Wireless Power Transmission for Solar Power Satelite

8/7/2019 Wireless Power Transmission for Solar Power Satelite

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Wireless Power Transmission forSolar Power Satellites

By

B.Ravindra Reddy

(MT097109)


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Outline

Background Solar Power Satellite

Microwave Power Transmission

Current Designs

Conclusion


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Background

1899-1990


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Nikola Tesla

1856-1943

Innovations: Alternating current

Wireless powertransmission

experiments atWardenclyffe


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Wardenclyffe

1899

Able to light lampsover 25 miles awaywithout using wires

High frequencycurrent, of a Teslacoil, could light lampsfilled with gas (likeneon)


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1940s to Present

World War II developed ability to convert

energy to microwaves using a magnetron, nomethod for converting microwaves back toelectricity

1964 William C. Brown demonstrated a

rectenna which could convert microwavepower to electricity


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Brief History of Solar Power

1940-50s Development of the Photovoltaic cell

1958 First US Satellite that used Solar Power

1970s Oil embargo brought increased interest

and study


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Details of the DOE Study

Construct the satellites in space

Each SPS would have 400 million solar cells Use the Space Shuttle to get pieces to a low

orbit station

Tow pieces to the assembly point using apurpose built space tug (similar to spaceshuttle)


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Advantages overEarth based solarpower

More intense sunlight

In geosynchronous orbit, 36,000 km (22,369miles) an SPS would be illuminated over 99%of the time

No need for costly storage devices for whenthe sun is not in view.


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Continued

Waste heat is radiated back into space

No air or water pollution is created during

generation


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Problems

Issues identified during the DOE study

Complexity30 years to complete Size6.5 miles long by 3.3 miles wide

Transmitting antenna mile indiameter(1 km)


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Continued

Costprototype would have cost $74 billion

Microwave transmission Interference with other electronic devices

Health and environmental effects


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1980s to Present

Japanese continued to study the idea of SPS

throughout the 1980s In 1995 NASA began a Fresh Look Study

Set up a research, technology, and investmentschedule


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NASA Fresh Look Report

SPS could be competitive with other energy

sources and deserves further study Research aimed at an SPS system of 250 MW

Would cost around $10 billion and take 20years

National Research Council found the researchworthwhile but under funded to achieve itsgoals


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Possible Designs


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Deployment Issues

Cost of transporting materials into space

Construction of satellite Space Walks

Maintenance

Routine

Meteor impacts


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Microwave Power Transmission

How the power getsto Earth


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From the Satellite

Solar power from the satellite is sent to

Earth using a microwave transmitter Received at a rectenna located on

Earth

Recent developments suggest that powercould be sent to Earth using a laser


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Microwave vs. Laser Transmission

Microwave

More developed High efficiency up to 85%

Beams is far below thelethal levels ofconcentration even for aprolonged exposure

Cause interference withsatellite communicationindustry

Laser

Recently developed solidstate lasers allow efficienttransfer of power

Range of 10% to 20%efficiency within a fewyears

Conform to limits on eyeand skin damage


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Rectenna

An antenna comprising a mesh of dipoles and diodes for

absorbing microwave energy from a transmitter and convertingit into electric power.

Microwaves are received with about 85%efficiency

Around 5km across (3.1 miles)

95% of the beam will fall on the rectenna


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Current Developments


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Details

Project in Development

inJ

apan Goal is to build a low

cost demonstrationmodel by 2025

8 Countries along theequator have agreed tobe the site of a rectenna


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Power to Mobile Devices

If microwave beams carrying power could be

beamed uniformly over the earth they couldpower cell phones

Biggest problem is that the antenna wouldhave to be 25-30 cm square


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Issues

Would require a network of hundreds of

satellites Air Force currently track 8500 man made objects in

space, 7% satellites

Would make telecommunications companies

into power companies


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Reliability

Ground based solar onlyworks during clear days,and must have storagefor night

Power can be beamed tothe location where it is

needed, dont have toinvest in as large a grid

A network of low orbitsatellites could providepower to almost anypoint on Earthcontinuously becauseone satellite would

always be in range


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Conclusions

More reliable than ground based solar power

In order for SPS to become a reality it severalthings have to happen:

Government support

Cheaper launch prices

Involvement of the private sector

Documents

Wireless Power Transmission for Solar Power Satelite