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  • Status of JAXA’s study of the microwave based and laser based space energy utilization systems

    Paper number

    IAC-06-C3.3.01

    Author

    Dr. Mitsushige Oda, Japan Aerospace Exploration Agency (JAXA), Japan

    Coauthor

    Mr. Masahiro Mori, Japan Aerospace Exploration Agency (JAXA), Japan

    Year

    2006

    Abstract

    Energy demands from human activates are growing rapidly. Oil price became double in a few years. Sooner or later, the oil resources will be exhausted. Reduction of CO2 gas is interest of major countries. The space solar power systems (SSPS) which collects energy in space and sends the collected energy by wireless are potential alternative energy source of future. JAXA is conducting research of SSPS for years. JAXA is studying two types of SSPS, the microwave based power transmission system (M-SSPS) and the laser based power transmission system (L-SSPS).

    M-SSPS is being studied by many countries for years. Concepts of M-SSPS can be categorized in several types. The earliest type used the Sun looking photovoltaic arrays and the Earth looking WPT (wireless power transmission) antenna. However this type of concepts went out from a reliability concern, since huge power must go through a rotating joint between the photovoltaic arrays and the WPT antenna. Static type SSPS were proposed next. However this type of concept can not generate continuous power, since the Sun’s direction from the photovoltaic arrays changes continuously. Recently proposed SSPS are mostly use solar light concentration mirrors. However, way of supporting and controlling position and direction of the mirrors would be a problem, since size and mass of the mirrors are massive. A traditional mechanical joint will not be possible to support and to control a massive mirror.

    JAXA is proposing a formation flying solar reflectors in order to avoid such a problem. In case solar collection mirrors are used, thermal management becomes important since, concentrated solar energy is provided to the photovoltaic arrays and only a part of injected energy becomes electricity and remaining energy becomes heat.

    Concepts of L-SSPS are relatively new. L-SSPS that JAXA is studying is a system which uses the direct solar pumping laser to send the energy to the destination point. Merit of L-SSPS over the M-SSPS is the better power conversion efficiency from the solar energy to the received energy on the ground. The efficiency of M-SSPS is mostly dominated by the efficiency of the photovoltaic arrays. Typical power conversion efficiency of the photovoltaic array from the Sun light to the electricity is roughly 15

    In the actual presentation, detailed report of the currently being studied configuration of the M-SSPS and the L-SSPS.

    Abstract document

    IAC-06-C3.3.01.pdf