1. Wireless Power Transmission for
Solar Power Satellites
By
D.Sriramulu 09jp1a0220

2. Nikola Tesla


1856-1943
Innovations:
– Alternating current
– Wireless power
transmission
experiments at
Wardenclyffe

3. Wardenclyffe

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)

4. 1940’s to Present
 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

5. Brief History of Solar Power
 1940-50’s
 1958
Development of the Photovoltaic cell
First US Satellite that used Solar Power
 1970’s
Oil embargo brought increased interest
and study

6. 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 space
shuttle)

7. 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 view.

8. Continued
 Waste
 No
heat is radiated back into space
air or water pollution is created during
generation

9. Continued
 Cost—prototype
would have cost $74 billion
 Microwave transmission
–
–
Interference with other electronic devices
Health and environmental effects

10. 1980’s to Present
 Japanese
continued to study the idea of SPS
throughout the 1980’s
 In 1995 NASA began a Fresh Look Study
–
Set up a research, technology, and investment
schedule

11. 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 20
years
 National Research Council found the research
worthwhile but under funded to achieve its
goals

12. Possible Designs

14. Deployment Issues
 Cost
of transporting materials into space
 Construction of satellite
–
Space Walks
 Maintenance
–
–
Routine
Meteor impacts

15. Microwave Power Transmission
How the power gets
to Earth

16. 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
power could be sent to Earth using a
laser

17. 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

18. Rectenna
“An antenna comprising a mesh of dipoles
and diodes for absorbing microwave energy
from a transmitter and converting it 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

19. Current Developments

20. Details



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

21. Power to Mobile Devices
 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

22. 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

23. Reliability


Ground based solar only
works during clear days,
and must have storage
for night
Power can be beamed to
the location where it is
needed, don’t have to
invest in as large a grid

A network of low orbit
satellites could provide
power to almost any
point on Earth
continuously because
one satellite would
always be in range

24. Conclusions
 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

25. thank you