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International cooperation for the acquisition of space-based energy
Pergamon
0038-092X(95)00086-0
Solar Energy Vol. 56, No. 1, pp. 79-85, 1996 Copyright © 1996 Elsevier Science Ltd Printed in Great Britain. All rights reserved 0038-092X/96 $15.00+0.00
INTERNATIONAL COOPERATION FOR THE ACQUISITION OF SPACE-BASED ENERGY R. BRYAN ERB Canadian Space Station Program, Canadian Space Agency, Houston Liaison Office, c/o NASA Johnson Space Center, Houston, TX 77058, U.S.A. Abstract--Acquisition of an adequate supply of economical and clean energy is a pressing global need to which space-based energy can contribute. New supplies of non-polluting energy from renewable sources are vital if the world economy is to be sustained and those in the Developing Countries are to have a prosperous future. The energy of the sun is the primary source of such non-polluting energy and there are advantages to capturing this energy first in space rather than on Earth. Acquisition of space-based energy is intrinsically an international matter for several reasons: the global nature of the need for energy; the distribution of the enabling technology among several countries; the need for significant financing; and the fact that responsibility for allocating key resources is an international matter. Approaches to acquiring space-based energy as presented around 1980 were not implemented because of perceived shortcomings in the technology of that era. However, the key technologies have advanced greatly since 1980. It is now timely to activate international cooperation to enable further this energy option for the future. This paper describes the important roles of government, industry and professional societies and provides recommendations for action by these entities.
1. INTRODUCTION
distributed via a grid or used to produce hydrogen and fuels. Various means of energy conversion have been studied, but the current emphasis is on photovoltaics. Alternative transmission approaches with lasers have been suggested; however, radio frequencies will be most useful in the near term because the technology is proven and conversion efficiencies are high. This space solar power for Earth approach to tapping the energy of the sun can provide continuous (baseload) power, unlike most means of capturing solar energy on the Earth. Space solar power for Earth is likely to have economic advantages over terrestrial installations. This advantage lies in the fact that in space the sun's energy can be captured 24 h a day and the total solar energy available to the satellite is 5-15 times that available on Earth, depending on location. This translates into a correspondingly reduced need for land on which to capture the energy. Furthermore, land under the rectennas can still be used for other purposes since the shading from the rectenna is only modest. Energy density of the wireless energy transmission is limited to levels that are safe for all life forms, in fact, less than one half the energy density of full sunlight. The development of space solar power for Earth is intrinsically a matter for international cooperation. There are several reasons for this which will be elaborated in this paper. Briefly, these reasons derive from the global nature of the need, the distribution of relevant technology
Acquisition of an adequate supply of economical and clean energy is one of the most pressing challenges facing global societyt. New supplies of energy from sources which are renewable and non-polluting are vital if those in the Industrialized Countries are to sustain their energy-intensive life styles in the long run and if those in the developing countries are to achieve similar energy-driven benefits. The hoped-for relief from nuclear fission has faded into a bad dream, and practical use of controlled fusion still a far-off vision. Thus the hope for a clean energy future rests on renewables, primarily solar energy. If the acquisition of new, clean supplies of energy can be accomplished, the planet's environment could heal after a twocentury long overindulgence of fossil fuel combustion. The importation to Earth of solar energy captured in space is one option for clean energy that should be developed. The approach is to capture solar energy in space on large satellite platforms, convert it to radio frequency energy and transmit it to receiving antennas that convert the radio frequency energy back into electrical energy. The electricity is then either tThe World Energy Congress (World Energy Council, 1992) postulates a global energy demand of 18.9 Terawatts (TW) by 2020. This should be compared with a present (1990) use rate of 12.2 TW. The additional demand will occur almost totally in the Developing Countries (Erb, 1994).
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and financial resources, and regulatory considerations. With international cooperation, importation of space-based power can become a new and profitable application of spacefaring, one that will benefit the economies of both industrialized and developing countries, and one which will move humanity along a path of sustainable development. It is possible that other options for sustainable energy may eventually come into being, but major shifts in energy supplies take several decades to accomplish. Thus it is important to pursue all reasonable options for an energy future that will sustain quality h u m a n life and development. 2. RATIONALE FOR INTERNATIONAL COOPERATION
2.1 Need for energy is global The need for increased energy supplies will occur largely in the Developing Countries. Economical energy will allow these countries to pursue their development and improve the living conditions of their peoples, t At least two additional benefits will be derived from an improvement in living conditions. First, there would be a reduction in the present vast disparity in living standards between the Industrialized and the Developing Countries. This disparity is roughly proportional to the ratio of energy use which is as much as 100 to 1. The persistence of such disparities can only be a cause of major international tensions and migration pressures. Second, the history of economic development shows us that a concomitant of improved living conditions is a reduction in population growth rates. Hence, improved energy availability in the Developing Countries could make a significant contribution to the stabilization of the world population. In addition to the economical benefits of providing adequate energy, it is important that the new energy supplies be environmentally clean. The global environment is in decline and the main culprit is the continued use of fossil tThe prevailing situation was described at the 15th World Energy Congress by Pachauri of India as follows: "A large part of the human race is today gripped by widespread poverty, which I-situationlcan only be improved through an absolute minimum level of energy use as an input to a range of activities that provide the most basic of servicesfor secure and stable human existence. These services include at least a clean water supply, refrigeration for the village health center, lighting at night and, perhaps, a community TV".
fuels. Other environmental degradation is due to an unsustainable use of wood for fuel. Importing electricity from space addresses the environmental issue by providing energy without adding to emissions or waste. While it is not realistic to think that major shifts to new energy sources can be made quickly, the sooner this happens the sooner the world's environment will have a chance to heal.
2.2 Technology is widely distributed Capturing solar energy in space and importing it to Earth offers a space-technology-enabled solution, but one for which no one country has all the capability. To date, only the Industrialized Countries have pursued space solar power for Earth. And yet the major need is in the Developing Countries. A logical and intrinsically international solution is to have the Industrialized Countries develop and operate the space segment, and the recipient Developing Countries build and operate the ground segments. Overall control would be through an international mechanism that would assure equity among participants. Significant demonstration and study work is presently being pursued on an international basis. The last decade has seen substantial progress with rocket experiments, microwavepowered aircraft flights, major conferences and serious research presented at international symposia. The pursuit of space solar power for Earth has been endorsed by entities such as the U.S. National Commission on Space (Paine Commission) (U.S. National Commission on Space, 1986) and U N E S C O via their World Solar Summit ( U N E S C O , 1993). Ground power transmission tests have been conducted recently in Japan and a pilot project on Reunion Island is being considered jointly by France and Japan. High-altitude aircraft applications of wireless power transmission are being pursued by U.S., French and Canadian interests. In 1992 the International Space University chose to study solar power satellites as one of their summer session design projects and followed up by creating an International Space Power Program. Japanese researchers at Kobe University and in the Institute for Space and Astronautical Sciences are carrying out leading-edge projects with a strong hardware emphasis, The Center for Space Power at Texas A & M University has advanced transmitting antenna technology in the frequency range most studied to date (2.45 GHz) with a slotted wave guide phased
Acquisition of space-based energy array and has developed efficient rectennas for use at higher frequencies. The University of Alaska, Fairbanks, has designed spacecraft that would receive their power from the Earth in energy propagation experiments and is participating with Japan in a microwave helicopter project. Recently, the American Institute of Aeronautics and Astronautics (AIAA) sponsored a Workshop on International Space Cooperation (1995), in which one working group addressed the space solar power for Earth topic.t Additional follow on activities are being pursued in conjunction with the AIAA and other professional and advocacy organizations.
2.3 The scale requires international financing The energy market is vast and dwarfs almost all other areas of economic activity. The worldwide market for electricity alone is approaching one trillion $U.S. Expanding the energy infrastructure to provide the additional energy needed will require a major capital investment. Varying assessments of the extent of the problem have been put forward. Goldemberg (1987)indicates that the Developing Countries alone would require some 100 billion $U.S. for the decade of the 1990s. Indications from the World Bank (Churchill) are that it could allocate perhaps 15% of the needed amount. Clearly, funding to expand the global energy infrastructure will pose a major challenge, even to international agencies and consortia. If space-based energy is to be a part of the mix of future energy sources, it too will require substantial capital. While it is not reasonable to expect much precision in current estimates, there have been thoughtful studies (Leonard, 1992) which indicate that an investment on the order of 20 billion $U.S. could emplace much of the infrastructure needed to develop space solar power for Earth including installation of the first satellite with a capability to deliver approximately one gigawatt. It is also reasonable to consider intermediate applications which might be profitable and both build confidence and contribute to the eventual large scale implementation of power satellites. Such applications include: ~fThispaper draws heavily on the results from this workshop and thanks are extended to the AIAA and to all the participants and consultants of the Solar Power to Earth Working Group for their contributions. The full results of the Workshop are available in the AIAA report.
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microwave-powered aircraft or aerostats for economical communications, resource monitoring and other surveillance; • terrestrial energy distribution by wireless transmission locally across difficult terrain; • terrestrial energy distribution over intercontinental distances via power relay satellites; • efficient powering of constellations of satellites including orbital transfer vehicles by power-serving satellites. Investments in renewable energy sources, including space-based energy, needs to be weighed against the costs of not promoting these options. While such costs are extremely difficult to assess, attempts have been made. For the U.S. economy only, the cost argument can be made as follows: • If global warming follows the path predicted by the Intergovernmental Panel on Climate Change, the global average temperature will likely increase about 2.5°C by 2030-2050 (World Meteorological Organization, 1991). • The economic impact to the U.S.A. of such a change is projected by Cline (1992) to be $60B + per year. • If preventive measures were taken to limit CO2 release, major costs would also be incurred. One suggested approach is to sequester CO2 in carbonate or some other disposable form. Such an approach is estimated to increase the cost of electricity by 30-100% (Holdren, 1990). Assessing U.S. electric costs of $170 billion SU.S. per year and taking a 50% increase for illustrative purposes, this measure could add $85 billion $U.S. per year to energy costs. Thus the costs of continuing our present energy practices are enormous and an investment in renewable/space-based energy would seem to be a prudent course of action.:~ •
2.4. International regulations control critical resources Importation of power from space will require the permission of the International Telecommunications Union ( I T U ) to use certain resources, specifically appropriate frequencies for the power transmission and satellite slots in geosynchronous orbit if that location is chosen :~Investments in renewable energy would, in all likelihood, serve to limit the length of time during which increased costs would be incurred. Some global warming and its attendant impact is probably inevitable and a shift to renewable energy sources can not occur soon enough (Erb, 1992) to prevent it.
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for operation. The involvement of many countries, including the Developing Countries which would be the primary recipients and users of the power, will be required to provide the needed consensus in the ITU. The assignment of appropriate operating frequencies may be one of the thorniest issues in power importation, given the intense and growing demand for bands within the electromagnetic spectrum. Consideration is currently being given to assigning to communications use some parts of the frequency range in the microwave spectrum presently allocated to industrial, scientific, and medical use.t Such incursions could make appropriate frequencies unavailable for crucial research and test programs. A sound approach is that recommended by Cheston (1981); i.e. to reactivate the 1979 request of the U.S.A. to study the feasibility of clearing the bands around 2450 MHz and, at the same time, to examine the usefulness of frequencies above 30 G H z for power transmission.
viability of space power importation is spotty. Other barriers are: • absence of a prominent space solar power agenda within any major international organization (although it is among the interests of many existing organizations); • lack of knowledge of past international work because the information is not easily accessible; • perception of high risk, again due to lack of information on critical technical issues; • lack of any substantial funding for demonstrations and development; • the interdependence between space transportation cost and acquisition of space solar power for Earth--transportation costs will remain high unless a major market such as space solar power for Earth develops and such a market is unlikely to develop with transportation costs at their present levels. 4. A N E W INITIATIVE IN SPACE-BASED
ENERGY 3. BARRIERS TO A C C E P T A N C E OF SPACEBASED ENERGY
It should be explicitly noted that there is a widely-held perception that space solar power importation is not an economically feasible option. This perception stems from the 1980 assessment (National Research Council, 1981) by the National Research Council of the U.S. Academy of Sciences of an extensive study conducted by the U.S. Department of Energy (DOE) and NASA in 1977-1980 to examine the feasibility of what was called the solar power satellite. This assessment asserted that the assumptions of the DoE/NASA study were too optimistic, especially in the area of photovoltaic cell performance and probable launch costs. The assessment went on to recommend that further relevant research be tracked and the situation be assessed from time to time, but that implementation not be pursued at that time. The situation of the early 1980s is still assumed by many to be the current reality. Such assumptions have largely prevented any U.S. governmental involvement since 1980 and this in itself is a major barrier to international cooperation. International acceptance of the tThis portion of the spectrum (2400-2500MHz) is known as the ISM Band. Comments on proposed changes to present allocations have been made by members of the community interestedin space solar power to Earth and by the International MicrowavePower Institute.
The barriers described in the preceding section are very real, but not insurmountable. A substantial resurgence of interest has occurred in several countries over the last few years. Importantly, solid experimental and theoretical work has been carried out, especially in wireless power transmission. Furthermore, outstanding progress has been made in the area of photovoltalcs, driven by terrestrial applications. Thus the time seems ripe for a new international initiative in space-based energy. A review of the status of the technologies required for space solar power for Earth shows that, except for launch costs, much has changed for the better in the intervening decade and a half since 1980. Even in the area of launch costs, there has been some movement and studies have shown that substantial reductions can be achieved. Furthermore, the rationale for pursuing new and renewable energy sources has been greatly strengthened in light of environmental concerns and global needs. The more important of the changes in technology are noted in Table 1. The outlook for future progress in the key technology area is also encouraging. Overall technical risk is declining as important areas of the technology mature. In particular, photovoltaics, wireless power transmission, and robotics are all advancing well. The use of space robotics for construction is a new and growing area, one
Acquisition of space-based energy
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Table 1. Changes in enabling technology for space-based energy Then (1980)
Now (1994)
Photovoltaics - - fledgling industry Expensive, over $100 per watt Low efficiency Small production
Photovoltaics--maturing industry Price dropping toward $1 per watt Improved efficiencies Single crystal Poly crystal Thin film Robust, expanding capacity
Transportation Pre-shuttle
Transportation Still costly, but more options Reusability demonstrated
Wireless power transmission Goldstone ground test ISM band initial steps taken
Wireless power transmission In-space transmission experiments More biological studies, no show stoppers Increased fear of electro-magnetic fields ISM band in jeopardy 5.8 and 35 GHz technology Laser development
Construction of solar power satellites Big fixtures/space factories
Construction of solar power satellites Robotic assembly (automation industry) No big fixture, build upon itself
Ground segment 10 13 km for 5 GW
Ground segment 3 km diameter for 1 GW Thin film-lightweight arrays
which should make quite unnecessary the large number of space-based construction workers called for in the studies of the 1970s. Finally, it should be possible to evolve toward the acquisition of space-based energy through logical steps from aircraft applications of wireless power transmission, to power relay satellites, to solar power satellites. Eventually, perhaps, solar power satellites will be built using extraterrestrial materials or, in the far future, the moon will be used for capture and transmission of solar energy. There has also been a major shift in the stimulus for pursuing space solar power for Earth. The initial stimulus in the early to mid 1970s was driven by concerns over the energy supply and the threat of cost increases. Especially important was the strategic aspect of the supply in light of oil embargoes. Furthermore, the interest at the time was solely in the U.S.A. Today, concerns focus on degradation of the planetary environment, on the dim prospects for healthy economies in the Developing Countries and on providing a global energy future that can be sustained indefinitely. 5. A N A P P R O A C H T O A C T I V A T E INTERNATIONAL COOPERATION IN
SPACE-BASED ENERGY The most fundamental step toward achieving international cooperation in space-based energy SE 56:1-G
is to promote its credibility and viability. All those interested in a sustainable world energy future, and those eager to see spacefaring escape its present stagnation, should promote awareness of that solar power from space for use on Earth as an application that could help solve a pressing human need. At the same time, for those interested in the space dimension, it could provide a market for a vastly larger and more economical space transportation capability.
5.1 A role for government and industry It is important to pursue space-based energy in a way that combines the skills and roles of both government and industry. It is the judgment of this author that a government megaprogram is not a workable approach, whether undertaken by one government or by several. Energy supply is a matter for the private sector in many countries, one shared with governments in other countries, and a totally governmental responsibility in still others. Government/ Industry partnerships would allow reasonable sharing of risk and yet harness the power of the profit motive. There are many precedents for this in past programs for large-scale infrastructure; e.g. the railroads in the U.S., the Suez Canal and the "Chunner'. A pivotal role exists in the U.S.A. for the Department of Energy and NASA. These agencies led the early work and then abandoned the
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field. This has critically lessened the credibility of space solar power f o r Earth in other countries. An important step is to reactivate interest within these U.S. agencies. The existence of a Department of Energy/NASA activity, beginning simply with responsible points of contact in each agency, would create an appropriate focus for international cooperation. The two agencies could, jointly, follow, understand and document international efforts, and be the clearing house and information source on the state of technical, environmental and socio-political aspects of power importation to Earth.~ Once the Department of Energy/NASA activity was well-established, it could provide liaison with other U.S. government departments (e.g. Commerce and EPA) to form and lead a G o v e r n m e n t - I n d u s t r y Council on space solar power f o r Earth. This Council could oversee the development of a National Space Power Plan which, in turn, could provide the basis for meaningful international collaboration. Another key factor in advancing power importation is to recognize that acceptance and progress will come from demonstrations and pilot operational activities, not from more paper studies. Bilateral and multilateral experimental and developmental programs could build upon existing efforts and relationships, utilizing existing and planned international experimental and development facilities, such as the International Space Station and ground-based test ranges. Such an approach would reduce economic and political risk though step-by-step activities each of which would be designed to provide significant technical results and to earn public confidence in the value, safety and feasibility of space solar power f o r Earth. 5.2 A role f o r professional societies
Professional societies serving the energy, space and environmental communities have a key role to play in authenticating space-based energy and in promoting its eventual implementation. One positive step that can be taken immediately is the creation of an International Council
on
Space
Solar
Power f o r
Earth.
Precedents for this exist in the astronomy and nuclear physics communities where such organizations foster international professional collaboration. The objectives of such a Council would tThe National Research Council assessment recommended that relevant research be tracked on a continuing basis by these agencies.
include international outreach and marketing efforts and the facilitation of international cooperative projects. The Council would actively foster the participation of Developing Countries, aid in industry/government/academia collaboration on an international basis, and continue regular Wireless Power Transmission Conferences. Specific actions which could be undertaken by this proposed Council are: • develop a position paper which would document the technical status of space-based energy as a starting point for renewed discussion; • establish an Internet-based network on space power. The first steps were taken at a recent AIAA Workshop which accepted a proposal from Japan for the creation of a Space Power Network (SP-Net) to facilitate increased international discussion and interaction; • convene a workshop to address the critical and interdependent nature of space transportation and space power requirements. 6. CONCLUSIONS A need exists for new sources of clean energy. Solar energy captured in space is one viable option. Implementation of this option can occur only with international cooperation. It is timely to activate new efforts in this area and important roles exist for industry, government and professional societies. 7. R E F E R E N C E S
Cheston T. S. Practical approaches to international space power. In Solar Power Satellites (Glaser P.E.), Chap. 4.4. Ellis Horwood, New York (1981). Churchill A. Representative of the World Bank. In 15th World Energy Congr., Madrid, Spain. Cline W. R. The Economics of Global Warming. Institute for International Economics, Washington, DC (1992). Erb R. B. Power from space--when? 43rd Cong. Int. Astronautical Federation, Paper IAF-92-0595, Washington, DC (1992). Erb R. B. Power from space--can it compete. 45th Congr. Int. Astronautical Federation, Paper IAF-94.R2.372,Jerusalem, Israel (1994). Glaser P. E. et al. Solar Power Satellites. Ellis Horwood, New York (1993). Goldemberg J. et al. Energy for a sustainable world. World Resources Institute (1987).
Holdren J. P. Energy in transition. Scientific Am. September (1990). Leonard R. S. Net present value analysis for satellite power systems. Institute for Sustainable Futures, Santa Fe,
NM (1992). National Research Council. Electric power from orbit: a critique of a satellite power system. National Academy Press, Washington, DC (1981). Pioneering the space frontier. Report of the U.S. National Commission on Space. Bantam Books (1986).
Acquisition of space-based energy Report of the AIAA Workshop on International Space Cooperation, Kona, Hawaii, 4-9 December 1994. Solar energy and space. Session at World Solar Summit, UNESCO, Paris, France (1993). World Energy Council, Round Up, 15th World Energy Congr., Madrid, Spain (1992).
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World Meteorological Organization/United Nations Environment Program Intergovernmental Panel on Climate Change. Climate Change--The IPCC Response Strategies. Island Press, Washington, DC (1991).
0038-092X(95)00086-0
Solar Energy Vol. 56, No. 1, pp. 79-85, 1996 Copyright © 1996 Elsevier Science Ltd Printed in Great Britain. All rights reserved 0038-092X/96 $15.00+0.00
INTERNATIONAL COOPERATION FOR THE ACQUISITION OF SPACE-BASED ENERGY R. BRYAN ERB Canadian Space Station Program, Canadian Space Agency, Houston Liaison Office, c/o NASA Johnson Space Center, Houston, TX 77058, U.S.A. Abstract--Acquisition of an adequate supply of economical and clean energy is a pressing global need to which space-based energy can contribute. New supplies of non-polluting energy from renewable sources are vital if the world economy is to be sustained and those in the Developing Countries are to have a prosperous future. The energy of the sun is the primary source of such non-polluting energy and there are advantages to capturing this energy first in space rather than on Earth. Acquisition of space-based energy is intrinsically an international matter for several reasons: the global nature of the need for energy; the distribution of the enabling technology among several countries; the need for significant financing; and the fact that responsibility for allocating key resources is an international matter. Approaches to acquiring space-based energy as presented around 1980 were not implemented because of perceived shortcomings in the technology of that era. However, the key technologies have advanced greatly since 1980. It is now timely to activate international cooperation to enable further this energy option for the future. This paper describes the important roles of government, industry and professional societies and provides recommendations for action by these entities.
1. INTRODUCTION
distributed via a grid or used to produce hydrogen and fuels. Various means of energy conversion have been studied, but the current emphasis is on photovoltaics. Alternative transmission approaches with lasers have been suggested; however, radio frequencies will be most useful in the near term because the technology is proven and conversion efficiencies are high. This space solar power for Earth approach to tapping the energy of the sun can provide continuous (baseload) power, unlike most means of capturing solar energy on the Earth. Space solar power for Earth is likely to have economic advantages over terrestrial installations. This advantage lies in the fact that in space the sun's energy can be captured 24 h a day and the total solar energy available to the satellite is 5-15 times that available on Earth, depending on location. This translates into a correspondingly reduced need for land on which to capture the energy. Furthermore, land under the rectennas can still be used for other purposes since the shading from the rectenna is only modest. Energy density of the wireless energy transmission is limited to levels that are safe for all life forms, in fact, less than one half the energy density of full sunlight. The development of space solar power for Earth is intrinsically a matter for international cooperation. There are several reasons for this which will be elaborated in this paper. Briefly, these reasons derive from the global nature of the need, the distribution of relevant technology
Acquisition of an adequate supply of economical and clean energy is one of the most pressing challenges facing global societyt. New supplies of energy from sources which are renewable and non-polluting are vital if those in the Industrialized Countries are to sustain their energy-intensive life styles in the long run and if those in the developing countries are to achieve similar energy-driven benefits. The hoped-for relief from nuclear fission has faded into a bad dream, and practical use of controlled fusion still a far-off vision. Thus the hope for a clean energy future rests on renewables, primarily solar energy. If the acquisition of new, clean supplies of energy can be accomplished, the planet's environment could heal after a twocentury long overindulgence of fossil fuel combustion. The importation to Earth of solar energy captured in space is one option for clean energy that should be developed. The approach is to capture solar energy in space on large satellite platforms, convert it to radio frequency energy and transmit it to receiving antennas that convert the radio frequency energy back into electrical energy. The electricity is then either tThe World Energy Congress (World Energy Council, 1992) postulates a global energy demand of 18.9 Terawatts (TW) by 2020. This should be compared with a present (1990) use rate of 12.2 TW. The additional demand will occur almost totally in the Developing Countries (Erb, 1994).
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and financial resources, and regulatory considerations. With international cooperation, importation of space-based power can become a new and profitable application of spacefaring, one that will benefit the economies of both industrialized and developing countries, and one which will move humanity along a path of sustainable development. It is possible that other options for sustainable energy may eventually come into being, but major shifts in energy supplies take several decades to accomplish. Thus it is important to pursue all reasonable options for an energy future that will sustain quality h u m a n life and development. 2. RATIONALE FOR INTERNATIONAL COOPERATION
2.1 Need for energy is global The need for increased energy supplies will occur largely in the Developing Countries. Economical energy will allow these countries to pursue their development and improve the living conditions of their peoples, t At least two additional benefits will be derived from an improvement in living conditions. First, there would be a reduction in the present vast disparity in living standards between the Industrialized and the Developing Countries. This disparity is roughly proportional to the ratio of energy use which is as much as 100 to 1. The persistence of such disparities can only be a cause of major international tensions and migration pressures. Second, the history of economic development shows us that a concomitant of improved living conditions is a reduction in population growth rates. Hence, improved energy availability in the Developing Countries could make a significant contribution to the stabilization of the world population. In addition to the economical benefits of providing adequate energy, it is important that the new energy supplies be environmentally clean. The global environment is in decline and the main culprit is the continued use of fossil tThe prevailing situation was described at the 15th World Energy Congress by Pachauri of India as follows: "A large part of the human race is today gripped by widespread poverty, which I-situationlcan only be improved through an absolute minimum level of energy use as an input to a range of activities that provide the most basic of servicesfor secure and stable human existence. These services include at least a clean water supply, refrigeration for the village health center, lighting at night and, perhaps, a community TV".
fuels. Other environmental degradation is due to an unsustainable use of wood for fuel. Importing electricity from space addresses the environmental issue by providing energy without adding to emissions or waste. While it is not realistic to think that major shifts to new energy sources can be made quickly, the sooner this happens the sooner the world's environment will have a chance to heal.
2.2 Technology is widely distributed Capturing solar energy in space and importing it to Earth offers a space-technology-enabled solution, but one for which no one country has all the capability. To date, only the Industrialized Countries have pursued space solar power for Earth. And yet the major need is in the Developing Countries. A logical and intrinsically international solution is to have the Industrialized Countries develop and operate the space segment, and the recipient Developing Countries build and operate the ground segments. Overall control would be through an international mechanism that would assure equity among participants. Significant demonstration and study work is presently being pursued on an international basis. The last decade has seen substantial progress with rocket experiments, microwavepowered aircraft flights, major conferences and serious research presented at international symposia. The pursuit of space solar power for Earth has been endorsed by entities such as the U.S. National Commission on Space (Paine Commission) (U.S. National Commission on Space, 1986) and U N E S C O via their World Solar Summit ( U N E S C O , 1993). Ground power transmission tests have been conducted recently in Japan and a pilot project on Reunion Island is being considered jointly by France and Japan. High-altitude aircraft applications of wireless power transmission are being pursued by U.S., French and Canadian interests. In 1992 the International Space University chose to study solar power satellites as one of their summer session design projects and followed up by creating an International Space Power Program. Japanese researchers at Kobe University and in the Institute for Space and Astronautical Sciences are carrying out leading-edge projects with a strong hardware emphasis, The Center for Space Power at Texas A & M University has advanced transmitting antenna technology in the frequency range most studied to date (2.45 GHz) with a slotted wave guide phased
Acquisition of space-based energy array and has developed efficient rectennas for use at higher frequencies. The University of Alaska, Fairbanks, has designed spacecraft that would receive their power from the Earth in energy propagation experiments and is participating with Japan in a microwave helicopter project. Recently, the American Institute of Aeronautics and Astronautics (AIAA) sponsored a Workshop on International Space Cooperation (1995), in which one working group addressed the space solar power for Earth topic.t Additional follow on activities are being pursued in conjunction with the AIAA and other professional and advocacy organizations.
2.3 The scale requires international financing The energy market is vast and dwarfs almost all other areas of economic activity. The worldwide market for electricity alone is approaching one trillion $U.S. Expanding the energy infrastructure to provide the additional energy needed will require a major capital investment. Varying assessments of the extent of the problem have been put forward. Goldemberg (1987)indicates that the Developing Countries alone would require some 100 billion $U.S. for the decade of the 1990s. Indications from the World Bank (Churchill) are that it could allocate perhaps 15% of the needed amount. Clearly, funding to expand the global energy infrastructure will pose a major challenge, even to international agencies and consortia. If space-based energy is to be a part of the mix of future energy sources, it too will require substantial capital. While it is not reasonable to expect much precision in current estimates, there have been thoughtful studies (Leonard, 1992) which indicate that an investment on the order of 20 billion $U.S. could emplace much of the infrastructure needed to develop space solar power for Earth including installation of the first satellite with a capability to deliver approximately one gigawatt. It is also reasonable to consider intermediate applications which might be profitable and both build confidence and contribute to the eventual large scale implementation of power satellites. Such applications include: ~fThispaper draws heavily on the results from this workshop and thanks are extended to the AIAA and to all the participants and consultants of the Solar Power to Earth Working Group for their contributions. The full results of the Workshop are available in the AIAA report.
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microwave-powered aircraft or aerostats for economical communications, resource monitoring and other surveillance; • terrestrial energy distribution by wireless transmission locally across difficult terrain; • terrestrial energy distribution over intercontinental distances via power relay satellites; • efficient powering of constellations of satellites including orbital transfer vehicles by power-serving satellites. Investments in renewable energy sources, including space-based energy, needs to be weighed against the costs of not promoting these options. While such costs are extremely difficult to assess, attempts have been made. For the U.S. economy only, the cost argument can be made as follows: • If global warming follows the path predicted by the Intergovernmental Panel on Climate Change, the global average temperature will likely increase about 2.5°C by 2030-2050 (World Meteorological Organization, 1991). • The economic impact to the U.S.A. of such a change is projected by Cline (1992) to be $60B + per year. • If preventive measures were taken to limit CO2 release, major costs would also be incurred. One suggested approach is to sequester CO2 in carbonate or some other disposable form. Such an approach is estimated to increase the cost of electricity by 30-100% (Holdren, 1990). Assessing U.S. electric costs of $170 billion SU.S. per year and taking a 50% increase for illustrative purposes, this measure could add $85 billion $U.S. per year to energy costs. Thus the costs of continuing our present energy practices are enormous and an investment in renewable/space-based energy would seem to be a prudent course of action.:~ •
2.4. International regulations control critical resources Importation of power from space will require the permission of the International Telecommunications Union ( I T U ) to use certain resources, specifically appropriate frequencies for the power transmission and satellite slots in geosynchronous orbit if that location is chosen :~Investments in renewable energy would, in all likelihood, serve to limit the length of time during which increased costs would be incurred. Some global warming and its attendant impact is probably inevitable and a shift to renewable energy sources can not occur soon enough (Erb, 1992) to prevent it.
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for operation. The involvement of many countries, including the Developing Countries which would be the primary recipients and users of the power, will be required to provide the needed consensus in the ITU. The assignment of appropriate operating frequencies may be one of the thorniest issues in power importation, given the intense and growing demand for bands within the electromagnetic spectrum. Consideration is currently being given to assigning to communications use some parts of the frequency range in the microwave spectrum presently allocated to industrial, scientific, and medical use.t Such incursions could make appropriate frequencies unavailable for crucial research and test programs. A sound approach is that recommended by Cheston (1981); i.e. to reactivate the 1979 request of the U.S.A. to study the feasibility of clearing the bands around 2450 MHz and, at the same time, to examine the usefulness of frequencies above 30 G H z for power transmission.
viability of space power importation is spotty. Other barriers are: • absence of a prominent space solar power agenda within any major international organization (although it is among the interests of many existing organizations); • lack of knowledge of past international work because the information is not easily accessible; • perception of high risk, again due to lack of information on critical technical issues; • lack of any substantial funding for demonstrations and development; • the interdependence between space transportation cost and acquisition of space solar power for Earth--transportation costs will remain high unless a major market such as space solar power for Earth develops and such a market is unlikely to develop with transportation costs at their present levels. 4. A N E W INITIATIVE IN SPACE-BASED
ENERGY 3. BARRIERS TO A C C E P T A N C E OF SPACEBASED ENERGY
It should be explicitly noted that there is a widely-held perception that space solar power importation is not an economically feasible option. This perception stems from the 1980 assessment (National Research Council, 1981) by the National Research Council of the U.S. Academy of Sciences of an extensive study conducted by the U.S. Department of Energy (DOE) and NASA in 1977-1980 to examine the feasibility of what was called the solar power satellite. This assessment asserted that the assumptions of the DoE/NASA study were too optimistic, especially in the area of photovoltaic cell performance and probable launch costs. The assessment went on to recommend that further relevant research be tracked and the situation be assessed from time to time, but that implementation not be pursued at that time. The situation of the early 1980s is still assumed by many to be the current reality. Such assumptions have largely prevented any U.S. governmental involvement since 1980 and this in itself is a major barrier to international cooperation. International acceptance of the tThis portion of the spectrum (2400-2500MHz) is known as the ISM Band. Comments on proposed changes to present allocations have been made by members of the community interestedin space solar power to Earth and by the International MicrowavePower Institute.
The barriers described in the preceding section are very real, but not insurmountable. A substantial resurgence of interest has occurred in several countries over the last few years. Importantly, solid experimental and theoretical work has been carried out, especially in wireless power transmission. Furthermore, outstanding progress has been made in the area of photovoltalcs, driven by terrestrial applications. Thus the time seems ripe for a new international initiative in space-based energy. A review of the status of the technologies required for space solar power for Earth shows that, except for launch costs, much has changed for the better in the intervening decade and a half since 1980. Even in the area of launch costs, there has been some movement and studies have shown that substantial reductions can be achieved. Furthermore, the rationale for pursuing new and renewable energy sources has been greatly strengthened in light of environmental concerns and global needs. The more important of the changes in technology are noted in Table 1. The outlook for future progress in the key technology area is also encouraging. Overall technical risk is declining as important areas of the technology mature. In particular, photovoltaics, wireless power transmission, and robotics are all advancing well. The use of space robotics for construction is a new and growing area, one
Acquisition of space-based energy
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Table 1. Changes in enabling technology for space-based energy Then (1980)
Now (1994)
Photovoltaics - - fledgling industry Expensive, over $100 per watt Low efficiency Small production
Photovoltaics--maturing industry Price dropping toward $1 per watt Improved efficiencies Single crystal Poly crystal Thin film Robust, expanding capacity
Transportation Pre-shuttle
Transportation Still costly, but more options Reusability demonstrated
Wireless power transmission Goldstone ground test ISM band initial steps taken
Wireless power transmission In-space transmission experiments More biological studies, no show stoppers Increased fear of electro-magnetic fields ISM band in jeopardy 5.8 and 35 GHz technology Laser development
Construction of solar power satellites Big fixtures/space factories
Construction of solar power satellites Robotic assembly (automation industry) No big fixture, build upon itself
Ground segment 10 13 km for 5 GW
Ground segment 3 km diameter for 1 GW Thin film-lightweight arrays
which should make quite unnecessary the large number of space-based construction workers called for in the studies of the 1970s. Finally, it should be possible to evolve toward the acquisition of space-based energy through logical steps from aircraft applications of wireless power transmission, to power relay satellites, to solar power satellites. Eventually, perhaps, solar power satellites will be built using extraterrestrial materials or, in the far future, the moon will be used for capture and transmission of solar energy. There has also been a major shift in the stimulus for pursuing space solar power for Earth. The initial stimulus in the early to mid 1970s was driven by concerns over the energy supply and the threat of cost increases. Especially important was the strategic aspect of the supply in light of oil embargoes. Furthermore, the interest at the time was solely in the U.S.A. Today, concerns focus on degradation of the planetary environment, on the dim prospects for healthy economies in the Developing Countries and on providing a global energy future that can be sustained indefinitely. 5. A N A P P R O A C H T O A C T I V A T E INTERNATIONAL COOPERATION IN
SPACE-BASED ENERGY The most fundamental step toward achieving international cooperation in space-based energy SE 56:1-G
is to promote its credibility and viability. All those interested in a sustainable world energy future, and those eager to see spacefaring escape its present stagnation, should promote awareness of that solar power from space for use on Earth as an application that could help solve a pressing human need. At the same time, for those interested in the space dimension, it could provide a market for a vastly larger and more economical space transportation capability.
5.1 A role for government and industry It is important to pursue space-based energy in a way that combines the skills and roles of both government and industry. It is the judgment of this author that a government megaprogram is not a workable approach, whether undertaken by one government or by several. Energy supply is a matter for the private sector in many countries, one shared with governments in other countries, and a totally governmental responsibility in still others. Government/ Industry partnerships would allow reasonable sharing of risk and yet harness the power of the profit motive. There are many precedents for this in past programs for large-scale infrastructure; e.g. the railroads in the U.S., the Suez Canal and the "Chunner'. A pivotal role exists in the U.S.A. for the Department of Energy and NASA. These agencies led the early work and then abandoned the
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field. This has critically lessened the credibility of space solar power f o r Earth in other countries. An important step is to reactivate interest within these U.S. agencies. The existence of a Department of Energy/NASA activity, beginning simply with responsible points of contact in each agency, would create an appropriate focus for international cooperation. The two agencies could, jointly, follow, understand and document international efforts, and be the clearing house and information source on the state of technical, environmental and socio-political aspects of power importation to Earth.~ Once the Department of Energy/NASA activity was well-established, it could provide liaison with other U.S. government departments (e.g. Commerce and EPA) to form and lead a G o v e r n m e n t - I n d u s t r y Council on space solar power f o r Earth. This Council could oversee the development of a National Space Power Plan which, in turn, could provide the basis for meaningful international collaboration. Another key factor in advancing power importation is to recognize that acceptance and progress will come from demonstrations and pilot operational activities, not from more paper studies. Bilateral and multilateral experimental and developmental programs could build upon existing efforts and relationships, utilizing existing and planned international experimental and development facilities, such as the International Space Station and ground-based test ranges. Such an approach would reduce economic and political risk though step-by-step activities each of which would be designed to provide significant technical results and to earn public confidence in the value, safety and feasibility of space solar power f o r Earth. 5.2 A role f o r professional societies
Professional societies serving the energy, space and environmental communities have a key role to play in authenticating space-based energy and in promoting its eventual implementation. One positive step that can be taken immediately is the creation of an International Council
on
Space
Solar
Power f o r
Earth.
Precedents for this exist in the astronomy and nuclear physics communities where such organizations foster international professional collaboration. The objectives of such a Council would tThe National Research Council assessment recommended that relevant research be tracked on a continuing basis by these agencies.
include international outreach and marketing efforts and the facilitation of international cooperative projects. The Council would actively foster the participation of Developing Countries, aid in industry/government/academia collaboration on an international basis, and continue regular Wireless Power Transmission Conferences. Specific actions which could be undertaken by this proposed Council are: • develop a position paper which would document the technical status of space-based energy as a starting point for renewed discussion; • establish an Internet-based network on space power. The first steps were taken at a recent AIAA Workshop which accepted a proposal from Japan for the creation of a Space Power Network (SP-Net) to facilitate increased international discussion and interaction; • convene a workshop to address the critical and interdependent nature of space transportation and space power requirements. 6. CONCLUSIONS A need exists for new sources of clean energy. Solar energy captured in space is one viable option. Implementation of this option can occur only with international cooperation. It is timely to activate new efforts in this area and important roles exist for industry, government and professional societies. 7. R E F E R E N C E S
Cheston T. S. Practical approaches to international space power. In Solar Power Satellites (Glaser P.E.), Chap. 4.4. Ellis Horwood, New York (1981). Churchill A. Representative of the World Bank. In 15th World Energy Congr., Madrid, Spain. Cline W. R. The Economics of Global Warming. Institute for International Economics, Washington, DC (1992). Erb R. B. Power from space--when? 43rd Cong. Int. Astronautical Federation, Paper IAF-92-0595, Washington, DC (1992). Erb R. B. Power from space--can it compete. 45th Congr. Int. Astronautical Federation, Paper IAF-94.R2.372,Jerusalem, Israel (1994). Glaser P. E. et al. Solar Power Satellites. Ellis Horwood, New York (1993). Goldemberg J. et al. Energy for a sustainable world. World Resources Institute (1987).
Holdren J. P. Energy in transition. Scientific Am. September (1990). Leonard R. S. Net present value analysis for satellite power systems. Institute for Sustainable Futures, Santa Fe,
NM (1992). National Research Council. Electric power from orbit: a critique of a satellite power system. National Academy Press, Washington, DC (1981). Pioneering the space frontier. Report of the U.S. National Commission on Space. Bantam Books (1986).
Acquisition of space-based energy Report of the AIAA Workshop on International Space Cooperation, Kona, Hawaii, 4-9 December 1994. Solar energy and space. Session at World Solar Summit, UNESCO, Paris, France (1993). World Energy Council, Round Up, 15th World Energy Congr., Madrid, Spain (1992).
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World Meteorological Organization/United Nations Environment Program Intergovernmental Panel on Climate Change. Climate Change--The IPCC Response Strategies. Island Press, Washington, DC (1991).