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SpaceBased Solar Power


Solar panels on satellite capture light, sends power to earth using microwave ... Solar panels do not take up land on Earth. Lots of space in space ... – PowerPoint PPT presentation

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Title: SpaceBased Solar Power

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

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 its
microwave beam.
  • Producing electricity in space from sunlight is
    used by hundreds of satellites in operation
  • In 1968, Dr. Peter Glaser, formerly of NASA,
    introduced the concept of a solar power satellite
    system with square miles of solar collectors in
    high geosynchronous orbit to collect and convert
    the sun's energy into a microwave beam to
    transmit energy to large receiving antennas
    (rectennas) on earth.
  • In 1999 NASA formed SERT, the Space Solar Power
    Exploratory Research and Technology program to
    perform design studies and evaluate feasibility.

Design Ideas
  • 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.

Sage-Hall Thrusters
Technology obstacles to overcome
  • NASA estimates a SSP will need to operate
    at 1000v or higher, which leads to
    self-destructive arcing. Current
    experimentation is at 300 v.
  • Wireless power transmission only
    recently became a reality, with
    small amounts of power over a few
  • Lots of design work left regarding the high
    temperature characteristics of the transmitting
    antenna and the solar array.

Example of self destructive arcing
Image http//
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

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

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
  • 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
  • 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

  • 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

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

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//

Microwave power distribution on the ground
  • Launch costs
  • Currently 10,000/kg
  • Not feasible with chemical rocket technology
  • Space elevator
  • SSP array costs
  • Must be very efficient
  • Currently 2.4 million/kW
  • Ground-based 5,000/kW
  • Operation and Maintenance