A great concern has been voiced in recent years over the extensive use of energy, the limited supply of resources, and the pollution of the environment from the use of present energy conversion systems. Electrical power accounts for much of the energy consumed. Much of this power is wasted during transmission from power plant generators to the consumer. The resistance of the wire used in the electrical grid distribution system causes a loss of 26-30% of the energy generated. This loss implies that our present system of electrical distribution is only 70-74% efficient. Nikola Tesla is best known for his remarkable statements regarding the wireless transmission of electrical power. His first efforts towards this end started in 1891 and were intended to simply "disturb the electrical equilibrium in the nearby portions of the earth... to bring into operation in any way some instrument." In other words the object of his experiments was simply to produce effects locally and detect them at a distance.

1. Prachi Patel
Romil Shah

2. 
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Background
Solar Power Satellite
Microwave Power Transmission
Current Designs
Legal Issues
Conclusion

3. 
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1856-1943
Innovations:
• Alternating current
• Wireless power
transmission
experiments at
Wardenclyffe

4. 
1899
• Able to light lamps over 25 miles away without
using wires
• High frequency current, of a Tesla coil, could
light lamps filled with gas (like neon)

5. 
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World War II developed ability to convert
energy to microwaves using a magnetron,
no method for converting microwaves
back to electricity
1964 William C. Brown demonstrated a
rectenna which could convert microwave
power to electricity

6. 
1968’s idea for Solar Power Satellites
proposed by Peter Glaser
• Would use microwaves to transmit power to
Earth from Solar Powered Satellites

Idea gained momentum during the Oil
Crises of 1970’s, but after prices
stabilized idea was dropped
• US Department of Energy research program
1978-1981

7. General Idea of SSP
NASA concept of
SERT sandwich

9. 
Construct the satellites in space
• Each SPS would have 400 million solar cells
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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 space
shuttle)

10. 
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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 view
Only a few days at spring and fall 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

11. 
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There are advantages
Possible power generation of 5 to 10 gigawatts
• “If the largest conceivable space power station were built
and operated 24 hours a day all year round, it could
produce the equivalent output of ten 1 million kilowattclass nuclear power stations.”
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 run between $3500 and
$5000 per pound
• 50 tons (112,000lbs)=$392,000,000

12. 
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Cost of transporting materials into space
Construction of satellite
• Space Walks
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Maintenance
• Routine
• Meteor impacts

13. 
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International Space Station
President’s plan for a return to the moon
Either could be used as a base for construction
activities

14. North Pole (SEE BELOW)
Moon’s Orbit
Sun Rays are Horizontal
at North & South Poles
•NEVER shine into Craters
•ALWAYS shine on Mountain
South Pole (SEE BELOW)
Solar Power
Direct
Generation on
Communication Mountaintop Wireless Power
Link
Transmission
for Rover Operations
in Shadowed Craters
POSSIBLE ICE DEPOSITS
•Craters are COLD: -300F (-200C)
•Frost/Snow after Lunar Impacts
•Good for Future Human Uses
•Good for Rocket Propellants

15. Phased Array used in
Japanese Field MPT
experiment

16. 
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Solar power from the satellite is sent to
Earth using a microwave transmitter
Received at a “rectenna” located on
Earth
Recent developments suggest that power
could be sent to Earth using a laser

17. 
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Frequency 2.45 GHz microwave beam
Retro directive beam control capability
Power level is well below international
safety standard

19. 
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
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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

20. “An antenna comprising a mesh of dipoles
and diodes for absorbing microwave
energy from a transmitter and converting it
into electric power.”
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Microwaves are received with about 85%
efficiency
Around 5km across (3.1 miles)
95% of the beam will fall on the rectenna

23. 
Size
• Miles across
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Location
• Aesthetic
• Near population center
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Health and environmental side effects

25. 
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Project in Development in Japan
Goal is to build a low cost demonstration model by
2025
8 Countries along the equator have agreed to be
the site of a rectenna
10 MW satellite delivering microwave power
• Will not be in geosynchronous orbit, instead
low orbit 1100 km (683 miles)
• Much cheaper to put a satellite in low orbit
• 200 seconds of power on each pass over
rectenna

26. 
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If microwave beams carrying power
could be beamed uniformly over the
earth they could power cell phones
Biggest problem is that the antenna
would have to be 25-30 cm square

28. 
Issues identified during the DOE study
• Complexity—30 years to complete
• Size—6.5 miles long by 3.3 miles wide
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 Transmitting antenna ½ mile in diameter(1 km)
Cost—prototype would have cost $74 billion
Microwave transmission
• Interference with other electronic devices
• Health and environmental effects
Would require a network of hundreds of satellites
• Air Force currently track 8500 man made objects in space,
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7% satellites
Would make telecommunications companies into
power companies

29. 
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Who will oversee?
Environmental Concerns
International

30. 
Possible health hazards
• Effects of long term exposure
• Exposure is equal to the amount that people
receive from cell phones and microwaves
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Location
• The size of construction for the rectennas is
massive

31. 
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Geosynchronous satellites would take up
large sections of space
Interference with communication
satellites
Low orbit satellites would require
agreements about rectenna locations and
flight paths

32. 
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More reliable than ground based solar
power
In order for SPS to become a reality it
several things have to happen:
• Government support
• Cheaper launch prices
• Involvement of the private sector

33. 1.
2.
3.
Lotfi Osman and Ali Gharsallah Zied Harouni, "Efficient 2.45 GHz
Rectenna Design with High Harmonic Rejection for Wireless Power
Transmission," IJCSI International Journal of Computer Science Issues,
vol. 7, no. 5, pp. 1-4, September 2010.
N.Shinohara, "Wireless Power Transmission for Solar Power Satellite
(SPS)," Georgia Institute of Technology.
César Meneses Ghiglino, "Ultra-Wideband (UWB) Rectenna design for
Electromagnetic Energy Harvesting,“ UNIVERSITAT POLITÈCNICA DE
CATALUNYA, CATALUNYA, thesis 2010.