04-10-2012, 04:54 PM
SOLAR POWER SATELLITE (SPS)
Solar Power Satellite (SPS).doc (Size: 1.25 MB / Downloads: 32)
ABSTRACT
This paper reports on the futuristic advances in power transmission through microwaves. Sun is a limitless source of Energy. A Space Power Satellite (SPS) orbiting round the earth traps solar energy and generates electric power using photovoltaic cells of sizable area. SPS transmits the generated power via a microwave beam to the receiving Rectenna site on earth. A RECTENNA (Rectifying antenna) comprises of a mesh of dipoles and diodes for absorbing microwave energy from a transmitter and converts it into electric power. We can in fact directly convert solar energy into electrical energy with the use of solar cells, but this process will be affected by day/night cycles, weather, and seasons. We are aware of the fact that light is an electromagnetic wave. Light rays never diffuse in space & if by any means these rays can be transmitted from space to earth then it will be a perfect solution for our desired need of 24 hrs power supplies. The 21st century endeavors and approaches for establishing human race in space can come true only if the basic requirement of human beings is satisfied i.e. 24hrs power, which can be efficiently served by rectenna. This paper presents the concept & evolution of satellite power system, SPS2000 (a research work by ISAS) and the impact of Microwave Power Transmission (MPT) on space plasma. In near future conventional power sources cannot meet total power demand, for which SPS is a best solution.
DC TO MICROWAVE GENRATION AND AMPLIFICATION
The technology employed for generating microwave radiation is extremely important for the SPS system. It should be highly efficient, very low noise, and have an acceptable weight/power ratio. A microwave energy transmitter often uses 2.45 GHz in the ISM band. There are two types of microwave generators and amplifiers, the microwave tube and the semiconductor amplifier. These have contrasting electric characteristics. The microwave tube magnetron can generate and amplify high power microwaves (over kilowatts) with a high voltage (over kilovolts). It is very economical. The semiconductor amplifier generate low power microwave (below 100W) with a low voltage (below fifteen volts). It currently is still expensive. The microwave tube has higher efficiency (over 70%) and the semiconductor has lower efficiency (below 50%).
Solar Power Satellite of SPS2000:
SPS2000 is a model of solar power satellites with microwave power output of 10 MW, which was proposed by the SPS working group of the Institute of Space and Astronautically Science (ISAS). The primary objective of SPS2000 research is to show whether SPS could be realized with the present technology and to find out technical problems. The conceptual study of SPS2000 is now being carried out under the assumption that the first construction will be started before the beginning of the twenty first century. SPS2000 transforms the DC power generated by huge solar arrays to microwave power at 2.45 GHz and transmits it to the rectennas on the earth while it moves from west to east in an equatorial low earth orbit (LEO) of 1100 km altitude.
CONCLUSION
In the future Rectenna stands as a milestone among non conventional energy resources. This technology is more reliable than ground based solar power. In order for SPS to become a reality it several things have to happen:
– Cheaper launch prices
– Involvement of the private sector