INTRODUCTION Now-a-days we are using the solar power to generate electricity by the solar panels mounted on the earth. In outer space, the sun always shines brightly. No clouds block the solar rays, and there is no nighttime. Solar collectors mounted on an orbiting satellite would thus generate power. A new method for power generation in which the solar power is converted into microwaves through satellites called Solar Power Satellites (SPS) and it is received using a special type of antennae called Rectenna, mounted on earth surface.

HISTORY Producing electricity in space from sunlight is used by hundreds of satellites in operation today. In 1968, Dr. Peter Glaser, formerly of NASA, introduced the concept of a solar power satellite system with square miles of solar collectors in high geosynchronous orbit to collect and convert the sun's energy into a microwave beam to transmit energy to large receiving antennas (Rectennas) on earth. In 1999 NASA formed SERT, the Space Solar Power Exploratory Research and Technology program to perform design studies and evaluate feasibility.

WHY TO USE SPS? The SPS concept arose because space has several major advantages over earth for the collection of solar power. There is no air in space, so the satellites would receive somewhat more intense sunlight, unaffected by weather. The Solar Power Satellite (SPS) concept would place solar power plants in orbit above Earth, where they would convert sunlight to electricity and beam the power to ground-based receiving stations. The latter problems have plagued ground based solar power concepts, but the SPS suffers none of the traditional limitations of ground-based solar power. With SPS maximum energy loss due to eclipses is only a 120 hours a year.

RECTENNA RECTENNA=RECTIFIER+ANTENNA. It converts microwave energy to DC electricity. Constructed from a SCHOTTKY diode placed between antenna dipoles. Efficiency-90%

ENERGY CONVERSION The SPS is a gigantic satellite designed as an electric power plant orbiting the Geostationary Earth Orbit (GEO). It consists of mainly three segments; i)solar energy collector to convert the solar energy into DC (direct current) electricity.we use photo voltaic cells. ii)DC-to-microwave converter, and large antenna array to beam down the microwave power to the ground. iii) incoming microwave radiation into DC current and hence the name Rectenna.

Solar panels on satellite capture light, sends power to earth using microwave wireless power transmission technology Signal sent from receiving antenna on earth (green) allows satellite to pinpoint it’s microwave beam.

SPS MODEL

MODELS TRANSMITTER & RECTENNA RECEIVER

Transmission of Power RECTENNA==Radio frequency energy  DC voltage  AC electricity  Homes,Factories,etc. DC input at solar cells to the DC output of Rectenna. DC to DC efficiency—63%

Environmental Effects The SPS will operate at a frequency designed to NOT be absorbed by water in the atmosphere, and to pass through the clouds and rain. SPS beam does not cause any effects to the environment,because micro waves have less frequency compared to others. It produces less heating effect.

Communication Satellites Benefits Extending life of satellites (e.g., selling old satellite to less developed countries) "Improved electromagnetic shielding and other minor modifications would be expected to eliminate or substantially reduce effects to allow normal performance."

Make your own RECTENNA

General Benefits No pollution after construction Source of energy is free Large amount of energy potential.

Space Advantages Dis- advantages of SPS Less atmosphere for sunlight to penetrate for more power per unit area Any location on Earth can receive power Satellite can provide power up to 96% of the time Solar panels do not take up land on Earth Lots of space in space Promote growth of space, solar, and power transmission tec VERY expensive initial cost Microwave/lasers may be harmful? Cosmic rays can deteriorate panels Maintenance Problems Very large receiving antennas on earth Solar winds could kick it off course

CONCLUSION Major way to face demand of ELECTRICITY. We need not bother about the exhaustment of natural resources which are used in generation of power. It will become boon to the next generations.

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