Glaser Proposes an Orbiting Solar Power Station

Peter E. Glaser published a detailed analysis of a proposed satellite system designed to generate energy photovoltaically and transmit the energy to Earth in the form of microwaves.

Summary of Event

In 1968, Peter E. Glaser proposed an alternative energy-production system within the context of dwindling fossil-fuel reserves. His original concept was published in the journal Solar Energy. The idea of harnessing solar energy for electrical needs on Earth was not original to Glaser. In 1965, the notion of satellite production of energy had been proposed by Leon Gaucher in an article also published in Solar Energy. Alternative energy
Solar power
[kw]Glaser Proposes an Orbiting Solar Power Station (1968)
[kw]Orbiting Solar Power Station, Glaser Proposes an (1968)
[kw]Solar Power Station, Glaser Proposes an Orbiting (1968)
Alternative energy
Solar power
[g]North America;1968: Glaser Proposes an Orbiting Solar Power Station[09570]
[g]United States;1968: Glaser Proposes an Orbiting Solar Power Station[09570]
[c]Space and aviation;1968: Glaser Proposes an Orbiting Solar Power Station[09570]
[c]Energy;1968: Glaser Proposes an Orbiting Solar Power Station[09570]
[c]Engineering;1968: Glaser Proposes an Orbiting Solar Power Station[09570]
Glaser, Peter E.
Gaucher, Leon

In his original paper, Glaser put the concerns of depleted oil reserves into perspective, noting that fossil-fuel use could be graphically represented as an impulsive function, meaning that, until relatively recently, there was no consumption of fossil fuels; in the late twentieth century, there had been a tremendous use, and the rise of that use had been rapid; demand for fossil fuels will likely remain high for several more centuries; and there will then be either no reserves of or no requirements for fossil fuels.

Glaser proposed construction of a satellite solar-power station to use photovoltaic cells to generate electricity in orbit and then transmit the energy to Earth for distribution and consumption. Glaser’s motivation was to provide an alternative to fossil fuels without a need to commit to large-scale production of nuclear power plants. This idea was advanced as the environmental movement was gaining in strength and visibility in the late 1960’s and came two years before the first celebration of Earth Day. The idea of a satellite solar-power station was advanced at a time when nuclear-fission reactors were still being produced in large numbers and new plants were on order, but before the problems of dealing with fission waste products had reached epic proportions. Glaser anticipated the problems associated with nuclear-fission waste products, and he also considered nuclear fusion, which could provide power without producing wastes, to be an uncertain future achievement.

Solar-cell efficiencies were well below theoretical limits in 1968. Solar cells had already found wide application for power generation on scientific, commercial, and military satellites but were not widely used on Earth to generate electricity. Glaser’s proposal assumed steady advances in photovoltaic design, including the production of thin-film organic solar cells. His proposal was engineered to avoid some other drawbacks of solar power: atmospheric absorption of solar radiation and decreased illumination by cloud cover, dust, and pollution as well as daily and seasonal variations of available solar intensity at a given site. By placing the solar-power system in Earth orbit, generation of energy under nearly constant illumination could be made continuous.

Glaser’s original proposal provided a thorough analysis of the solar-power satellite (SPS) system, including many specific details. He projected annual U.S. electrical energy consumption through the year 2000 and drew upon that extrapolation in designing his proposal. The original proposal suggested using SPS to provide for the electrical needs of a region rather than the entire nation.

The proposed satellite system was designed to meet a number of criteria. The satellite could not be so great in surface area as to significantly shadow land directly beneath it. The satellite would have to be constructed with photovoltaics approaching theoretical efficiency limitations to keep cost and size down to manageable limits. The SPS system would have to be inserted (or constructed) in an orbital position that would ensure constant exposure to solar radiation.

A NASA artist’s rendering of a solar power satellite.


In his 1968 paper, Glaser described a two-satellite system, with each satellite placed at the geosynchronous altitude of 35,680 kilometers. These would be separated by about 21 degrees or 12,640 kilometers. In this configuration, both satellites would be able to transmit energy to the same point on the ground by direct line-of-sight. When one satellite passed into shadow, the other would still be illuminated and able to generate electrical power.

The satellites were designed to provide twenty-five gigawatts of power, using technology available in 1968. Glaser calculated that, using solar cells of 20 percent efficiency, 22.3 square kilometers of solar collector would be required. That would correspond to a 5.3-kilometer-diameter dish. The choice of means to transmit the energy in a suitable form to Earth had to take several factors into consideration, not the least of which was atmospheric absorption. Glaser selected microwaves of ten-centimeter wavelength, a region of the electromagnetic spectrum to which Earth’s atmosphere is nearly transparent.


Interest in a solar-power satellite system has been sporadic since Glaser first proposed the SPS concept. Prior to the 1990’s, the last serious study of a full SPS concept was done in 1979. Despite strenuous backing from politically active pro-SPS groups such as the L-5 Society and others, the U.S. Department of Energy Department of Energy, U.S. (DOE) canceled its SPS program in 1979.

Cancellation of the SPS program by the DOE came after a pair of studies. One was performed by the National Academy of Sciences National Academy of Sciences, U.S. in response to requests by the National Science Foundation (NSF) and the National Aeronautics and Space Administration (NASA) for independent opinions on the SPS; the other was performed by the Office of Technology Assessment Office of Technology Assessment, U.S. (OTA). The focus of the studies was the need for, design, cost-effectiveness, and environmental effects of a 300 gigawatt SPS system consisting of a string of sixty satellite stations and a ground-based technological infrastructure to construct and operate the SPS system. Both studies concluded that electrical power requirements projected for the next century justified the need for such a power-generation capability and that the necessary technology could be developed. The OTA report specifically noted, however, that an operational SPS would have inherent unknown environmental effects including long-term exposure of living things to low-level microwave radiation, heating of the troposphere by energetic beams and subsequent effects on climates, and pollution from the enormous number of rocket launches (twenty thousand or more) that would be needed to transport the raw materials into space.

In 1993, Spacecause inaugurated a new SPS initiative in conjunction with the Sunsat Energy Council. This study not only proposed the full-blown orbital array of SPS stations but also proposed more modest, more immediately demonstrable and practical uses of energy-transmission technology. One such application would be the development of a high altitude long-endurance (HALE) aircraft. Energy could be beamed directly to the HALE aircraft, which could remain aloft for months, serving as a platform for other technological applications as it routinely circled around the energy-transmission site.

In addition, solar energy generated using advanced photovoltaic systems could be transmitted to remote regions of the globe where local energy production would be difficult or environmentally hazardous. Such a system would involve the use of satellites not as generating stations but as relays, much as communications satellites in geosynchronous orbit are used as relays to make worldwide telecommunications possible. Remote transmission of solar-generated power could also be used to make electric automobiles more practical. For example, automobiles could be equipped to accept energy transmitted to special highways from which the cars would recharge their batteries while traveling. It thus seems possible that the SPS concept could achieve fruition by turning its focus to Earth and using space only as a relay station. Alternative energy
Solar power

Further Reading

  • Glaser, Peter E. “Satellite Solar Power Station.” Solar Energy 12 (1969): 353-361. Provides the first thorough examination of the large-scale production of electrical power by the alternate means of solar power, principally focused on satellite-based systems.
  • Glaser, Peter E., Frank P. Davidson, and Katinka I. Csigi, eds. Solar Power Satellites: A Space Energy System for Earth. New York: Wiley, 1998. An updated discussion of solar-power satellite systems. See the accompanying text below.
  • _______. Solar Power Satellites: The Emerging Energy Option. New York: Ellis Horwood, 1993. Thoroughly describes all aspects of solar-power satellite systems. Provides in-depth analysis of the technology, using easily understandable tables, charts, and illustrations. Discusses associated legal and environmental problems.
  • Halacy, D. S., Jr. The Coming Age of Solar Energy. New York: Harper & Row, 1973. An excellent review of various aspects of the utilization of solar energy.
  • Heppenheimer, T. A. Toward Distant Suns. Harrisburg, Pa.: Stackpole Books, 1979. Describes futuristic but realistic space-travel plans. Includes discussions of solar-power satellites. Illustrated.
  • Hopkins, Mark. “Satellite Power Stations.” Ad Astra 6 (March/April, 1994): 35. Describes an SPS initiative begun in early 1993 to incorporate different factions within industry, the Sunsat Energy Council, and government to develop practical applications of the transmission of energy to remote regions of the earth.
  • O’Leary, Brian. “Asteroid Mining.” Astronomy 6 (November, 1978): 6-15. Examines the transport of asteroids to Earth for mining of their precious ores and the use of solar-power generation in space.
  • O’Neill, Gerard K. The High Frontier: Human Colonies in Space. Garden City, N.Y.: Anchor Books, 1982. A thorough evaluation of the possibility of creating a large habitat in Earth orbit capable of supporting thousands of individuals. Illustrated.
  • “OTA and NAS Evaluate Solar Power Satellite Problems.” Physics Today (October, 1981): 53-54. Describes a report issued by the Office of Technology Assessment and the National Academy of Sciences prepared in response to a request from the House Committee on Science and Technology. Assesses solar-power satellite technology according to four different design options, which are compared to other potential energy sources such as nuclear fusion, ground-based photovoltaics, and solar-thermal systems.
  • Stanley, Tomm. Going Solar: Understanding and Using the Warmth in Sunlight. White River Junction, Vt.: Chelsea Green, 2004. An excellent introductory guide to solar energy and power, with many illustrations and photographs. Sections cover “History and the Basic Principles of Solar Design,” “The Science Behind the Sunlight,” “The Nature of Materials,” and “Practical Applications.” Highly recommended for all levels.

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