Post on 09-Feb-2017
Prachi PatelRomil Shah
Background Solar Power Satellite Microwave Power Transmission Current Designs Legal Issues Conclusion
1856-1943 Innovations:
• Alternating current• Wireless power
transmission experiments at 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)
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
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
General Idea of SSP
NASA concept of SERT sandwich
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)
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
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 kilowatt-class 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
Cost of transporting materials into space
Construction of satellite• Space Walks
Maintenance• Routine• Meteor impacts
International Space Station President’s plan for a return to the moon Either could be used as a base for construction
activities
Wireless Power Transmissionfor Rover Operationsin Shadowed Craters
Solar PowerGeneration on Mountaintop
Direct Communication
Link
Moon’s OrbitNorth Pole (SEE BELOW)
South Pole (SEE BELOW)
Sun Rays are Horizontal at North & South Poles•NEVER shine into Craters•ALWAYS shine on Mountain
POSSIBLE ICE DEPOSITS •Craters are COLD: -300F (-200C)•Frost/Snow after Lunar Impacts•Good for Future Human Uses•Good for Rocket Propellants
Phased Array used in Japanese Field MPTexperiment
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
Frequency 2.45 GHz microwave beam Retro directive beam control
capability Power level is well below
international safety standard
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
“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
Size•Miles across
Location•Aesthetic•Near population center
Health and environmental side effects
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
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
Issues identified during the DOE study• 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 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, 7% satellites Would make telecommunications companies
into power companies
Who will oversee? Environmental Concerns International
Possible health hazards• Effects of long term exposure• Exposure is equal to the amount that people
receive from cell phones and microwaves Location
• The size of construction for the rectennas is massive
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
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
1. 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.
2. N.Shinohara, "Wireless Power Transmission for Solar Power Satellite (SPS)," Georgia Institute of Technology.
3. César Meneses Ghiglino, "Ultra-Wideband (UWB) Rectenna design for Electromagnetic Energy Harvesting,“ UNIVERSITAT POLITÈCNICA DE CATALUNYA, CATALUNYA, thesis 2010.