24-05-2014, 11:31 AM
Solar Power Satellite
[attachment=63642]
ABSTRACT
The concept of placing enormous solar power satellite (SPS) systems in space represents one
of a handful of new technological options that might provide large-scale, environmentally clean base load
power into terrestrial markets. In the United States, the SPS concept was examined extensively during the late
1970s by the U.S. Department of Energy (DOE) and the National Aeronautics and Space Administration
(NASA). More recently, the subject of space solar power (SSP) was re-examined by NASA from 1995-1997 in
the “Fresh Look Study” and during 1998 in an SSP “Concept Definition Study.” As a result of these efforts,
in 1999-2000, NASA undertook the SSP Exploratory Research and Technology (SERT) program, which
pursued preliminary strategic technology research and development to enable large, multimegawatt SSP
systems and wireless power transmission (WPT) for government missions and commercial markets (in space
and terrestrial). During 2001-2002, NASA has been pursuing an SSP Concept and Technology Maturation
(SCTM) [1] program follow-up to the SERT, with special emphasis on identifying new, high-leverage
technologies that might advance the feasibility of future SSP systems.
INTRODUCTION
In outer space there is an uninterrupted availability of huge amount of solar energy in the form of light and heat.
So the use of satellites primarily aimed at collecting the solar energy and beam it back to the earth is being
considered. In geosynchronous orbit, i.e. 36,000 km (22,369 miles), a Solar Power Satellite (SPS) would be able
to face the sun 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. Unused heat is radiated back into the
space. Power can be beamed to the location where it is needed, need not have to invest in as large as a grid.
Electrical power accounts for much of the energy consumed. On the one hand, the major loss of power
occurs during transmission, from generating stations to the end users. The resistance of the wire in the
electrical grid distribution system causes a loss of 26% to 30% of the energy generated. Therefore, the loss
implies that our present system of electrical transmission is 70% to 74% efficient. On the other hand, the
generation is done primarily based on fossil fuels, which will not last long (say by 2050)
Converting DC to Microwave Power
To convert the DC power to microwave for the transmission through antenna towards the earth‟s receiving
antenna, microwave oscillators like Klystrons, Magnetrons can be used. In transmission, an alternating current is
created in the elements by applying a voltage at the antenna terminals, causing the elements to radiate an
electromagnetic field. [3]
The DC power must be converted to microwave power at the transmitting end of the system by using
microwave oven magnetron. The heat of microwave oven is the high voltage system. The nucleus of high
voltage system is the magnetron tube. The magnetron is diode type electron tube, which uses the interaction of
magnetic and electric field in the complex cavity to produce oscillation of very high peak power. It employs
radial electric field, axial magnetic field, anode structure and a cylindrical cathode.
The cylindrical cathode is surrounded by an anode with cavities and thus a radial electric field will exist. The
magnetic field due to two permanent magnets which are added above end below the tube structure is axial. The
upper magnet is North Pole and lower magnet is South Pole. The electron moving through the space tends to
build up a magnetic field around itself. The magnetic field on right side is weakened because the self-induced
magnetic field has the effect of subtracting from the permanent magnetic field. So the electron trajectory bends
in that direction resulting in a circular motion of travel to anode. This process begins with a low voltage being
applied to the cathode, which causes it to heat up. The temperature rise causes the emission of more electrons.
This cloud of electrons would be repelled away from the negatively charged cathode. The distance and velocity
of their travel would increase with the intensity of applied voltage.
TRANSMISSION
As the electro-magnetic induction and electro-magnetic radiation has disadvantages we are going for
implementation of electrical conduction and resonant frequency methods. Of this, the resonant induction method
is the most implement able due to the reasons given later. In the distant future this method could allow for
elimination of many existing high tension power transmission lines and facilitate the inter connection of electric
generation plants in a global scale.
The microwave source consists of microwave oven magnetron with electronics to control the output power.
The output microwave power ranges from 50w to 200w at 2.45GHz. A coaxial cable connects the output of the
microwave source to a coax-to-wave adaptor. This adapter is connected to a tuning waveguide ferrite circulator
is connected to a tuning waveguide section to match the wave guide impedance to the antenna input impedance.
The slotted wave guide antenna consists of 8 waveguide sections with 8 slots on each section. These 64 slots
radiate the power uniformly through free space to the rectifying antenna (rectenna). The slotted waveguide
antenna is ideal for power transmission because of its high aperture efficiency (>95%) and high power handling
capability.
CONCLUSION
The increasing global energy demand is likely to continue for many decades. New power plants of all sizes will
be built. Fossils fuels will run off in another 3-4 decades. However energy independence is something only
Space based solar power can deliver. Space based solar power (SBSP) concept is attractive because it is much
more advantageous than ground based solar power.
It has been predicted that by 2030, the world needs 30TW power from renewable energy sources and solar
energy alone has the capability of producing around 600TW. The levels of CO 2 gas emission can be minimized
and brought under control. Thus the problem of global warming will be solved to a great extent.
Based on current research space based solar power should no longer be envisioned as requiring
unimaginably large initial investments. Moreover, space solar power systems appear to possess many
significant environmental advantages when compared to alternative approaches to meeting increasing terrestrial
demands for energy including necessity of considerably less land area than terrestrial based solar power
systems.Though the success of space solar power depends on successful development of key technology, it is
certain the result will be worth the effort.
Space solar power can completely solve our energy problems long term. The sooner we start and the harder
we work, the shorter "long term" will be.
[attachment=63642]
ABSTRACT
The concept of placing enormous solar power satellite (SPS) systems in space represents one
of a handful of new technological options that might provide large-scale, environmentally clean base load
power into terrestrial markets. In the United States, the SPS concept was examined extensively during the late
1970s by the U.S. Department of Energy (DOE) and the National Aeronautics and Space Administration
(NASA). More recently, the subject of space solar power (SSP) was re-examined by NASA from 1995-1997 in
the “Fresh Look Study” and during 1998 in an SSP “Concept Definition Study.” As a result of these efforts,
in 1999-2000, NASA undertook the SSP Exploratory Research and Technology (SERT) program, which
pursued preliminary strategic technology research and development to enable large, multimegawatt SSP
systems and wireless power transmission (WPT) for government missions and commercial markets (in space
and terrestrial). During 2001-2002, NASA has been pursuing an SSP Concept and Technology Maturation
(SCTM) [1] program follow-up to the SERT, with special emphasis on identifying new, high-leverage
technologies that might advance the feasibility of future SSP systems.
INTRODUCTION
In outer space there is an uninterrupted availability of huge amount of solar energy in the form of light and heat.
So the use of satellites primarily aimed at collecting the solar energy and beam it back to the earth is being
considered. In geosynchronous orbit, i.e. 36,000 km (22,369 miles), a Solar Power Satellite (SPS) would be able
to face the sun 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. Unused heat is radiated back into the
space. Power can be beamed to the location where it is needed, need not have to invest in as large as a grid.
Electrical power accounts for much of the energy consumed. On the one hand, the major loss of power
occurs during transmission, from generating stations to the end users. The resistance of the wire in the
electrical grid distribution system causes a loss of 26% to 30% of the energy generated. Therefore, the loss
implies that our present system of electrical transmission is 70% to 74% efficient. On the other hand, the
generation is done primarily based on fossil fuels, which will not last long (say by 2050)
Converting DC to Microwave Power
To convert the DC power to microwave for the transmission through antenna towards the earth‟s receiving
antenna, microwave oscillators like Klystrons, Magnetrons can be used. In transmission, an alternating current is
created in the elements by applying a voltage at the antenna terminals, causing the elements to radiate an
electromagnetic field. [3]
The DC power must be converted to microwave power at the transmitting end of the system by using
microwave oven magnetron. The heat of microwave oven is the high voltage system. The nucleus of high
voltage system is the magnetron tube. The magnetron is diode type electron tube, which uses the interaction of
magnetic and electric field in the complex cavity to produce oscillation of very high peak power. It employs
radial electric field, axial magnetic field, anode structure and a cylindrical cathode.
The cylindrical cathode is surrounded by an anode with cavities and thus a radial electric field will exist. The
magnetic field due to two permanent magnets which are added above end below the tube structure is axial. The
upper magnet is North Pole and lower magnet is South Pole. The electron moving through the space tends to
build up a magnetic field around itself. The magnetic field on right side is weakened because the self-induced
magnetic field has the effect of subtracting from the permanent magnetic field. So the electron trajectory bends
in that direction resulting in a circular motion of travel to anode. This process begins with a low voltage being
applied to the cathode, which causes it to heat up. The temperature rise causes the emission of more electrons.
This cloud of electrons would be repelled away from the negatively charged cathode. The distance and velocity
of their travel would increase with the intensity of applied voltage.
TRANSMISSION
As the electro-magnetic induction and electro-magnetic radiation has disadvantages we are going for
implementation of electrical conduction and resonant frequency methods. Of this, the resonant induction method
is the most implement able due to the reasons given later. In the distant future this method could allow for
elimination of many existing high tension power transmission lines and facilitate the inter connection of electric
generation plants in a global scale.
The microwave source consists of microwave oven magnetron with electronics to control the output power.
The output microwave power ranges from 50w to 200w at 2.45GHz. A coaxial cable connects the output of the
microwave source to a coax-to-wave adaptor. This adapter is connected to a tuning waveguide ferrite circulator
is connected to a tuning waveguide section to match the wave guide impedance to the antenna input impedance.
The slotted wave guide antenna consists of 8 waveguide sections with 8 slots on each section. These 64 slots
radiate the power uniformly through free space to the rectifying antenna (rectenna). The slotted waveguide
antenna is ideal for power transmission because of its high aperture efficiency (>95%) and high power handling
capability.
CONCLUSION
The increasing global energy demand is likely to continue for many decades. New power plants of all sizes will
be built. Fossils fuels will run off in another 3-4 decades. However energy independence is something only
Space based solar power can deliver. Space based solar power (SBSP) concept is attractive because it is much
more advantageous than ground based solar power.
It has been predicted that by 2030, the world needs 30TW power from renewable energy sources and solar
energy alone has the capability of producing around 600TW. The levels of CO 2 gas emission can be minimized
and brought under control. Thus the problem of global warming will be solved to a great extent.
Based on current research space based solar power should no longer be envisioned as requiring
unimaginably large initial investments. Moreover, space solar power systems appear to possess many
significant environmental advantages when compared to alternative approaches to meeting increasing terrestrial
demands for energy including necessity of considerably less land area than terrestrial based solar power
systems.Though the success of space solar power depends on successful development of key technology, it is
certain the result will be worth the effort.
Space solar power can completely solve our energy problems long term. The sooner we start and the harder
we work, the shorter "long term" will be.