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Solar Power Satellites and Microwave Power Transmission Andrew K. Soubel Energy Law Spring 2004 Chicago-Kent College of Law [email protected]
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Solar Power Satellites and Microwave Power Transmission
Andrew K. Soubel
Energy Law Spring 2004
Chicago-Kent College of Law
Outline
BackgroundSolar Power SatelliteMicrowave Power TransmissionCurrent DesignsLegal IssuesConclusionBackground
1899-1990
Nikola Tesla
1856-1943Innovations:Alternating current
Wireless power transmission experiments at Wardenclyffe
Image: www.mercury.gr/tesla/ lifeen.html
MSN Encarta, Nikola Tesla,(accessed April 10, 2004)
Wardenclyffe
1899Able 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)
Image: www.tfcbooks.com/images/teslafaq/ wardenclyffe.gif
MSN Encarta, Nikola Tesla,(accessed April 10, 2004)
1940s to Present
World War II developed ability to convert energy to microwaves using a magnetron, no method for converting microwaves back to electricity1964 William C. Brown demonstrated a rectenna which could convert microwave power to electricityWikipedia, Microwave Power Transmission,(accessed April 10, 2004)
Brief History of Solar Power
1940-50s Development of the Photovoltaic cell1958 First US Satellite that used Solar Power1970s Oil embargo brought increased interest and studySimply Solar, History Page,(accessed April 10, 2004)
Solar Power from Satellites
1968s idea for Solar Power Satellites proposed by Peter GlaserWould use microwaves to transmit power to Earth from Solar Powered Satellites
Idea gained momentum during the Oil Crises of 1970s, but after prices stabilized idea was droppedUS Department of Energy research program 1978-1981
David, Leonard, Bright Future for Solar Power Satellites, (accessed April 10, 2004)
Space Power, SPS Timeline,(accessed April 10, 2004)
Details of the DOE Study
Construct the satellites in spaceEach SPS would have 400 million solar cells
Use the Space Shuttle to get pieces to a low orbit stationTow pieces to the assembly point using a purpose built space tug (similar to space shuttle)US Department of Energy, EREC Brief Solar Power Satellites,(accessed April 10, 2004)
Advantages over Earth based solar power
More intense sunlightIn geosynchronous orbit, 36,000 km (22,369 miles) an SPS would be illuminated over 99% of the timeNo need for costly storage devices for when the sun is not in viewOnly a few days at spring and fall equinox would the satellite be in shadow
Wikipedia, Solar Power Satellite, (accessed April 10, 2004)
Continued
Waste heat is radiated back into spacePower can be beamed to the location where it is needed, dont have to invest in as large a gridNo air or water pollution is created during generationWikipedia, Solar Power Satellite, (accessed April 10, 2004)
Problems
Issues identified during the DOE studyComplexity30 years to complete
Size6.5 miles long by 3.3 miles wide
Transmitting antenna mile in diameter(1 km)
David, Leonard, Bright Future for Solar Power Satellites, (accessed April 10, 2004)
Space Power, SPS Timeline,(accessed April 10, 2004)
US Department of Energy, EREC Brief Solar Power Satellites,(accessed April 10, 2004)
Continued
Costprototype would have cost $74 billionMicrowave transmissionInterference with other electronic devices
Health and environmental effects
David, Leonard, Bright Future for Solar Power Satellites, (accessed April 10, 2004)
1980s to Present
Japanese continued to study the idea of SPS throughout the 1980sIn 1995 NASA began a Fresh Look StudySet up a research, technology, and investment schedule
David, Leonard, Bright Future for Solar Power Satellites, (accessed April 10, 2004)
Space Power, SPS Timeline,(accessed April 10, 2004)
NASA Fresh Look Report
SPS could be competitive with other energy sources and deserves further studyResearch aimed at an SPS system of 250 MW Would cost around $10 billion and take 20 yearsNational Research Council found the research worthwhile but under funded to achieve its goalsSpace Power, SPS Timeline,(accessed April 10, 2004)
US Department of Energy, EREC Brief Solar Power Satellites,(accessed April 10, 2004)
NASA, Space Solar Power Home,(accessed April 10, 2004)
Specifications
Collector area must be between 50 (19 sq miles) and 150 square kilometers (57 sq miles)50 Tons of materialCurrent rates on the Space Shuttle run between $3500 and $5000 per pound
50 tons (112,000lbs)=$392,000,000
Wikipedia, Solar Power Satellite, (accessed April 10, 2004)
Wikipedia, Microwave Power Transmission, (accessed April 10, 2004)
Continued
There are advantagesPossible power generation of 5 to 10 gigawattsIf 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.
Quote: Gomes, Pedro, Microwave Power Transmission,(accessed April 10, 2004)
Possible Designs
http://www.spacedaily.com/images/solar-sps-satellite-bg.jpg
http://www.ssi.org/assets/images/slide02.jpg
http://www.ssi.org/assets/images/SPS_summary.jpg
Deployment Issues
Cost of transporting materials into spaceConstruction of satelliteSpace Walks
MaintenanceRoutine
Meteor impacts
Wikipedia, Solar Power Satellite, (accessed April 10, 2004)
Possible Solutions
International Space StationPresidents plan for a return to the moonEither could be used as a base for construction activitiesImage: http://ems.calumet.purdue.edu/engr/pics/International%20Space%20Station.jpg
CNN, Bush Unveils Vision for Moon and Beyond,
Microwave Power Transmission
How the power gets to Earth
From the Satellite
Solar power from the satellite is sent to Earth using a microwave transmitterReceived at a rectenna located on EarthRecent developments suggest that power could be sent to Earth using a laserISIS, Highlights in Space 2000, (accessed April 10, 2004)
Microwaves
Frequency 2.45 GHz microwave beamRetro directive beam control capabilityPower level is well below international safety standardNagatomo, Makoto, Conceptual Study of a Solar Power Satellite, SPS 200, (accessed April 10, 2004)
Microwave vs. Laser Transmission
MicrowaveMore 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
LaserRecently 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
ISIS, Highlights in Space: 2000, (accessed April 10, 2004)
Wikipedia, Solar Power Satellite, (accessed April 10, 2004)
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% efficiencyAround 5km across (3.1 miles)95% of the beam will fall on the rectennaQuote: http://www.spacetalent.com/cgi/glossary.cgi?gl=term&term=Rectenna
Wikipedia, Solar Power Satellite, (accessed April 10, 2004)
Rectenna Design
Currently there are two different design types being looked atWire mesh reflector
Built on a rigid frame above the ground
Visually transparent so that it would not interfere with plant life
Magic carpet
Material pegged to the ground
Space Future, Beam It Down: How the New Satellites Can Power the World, (accessed April 11, 2004)
5,000 MW Receiving Station (Rectenna).This station is about a mile and a half long.
www.powersat.com/ image_library.html
Rectenna Issues
SizeMiles across
LocationAesthetic
Near population center
Health and environmental side effectsAlthough claim that microwaves or lasers would be safe, how do you convince people
Current Developments
SPS 2000
http://www.spacefuture.com/power/sps2000.shtml
Details
Project in Development in JapanGoal is to build a low cost demonstration model by 20258 Countries along the equator have agreed to be the site of a rectennaNagatomo, Makoto, Conceptual Study of a Solar Power Satellite, SPS 200, (accessed April 10, 2004)
US Department of Energy, EREC Brief Solar Power Satellites,(accessed April 10, 2004)
Continued
10 MW satellite delivering microwave powerWill 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
Gomes, Pedro, Microwave Power Transmission,(accessed April 10, 2004)
Collins, Patrick, Future Demand for Microwave Power From Space in China and Indonesia, (accessed April 10, 2004)
Power to Mobile Devices
If microwave beams carrying power could be beamed uniformly over the earth they could power cell phonesBiggest problem is that the antenna would have to be 25-30 cm squareGomes, Pedro, Microwave Power Transmission,(accessed April 10, 2004)
http://www.spacefuture.com/pr/archive/conceptual_study_of_a_solar_power_satellite_sps_2000.shtml
Low Orbit
Communications industry proposing to have hundreds of satellites in low earth orbit These satellites will use microwaves to beam communications to the groundCould also be used to beam powerSpace Future, Beam It Down: How the New Satellites Can Power the World, (accessed April 11, 2004)
Continued
Since a low orbit microwave beam would spread less, the ground based rectenna could be smallerWould allow collectors on the ground of a few hundred meters across instead of 10 kilometersIn low orbit they circle the Earth in about every 90 minutesSpace Future, Beam It Down: How the New Satellites Can Power the World, (accessed April 11, 2004)
Issues
Would require a network of hundreds of satellitesAir Force currently track 8500 man made objects in space, 7% satellites
Would make telecommunications companies into power companiesSpace Future, Beam It Down: How the New Satellites Can Power the World, (accessed April 11, 2004)
USSTRATCOM,Re-Entry Assessment and Space Surveillance Fact Sheet, (last updated March 2004)
Reliability
Ground based solar only works during clear days, and must have storage for nightPower can be beamed to the location where it is needed, dont have to invest in as large a gridA network of low orbit satellites could provide power to almost any point on Earth continuously because one satellite would always be in rangeSpace Future, Beam It Down: How the New Satellites Can Power the World, (accessed April 11, 2004)
Wikipedia, Solar Power Satellite, (accessed April 10, 2004)
Legal Issues
Who will oversee?Environmental ConcernsInternationalNASA
Funding the researchIn charge of space flight for the United StatesWould be launching the satellites and doing maintenanceFCC
Federal Communications CommissionThe FCC was established by the Communications Act of 1934 and is charged with regulating interstate and international communications by radio, television, wire, satellite and cable.
http://www.fcc.gov/aboutus.html
Environmental
Possible health hazardsEffects of long term exposure
Exposure is equal to the amount that people receive from cell phones and microwaves
LocationThe size of construction for the rectennas is massive
Space Future, Beam It Down: How the New Satellites Can Power the World, (accessed April 11, 2004)
International
Geosynchronous satellites would take up large sections of spaceInterference with communication satellitesLow orbit satellites would require agreements about rectenna locations and flight pathsConclusions
More reliable than ground based solar powerIn order for SPS to become a reality it several things have to happen:Government support
Cheaper launch prices
Involvement of the private sector
