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Presentation Transcript

Space-Based Solar Power: 

Space-Based Solar Power James Harkins, Dan Livingston, Alex Wong, Aaron Sanders

How it works: 

How it works Solar panels on satellite capture light, sends power to earth using microwave wireless power transmission technology Signal sent from receiving antenna on earth (green) allows satellite to pinpoint it’s microwave beam.

History: 

History

Design Ideas: 

Design Ideas Sage-Hall Thrusters Thrusters must be used to counteract solar winds The space-based antenna needs to be at least 1 km in diameter, making it far larger than any satellite ever proposed. Recieveing antenna (an array of wires) must cover 20,000 acres. Sidebands not worth capturing Laser alternative to microwave power transmission.

Technology obstacles to overcome: 

Technology obstacles to overcome Example of self destructive arcing Image: http://gltrs.grc.nasa.gov/reports/2000/TM-2000-210210.pdf 

Solar Arrays: 

Solar Arrays Weight between 0.5 kg/kW to 10 kg/kW Lifespan is about 20 years Exposure to charged particles can reduce the lifespan drastically Naturally degrades about 1 to 2 percent per year Efficiency up to 30% Solar radiation is 5-10 times greater in space

Power: 

Power Efficiency of power transmission is about 50% Microwave transmission will diffract greatly Total efficiency is about 7% Power yield from rectenna is about 90 W/m2 Lasers are an alternative to microwaves Rectenna will only need to be 180m in diameter

Benefits of SSP: 

Benefits of SSP

General Benefits: 

General Benefits No pollution after construction No ghg during power generation Source of energy is free Large amount of energy potential.

Space Advantages: 

Space Advantages Less atmosphere for sunlight to penetrate for more power per unit area Any location on Earth can receive power Satellite can provide power up to 96% of the time Solar panels do not take up land on Earth Lots of space in space Promote growth of space, solar, and power transmission technology

Problems with SSP: 

Problems with SSP VERY expensive initial cost Microwave/lasers may be harmful? Cosmic rays can deteriorate panels Maintenance Problems Very large receiving antennas on earth Solar winds could kick it off course Would need a complex propulsion system

VERY Expensive Initial Costs: 

VERY Expensive Initial Costs Cost of Lifting Cargo Into Space using Space Shuttle is currently $10000/kg Reusable Launch Systems looking to reduce this cost are underdeveloped Space Elevator

Microwave Concerns: 

Microwave Concerns At the earth's surface, the microwave beam has a maximum intensity in the center of 23 mW/cm2 (less than l/4 the solar constant) and an intensity of less than 1 mW/cm2 outside of the rectenna fenceline Retrodirective phased array antenna/rectenna + ≠ http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19800022396_1980022396.pdf

Very large antennas/rectennas: 

Very large antennas/rectennas The distance between the antenna and rectenna will be roughly the distance from Earth to geosynchronous orbit (22,300 miles) For best efficiency the satellite antenna must be circular between 1 and 1.5 kilometers in diameter The ground rectenna would need to be elliptical and around 14 kilometers by 10 kilometers http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19800022396_1980022396.pdf

Very large antennas/rectennas (cont.): 

Very large antennas/rectennas (cont.) Anything smaller would result in excessive losses due to sidelobes. To collect and convert the desired energy the satellite would need between 50 and 100 square kilometers of collector area using standard ~14% efficient monocrystalline silicon solar cells making this much larger than most man-made structures on Earth. Though not unfeasible, such an enormous undertaking in orbit has never been attempted image: http://www.spacefuture.com/archive/conceptual_study_of_a_solar_power_satellite_sps_2000.shtml   Microwave power distribution on the ground surface.

Targets: 

Targets Launch costs: < $250/kg Currently: $10,000/kg Not feasible with chemical rocket technology Space elevator SSP array costs: < $1,000/kW Must be very efficient Currently: $2.4 million/kW Ground-based: $5,000/kW Operation and Maintenance: < $0.01/kWh

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