Ecoefficiency characterizes industries that add the most value to the global GNP with the least use of finite resources and the least environmental impacts. The U.S. has a lead today. This lead - still unrecognized and still far beyond the horizons of most business - is rooted in our successful space program. A true example of technology transfer, space technologies coupled with solar energy conversion systems hold the potential for a new industry and a new chance for world industrial leadership. when space technology systems in Earth's orbit and wireless power transmission combine to provide energy from space for use on Earth (1), the U.S. can reclaim its technological lead.

Wireless Power Transmission ( WPT) Background

The vision of achieving WPT on a global scale was proposed over 100 years ago when Nikola Tesla first started experiments with WPT, culminating with the construction of a tower for WPT on Long Island, New York, in the early 1900s. Tesla's objective was to develop the technology for transmitting electricity to anywhere in the world without wires. He filed several patents describing wireless power transmitters and receivers. However, his knowledge of electrical phenomena was largely empirical and he did not achieve his objective of WPT, although he was awarded the patent for wireless radio in 1940.

The development of WPT was not effectively pursued until the 1960s when the U.S. Air Force funded the development of a microwave-powered helicopter platform (2). A successful demonstration of a microwave beam-riding helicopter was performed in 1965. This demonstration proved that a WPT system could be constructed and that effective microwave generators and receivers could be developed for efficient conversion of microwaves into DC electricity.

The growing interest in solar energy conversion methods and solar energy applications in the 1960s and the limitations for producing cost-effective baseload power caused by adverse weather conditions and diurnal changes led to the solar power satellite concept in 1968 (3) as a means to convert solar energy with solar cell arrays into electricity and feed it to a microwave generator forming part of a planar, phased-array antenna. In geosynchronous orbit, the antenna would direct a microwave beam of very low power density precisely to one or more receiving antennas at desired locations on Earth. At a receiving antenna, the microwave energy would be safely and very efficiently reconvened into electricity and then transmitted to users.

The first technical session on solar power satellites ( SPS) was held in 1970 at the International Microwave Power Institute Symposium (4) at which representatives of Japan, European countries, and the former Soviet Union were present. Based on preliminary studies, a plan for an SPS program was prepared by an NSF/NASA panel in 1972 (5), and the first feasibility study of SPS was completed for NASA/Lewis Research Center in 1974 (6).

Shortly after the "oil shock" of October 1973, Japan staned to implement the Sunshine Plan to develop renewable energy sources. Japan's Plan included, as a long-term objective, the development of SPS. Back in the U.S. in 1975, a successful demonstration of microwave wireless power transmissions was performed at the NASA Deep Space Antenna facility at Goldstone, California. In this demonstration of point-to-point WPT, 30 kW of microwaves were beamed over a distance of one mile to a receiving antenna. Microwaves were converted directly into DC at an average efficiency of 82%, confounding critics who claimed that such high conversion efficiencies could not be achieved. By 1976 engineering, environmental, and economic analyses of several SPS concepts had been performed by NASA The Office of Management and Budget, in its deliberations on the Fry 1977 budget, directed that further study of this concept be the responsibility of the Energy Research and Development Administration (ERDA), which subsequently became the Department of Energy (DoE). The SPS Concept Development and Evaluation Program (CDEP), performed by DoE/NASA and its contractors, used a NASA-developed SPS Reference System configuration as a basis for conducting environmental, societal, and comparative economic assessments, The DOE/NASA assessment team, as well as a majority of scientists, engineers, and analysts who participated in the CDEP recommended that the program be continued at a modest funding level, and SPS assessments directed at resolving or reducing significant uncertainties associated with microwave radiation effects and SPS design considerations, and to continue some promising experiments (7). By 1980 the CDEP was brought to its scheduled conclusion and not continued in a follow-on program, partly because the economic pressures of the oil crisis had passed, partly because of changed priorities for renewable energy development, and partly because of expectations that nuclear and eventually fusion power would meet future growth in energy demands.

Organization of Japan's WPT Development Program

In the meantime, Japanese industry followed the SPS CDEP program with growing interest, and started research and technology development efforts in the 1980s on various applicable technologies. Government-sponsored space activities are coordinated by the Japanese Space Activities Comniission in the Prime Minister's Office and the Ministry of Education's Institute of Space and Astronautical Science. Private sector space activities in Japan are coordinated by the Federation of Economic Organization (Keidanren) through its Space Activities Promotion Council, the Space Committee of the Society of Japanese Aerospace Companies, and the Space Technology Research and Development Group of Japan, in addition to other groups involved with Space Station, Communications, Remote Sensing, and Space Utilization. The construction industry has carried out research on SPS and a lunar base since 1987. An overview of Japan's Space Power development efforts was presented at the 1988 International Conference on Space Power, Cleveland, Ohio, under the auspices of the International Astronautical Federation.

In 1987, several representatives from Japan participated in the Planning Conference for the International Space Year (ISY), Kona, Hawail, where a session on Space Industrialization was devoted to space power development and demonstration projects using WPT:

"...1) to evaluate the feasibility of collecting and converting solar energy, and transmitting energy at levels necessary to facilitate industrial applications either in orbit or on Earth;

2) to operate space and ground facilities capable of conducting engineering and scientific tests to provide critical data; and

3) to evaluate the applicability of new technology to space power..." and presentations on SPS in medium altitude equatorial orbit (8).

The commitment of Japan to the development of space power is indicated by participants on the Space Power Committee of the International Astronautical Federation and specifically in SPS related activities based on papers delivered at SPS 91, Paris (9), and SPS 92, Rio de Janeiro (10). The Institute of Space and Astronautical Science (ISAS) organized a Working Group on SPS and holds Annual Space Energy Symposia. At the Twelfth ISAS Space Energy Symposium (11) reports on Microwave Energy Transmission Systems (METS) included: the successful MILAX airplane experiment performed in August 1992; technical details on the ISY METS rocket experiment that was successfully flown 18 February 1993; and technologies for SPS 2000, an SPS demonstrator designed to beam 10 MW from low-Earth orbit to a receiving antenna on Earth were presented. SPS 2000 is currently being developed by representatives from academic institutions and industry in the SPS Working Group.

Japan also hosted the International Space University's summer session in 1992. This six-week student project focussed on SPS. Additionally, a group of Japanese authors are presenting the results of a study on a new concept for SPS at the 44th International Astronautical Federation Congress, Graz, Austria, October 1993.

A Japanese industry mission, including 14 industry representatives, visited the U.S. in January 1992 under the auspices of the Japan External Trade Organization, to discuss SPS-related space activities (12).

Current Japanese WPT Projects

The SPS 2000 study team finished the first phase of their study as announced in the SPS 2000 Newsletter, April 1993 (13), and displayed a 1/50 scale model at several industry supported exhibitions in Japan.

In parallel with technical studies of SPS, the "Microwave Country" project, as a follow-on to the "Microwave Garden," will beam 10 kW of microwaves from a microwave antenna installed on a tower to a receiving antenna to study ecological effects of microwaves, influence of weather conditions on microwave reflection from the ground surface, and development of elements of the transmitting antenna.

In addition, the project "Microwave Power Transmitting Experiment to a Mountain" is in the planning stage, with the objective to perform functional tests on the transmitting and receiving antennas, and to promote public recognition of the benefits of WPT. The transmitting antenna is to be located 12 km from the summit of Mt Fuji and designed to beam 100 kW over a distance of 12 km to a receiving antenna on the summit.

The Japanese Ministry of International Trade and Industry, as quoted in the Sankei Shimbun, Tokyo, announced in February 1993 that in accordance with the "New Sunshine Plan," a global SPS system is to be in place by 2040. Several of the government agencies and industrial organizations previously mentioned will study the viability of this project based on the output of previous studies and results of ground and space flight tests already completed and planned.

WPT is an enabling technology for utilizing renewable and inexhaustible energy sources on Earth and in space to meet projected electrical energy demands in the 21st century on a global scale. Achieving per capita increases in energy use without adversely affecting Earth's ecology will be a significant influence on reductions in the rate of population growth without draconic measures. Increasing living standards have led to reductions in birth rates in developed countries as a byproduct of industrialization in the 19th and 20th centuries (14). Global electric power production is about a $1 trillion per year market currently, and represents the largest market on Earth. Penetration of this market by gradually substituting WPT to access renewable and inexhaustible energy sources anywhere on Earth and in space is an opportunity that Japan has recognized.

Japan has the capability to develop and apply the required technologies to develop the WPT systems for several applications. Japan can gain access to space either with its own launch vehicles or by utilizing the launchers developed by other countries to meet launch requirements. Low-cost access from Earth to space may be of reduced importance in the 21st century for large-scale engineering projects, when extraterrestrial material resources can be obtained from the Moon or asteroids for construction of power relay satellites and solar power satellites in Earth orbits or on the Moon.

MITI's "New Sunshine Plan" to construct a global SPS system in 50 years may be visionary, but this timespan is appropriate for a macroengineering project with global benefits.

Evolving WPT Markets

Markets that will be made accessible with WPT will have a profound influence on global business activities and industry competitiveness. The following are examples of the future commercial opportunities of WPT:

1. Roadway powered electric vehicles for charging electric batteries with WPT from microwave generators embedded in the roadway while a vehicle is travelling at highway speed, thus eliminating stops to exchange or recharge batteries greatly extending travel range.

2. High-altitude, long-endurance aircraft maintained at a desired location for weeks or months at 20 km for communications and surveillance instead of satellites, at greatly reduced costs.

3. Power relay satellites to access remote energy sources by uncoupling primary electricity generation from terrestrial transmission lines (15). Power is transmitted from distant sites to geosynchronous orbit and then reflected to a receiver on Earth in a desired location.

4. Solar power satellites in low-Earth or geosynchronous orbit or on the Moon to supply terrestrial power demands on a global scale (16).

Impacts of WPT Development on U.S. Industry

Evolution of the opportunities to participate in the development and applications of appropriate WPT systems would provide not only an outlet for the considerable experience and talents residing in the U.S. aerospace and manufacturing industries, but ensure that these industries remain competitive in the markets for environmentally compatible energy sources where carbon is no longer the essential element for electrical power generation.

The current opportunities that Japan's industry is providing will be the basis not only for energy independence domestically from imported energy sources, but as a supplier of "clean" energy, thus gaining political influence globally.

WPT systems have not been considered seriously by U.S. government agencies since 1980. The implications of successful developments of WPT systems by the Japanese are profound enough to merit a deliberate decision either to pursue development or abandon pursuit of WPT markets to other countries with consequences that may result in adverse impacts on U.S. industry in the 21st century and beyond.

Now is the time to plan for the future that can be discerned in broad outlines. The inability to see the future except as a continuation of the present and not to plan for it will prevent but a mystical anticipation of it. The evolution of the human species into space will continue - there is no turning back from the High Frontier. The U.S. is still in a position to lead a WPT effort but not for long. The question is not whether we harness power from Space; but rather who will get there first to impact the global economy.

1. P E Glaser, Fall 1989, " Solar Power Satellites [3]", The Journal of Practical Applications in Space, Vol.1, No.1, pp.7-28
2. W C Brown, 1965, Experimental Airborne Microwave-Supponed Flat-form, Technical Report, RADC-TR-65-188, Rome Air Development Center, Rome, NY
3. P E Glaser, 1968, " Power From The Sun: Its Future", Science, Vol. 162, pp.857-866
4. (anon), December 1970, " Satellite Solar Power Station and Microwave Transmission to Earth", Journal of Microwave Power, Special Issue, Vol.5, No.6
5. National Science Foundation, 1972, " An Assessment of Solar Energy as a National Resource", NSF/NASA Solar Energy Panel, University of Maryland, College Park
6. P E Glaser et al, 1974, " Feasibility Study of a Satellite Solar Power Station", NASA, Lewis Research Center, OH, CR-2357
7. F A Koornanoff and C E Bloomquist, 1993, "The satellite power system: concept development and evolution programme" in Solar Power Satellites - the emerging energy option. P E Glaser, F P Davidson, and K I Csigi, editors, Ellis Horwood, Chichester, UK, pp. 26-59
8. R Akiba and H Yokota, 1988, " Systems Analysis of Energy Storage Orbital Power Station (ESOPS) in Medium Altitude Equatorial Orbit", Proceedings of the Pacific ISY Conference, August 1987, Kona, Hawaii, University of Hawaii at Manoa, Hawaii Institute of Geophysics
9. N Kaya, H Matsumoto and R Akiba, 1991, "Rocket Experiment METS - Microwave Energy Transmission in Space," Proceedings of 2nd International Symposium, SPS 91, Societe des Electriciens at des Electroniciens (SEE), Paris
10. Y Kuroda, 1992, "A Japanese Perspective on Power from Space for Earth", SPS Rio 92 - Space Power Systems and Environment in the 21st Century Symposium, SEE, Paris
11. M Nagatomo, Coordinator for the Twelfth ISAS Space Energy Symposium, March 10 and 11, 1993, Institute of Space and Astronautical Science (ISAS), Sagamihara
12. Japan External Trade Organization, 1991, " Solar Power Satellite R&D in Japan", New Technology Japan, Special Issue, New York, NY
13. M Nagatomo (ed), 1993, " SPS 2000 Newsletter", SPS 2000 Task Team, ISAS, No.7
14. P E Glaser, 1992, " The Potential of the Solar Power Satellite", in Solar Power Satellites - the emerging energy option, Ellis Horwood, Chichester, UK, p.2
15. P E Glaser, 1993, "The Power Relay Satellite," Wireless Power Transmission Conference, San Antonio, Texas, 23-25 February 1993, Center for Space Power, Texas A&M University, College Station, Texas.
16. D R Criswell, 1993, "Solar Power System Based on the Moon," Solar Power Satellites - the emerging energy option, Ellis Horwood, Chichester, UK, pp.272-288