Solar Power Satellite Concept Research Articles

Conceptual design and orbit-attitude coupled analyses of free-drift solar power satellite

Solar power satellite is known as a promising source of clean energy from space in the future. One of the key problems of current solar power satellite concepts is the huge cost because of the excessively large mass and fuel consumption. The objective of this paper is to propose a new Free-Drift Solar Power Satellite concept that reduce mass and fuel consumption. Firstly, Sun-frozen orbit in geosynchronous Laplace plane and quasi-Sun-pointing attitude are designed to significantly save orbital and attitude control fuel. To this end, an orbit-attitude coupled modelling method considering space perturbations is proposed for multibody systems. Orbital and attitude dynamics and control are studied to substantiate the orbit and attitude design. Secondly, two transmitting antennas and three solar arrays are adopted and allocated elaborately to reduce structural deformations and attitude disturbance. The mass of the transmitting cables from solar arrays to transmitting antennas is also reduced by the proposed layout. Finite element analysis is performed to validate the design of supporting structures. Finally, other subsystems are briefly introduced and the system parameters are summarized.

Optical study of a cocktail structural Space-based Solar Power Station

SPS-ALPHA as the most innovative and practical concept of Solar Power Satellite (SPS), has been widely concerned in the world. It adopts axisymmetric sigmoid curve-based/cocktail shape as the entire structure composed by several thousands of hexagonal “Reflectors and Deployment Modules” (RDM) that enables extremely high modularity and low cost of machining/space transport. SPS-ALPHA system, on the whole, can be treated as a dense array concentrated photovoltaic (DA-CPV) system. The blocking shadow effect and cosine effect of ray path exist that make the optical efficiency fluctuate with different tracking angles, resulting the trade-off exists between optical efficiency and irradiance uniformity. The current study aims to find the optimal design parameters of RDM when high optical efficiencies and stable irradiance distribution are both achieved for effective PV layout design. To meet this target, Ant Colony Optimization (ACO) algorithm combined with dynamic source-target mapping was adopted to find suitable aiming vectors of modular reflectors. The optical transmission characteristics under different incident degrees were investigated using a two-step Monte-Carlo ray tracing (MCRT) method. Afterwards the optimized results and sensitivity analysis for RDM would be undertook. The article can provide basic data and reference for engineering constructions of SPS-ALPHA in next step.

SOLAR POWER SATELLITE AND MICROWAVE TRANSMISSION FROM SPACE TO EARTH FOR GENERATING ELECTRICAL POWER

A solar power satellite (SPS) is a renewable energy system that converts the sun’s energy into electricity in space and transmits it to Earth using microwaves. One of the most challenging technologies for the SPS is microwave power transmission from the geostationary orbit to the ground. The technologies for microwave power transmission have been studied for more than 40 years since the initial demonstrations in the 1960s; however, for SPS application, considerable research, especially on high-efficiency power conversion between direct current (dc) and radio frequency (RF) and on high-accuracy microwave beam control over a long range, is still needed. This paper introduces the concept of SPS and presents the technologies and issues associated with microwave power transmission from space to ground to generate electrical power.

Microwave Power Transmission Technologies for Solar Power Satellites

A solar power satellite (SPS) is a renewable energy system that converts the sun's energy into electricity in space and transmits it to Earth using microwaves. The SPS concept, first proposed in 1968 in the United States, has recently started attracting increased public attention as a promising energy system that can be used to resolve global environmental and energy problems. One of the most challenging technologies for the SPS is microwave power transmission from the geostationary orbit to the ground. The technologies for microwave power transmission have been studied for more than 40 years since the initial demonstrations in the 1960s; however, for SPS application, considerable research, especially on high-efficiency power conversion between direct current (dc) and radio frequency (RF) and on high-accuracy microwave beam control over a long range, is still needed. This paper introduces the concept of SPS and presents the technologies and issues associated with microwave power transmission from space to ground. Current research status and the future development prospects for microwave power transmission toward commercial SPS use are also described.

PROPOSITION OF A NEW METHOD ON THE TWO-DIMENSIONAL DEPLOYING OF PLANE PANELS AND ITS STABILIZATION

With concerns about dependence on fossil fuel and emission of carbon dioxide, a concept of Solar Power Satellite was proposed by Dr. Peter Glaser in America, 1968. The concept is to construct huge solar cell panels in space and send electric energy to earth as micro wave. It was planned in America and in Japan around 1980 as structures whose scale extent is from several hundred meters to kilometers. This thesis will focus on the problem of transportation and construction of such huge plane panel structures and propose how to fold and deploy them two-dimensionally and stabilize it.

Introductory Remarks to “Solar Power Satellites”

The concept of Solar Power Satellite (SPS) is to utilize the space surrounding the earth to tap energy for human society. SPS generates electric power in space using the solar radiation energy and converts it to the microwave power beam to the receiving antenna on the ground. The microwave power is converted to the commercial utility power. SPS has a great potentiality for the large-scale clean energy system to replace the fossil energy plants. To realize the SPS concept, scientific research is widely required for the associated technologies, environmental issues, and social aspects. This special issue is devoted to report the current status of research for microwave power transmission, high voltage solar array, ultra-large antennas, microwave-ionosphere interactions, and construction and structure. This status report will hopefully be a help in promoting the SPS-related research in the field of vacuum science and technology.

A new concept of solar power satellite: Tethered-SPS

Tethered solar power satellite (Tethered-SPS) consisting of a large panel with a capability of power generation/transmission and a bus system which are connected by multi-wires is proposed as an innovative solar power satellite (SPS). The power generation/transmission panel is composed of a huge number of perfectly equivalent power modules. The electric power generated by the solar cells at the surface of each module is converted to the microwave power in the same module. Since the modules are controlled by the bus system using wireless LAN, no wired signal/power interfaces are required between the modules. The attitude in which the microwave transmission antenna is directed to the ground is maintained by the gravity gradient force. The tethered panel is composed of individual tethered subpanels which are loosely connected to each other. This configuration enables an evolutional construction in which the function of the SPS grows as the construction proceeds. A scale model of the tethered subpanel can be used for the first step demonstration experiment of the SPS in the near future.

Fundamental experiments for the development of high-performance cold plates in a feasability study on space solar power system

To realize a concept of solar power satellite with high power generation, it is a promising method to transfer the power by laser beam using active mirror type amplifiers where cooling of the laser material accepting highly condensed sunray is inevitable. To remove high heat flux density from a large area, a structure of cold plate consisted of two parallel plates is devised and the effective liquid supply directly to the bottom of flattened bubbles due to nucleate boiling is realized by the auxiliary liquid feeder. The critical heat flux is increased by more than 1.5 times from that without the additional liquid supply. The technology can be applied not only to space but widely to the development of high-performance cold plates employed on ground.

A TECHNICAL OVERVIEW OF THE “SUNTOWER” SOLAR POWER SATELLITE CONCEPT

During 1995–1996, the National Aeronautics and Space Administration (NASA) conducted a far-reaching reexamination of the technologies, systems concepts and terrestrial markets that might be involved in future space solar power (SSP) systems. The principal objective of this “fresh look” study was to determine whether a solar power satellite (SPS) and associated systems could be defined that could deliver energy into terrestrial electrical power grids at prices equal to or below ground alternatives in a variety of markets, do so without major environmental drawbacks, and which could be developed at a fraction of the initial investment projected for the SPS Reference System of the late 1970s. One of the key concepts emerging from the “fresh look” SSP study is the “SunTower” SPS system. This concept exploits a variety of innovative technologies and design approaches to achieve a potential breakthrough in establishing the technical and programmatic feasibility on initial commercial SSP operations. Capable of being deployed to either low Earth orbit or middle Earth orbit altitudes and various inclinations, the SunTower concept involves essentially no in-space infrastructure and requires no unique heavy lift launch vehicle. The concept, which can provide power to global market places appears to allow up to a factor of 30:1 reduction in initial investment requirements, compared to the 1979 SPS Reference Concept. This paper presents a technical overview of the SunTower SPS concept, including key technologies, sensitivity trades, operational scenarios. Potential non-SPS space program uses of the SunTower concept and related technologies are identified, including human exploration, space science and commercial space applications.

European Sail Tower SPS concept

Based on a DLR-study in 1998/99 on behalf of ESA/ESTEC called “System Concepts, Architectures and Technologies for Space Exploration and Utilization (SE&U)” a new design for an Earth-orbiting Solar Power Satellite (SPS) has been developed. The design is called “European Sail Tower SPS” and consists mainly of deployable sail-like structures derived from the ongoing DLR/ESA solar sail technology development activity. Such a SPS satellite features an extremely light-weight and large tower-like orbital system and could supply Europe with significant amounts of electrical power generated by photovoltaic cells and subsequently transmitted to Earth via microwaves. In order to build up the sail tower, 60 units - each consisting of a pair of square-shaped sails - are moved from LEO to GEO with electric propulsion and successively assembled in GEO robotically on a central strut. Each single sail has dimensions of 150m × 150 m and is automatically deployed, using four diagonal light-weight carbon fiber (CFRP) booms which are initially rolled up on a central hub. The electric thrusters for the transport to GEO could also be used for orbit and attitude control of the assembled tower which has a total length of about 15 km and would be mainly gravity gradient stabilized. Employing thin film solar cell technology, each sail is used as a solar array and produces an electric power in orbit of about 3.7 MW e. A microwave antenna with a diameter of 1 km transmits the power to a 10 km rectenna on the ground. The total mass of this 450 MW SPS is about 2100 tons. First estimates indicate that the costs for one kWh delivered in this way could compete with present day energy costs, if launch costs would decrease by two orders of magnitude. Furthermore, mass production and large numbers of installed SPS systems must be assumed in order to lower significantly the production costs and to reduce the influence of the expensive technology development. The paper presents the technical concept and an economic assessment as well as results of a recent solar sail deployment ground demonstration at DLR's facilities in Cologne.

An overview of the solar power satellite option

The objective of the solar power satellite (SPS) is to convert solar energy in space for use on earth. Its most significant benefit is the potential for continuously generating large-scale electric power for distribution on a global basis. The SPS system is outlined, and the status of the SPS concept development is reviewed. Assessments of key issues are reported including economic considerations and environmental issues as well as physical resource requirements. Legal issues and the need for international agreements on SPS operations are outlined. International SPS-related activities within the context of evolving space programs are discussed. An approach for an evolutionary advancement of SPS to meet requirements for power supplied for use on earth and in space is presented, and a growth path to achieving the potential of power from space for use on earth is outlined. The significance of advancements in technologies applicable to the development of the SPS are discussed. >

Solar Power Satellite: Effects of Microwave on Biological and Ecological Systems

Space energetics has been assigned to a major field of engineering science in space. It relates to important components of infrastructure for future utilization of space and its civilization. Solar Power Satellite (SPS) is one of targets which will be developed in the next century. This project concerns with energy environment problems on earth. Solar power is converted to electric power on orbit and transmitted to ground. This "clean" energy is supposed to eliminate global change of atmospheric environment caused by the usage of fossil fuels. The green house effects at increased carbon dioxide concentration will bring catastrophic change of thermal structure in atmosphere near future. Key technologies for SPS is now planned to be developed. The project named Space Energetics and Environment Laboratory (SEEL) was proposed to be implemented on the space station, now on a free flyer, SFU. SEEL is composed of several experiments, such as Space Plasma, Electric Propulsion, Space Radar, Microwave Power Transmission, and Space Laser.Deployment and dynamical control of large structure in space, electric power generation by solar heat engines, and many related experiments make up a technology package for space energetics. Among these experiments listed above, evaluation of environmental effects caused by SPS is an important part of our study. Working group on SPS was established in ISAS last year. It organizes research programs relevant to SPS development. One of subgroups of this working group is dedicated to ''Biology and Ecology". Programatics of Japanese SPS, macroeconomic aspects and other issues of SPS have been discussed at ISAS Space Energy Symposium and other places. Assessment of SPS was once performed by DOE and NASA. Points of finding and needs of further studies were described in their reports published under the name of SPS Concept Development and Evaluation Program. With their reference system, biological and ecological systems are exposed to microwave radiation. Biological effects of microwave radiation are not well known. Safety standards for exposure of man under high frequency electromagnetic fields differs in many countries.Mechanism of microwave acting on biological organisms has been remained to be answered. Methodology of risk assessment for long term exposure with weak microwave should be also established. It is suggested to promote systematic research on the biological and ecological effects of microvave. In societal assessment, there are several problems which originate in nationality. Siting of rectina in Japan might be offshore, because of its small land area and high population density. Such a domestic features should be also considered in our study. Involvement of biologists is strongly requested at the beginning of Japanese SPS project. Their participation is important to break down work and to define requirements for the activity of SPS working group. On the other hand, SPS might open another curiosity of biologist on interaction of electromagnetism and living systems.

Electromagnetic Energy: Book Reviews and Abstracts

AbstractThe history of power transmission by radio waves is reviewed from Heinrich Hertz to the present time with emphasis upon the free-space microwave power transmission era beginning in 1958. The history of the tech-nology is developed in terms of its relationship to the intended applications. These include microwave powered aircraft and the Solar Power Satellite concept.

The History of Power Transmission by Radio Waves

The history of power transmission by radiowaves is reviewed from Heinrich Hertz to the present time with emphasis upon the free-space microwave power transmission era beginning in 1958. The history of the technology is developed in terms of its relationship to the intended applications. These include microwave powered aircraft and the Solar Power Satellite concept.

Increasing power input to a single solar power satellite rectenna by using a pair of satellites

An outline of the solar power satellite concept is given, and some remarks are made regarding the desirability of increasing the power handling capability of the receiving site. Three arrangements, each based on the use of a pair of satellites, are described by means of which the power handled by a single site may be doubled.

The solar power satellite concept - A space program perspective

The Space Shuttle will reduce the cost of transportation to space from thousands of dollars per pound to hundreds of dollars per pound. Studies of future systems indicate that these costs may be further reduced to tens of dollars per pound by using large space freighters, which would be required to build solar power satellites. It is pointed out that the Space Shuttle will provide a versatile tool in the 1980's to support the exploration of the solar power satellite concept as well as other space programs of the future. Three apparently different applications, related to materials processing in space, advanced satellite communications, and solar power satellites, have a number of common requirements. These include the need for large solar power arrays in space and/or the need to construct large systems in space. Consequently, a space program which includes development of the techniques for large power supplies and structural systems provides the basis for selecting and implementing any or all of these promising applications.