Wireless Power Transmission - Soubel (2)

8/4/2019 Wireless Power Transmission - Soubel (2)

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Solar Power Satellites andMicrowave Power Transmission

Andrew K. Soubel

Energy Law Spring 2004

Chicago-Kent College of Law

[email protected]


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Outline

Background

Solar Power Satellite Microwave Power Transmission

Current Designs

Legal Issues 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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Solar Power from Satellites

1968s idea for Solar Power Satellitesproposed by Peter Glaser Would use microwaves to transmit power to Earth

from Solar Powered Satellites

Idea gained momentum during the Oil Crises of1970s, but after prices stabilized idea was

dropped US Department of Energy research program 1978-

1981


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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 a

purpose built space tug (similar to spaceshuttle)


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Advantages over Earth based solar

power

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 when

the sun is not in view Only a few days at spring and fall equinox would the

satellite be in shadow


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Continued

Waste heat is radiated back into space

Power can be beamed to the location where itis needed, dont have to invest in as large a

grid

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 energysources 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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Specifications

Collector area must be between 50 (19 sq

miles) and 150 square kilometers (57 sq miles) 50 Tons of material

Current rates on the Space Shuttle runbetween $3500 and $5000 per pound

50 tons (112,000lbs)=$392,000,000


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Continued

There are advantages

Possible power generation of 5 to 10 gigawatts If the largest conceivable space power

station were built and operated 24 hours aday all year round, it could produce the

equivalent output of ten 1 million kilowatt-class nuclear power stations.


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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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Possible Solutions

International SpaceStation

Presidents plan for a

return to the moon

Either could be used asa base for construction

activities


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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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Microwaves

Frequency 2.45 GHz microwave beam

Retro directive beam control capability Power level is well below international

safety standard


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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 solid

state 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 converting it into electricpower.

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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Rectenna Design

Currently there are two different design typesbeing looked at

Wire mesh reflector

Built on a rigid frame above the ground

Visually transparent so that it would not

interfere with plant life Magic carpet

Material pegged to the ground


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5,000 MW Receiving Station(Rectenna). This station is about a

mile and a half long.


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Rectenna Issues

Size

Miles across

Location

Aesthetic

Near population center

Health and environmental side effects Although claim that microwaves or lasers

would be safe, how do you convince people


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Current Developments


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SPS 2000


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Details

Project in Developmentin Japan

Goal is to build a lowcost demonstrationmodel by 2025

8 Countries along the

equator have agreed tobe the site of a rectenna


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Continued

10 MW satellite delivering microwave power

Will not be in geosynchronous orbit, insteadlow orbit 1100 km (683 miles)

Much cheaper to put a satellite in low orbit

200 seconds of power on each pass overrectenna


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Power to Mobile Devices

If microwave beams carrying power could bebeamed 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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Low Orbit

Communications industry proposing to havehundreds of satellites in low earth orbit

These satellites will use microwaves to beamcommunications to the ground

Could also be used to beam power


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Continued

Since a low orbit microwave beam wouldspread less, the ground based rectenna couldbe smaller

Would allow collectors on the ground of a fewhundred meters across instead of 10

kilometers In low orbit they circle the Earth in about every

90 minutes


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Issues

Would require a network of hundreds ofsatellites

Air Force currently track 8500 man made objects inspace, 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 provide

power to almost anypoint on Earthcontinuously becauseone satellite would

always be in range


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Legal Issues

Who will oversee?

Environmental Concerns International


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NASA

Funding the research

In charge of space flight for the United States Would be launching the satellites and doing

maintenance


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FCC

Federal Communications Commission

The FCC was established by theCommunications Act of 1934 and is chargedwith regulating interstate and internationalcommunications by radio, television, wire,satellite and cable.


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Environmental

Possible health hazards

Effects of long term exposure

Exposure is equal to the amount that people receivefrom cell phones and microwaves

Location

The size of construction for the rectennas ismassive


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International

Geosynchronous satellites would take up largesections of space

Interference with communication satellites

Low orbit satellites would require agreementsabout rectenna locations and flight paths


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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

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Wireless Power Transmission - Soubel (2)

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