A seminar on

Space Solar Power Satellite

By AMIT KUMAR

IV YEAR VI SEM

CONTENT INTRODUCTION

NEED OF SSPS

DESIGN OF THE SATELLITE BASED SYSTEM

1.SOLAR ENERGY CONVERSION - SOLAR PHOTONS TO DC

2.CONVERTING DC TO MICROWAVE POWER

KLYSTRONS

MAGNETRON

3.TRANSMISSION

4.RECTENNA

SSPS: REQUIREMENT, PROBLEMS, DEPLOYMENT ISSUES, PROBLEM SOLUTION

WIRELESS POWER TRANSFER

i. MICROWAVE

ii. MICROWAVE VS. LASER TRANSMISSION

iii.ADVANTAGES OVER EARTH BASED SOLAR POWER

CONCLUSION

REFERENCES

The SPS is a gigantic satellite designed as an electric power plant orbiting in the Geostationary Earth Orbit (GEO) which uses wireless power transmission(WPT) technique to transfer electrical power.

Space-based solar power essentially consists of four functional units:

a) A Solar energy collector to convert the solar energy into DC (Direct current) electricity.

b) A DC to Microwave converter. c) Large antenna array to beam the Microwave power to

the ground. d) A means of receiving power on earth, for example via

microwave antennas (Rectenna).

INTRODUCTION

NEED OF SSPS

Increasing global energy demand

Nonrenewable energy sources are limited

environmental problems

High Transmission and Conversion Efficiency

Ease of Transmission(remote location)

Non-hazardous Radiation

There is no variation of power supply during the course of the day and night, or from season to season(24x7).

SOLAR SPACE SATELLITE SYSTEM

1.SOLAR ENERGY CONVERSION - SOLAR PHOTONS TO DC

The basic methods of converting sunlight to electricity is photovoltaic conversion (PV) .

In an SPS implementation, photovoltaic cells will likely be rather different from the glass-pane protected solar cell panels They will be optimized for weight They will be designed to be tolerant to the space radiation environment They will not need to be encapsulated against corrosion by the elements. They do not require the structural

support as required for terrestrial use.

PHOTOVOLTAIC CONVERSION

2.CONVERTING DC TO MICROWAVE POWER There are mainly three dc-to-RF power converters:

magnetrons, klystrons and solid state amplifiers. Requirement of a transmitter

i. ability to convert dc power to RF power efficientlyii. Radiate the power to a controlled manner with low

loss. The transmitter’s efficiency drives the end-to-end

efficiency as well as thermal management system . Components of a transmitter

1. dc-to-RF converter 2. transmitting antenna.

Power distribution at the transmitting antenna=(1-r²), where r is the radius of antenna .

Here a high velocity electron beam is formed, focused and send down a glass tube to a collector electrode

which is at high positive potential with respect to the cathode. As the electron beam having constant velocity approaches gap A, they are velocity modulated by the RF voltage existing across this gap. Thus as the beam progress further down the drift tube,

bunching of electrons takes place. This variation in current enables the klystron to have significant gain. Thus the catcher cavity is excited into oscillations at its resonant frequency and a large output is obtained.

KLYSTRONS

MAGNETRONS

high power microwave oscillator(1KW)WORKING Supply given (A=max 4.5kV, C=3.75 V) heated cathode at the Centre electrons are released from it by the process called ‘Thermo

Ionic Emission’ & electrons move towards anode. Due to crossed electric and magnetic fields they move in

circular path around anode The cavities thus resonate and emit microwave radiations

3.TRANSMISSION Two primary options for transferring power from the

spacecraft to a receiver: microwave and laser The microwave technology consists of three parts:

1. TRANSMITTER :The transmitter takes the DC produced by the Solar panels and beams it in the form of microwaves.

2. BEAM CONTROL: The beam control accurately points the transmitter towards the receiver and adjusts the beam amplitude/ phase so that the system can transmit energy with high efficiency.

3. RECEIVING RECTIFYING ANTENNA (RECTENNA) :The rectifying antenna receives the microwaves and converts it back to DC.

4.RECTENNA

It is a special type of antenna that rectifies the incoming microwave radiation into DC current

RECTIFIER

ANTENNA

RECTENNA

Figure :schematic of rectenna circuit

around 10km across 95% of the beam will fall on the rectenna the total received power is in the Gigawatts

(GW)

Figure :5,000 MW Receiving Station (Rectenna).

SPACE SOLAR POWER SATELLITE

The technologies and infrastructure required to make space solar power feasible include:

• Low-cost, environmentally-friendly launch vehicles

• Large scale in-orbit construction and operations

• Power transmission.

REQUIREMENTS

PROBLEMS RELATED It can be used as a weapon

High power microwave source and high gain antenna can be used to deliver an intense burst of energy

Complexity—30 years to complete Size—6.5 miles long by 3.3 miles wide Transmitting antenna ½ mile in diameter(1 km) Cost—prototype would have cost $74 billion safety of space workers in a heavy-radiation environment Microwave transmission

Interference with other electronic devices Health and environmental effects Interaction with Space (Plasma heating, interactions and

excitation of electrostatic waves in MHz bands)

DEPLOYMENT ISSUES

Cost of transporting materials into space installation of satellite

o Space Walks Maintenance

o Routineo Meteor impacts

Geosynchronous orbit is already in heavy use

POSSIBLE SOLUTIONS

International Space Station Using new technology

Space Power Radio TransmissionSystem (SPORTS)

Solar Power Radio Integrated Transmitter (SPRITZ),developed in 2000 Figure: space station

The use of a cyclotron wave converter (CWC) for DC conversion showed that 90% rectenna efficiency could be achieved

WIRELESS POWER TRANSFER

Microwaves have other features such as larger band width, smaller antenna size, sharp radiated

beams they propagate along straight lines.

frequency in the range of 2-3 GHz are consider optimal for the transmission of power from SPS to the ground rectennas site

Retro directive beam control capability: accurate target detection and high efficient beam forming

Power level is well below international safety standard(300GW) The overall efficiency of the WPT system can be improved by

Increasing directivity of the antenna array Using dc to ac inverters with higher conversion efficiency Using schottky diode with higher ratings

MICROWAVE

MICROWAVE VS. LASER TRANSMISSION

Microwave More developed High efficiency up to

85% Beams is far below the

lethal levels of concentration even for a prolonged exposure

Cause interference with satellite communication industry

Laser Recently developed

solid state lasers allow efficient transfer of power

Range of 10% to 20% efficiency within a few years

Conform to limits on eye and skin damage

ADVANTAGES OVER EARTH BASED SOLAR POWER More intense sunlight In geosynchronous orbit, 36,000 km (22,369 miles) an SPS

would be illuminated over 99% of the time No need for costly storage devices for when the sun is not

in viewo Only a few days at spring and full equinox would the

satellite be in shadow Waste heat is radiated back into space Power can be beamed to the location where it is needed,

don’t have to invest in as large a grid No air or water pollution is created during generation

CONCLUSION The SPS will be a central attraction of space and energy

technology in coming decades The increasing global energy demand is likely to continue for many decades. Fossils fuels will run off in another 3-4decades. However energy independence is something only Space based solar power can deliver.

Space based solar power (SBSP) concept is attractive because it is much more advantageous than ground based solar power. It has been predicted that by 2030, the world needs 30TW power from renewable energy sources and solar energy alone has the capability of producing around 600TW.

The levels of CO2 gas emission can be minimized and brought under control. Thus the problem of global warming will be solved to a great extent.

REFERENCES[1] Hiroshi Matsumoto, “Research on solar power satellites and microwave power transmission in Japan”, IEEE microwave magazine, pp.36-45, Dec 2002. Ms. S.G. Satavekar200[2] James O. Mcspadden & John C. Mankins,”Space solar power programs and microwave wireless power transmission technology”, IEEE microwave magazine, pp.46-57, Dec 2002.[3] J.C. Mankins,”A fresh look at space solar power: new architectures, concepts and technologies” in 38th Astronautical Federation.[4] Seth Potter, “Solar power satellites: an idea whose time has come [online] Available on www.freemars.org/history/sps.html, last updated on Dec.1998[5] Consumer Energy Information: EREC Reference Briefs [online] Available on www.eere.gov/consumerinfo/rebriefs/123.html,last updated onApr.03.[6] Mc Graw Hill Encyclopedia of Science and Technology, vol.16, pp.41.[7] Om P.Gandhi,” Microwave engineering and application”, PHI.[8] Geoffrey A.Landis,” A super synchronous solar power “, Presented at SPS- 97: Space &electric power for humanity, 24-25 Aug 1997, Montreal, Canada.[9] Geoffrey A.Landis,”An evolutionary path to SPS”, Space power, vol.9, no.4,pp.365-371, 1990.[10] S.S.Ahmed, T.W.Yeong and H.B.Ahmad,”Wireless power transmission and its annexure to the grid system”, IEE Proc.-Gener.Transm.Distrib. Vol.150, No.2, March 2003.[11] Kennedy “Electronics Communication Systems”, Tata McGraw Hill.[12] B.O’Leary,”The construction of satellite solar power stations from non terrestrial materials: feasibity and economics”, Alternative energy sources, Vol.3, pp.1155-1164.