Solar Power Satellite (SPS) helps in capturing energy from the ‘Sun’ and transmits to the Earth. This article explains in detail about what is Solar Power Satellite (SPS), it’s architecture, how it works, its applications, advantages and disadvantages.
What is Solar Power Satellite
Solar Power Satellite is basically used to generate electricity using Solar power. This concept of transmitting the power from space to earth was proposed in the year 1968 by a scientist Peter Glaser.
Fig. 1 – Introduction to SPS
The energy in the space i.e. sunlight is captured and converted to DC current (Direct Current). This is converted to Microwave power using a converter. The Microwaves are directed towards the desired location on the earth using microwave antenna also called as Rectenna.
SPS operates outside atmosphere in a vacuum environment. It can be the best substitute or alternative to Fossil Fuels. This type of power generation through Solar Power Satellite does not cause pollution and does not require transmission lines or cables to transmit power to the desired location.
In the year 2008, Japan announced Space Solar Power as their national goal. The first test of Solar Power generation was conducted by US Naval Research Laboratory in May 2020. In the near future, Space Solar Power will eliminate the use of fossil fuels and will provide clean energy.
Fig. 2 – Image of Solar Power Satellite
Architecture of SPS
The system is proposed to consist of three main components namely:
- Transmitter Module
- Receiver Module
Initially Solar Photons are converted to Direct Current using Solar Cells. These are semiconductor cells made up of Silicon or Gallium Arsenide which helps in the conversion of Solar power to Electrical power. These Photovoltaic cells are resistant to thermal and radiation degradation.
DC (Direct Current) is converted to Microwave for the transmission through Antenna. This is achieved through Microwave Oscillators like Klystrons or Magnetrons. Microwaves frequency ranges from 0.3 – 300 GHz.
Alternatively, DC can be converted to Infrared laser radiation and transmitted to Receiver Module as a Laser beam. The Microwave is transmitted as a power beam to the Receiver on the earth’s surface.
The Receiver Antenna is called as Rectenna. It receives Microwave Power that is transmitted from the Transmitter Module. Single Satellite can power different Rectennas. Rectenna that is initially equipped with the Pilot beam receives the transmitted beam. Rectenna consists of billions of Dipole antenna on a Grid.
The Received power is rectified using Rectifier Circuits that would convert Microwave power to DC power. The DC is processed and converted to AC (Alternating Current) and supplied through transmission lines. Receiver Module has a Control Unit that helps in maintaining orientation of Solar Cells of Solar Power Satellite facing Sun. It also keeps a check on the Satellite’s position.
Fig. 3 – Architecture of Solar Power Satellite
How does Solar Power Satellite Work
The proposed reference system of SPS by NASA consists of a Satellite with large number of Photo-Voltaic cells also called Solar Array. The satellite operates from Geo-Synchronous Orbit above the Earth’s equator.
The Control Unit controls the position and operation of the satellite. The Solar Panels are oriented towards the ‘SUN’ so that maximum Solar energy is captured. It controls the alignment of Transmitter and Receiver with the help of Rotary joints. This helps in Transmission and Reception to be reliable and effective.
The Solar energy is converted to DC (Direct Current) and further converted to Microwaves which are transmitted to Receiver Module on the Earth’s surface. The Receiver Module receives the Microwave energy and converts into DC. This is further processed to AC and sent through transmission lines to the destined locations.
Fig. 4 – Working of SPS
Applications of Solar Power Satellite
The applications include:
- It could be used to generate Electricity.
- It could also power space vehicles.
- It can also be used for space-based applications.
Advantages of Solar Power Satellite
- Due to lack of diffusing atmosphere, it provides higher collection rate and longer collection period.
- Transmission to the required location is possible and simple.
- Losses of energy which happens because of reflection and absorption in the atmosphere is negligible as the conversion of Sunlight to Microwaves is outside the atmosphere.
- As Solar Power does not emit Green House gases, it is a form of sustainable and clean energy.
Disadvantages of Solar Power Satellite
- Implementation cost is high.
- System is complex.
- The Solar Power Satellite is prone to damage easily due to high Radiation and Micro meteoroids.
- Storage of electricity is also an issue.
- Providing uniform power beam using Klystrons is critical.
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