What is a Space-based Solar Power (SBSP)?
The idea of harnessing solar energy in space where the sunlight is limitless and the sun’s rays never stop beaming down the Earth may seem implausible, but with such modern technology, we have today, it will likely to happen. In fact, during early 2018, scientists from the California Institute of Technology make a public statement about their successful creation of a prototype that is capable of harnessing and transmitting solar energy from space to Earth.
This concept is called the space-based solar power. This idea is not new today for this technology was already mentioned way back in the year 1941 by Isaac Asimov in his science fiction story entitled “Reason”. Today, this technology is developing rapidly and researches about this spaced-based solar power have been
Research on space-based solar power has been existing and progressing at Caltech, where professors Ali Hajimiri, Sergio Pellegrino and Harry Atwater and have received funding from the Northrop Grumman Corporation to study and explore the potentials of this technology source of clean energy.
Space-based solar power (SBSP) is the new rising solar energy concept where solar power is being collected in outer space and transmitted down to Earth. These are large structures placed in space to harness solar energy and convert it into a form of energy and then transmit it wirelessly to any remote receiver stations it could be on Earth or on aircraft, spacecraft or surfaces of other planets.
In much simpler terms, they will put some mechanism in outer space to harness the sun’s energy continuously and wirelessly transmit that energy to Earth. This would happen both day and night, even during the rainy season or summer season. The captured energy will be received by the Earth through a special antenna called rectenna. By this, the power will be easily distributed across the Earth.
The space-based solar power is a good tool to save and collect energy and this can resolve greenhouse gas emissions problems we’re facing today. Aside from that, this solar power technology can provide large quantities of energy to every region on Earth with less environmental impact.
The solar energy available in space is literally billions of times greater than the energy we normally use today. And since the lifetime of the sun is estimated at around 4 to 5 billion years, this will make space-based solar power technology a truly long-term energy solution. Also, this technology on a larger scale basis with the combination of demonstrated wireless power transmission can nearly supply all of the electrical needs of the Earth.
In addition, this will help in eliminating fossil fuels which are the main source of energy of our transportation system and space solar power can provide clean energy to power any future electric transportation system. Indeed, this new technology has a wide variety of substantial benefits to both the environment and the people compared to other sources of energy.
The innovation of the first silicon solar cell in 1954, encouraged a series of discoveries in the solar energy domain. Also, the space industry was considered the first one to use solar technology to generate power for spacecraft, in the 1960s. In addition, solar cells powered the first artificial earth satellite–Vanguard 1.
How does Spaced-based Solar Power Work?
It transforms solar energy into electricity via photovoltaic cells in geostationary orbit around Earth. Then the converted power is being transmitted through electromagnetic waves at 2.45 GHz to the receiver stations on Earth using the rectennas which convert the energy back into electricity used in the local power grid.
The self-assembling satellites are being launched into space, together with reflectors and a laser power transmitter or a microwave. Then, reflectors or inflatable mirrors will be spread over the vast field of space and directing solar radiation onto solar panels. These solar panels will convert solar power into a microwave or a laser and beam the power continuously down to Earth. Whereas, on Earth, the power-receiving stations will collect the beam and will add it to the power grid.
Space-based Solar Power Designs
There are two most commonly known designs of space solar power, they are the Microwave Transmitting satellite which is larger and deeper satellite, and the Laser transmitting satellite which is smaller and used nearly.
Microwave Transmitting Satellite
Microwave transmitting satellites orbit Earth about 35,000 kilometres above Earth’s surface in geostationary orbit (GEO). The designs for microwave transmitting satellites are gigantic and it goes with solar reflectors that span up to 3 km and weighing over 80,000 metric tons. These satellites are capable of generating multiple gigawatts of power, which is enough to power the major cities in the United States.
Since its microwave has a long wavelength it also requires a long antenna which will allow power to be beamed through the Earth’s atmosphere, either during rainy or summer season, however, low-intensity levels are hardly stronger than the midday sun.
On the other hand, the assembling, operating and launching cost of these microwave-equipped GEO satellites is estimated in tens of billions of dollars. Also, it would likely require as many as 40 launches for all necessary materials to reach space. Whereas, the rectenna used for harnessing the microwave beam is ranging between 3 and 10 km in diameter, which is the size of a huge area of land is a challenge to purchase and develop.
Laser Transmitting Satellite
Compared to Microwave transmitting satellites, Laser transmitting satellites only orbit in a low Earth orbit (LEO) which is only about 400 km above the Earth’s surface. Also, this satellite weighs in less than 10 metric tons, just a fraction of the weight of its microwave counterpart. This design is way cheaper than the first one, too. They predict that the launching and operating of a laser-equipped SBSP satellite would cost around 500 million dollars.
Aside from that, it is possible to launch the entire self-assembling satellite using only a single rocket, significantly reducing the cost and time of production. Also, by using a laser transmitter, the beam will only be about 2 meters in diameter, instead of several kilometres, which is an undeniably huge reduction.
This works by the satellite’s solar power beaming system that employs a diode-pumped alkali laser. This laser is about the size of a kitchen table which is powerful enough to beam power to the Earth, with extremely high efficiency, over 50 percent. Furthermore, its first demonstration happened at LLNL in the year 2002 and still under development today.
This satellite is smaller in size and correspondingly has a lower capacity of about 1 to 10 megawatts. Making this satellite as the best part of a fleet of similar satellites, being utilized together.
Despite being far lighter, cheaper satellite and easier to deploy than its microwave counterpart, still there are serious challenges remain to develop this satellite.
Advantages and Drawbacks of Space-based Solar Power
Advantages of Space-based Solar Power
One of the fundamental advantages of a space-based solar power is its capacity to provide and generate a continuous supply of power to the earth, unlike those solar power systems on Earth which can only offer limited solar energy. As space-based solar power orbits 35,000 km above the earth’s surface it is obviously facing the sun all the time, which definitely helps in providing a constant energy output.
Aside from that, an SBSP has a wireless power transfer system which makes it easier to distribute energy all over the earth. Thus, reducing the requirements of a larger-scale electricity grid on all regions of the earth just to allocate the power.
Here’s a list of specific advantages of SBSP:
- Space-based solar power can take advantage of the current and historic investment in aerospace to expand employment opportunities in solving the arising problems of climate change and energy security.
- SBSP does not emit greenhouse gases, unlike ethanol, oil, gas and coal plants.
- Space solar power will provide true energy independence for the nations that develop it, eliminating a major source of national competition for limited Earth-based energy resources.
- Space-based solar power does not depend upon the increasing scarcity of freshwater resources.
- Unlike nuclear power plants, SBSP is not producing hazardous and perilous waste, which is needed to be stored and guarded for hundreds of years.
- Space solar power is available 24 hours a day and 7 days a week, as well as in huge quantities. It also works regardless of the weather, wind speed, daylight and seasons.
- It only requires dependence on stable resources, unlike others that use foreign oil providers to meet energy needs.
- Space solar power is easy to export and distributed virtually in any region in the world.
- SBSP can also be used for the desalination of seawater.
- It does not depend on natural-gas-derived fertilizer.
Drawbacks Space-based Solar Power
One of the main drawbacks of any space-based solar power satellite is its construction particularly those satellites with large structures. Not only does it require significant amounts of material to be launched into space, but these materials are also needed to be assembled, maintained and replaced over time. As a matter of fact, because of the raspy environment in space, the lifespan of some currently launched solar panels in space is significantly shorter compared to those placed on the earth’s surface.
Another thing is the wireless power transmission which is transmitted via electromagnetic waves at high transfer efficiencies. To remain in a safe condition, the satellite must require a huge receiver rectenna. Aside from that, one of its challenges is the launching, development and maintenance costs, which is highly expensive.
Space-based Solar Power Cost
For the low cost: 4,000 metric tons (4M kg) x $9,000 launch cost per kg it is estimated at around 36 billion dollars. Whereas, for a high cost: 80,000 metric tons (80M kg) x $43,000 launch cost per kg it is estimated at around 3.4 trillion dollars.
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Theexperimental solar plant will make use of orbiting satellites equippedwith solar cells that transform the sun’s energy into electricity.Electricity generated by the process would be converted into radiofrequency transmittable energy, which will be collected by a receivingstation in Fresno, California, before being transferred to PG&E’spower grid.
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