Solar Power Transmission
posted by: Jasmine Greene 16 days ago
Jasmine Greene
The idea of having a space station that beams down solar energy to earth has been a popular topic in many sci-fi communities, but it may not be fiction for much longer. Officials in the US and Japanese government have begun funding research into the creation of real space-based solar power stations.
In Japan, the space solar power system (SSPS) and the Japan Aerospace Exploration Agency (JAXA) are currently working together with 16 other companies (including Mitsubishi) on a geostationary solar space station. The station would collect the solar energy by way of photovoltaic cells and then transmit this energy to earth via laser or microwave form. This would then be converted into electricity for commercial power grids or stored energy as hydrogen. This space station could potentially transmit one gigawatt of energy to earth - equivalent to the output of a large nuclear plant [Source: Scientific American]. The US, along with the small island nation of Palau, also are working in conjunction to create an orbital solar power station and are planning to erect a "rectifying antenna," to demonstrate the effectiveness of this technology. The antenna would be 260 feet in diameter and would be set up to collect 1 MW, enough energy to power over 1,000 homes, from a satellite orbiting some 300 miles above [Source: Treehugger].
How it Works
There are three parts to the solar space station:
1. solar cells or heat engines to collect energy
2. microwave or lasers to transmit energy to earth
3. rectennas (rectifying antennas) to collect the energy and distribute the energy on earth.
Most of the countries have opted for photovoltaic cells in order to collect th energy from the sun. One of the greatest advantages of having these cells out in space is that they can collect energy all the time. In space, the sun's rays are never compromised by clouds or increment weather like on earth. Therefore, these stations can collect 144% more energy than any terrestrial solar panels [Source: Wikipedia]. Of course, there needs to be a a way to transmit this energy wirelessly, since having cables from space to earth is impractical. Japan has opted for laser transmission. The lasers use plates built from a ceramic material containing chromium, which absorbs sunlight and neodymium, which converts it into laser beams. These new lasers outperformed earlier demonstrating a solar-to-laser energy conversion efficiency of 42% [Source: Treehugger]. On the other hand, many other countries have opted for microwave transmission. In fact, with the use of a rectifying antenna, the microwave-to-electricity conversion is about 90% [Source: Wikipedia], making it much more efficient than lasers.
Problems and Solutions
Of course with any new technological advances, there are always downfalls. One of the major downfalls of building a space solar power station is the huge cost and space to make the technology work. With a rough estimation of $21 billion, this could be one of the most expensive alternative energy sources. The money would go towards "thin-film condenser mirrors, solar panels and a microwave transmitter..., as well as a 100-unit laser array of 5,000 metric tons that would be 10 kilometers long" [Source: Scientific American]. While the intial cost is expensive, Suzuki and his colleagues are aiming to produce stable, cheap power and hydrogen at a target price of 6.5 cents per kilowatt-hour, which is in-line with conventional power generation [Source: Scientific American]. And since the space station itself is in space, it will not suffer the effects of weather, making maintenance and upkeep much cheaper.
Of course, because it is in space, there are many extraterrestrial problems like meteroid or space junk collisions that could throw the station off course. This leads into another huge safety problem: stray microwave beams. While in theory 95% of the microwave radiation is directed towards the antenna, if it were to miss or become misdirected, these beams could affect nearby towns. While science says that these beams are 10 mW/cm2 -completely withing the OSHA workplace standard [Source: OSHA] - scientists and developers have introduced a fail-safe beam targeting by using a retrodirective phased array antenna. A "pilot" beam is directed towards the antenna which sets up the phase front. The antenna then compares the pilot beam's phase front with an internal clock in order to control the phase of the outgoing signal. This centers the beam directly on the rectenna. If the pilot beam is lost for any reason (if the transmitting antenna is turned away from the rectenna, for example) the phase control value fails and the microwave power beam is automatically defocused [Source: Wikipedia].
While there is still a long way to go until the actual station is completed, the Japanese and US government expect a demonstration of the technology to reach completion in three to four years. Should the demonstration go successfully, space-based solar power stations may not be a thing of fiction after all.
In Japan, the space solar power system (SSPS) and the Japan Aerospace Exploration Agency (JAXA) are currently working together with 16 other companies (including Mitsubishi) on a geostationary solar space station. The station would collect the solar energy by way of photovoltaic cells and then transmit this energy to earth via laser or microwave form. This would then be converted into electricity for commercial power grids or stored energy as hydrogen. This space station could potentially transmit one gigawatt of energy to earth - equivalent to the output of a large nuclear plant [Source: Scientific American]. The US, along with the small island nation of Palau, also are working in conjunction to create an orbital solar power station and are planning to erect a "rectifying antenna," to demonstrate the effectiveness of this technology. The antenna would be 260 feet in diameter and would be set up to collect 1 MW, enough energy to power over 1,000 homes, from a satellite orbiting some 300 miles above [Source: Treehugger].
How it Works
There are three parts to the solar space station:
1. solar cells or heat engines to collect energy
2. microwave or lasers to transmit energy to earth
3. rectennas (rectifying antennas) to collect the energy and distribute the energy on earth.
Most of the countries have opted for photovoltaic cells in order to collect th energy from the sun. One of the greatest advantages of having these cells out in space is that they can collect energy all the time. In space, the sun's rays are never compromised by clouds or increment weather like on earth. Therefore, these stations can collect 144% more energy than any terrestrial solar panels [Source: Wikipedia]. Of course, there needs to be a a way to transmit this energy wirelessly, since having cables from space to earth is impractical. Japan has opted for laser transmission. The lasers use plates built from a ceramic material containing chromium, which absorbs sunlight and neodymium, which converts it into laser beams. These new lasers outperformed earlier demonstrating a solar-to-laser energy conversion efficiency of 42% [Source: Treehugger]. On the other hand, many other countries have opted for microwave transmission. In fact, with the use of a rectifying antenna, the microwave-to-electricity conversion is about 90% [Source: Wikipedia], making it much more efficient than lasers.
Problems and Solutions
Of course with any new technological advances, there are always downfalls. One of the major downfalls of building a space solar power station is the huge cost and space to make the technology work. With a rough estimation of $21 billion, this could be one of the most expensive alternative energy sources. The money would go towards "thin-film condenser mirrors, solar panels and a microwave transmitter..., as well as a 100-unit laser array of 5,000 metric tons that would be 10 kilometers long" [Source: Scientific American]. While the intial cost is expensive, Suzuki and his colleagues are aiming to produce stable, cheap power and hydrogen at a target price of 6.5 cents per kilowatt-hour, which is in-line with conventional power generation [Source: Scientific American]. And since the space station itself is in space, it will not suffer the effects of weather, making maintenance and upkeep much cheaper.
Of course, because it is in space, there are many extraterrestrial problems like meteroid or space junk collisions that could throw the station off course. This leads into another huge safety problem: stray microwave beams. While in theory 95% of the microwave radiation is directed towards the antenna, if it were to miss or become misdirected, these beams could affect nearby towns. While science says that these beams are 10 mW/cm2 -completely withing the OSHA workplace standard [Source: OSHA] - scientists and developers have introduced a fail-safe beam targeting by using a retrodirective phased array antenna. A "pilot" beam is directed towards the antenna which sets up the phase front. The antenna then compares the pilot beam's phase front with an internal clock in order to control the phase of the outgoing signal. This centers the beam directly on the rectenna. If the pilot beam is lost for any reason (if the transmitting antenna is turned away from the rectenna, for example) the phase control value fails and the microwave power beam is automatically defocused [Source: Wikipedia].
While there is still a long way to go until the actual station is completed, the Japanese and US government expect a demonstration of the technology to reach completion in three to four years. Should the demonstration go successfully, space-based solar power stations may not be a thing of fiction after all.
Read more: environment & wildlife, solar space energy, solar space power station
comments
This is very interesting say the least.
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still, this could set a great example for subsequent techniques for alternative energy...dot be afraid to think outside the box...or atmosphere
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Don't forget all the oil those rockets will burn to put all that solar technology up in space, and the oil/coal which will be burnt to make the panels. Isn't the sun already beaming around 1100 W/sqm (on average) down on our planet without the panels in space? I am all for space technology and am a scifi nerd at heart, but this is freaking ridiculous! Like a previous poster said, you could buy a hell of a lot of solar technology for $21 billion. This kind of investment would create huge numbers of jobs, it would increase the development of new and more efficient solar technology, and would decrease the cost per watt. This reminds me of how the Americans spent $6 million making a pen to write in space; while the Russians used a pencil. That $6 million might of been better spent on their hopeless healthcare or feeding a bunch of hungry people!
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living in a very hot country,saudi arabia i wonder why there is still not much to see here about using solar energy!i dream to see these solar pannels on all roofs...and so on!!!
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In Rehoboth Delaware we are developing our first Wind Power site. It will be located out in the ocean. It took our citizens years of fighting to make it possible. Congressman Mike Castle the repuke, stood in the way at every point. Senator Tom Carper a neo con demorat, also did nothing to help us. In fact, they helped hire behind the scenes industry lobbyists to prevent wind power. We have a power plant in Millsboro, Del. which has created a "cancer cluster". The legislators and government know about the cancer clusters, but refuse to tell the citizens. The EPA is worthless in the pockets of big power companies. We have a nuclear power plant located across the Delaware River built on an artificial island that is so dangerous, if it blew would take out Wilmington and many towns. There is no evacuation plan, because they know no one could get out should a nuclear disasater occur. This plant is so old it fails regularly yet the NRC is pushing to license this monstrosty for another 20 years. Legislators do nothing to support the citizens and our demand that plant be shut down...the voices from the citizens through hearing after hearing are drowned out by the industry and their lobbyists.
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I love science, and the way it has been used in the past to alleviate human suffering and make the earth a better place to live.
But whether feasible or not, the projected cost alone of venturing into establishing a Space Solar Power Transmission Station makes the project a totally preposterous mission.
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For now perhaps, the simpler the better---if we can control solar energy via panels installed on Earth, let's go that way. With all the people starving in the world, the money to be spent on sending up solar panels into space could be used to feed the hungry, provide medical attention and facilities to countries that need them badly, and so many other urgent purposes.
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Thank you Lee H.! As soon as I started reading this article, I was thinking the same thing! If we really wanted to start up a space solar plant, maybe we should first clean up the mess that we made in the first place out there... AFTER we get solar more wide-spread on the ground!
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The idea is compelling, but space is a dangerous place filled with an untold number of man made and natural debris that could easily destroy any large structure. What would keep this from happening? Surely, investment of this magnitude knows, or at least is aware of this possibility.
Besides, why not invest in earth bound solar energy instead, where the costs would be less and maintenance would be much easier. A lot of ideas are good, but impractical. I suspect this is just one in that category.
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I still can never figure out why most comments on solar energy, whether present or future, are negative.
This will be but one part of the long term solution. For those of us who understand that our current rate of fossil fuel consumption cannot continue, we grasp this idea quickly. Why does everything boil down to the cost? Really, why?
My hat is off to the Japanese for having the courage to get on with this project. All the tech challenges are not completely solved, but I have no doubt that they will be.
As far as ground based solar power systems go, there are many solar plants in the works designed to produce small to medium quantities of power.
A space based unit such as this eliminates the worst of the problems, which is cloud cover and night time darkness. As long as the power can be transmitted in a clean fashion, there should be no reason for it not to be successful.
There is still 20+ years before it will become effective, and in the ensuing time, surely there can be no doubt that solar panel efficiencies will increase dramatically.
While we are aware of the 1 KW/square meter on earth, I wonder what that will be out in space? NASA very likely already has that answer.
I certainly wish them well.
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