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.