grid fluctuate depending on time of day, but typical household delivery costs about 5 cents per kilowatt hour in North America. If the lifetime of an SPS is 20 years and it delivers 5 gigawatts to the grid, the commercial value of that power is 5,000,000,000 / 1000 = 5,000,000 kilowatts, which multiplied by $.05 per kW•h gives $250,000 revenue per hour. $250,000 × 24 hours × 365 days × 20 years = $43,800,000,000. By contrast, in the United Kingdom (October 2005) electricity can cost 9–22 cents per kilowatt hour. This would translate to a lifetime output of $77–$193 billion for power delivered to the UK. Look up grid in Wiktionary, the free dictionary. ... ¢ c A United States cent, or 1¢ or a penny In currency, the cent is a monetary unit that equals 1/100 of various countries basic monetary units. ... The kilowatt-hour (symbol: kW·h) is a unit for measuring energy. ... 1000000000 Watts ... United States one-dollar bill Canadian one-dollar coin (Loonie) One New Taiwan dollar Australian one-dollar coin 500 old Zimbabwean dollars The dollar (often represented by the dollar sign: $) is the name of the official currency in several countries, dependencies and other regions. ... The watt-hour (symbol W·h (US) Wh (Rest of World)) is a unit of energy. ... Look up revenue in Wiktionary, the free dictionary. ... One thousand million (1,000,000,000) is the natural number following 999,999,999 and preceding 1,000,000,001. ...

Comparison with fossil fuels

The relatively low price of energy today is entirely dominated by the low cost of carbon based fossil fuels (eg, petroleum (crude oil), coal and natural gas. For other uses, see Carbon (disambiguation). ... Fossil fuels are hydrocarbon-containing natural resources such as coal, petroleum and natural gas. ... Pumpjack pumping an oil well near Lubbock, Texas Ignacy Łukasiewicz - inventor of the refining of kerosene from crude oil. ... Pumpjack pumping an oil well near Sarnia, Ontario Petroleum (from Greek petra – rock and elaion – oil or Latin oleum – oil ) or crude oil is a thick, dark brown or greenish liquid. ... Coal Coal (IPA: ) is a fossil fuel formed in swamp ecosystems where plant remains were saved by water and mud from oxidization and biodegradation. ... This article is about the fossil fuel. ...

There are several problems with existing energy delivery systems. They are subject to (among other problems)

• political instability for various reasons in various locations -- so that there are large hidden costs in maintaining military or other presence so as to continue supplies
• depletion (some well regarded estimates suggest that oil and gas reserves have been in net decline for some time and that price increases and supply decreases are inevitable),
• greenhouse pollution -- all fossil fuel combustion emits enormous quantities of carbon dioxide (CO₂), a greenhouse gas, contributing to global warming and climate change^[51].

Following the Kyoto Treaty, 141 countries introduced the first system of mandatory emissions control via carbon credits. The ultimate direction of such policies is to increase efficiency of fossil fuel use, perhaps to the point of elimination in some countries or even globally. But, the energy requirements of third world or developing countries (e.g. China and India) are increasing steadily. Because of the net increase in demand, energy prices will continue to increase, though how fast and how high are less easily predicted. This article is about the chemical reaction combustion. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Top: Increasing atmospheric CO2 levels as measured in the atmosphere and ice cores. ... Global warming refers to the increase in the average temperature of the Earths near-surface air and oceans in recent decades and its projected continuation. ... Variations in CO2, temperature and dust from the Vostok ice core over the last 450,000 years For current global climate change, see Global warming. ... Earth as seen by Apollo 17 The Kyoto Protocol is an amendment to the United Nations Framework Convention on Climate Change (UNFCCC), an international treaty on global warming. ... This article deals with carbon credits for international trading. ... For the Jamaican reggae band, see Third World (band). ... A developing country is a country with low average income compared to the world average. ...

Comparison with nuclear power (fission)

Detailed analyses of the problems with nuclear power specifically (nuclear fission) are published elsewhere^[52]. Some are given below, with some comparative comments: This article is about applications of nuclear fission reactors as power sources. ... An induced nuclear fission event. ...

• nuclear proliferation -- not a problem with SPS
• disposal and storage of radioactive waste -- not a problem with SPS
• preventing fissile material from being obtained by terrorists or their sponsors -- not a problem with SPS
• public perception of danger -- problem with both SPS and nuclear power
• consequences of major accident, e.g., Chernobyl -- effectively zero with SPS, save on launch (during construction or for maintenance)
• military and police cost of protecting the public and loss of democratic freedoms -- control of SPS would be a power/influence center, perhaps sufficient to translate into political power. However, this has not yet happened in the developed world with nuclear power.

On balance, SPS avoids nearly all of the problems with current nuclear power schemes, and does not have larger problems in any respect, although public perception of microwave power transfer (ie, in the beams produced by an SPS and received on Earth) dangers could become an issue. World map with nuclear weapons development status represented by color. ... Radioactive waste are waste types containing radioactive chemical elements that do not have a practical purpose. ... This article or section should be merged with Fissile Fissile material is composed of atoms that can undergo nuclear fission and sustain a fission chain reaction. ... Terrorism refers to the use of violence for the purpose of achieving a political, religious, or ideological goal. ... This article is about the city of Chernobyl. ... Democracy is a form of government under which the power to alter the laws and structures of government lies, ultimately, with the citizenry. ... Statue of Liberty - Liberty is one meaning of freedom. Definition Freedom refers in a very general sense to the state of being free (unrestricted, unconfined or unfettered). ...

Comparison with nuclear fusion

Nuclear fusion is a process used in thermonuclear bombs (e.g., the H-bomb). Projected nuclear fusion power plants would not be explosive, and will likely be inherently failsafe. However, sustained nuclear fusion generators have only just been demonstrated experimentally, despite well funded research over a period of several decades (since approximately 1952^[53]). There is still no credible estimate of how long it will be before a nuclear fusion reactor could become commercially possible; fusion research continues to receive substantial funding by many nations. For example, the ITER facility currently under construction will cost €10 billion^[54]. There has been much criticism of the value of continued funding of fusion research^[55]. Proponents have successfully argued in favor of ITER funding^[56]. The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... At the end of the 20th century, Thermonuclear has came to imply anything which has to do with fusion nuclear reactions which are triggered by particles of thermal energy. ... This article is about explosive devices. ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 km (11 mi) above the epicenter. ... ITER is an international tokamak (magnetic confinement fusion) research/engineering project designed to prove the scientific and technological feasibility of a full-scale fusion power reactor. ...

By contrast, SPS does not require any fundamental engineering breakthroughs, has already been extensively reviewed from an engineering feasibility perspective over some decades, and needs only incremental improvements of existing technology^[1] to be deployed. Despite these advantages, SPS has received minimal research funding to date.

Comparison with terrestrial solar power

In the case of the United Kingdom, the country as a whole is further north than even most inhabited parts of Canada, and hence receives little insolation over much of the year, so conventional solar power is not competitive at 2006 per-kilowatt-hour delivered costs. However, per-kilowatt-hour photovoltaic costs have been in exponential decline^[57] for decades, with a 20-fold decrease from 1975 to 2001, so this situation may change. Not to be confused with insulation. ... Solar power from a parabolic reflector. ... The term exponential may refer to any of several topics in mathematics: Exponential distribution Exponential function Exponential growth, exponential decay Exponential time Matrix exponential Exponential map (in differential geometry) All relate in some fashion to exponents. ...

Let us consider a ground-based solar power system versus an SPS generating an equivalent amount of power. Solar power from a parabolic reflector. ...

• Such a system would require a very large solar array built in a well-sunlit area, the Sahara Desert for instance. An SPS requires much less ground area per kilowatt (approx 1/5th). There is no such area in the UK.
• The rectenna on the ground is much larger than the area of the orbiting solar panels. A ground-only solar array would have the advantage, compared to a GEO (Geosynchronous orbit) solar array, of costing considerably less to construct and requiring no significant technological advances. A small version of such a ground based array has recently been completed by General Electric in Portugal.
• The receiving SPS rectenna will be quite simple, cheap, and even transparent, with fewer land use issues than a conventional terrestrial solar array. Crops could be grown beneath the rectenna, so the land needed could be dual-use. By comparison, ground-based solar panels would completely block sunlight thus destroying vegetation and having a considerable effect on local ecology, which in turn would result in increased soil erosion, drainage and runoff problems (increased flood risk) and loss of habitats, though this would be reduced somewhat for desert installations.
• A terrestrial solar station intercepts an absolute maximum of only one third of the solar energy an array of equal size could intercept in space, since no power is generated at night and less light strikes the panels when the Sun is low in the sky or weather interferes. A solar panel in the contiguous United States on average delivers 19 to 56 W/m² ^[58]. By comparison an SPS rectenna would deliver about 23mW/cm² (230 W/m²)^[34] continuously, hence the size of rectenna required per collected watt would be about 8.2% to 24% that of a terrestrial solar panel array with equivalent power output, neglecting weather and night/day cycles. Assuming, of course, current levels of solar cell efficiency.
• Further, if it is assumed that a ground-based solar array must supply baseload power (not true for every projected configuration), some form of energy storage would be required to provide power at night, such as hydrogen generation/storage, compressed air, or pumped storage hydroelectricity. With present technology, energy storage on this scale is prohibitively expensive, and will incur energy losses as well.
• Weather conditions would also interfere with power collection, and will cause wear and tear on solar collectors which will be avoided in Earth orbit; for instance, sandstorms cause devastating damage to human structures via, for example, abrasion of surfaces as well as mechanically large wind forces causing direct physical damage. Terrestrial systems are also more vulnerable to terrorism than an SPS's rectenna since they are more expensive, complex, intolerant of partial damage, and harder to repair/replace. Wear and tear on orbital installations will be of very different character, for quite different reasons, and can be reduced by care in design and fabrication. Long experience with terrestrial installations shows that there is substantial, inescapable maintenance for any economically feasible electrical installation.
• Terrestrial solar panel locations are inherently fixed, but beamed microwave power allows one to adaptively re-route delivered power near to places it is needed (within limits -- rectennas near the SPS's horizon (e.g., at high latitudes) will not be as efficient). A station in the Sahara could provide practical power only to the surrounding area; current demand is relatively low there. That is, at least until long distance superconducting distribution becomes possible, which will make remotely sited Earth surface collection systems more practical, and distribution of generated power equally so, including that from an SPS.
• Remote tropical location of an extensive photovoltaic generator is a somewhat artificial scenario, as photovoltaic costs continue to decline. Deployment of ground-based photovoltaics can be distributed (say to rooftops), but nevertheless, the required acreage (at any credible solar cell efficiency) will remain very large, and maintenance cost and effort will increase substantially compared to a large centralized design. In any case, dispersed installation is not possible for some terrestrial solar collectors.
• Energy payback time for the capital costs of terrestrial PV cells has been typically in the 5-15 year range, depending largely on existing local cost structures. Payback for an orbital installations is likely to be quicker due to the higher total insolation rate, which will, of course be essentially continuous, without interruptions during nighttimes or bad weather. While it is true some of the potential energy available would not be collected (cell inefficienies will assure this in any case), that some would be lost internally at the SPS (no equipment is loss free), and that still more would be lost in transmission back to the Earth, the engineering feasibility studies have established that none of these losses will be large enough to make an SPS project infeasible on those grounds. Losses due to conventional fossil fuel generation are of larger magnitude than in an SPS design, and are more than merely lost efficiency as such losses all contribute to pollution (eg, exhaust gases).

Both SPS and ground-based solar power could be used to produce chemical fuels for transportation and storage, as in the proposed hydrogen economy. Or they could both be used to run an energy storage scheme (such as pumping water uphill at a hydropower generation station). The Sahara is the worlds second largest desert (second to Antarctica), over 9,000,000 km² (3,500,000 mi²), located in northern Africa and is 2. ... “GE” redirects here. ... See: transparency (optics) alpha compositing GIF#Transparency transparency (overhead projector) market transparency transparency (telecommunication) transparency (computing) For X11 pseudo-transparency, see pseudo-transparency. ... Land use is the pattern of construction and activity land is used for. ... This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Severe soil erosion in a wheat field near Washington State University, USA. Erosion is the displacement of solids (soil, mud, rock, and so forth) by the agents of wind, water, ice, or movement in response to gravity. ... Drainage is the natural or artificial removal of surface and sub-surface water from a given area. ... Run-off or runoff may refer to one of the following. ... A habitat (from the Latin for it inhabits) is the place where a particular organism usually lives or grows. ... A base load power plant is one that provides a steady flow of power regardless of total power demand by the grid. ... For delivered electrical power, see Electrical power industry. ... Energy storage is the storing of some form of energy that can be drawn upon at a later time to perform some useful operation. ... Diagram of the TVA pumped storage facility at Racoon Mountain Pumped storage hydroelectricity is a method of storing and producing electricity to supply high peak demands. ... For the geological process, see Weathering or Erosion. ... Look up sandstorm in Wiktionary, the free dictionary. ... Abrasion on the palm of a right hand, shortly after falling Abrasions on elbow and lower arm, still healing. ... In physics, a net force acting on a body causes that body to accelerate; that is, to change its velocity. ... Terrorist redirects here. ... A hydrogen economy is a hypothetical economy in which energy is stored and transported as hydrogen (H2), particularly as an energy carrier for vehicle applications (e. ...

Many advances in solar cell efficiency (eg, improved construction techniques) that make an SPS more economically feasible might make a ground-based system more economic as well. Also, many SPS designs assume the framework will be built with automated machinery supplied with raw materials, typically aluminium. Such a system could be (more or less easily) adapted for operation on Earth, no launching required. However, Earth-based construction already has access to inexpensive human labor that would not be available in space, so such construction techniques would have to be extremely competitive to be significant on Earth. Aluminum redirects here. ...

Solar Panel Mass Production

Currently the costs of solar panels are too high to use them to produce bulk domestic electricity in most situations. However, mass production of the solar panels necessary to build a SPS system would be likely to reduce those costs sufficiently to change this -- perhaps substantially -- especially as fossil fuel costs have been increasing rapidly. But, any panel design suited to SPS use is likely to be quite different than earth suitable panels, so not all such improvements will have this effect. This may benefit earth based array designs as costs may be lower (see the cost analysis above), but will not be able to take advantage of maximum economies of scale, and so piggyback on production of Earth based panels.

It should be noted, however, that there are also frequent developments in the production of solar panels. Thin film solar panels and so-called "nanosolar" might increase collection efficiency, reduce production costs as well as weight, and therefore reduce the total cost of an SPS installation. In addition, private space corporations could become interested in transporting goods (such as satellites, supplies and parts of commercial space hotels) to LEO (Low Earth orbit), since they already are developing spacecraft to transport space tourists^[59][60]. If they can reduce costs, this will also increase the economic feasability of an SPS. A low Earth orbit (LEO) is an orbit in which objects such as satellites are below intermediate circular orbit (ICO) and far below geostationary orbit, but typically around 350 - 1400 km above the Earths surface. ...

Comparison with Other Renewables (wind, tidal, hydro, geothermal)

Other renewable energy sources (e.g., wind energy, tidal energy, hydro-electric, geothermal, ethanol), have the capacity to supply only a tiny fraction of the global energy requirement, now or in the foreseeable future. For most, the limitation is geography as there simply are very few sites in the world where generating systems can be built, and for hydro-electric projects in particular, there are few sites still open. For 2005, in the US, hydro-electric power accounted for 6.5% of electricity generation, and other renewables 2.3%^[61]. The U.S. Govt. Energy Information Administration projects that in 2030 hydro-power will decline to 3.4% and other renewables will increase to 2.9%^[62]. Renewable energy (sources) or RES capture their energy from existing flows of energy, from on-going natural processes, such as sunshine, wind, flowing water, biological processes, and geothermal heat flows. ... This article needs to be cleaned up to conform to a higher standard of quality. ... Tidal power is a means of electricity generation achieved by capturing the energy contained in moving water mass due to tides. ... Hydroelectric dam diagram The waters of Llyn Stwlan, the upper reservoir of the Ffestiniog Pumped-Storage Scheme in north Wales, can just be glimpsed on the right. ... Krafla Geothermal Station in northeast Iceland Geothermal power is energy generated by heat stored beneath the Earths surface. ... Grain alcohol redirects here. ... The Energy Information Administration (EIA), as part of the U.S. Department of Energy, collects and disseminates data on energy reserves, production, consumption, distribution, prices, technology, and related international, economic, and financial matters. ...

Ocean-based windpower is one possibility (there being large areas for potential installations), but it is strongly affected by two factors; the difficulty of long distance power transmission as many regions of high demand are not near the sea, and be the very large difficulty of coping with corrosion, contamination, and survivability problems faced by all seaborne installations. Wind turbine in Luxembourg Horizontal axis wind turbine, the Enercon model E-66 wind energy converter, in Germany. ... Power transmission is the movement of energy from its place of generation to a location where it is applied to performing useful work. ...

Ethanol power production depends on farming in the case of corn or sugar cane origin ethanol, currently the two leading sources. There is insufficient farming capacity for both significant energy production and food production. Corn prices have risen substantially in 2006 and 2007, partly as a result of nascent ethanol production demand. Ethanol from cellulose (eg, agricultural waste or purpose collected non-cultivated plants, eg, switchgrass)) is not practicable as of 2007, though pilot plants are indevelopment. Processing improvements (eg, a breakthrough in enzyme processing) may change this relative disadvantage. Binomial name Panicum virgatum L. Switchgrass (Panicum virgatum) is a warm season grass and is one of the dominant species of the central North American tallgrass prairie. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ...

Current work

For the past several years there has been no line item for SPS in either the NASA nor DOE budgets, a minimal level of research has been sustained through small NASA discretionary budget accounts.

NASA's "Fresh Look" study in 2000^[63]

NASDA (Japan's national space agency) has been researching in this area steadily for the last few years. In 2001 plans were announced to perform additional research and prototyping by launching an experimental satellite of capacity between 10 kilowatts and 1 megawatt of power.^[64][65] NASDA was the National Space Development Agency of Japan. ...

The National Space Society (a non-profit NGO) maintains a web page where the latest SPS related references are posted and kept current ^[66]. National Space Society logo The National Space Society (NSS) is an international nonprofit 501(c)(3), educational, and scientific organization specializing in space advocacy. ... NGO is an abbreviation or code for: Non-governmental organization Nagoya Airport (IATA code) This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...

In May 2007 a workshop was held at MIT in the U.S.A. to review the current state of the market and technology^[67] Mapúa Institute of Technology (MIT, MapúaTech or simply Mapúa) is a private, non-sectarian, Filipino tertiary institute located in Intramuros, Manila. ... For other uses, see United States (disambiguation) and US (disambiguation). ...

In 2007 the US Department of Defense expressed interest in studying the concept^[68]. The United States Department of Defense, abbreviated DoD or DOD and sometimes called the Defense Department, is a civilian Cabinet organization of the United States government. ...

On 10/10/2007 The National Security Space Office of the US Department of Defense, published an assessment report ^[69]. The report was released at a press conference which simultaneously announced the formation of the Space Solar Alliance for Future Energy which intends to pursue the recommendations of the NSSO-Led Study.

In fiction

Space stations transmitting solar power have appeared in science-fiction works like Isaac Asimov's Reason (1941), that centers around the troubles caused by the robots operating the station. Isaac Asimov (January 2?, 1920?[1] – April 6, 1992), IPA: , originally Исаак Озимов but now transcribed into Russian as Айзек Азимов) was a Russian-born American Jewish author and professor of biochemistry, a highly successful and exceptionally prolific writer best known for his works of science fiction and for his popular science books. ... Reason is a science fiction short story by Isaac Asimov that was first published in the April 1941 issue of Astounding Science Fiction and collected in I, Robot (1950), The Complete Robot (1982), and Robot Visions (1990). ... Isaac Asimovs Robot Series is a series of books by Isaac Asimov, both collections of short stories and novels. ...

See also

energy Portal

• Space solar power
• Energy economics
• Energy storage
• Exergy
• Energy quality
• Future energy development
• Microwave power transmission
• Renewable energy
• Spectrolab
• Thinned array curse
• Wireless energy transfer

Image File history File links Portal. ... Space-based solar power (SSP) is the conversion of solar energy into power, usable either in space or on earth, from a location no closer to Earth than Low Earth Orbit (LEO). ... A new start for the article is proposed under Energy economics/new. ... Energy storage is the storing of some form of energy that can be drawn upon at a later time to perform some useful operation. ... Exergy is defined differently in different fields of study. ... Energy quality the contrast between different forms of energy, the different trophic levels in ecological systems and the propensity of energy to convert from one form to another. ... Future energy development, providing for the worlds future energy needs, currently faces great challenges. ... This article does not cite any references or sources. ... Renewable energy effectively utilizes natural resources such as sunlight, wind, tides and geothermal heat, which are naturally replenished. ... Spectrolab is a Boeing company headquartered in Sylmar, California that manufacturers space solar cells and panels. ... The thinned array curse (sometimes, sparse array curse) is a theorem in electromagnetic theory of transmitters. ... It has been suggested that Power beaming be merged into this article or section. ...

References

Dr. Peter Glaser, creator of the Solar Power Satellite concept Photo courtesy National Space Society Dr. Peter Glaser, Vice President, Advanced Technology (retired), was associated with Arthur D. Little, Inc. ... is the 326th day of the year (327th in leap years) in the Gregorian calendar. ... Year 1968 (MCMLXVIII) was a leap year starting on Monday (link will display full calendar) of the Gregorian calendar. ... is the 359th day of the year (360th in leap years) in the Gregorian calendar. ... For the song by James Blunt, see 1973 (song). ... is the 102nd day of the year (103rd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... Geoffrey A. Landis emerged in the late 1980s as one of the foremost scientist-writers in the science fiction genre. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 73rd day of the year (74th in leap years) in the Gregorian calendar. ... Gerard Kitchen ONeill (1927 - 1992) was a U.S. physicist and space pioneer. ... Gerard Kitchen ONeill (1927 - 1992) was a U.S. physicist and space pioneer. ... Brian OLeary was the planetary scientist in the NASA astronaut corps during the Apollo program, the Deputy team leader for NASA Mariner 10 Venus-Mercury television science team. ... Gerard Kitchen ONeill (1927 - 1992) was a U.S. physicist and space pioneer. ... is the 33rd day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... IPCC is the science authority for the UNFCCC The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by two United Nations organizations, the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), to evaluate the risk of climate change brought on by humans, based mainly on... IPCC is science authority for the UNFCCC The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by two United Nations organizations, the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) to assess the risk of human-induced climate change. The Panel is open to all... This article is about applications of nuclear fission reactors as power sources. ... Timeline of significant events in the study and use of nuclear fusion: 1929 - Atkinson and Houtermans used the measured masses of light elements and applied Einsteins discovery that E=mc² to predict that large amounts of energy could be released by fusing small nuclei together. ... ITER is an international tokamak (magnetic confinement fusion) research/engineering project designed to prove the scientific and technological feasibility of a full-scale fusion power reactor. ... ITER is an international tokamak (magnetic confinement fusion) research/engineering project designed to prove the scientific and technological feasibility of a full-scale fusion power reactor. ... ITER is an international tokamak (magnetic confinement fusion) research/engineering project designed to prove the scientific and technological feasibility of a full-scale fusion power reactor. ... Solar power from a parabolic reflector. ... May 14 is the 134th day of the year (135th in leap years) in the Gregorian calendar. ... Dr. Peter Glaser, creator of the Solar Power Satellite concept Photo courtesy National Space Society Dr. Peter Glaser, Vice President, Advanced Technology (retired), was associated with Arthur D. Little, Inc. ...

External links

• The World Needs Energy from Space Space-based solar technology is the key to the world's energy and environmental future, writes Peter E. Glaser, a pioneer of the technology.
• Space-Based Solar Power Efforts A synopsis of proposals and feasibility of lunar and high-orbital solar power stations, including assessments of cost.
• Reinventing the Solar Power Satellite", NASA 2004-212743, report by Geoffrey A. Landis of NASA Glenn Research Center
• Japan's plans for a Solar Power Station in Space - the Japanese government hopes to assemble a space-based solar array by 2040.
• Power From Space Blog about using solar power satellites to reduce reliance on burning hydrocarbons.
• Environmental Community & Alternative Energy Information
• Whatever happened to solar power satellites? An article that covers the hurdles in the way of deploying a solar power satellite.
• Solar Power Satellite from Lunar and Asteroidal Materials Provides an overview of the technological and political developments needed to construct and utilize a multi-gigawatt power satellite. Also provides some perspective on the cost savings achieved by using extraterrestrial materials in the construction of the satellite.
• A renaissance for space solar power? by Jeff Foust, Monday, August 13, 2007 Reports on renewed institutional interest in SSP, and a lack of such interest in past decades.