08-03-2011, 04:20 PM
Presented By:
B.Ravindra Reddy
[attachment=9807]
Wireless Power Transmission for Solar Power Satellites
Background
1899-1990
Nikola Tesla
1856-1943
Innovations:
– Alternating current
– Wireless power transmission experiments at Wardenclyffe
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)
1940’s to Present
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
Brief History of Solar Power
1940-50’s Development of the Photovoltaic cell
1958 First US Satellite that used Solar Power
1970’s Oil embargo brought increased interest and study
Details of the DOE Study
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)
Advantages over Earth based solar power
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.
Waste heat is radiated back into space
No air or water pollution is created during generation
Problems
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)
Continued
Cost—prototype would have cost $74 billion
Microwave transmission
– Interference with other electronic devices
– Health and environmental effects
1980’s to Present
Japanese continued to study the idea of SPS throughout the 1980’s
In 1995 NASA began a Fresh Look Study
– Set up a research, technology, and investment schedule
NASA Fresh Look Report
SPS could be competitive with other energy sources and deserves further study
Research aimed at an SPS system of 250 MW
Would cost around $10 billion and take 20 years
National Research Council found the research worthwhile but under funded to achieve its goals
Deployment Issues
Cost of transporting materials into space
Construction of satellite
– Space Walks
Maintenance
– Routine
– Meteor impacts
Microwave Power Transmission
How the power gets to Earth
From the Satellite
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
Microwave vs. Laser Transmission
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
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% efficiency
Around 5km across (3.1 miles)
95% of the beam will fall on the rectenna
Current Developments
Details
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
Power to Mobile Devices
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
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
Reliability
Ground based solar only works during clear days, and must have storage for night
Power can be beamed to the location where it is needed, don’t have to invest in as large a grid
A network of low orbit satellites could provide power to almost any point on Earth continuously because one satellite would always be in range
Conclusions
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
B.Ravindra Reddy
[attachment=9807]
Wireless Power Transmission for Solar Power Satellites
Background
1899-1990
Nikola Tesla
1856-1943
Innovations:
– Alternating current
– Wireless power transmission experiments at Wardenclyffe
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)
1940’s to Present
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
Brief History of Solar Power
1940-50’s Development of the Photovoltaic cell
1958 First US Satellite that used Solar Power
1970’s Oil embargo brought increased interest and study
Details of the DOE Study
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)
Advantages over Earth based solar power
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.
Waste heat is radiated back into space
No air or water pollution is created during generation
Problems
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)
Continued
Cost—prototype would have cost $74 billion
Microwave transmission
– Interference with other electronic devices
– Health and environmental effects
1980’s to Present
Japanese continued to study the idea of SPS throughout the 1980’s
In 1995 NASA began a Fresh Look Study
– Set up a research, technology, and investment schedule
NASA Fresh Look Report
SPS could be competitive with other energy sources and deserves further study
Research aimed at an SPS system of 250 MW
Would cost around $10 billion and take 20 years
National Research Council found the research worthwhile but under funded to achieve its goals
Deployment Issues
Cost of transporting materials into space
Construction of satellite
– Space Walks
Maintenance
– Routine
– Meteor impacts
Microwave Power Transmission
How the power gets to Earth
From the Satellite
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
Microwave vs. Laser Transmission
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
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% efficiency
Around 5km across (3.1 miles)
95% of the beam will fall on the rectenna
Current Developments
Details
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
Power to Mobile Devices
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
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
Reliability
Ground based solar only works during clear days, and must have storage for night
Power can be beamed to the location where it is needed, don’t have to invest in as large a grid
A network of low orbit satellites could provide power to almost any point on Earth continuously because one satellite would always be in range
Conclusions
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