Posts: 3,561
Threads: 923
Joined: Sep 2010
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Andrew K. Soubel
Energy Law Spring 2004
Outline
Background
Solar Power Satellite
Microwave Power Transmission
Current Designs
Legal Issues
Conclusion
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
Solar Power from Satellites
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
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
Only a few days at spring and fall equinox would the satellite be in shadow
Continued
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
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)
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
Specifications
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
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.”
Deployment Issues
Cost of transporting materials into space
Construction of satellite
Space Walks
Maintenance
Routine
Meteor impacts
Possible Solutions
International Space Station
President’s plan for a return to the moon
Either could be used as a base for construction activities
Microwave Power Transmission
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
Microwaves
Frequency 2.45 GHz microwave beam
Retro directive beam control capability
Power level is well below international safety standard
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
Rectenna Design
Currently there are two different design types being looked at
Wire 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
Rectenna Issues
Size
Miles across
Location
Aesthetic
Near population center
Health and environmental side effects
Although claim that microwaves or lasers would be safe, how do you convince people
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
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
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
Low Orbit
Communications industry proposing to have hundreds of satellites in low earth orbit
These satellites will use microwaves to beam communications to the ground
Could also be used to beam power
Since a low orbit microwave beam would spread less, the ground based rectenna could be smaller
Would allow collectors on the ground of a few hundred meters across instead of 10 kilometers
In low orbit they circle the Earth in about every 90 minutes
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
Legal Issues
Who will oversee?
Environmental Concerns
International
NASA
Funding the research
In charge of space flight for the United States
Would be launching the satellites and doing maintenance
FCC
Federal Communications Commission
The 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.
Environmental
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
International
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
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
Posts: 5,362
Threads: 2,998
Joined: Feb 2011
presented by:
Andrew K. Soubel
[attachment=9884]
Solar Power Satellites and Microwave Power Transmission
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
Solar Power from Satellites
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
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
– Only a few days at spring and fall equinox would the satellite be in shadow
Continued
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
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)
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
Specifications
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
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.”
Possible Designs
Deployment Issues
Cost of transporting materials into space
Construction of satellite
– Space Walks
Maintenance
– Routine
– Meteor impacts
Possible Solutions
International Space Station
President’s plan for a return to the moon
Either could be used as a base for construction activities
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
Microwaves
Frequency 2.45 GHz microwave beam
Retro directive beam control capability
Power level is well below international safety standard
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
Rectenna Design
Currently there are two different design types being looked at
– Wire 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
5,000 MW Receiving Station (Rectenna). This station is about a mile and a half long.
Rectenna Issues
Size
– Miles across
Location
– Aesthetic
– Near population center
Health and environmental side effects
– Although claim that microwaves or lasers would be safe, how do you convince people
Current Developments
SPS 2000
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
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
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
Low Orbit
Communications industry proposing to have hundreds of satellites in low earth orbit
These satellites will use microwaves to beam communications to the ground
Could also be used to beam power
Since a low orbit microwave beam would spread less, the ground based rectenna could be smaller
Would allow collectors on the ground of a few hundred meters across instead of 10 kilometers
In low orbit they circle the Earth in about every 90 minutes
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
Legal Issues
Who will oversee?
Environmental Concerns
International
Posts: 5,362
Threads: 2,998
Joined: Feb 2011
Presented By
Siva shanker.K
Pradeep reddy.B
[attachment=10757]
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
Solar Power from Satellites
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
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
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
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)
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
Specifications
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
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.”
Posts: 5,362
Threads: 2,998
Joined: Feb 2011
[attachment=10781]
Background
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
Power can be beamed to the location where it is needed, don’t have to invest in as large as a grid
No air or water pollution is created during generation
AIM OF MPT
The conversion of direct power from the photovoltaic cells, tomicrowave power on the satellites on geosynchronous orbit above theEarth.
The formation and control of microwave beam aimed precisely at fixedlocations on the Earths surface.
The collection of the microwave energy and its conversion into electrical energy at the earth’s surface.
ADVANTAGES
The full solar irradiation would be available at all times expect when the sun is eclipsed by the earth. Thus about five times energy could becollected, compared with the best terrestrial sites.
The power could be directed to any point on the earth’s surface.
The zero gravity and high vacuum condition in space would allow much lighter, low maintenance structures and collectors.
The power density would be uninterrupted by darkness, clouds, or precipitation, which are the problems encountered with earth based solararrays.
No fuel required.
No waste product.
DISADVANTAGES
The entire structure is massive.
High cost and require much time for construction.
Risks involved withmalfunction.
CONCLUSION
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
Posts: 5,362
Threads: 2,998
Joined: Feb 2011
[attachment=12405]
1.INTRODUCTION
The area of wireless power transmission is very interesting. One of the major issue in power system is the losses occurs during the transmission and distribution of electrical power. As the demand increases day by day, the power generation increases and the power loss is also increased. The major amount of power loss
occurs during transmission and distribution. The percentage of loss of power during transmission and distribution is approximated as 26%. The main reason for power loss during transmission and distribution is the resistance of wires used for grid. The efficiency of power transmission can be improved to certain level by using high strength composite over head conductors and underground cables that use high temperature super conductor. But, the transmission is still inefficient.
The technology is in its infancy but the overall benefits from its maturation could be significant to society as a whole. World population is expected to continue to grow exponentially. Five sixths of the world’s population lives in developing nations. Most developing nations such as China, India, and Pakistan are rapidly improving their standard of living. All of these trends point to an energy demand that will grow at even a larger rate. Wireless power transmission could one day allow us to generate solar power on a satellite and beam it down to Earth, transmit power to a water treatment plant for a disaster relief operation or power a flying communication relay station from a terrestrial station. There are a few engineering hurtles yet to overcome to make this technology viable to today’s investors, but with the rising demand for energy and the rapid improvements being made it is just a matter of time before wireless power transmission becomes an industry of its own.
It is known that electromagnetic energy is associated with the propagation of electromagnetic waves. Theoretically, we can use all electromagnetic waves for a wireless power transmission (WPT). The difference between the WPT and communication systems is only efficiency. Maxwell’s Equations indicate that the electromagnetic field and its power diffuse to all directions. Though we transmit energy in a communication system, the transmitted energy is diffused to all directions. Though the received power is enough for a transmission of information, the efficiency from the transmitter to receiver is quiet low. Therefore, we do not call it the WPT system.
Typical WPT is a point-to-point power transmission. For the WPT, we had better concentrate power to receiver. It was proved that the power transmission efficiency can approach close to 100%. We can more concentrate the transmitted microwave power to the receiver aperture areas with taper method of the transmitting antenna power distribution. Famous power tapers of the transmitting antenna are Gaussian taper, Taylor distribution, and Chepachet distribution. Such taper of the transmitting antenna is commonly used for suppression of side lobes. It corresponds to increase in the power transmission efficiency. Concerning the power transmission efficiency of the WPT, there are some good optical approaches in Russia.
Future suitable and largest application of the WPT via microwave is a Space Solar Power Satellite (SPS). The SPS is a gigantic satellite designed as an electric power plant orbiting the Geostationary Earth Orbit (GEO). It consists of mainly three segments; solar energy collector to convert the solar energy into DC (direct current) electricity, DC-to-microwave converter, and large antenna array to beam down the microwave power to the ground. The first solar collector can be either photovoltaic cells or solar thermal turbine. The second DC-to-microwave converter of the SPS can be either microwave tube system and/or semiconductor system. It may be their combination. The third segment is a gigantic antenna array.
Table 1.1 shows some typical parameters of the transmitting antenna of the SPS. An amplitude taper on the transmitting antenna is adopted in order to increase the beam collection efficiency and to decrease side lobe level in almost all SPS design. A typical amplitude taper is called 10 dB Gaussian in which the power density in the center of the transmitting antenna is ten times larger than that on the edge of the transmitting antenna.
The SPS is expected to be operational around 2030.Before realization of the SPS, we can consider other applications of WPT. In recent years, mobile devices advanced significantly and require decreasing power consumption . It means that we can use the diffused weak microwave power as power source of the mobile devices with low power consumption such as RF-ID. The RF-ID is radio IC-tug with wireless power transmission and wireless information. This is a new WPT
Application like broadcasting.
2.HISTORY OF WIRELESS POWER TRANSMISSION
The discussion of wireless power transmission as an alternative to transmission line power distribution started in the late 19th century. In 1888, bolstered by Maxwell's theory, Heinrich Hertz succeeded in showing experimental evidence of radio waves by his spark-gap radio transmitter. The prediction and evidence of the radio wave in the end of 19th century was start of the wireless power transmission.
Both Heinrich Hertz and Nicolai Tesla theorized the possibility of wireless power transmission. Tesla demonstrated it in 1899 by powering fluorescent lamps 25 miles from the power source without using wires. Despite the novelty of Tesla’s demonstration and his personal efforts to commercialize wireless power transmission, he soon ran out of funding because it was much less expensive to lay copper than to build the equipment necessary to transmit power through radio waves.
Nicolai Tesla suggested an idea of the wireless power transmission and carried out the first WPT experiment in 1899. He said “This energy will be collected all over the globe preferably in small amounts, ranging from a fraction of one to a few horse-powers. One of its chief uses will be the illumination of isolated homes”.
William C. Brown contributed much to the modern development of microwave power transmission which for many reasons dominates research and development of wireless transmission today. In the early 1960s brown invented the rectenna which directly converts microwaves to DC current.
To concentrate the transmitted power and to increase transmission efficiency, we have to use higher frequency than that used by Tesla. In 1930s, much progress in generating high-power microwaves, namely 1-10 GHz radio waves, was achieved by invention of the magnetron and the klystron. After World War II, high power and high efficiency microwave tubes were advanced by development of radar technology. We can concentrate a power to receiver with microwaves. We call the wireless power transmission with microwaves as microwave power transmission (MPT). Based on the development of the microwave tubes during the World War II, W. C. Brown started the First MPT research and development in 1960.
Despite these advances wireless power transmission has not been adopted for commercial use except for the sole exception of pacemakers and electric toothbrush rechargers. However, research is ongoing because of the many promising applications suited for wireless power transmission.
First of all, he developed a rectenna, rectifying antenna which he named, for receiving and rectifying microwaves. The efficiency of the first rectenna developed in 1963 was 50 % at output 4WDC and 40% at output 7WDC respectively.
With the rectenna, he succeeded in MPT experiments to wired helicopter in 1964 and to free-flied helicopter in1968 (Fig. 1). In 1970s; he tried to increase DC-RF-transmission-RF-DC total efficiency with 2.45 GHz microwave. In 1970, overall DC-DC total efficiency was only 26.5 % at 39WDC in Marshall Space Flight Center.
After 1990s, many MPT laboratory and field experiments were carried out in the world. We often use 2.45 GHz or 5.8 GHz of the ISM band (ISM=Industry, Science, and Medical) for the MPT system. A Canadian group demonstrated fuel-free airplane flight experiment with MPT in 1987 which was called SHARP (Stationary High Altitude Relay Platform) with 2.45 GHz.
In USA, there were many MPT research and development projects after W. C. Brown: for instance, retro directive microwave transmitters, rectenna, new devices and microwave circuit technologies.