It is pegged as the key to mankind’s survival. Space based solar power is the alternative to energy and gas emissions problem. According to American international nonprofit organization, National Space Society, solar power harnessed from space can generate large quantities of energy to each and every person on Earth, with very little environmental impact.
With advancing economies and shortage of fuel, derived from oil, coal and natural gas and heightened concerns over energy supply, energy dependent economies are training their eyes on clean energy, especially space based solar power.
NASA has taken big steps in collecting energy from the sun, in outer space. Dubbed SPS-ALPHA, Solar Power Satellite via Arbitrarily Large PHased Array (built on the concept of Retrodirective Phased Array), is a proposed first-of-its-kind solar power satellite that has the potential of delivering energy to one/-third of humanity. An affordable green energy option, it is supposed to be operational by 2025, could revolutionize disaster relief and become a way of life.
How can energy be harnessed from sun in deep space
According to National Space Society, the sun has a lifetime of 4-5 billion years, making it an ideal source for long term energy solution. Now, earth receives only a single part out of the 2.3 billion of the Sun's output. According to Space Canada, a facilitator and enabler for space-based solar power, one of the major advantages of space-based solar power is that it is abundant and there are no carbon emissions.
Space based solar power is an idea that has been around as long as space program itself. In the early days, visionaries imagined astronauts building structures in space the size of small towns. It was a dream to provide clean, abundant and reliable electricity and the most promising way to get that energy to the ground is via low intensity microwave beams.
All one has to do is gather it up. But, the shadow of the earth gets in the way. To capture the energy of the sun efficiently, scientists propose building satellite out of the shadow, in deep space where the sun always shines. Solar panels in proper orbit absorb ten times the energy than those on the ground. And they do it 24/7.
Space based solar power – a bold idea whose time has come
According to space Canada video, in space, where weight is no problem, gossamer thin structures can grow like a normal flower petals, many kilometress on the side and sunlight gathered by huge arrays can be converted into a microwave or laser beam, then transmitted to special ground stations on earth. This can provide more than all of our current energy needs.
However, unlike communication satellite that use one transmitter to send one beam, the solar satellite beam involves millions of components that working together in harmony. The transmitter of a solar power satellite makes up many small wave micro transmitters and each one only produces the power of a light bulb.
But there are lot of them spread out through a very large area that is called Retrodirective Phased Array that means that signals from all the transmitters are coordinated like an orchestra to produce a focused beam. Now, the conductor for the solar power satellite is called a pilot beam that comes from the ground. The receiving station on the ground shifts the beam up to the satellite, telling the array where to the point the beam and synchronize their transmission. The pilot signal provides a reference that all of the transmitters can lock on to, thereby focusing their energy on the same location.
The amazing part of Retrodirective Phased Array is that the beam can be steered to a different part on the ground without any moving parts, the whole process takes place in milliseconds. While this beam carries a lot of energy, its intensity is low because all the transmitters are small and spread over a large area and it poses no threat to life on the ground or to the air.
Looking ahead – developing a prototype
No longer reserved for sci-fi films, Space Canada reveals the elements of this type of array have already been demonstrated on earth, that means the technology is there and the physics works. The next step is developing a small prototype in low earth orbit, only a few hundred kilometers up. It’s here the proposed SPS-ALPHA comes into play. In low earth orbit, the satellite continuously passes over the ground circling the earth every hour and a half keeping the beam focused on a series of targets. Then it moves up to the geostationary orbit where the satellite remains fixed over the same spot over the earth and point the beam to different locations on the ground.
California-headquartered Solaren Corporation is on a mission to provide clean power to the planet by “designing, developing, launching and operating the world’s first Space Solar Power plants.” In a statement, Gary Spirnak led company revealed, “Though the concept has existed since the 1970s, it’s been revisited and abandoned because getting all the parts up there in outer space, and the people to put it all together, is supremely expensive. With the advent of super small, mass-produced satellites and reusable booster rockets, scientists are beginning to give a crack at making space solar a reality”.
Challenges in making space solar power an everyday utility
John Mankins, space solar power advocate who reportedly received a funding from NASA’s Institute of Advanced Concepts, 2011 to refine the space solar power plant concept cited though the technology required to make space solar a reality already existed, it is forbiddingly expensive. The financial hurdle is the biggest barrier to making solar power a reality. Gary Spirnak shared in the statement that one of the biggest challenges is getting the cost down to low double digits or even single digits of cents per kilowatt-hour is a must to make space solar a competitive utility.
An idea, completely reliant on massive infrastructure investments for space solar to work. First up, one needs solid-state power amplifiers that can efficiently convert electricity from gathered sunlight into radio-frequency waves, then there are receivers on the ground that can re-convert RF waves into electricity. According to Solaren, RF converters, the technology behind cell phones is key to space solar research as well.
Another hurdle is undertaking a massive construction project in space. The largest space construction project ever undertaken was the International Space Station that has a price tag of $100 billion. This is small compared to a solar powered satellite but with private players such as SpaceX building powerful rockets making it cheaper to reach space, build things in low earth orbit could become a reality. Not to forget, the payback from the energy solar powered satellites provide is enormous.
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Richa Bhatia is a seasoned journalist with six-years experience in reportage and news coverage and has had stints at Times of India and The Indian Express. She is an avid reader, mum to a feisty two-year-old and loves writing about the next-gen technology that is shaping our world.