The sun is an endless source of energy, and the search for sustainable energy sources has led to technological developments to trap it. Every hour more solar energy reaches the Earth’s surface than what we can use in a year. We need to catch this energy source and make effective use of it. Photovoltaics are doing the job of capturing the sun’s rays and turning them into a fuel source, but the efforts are still falling short.
There are certain inherent challenges in turning this fuel source into useful energy. About 30 percent of the solar energy is reflected back in to the atmosphere. A significant amount of UV light is lost in the ozone layer and infrared wavelengths are absorbed by methane, carbon dioxide and water vapor. About 70% of the total light reaches the Earth’s surface.
A good way to capture the maximum amount of radiation is to put photovoltaics on satellites in space and objects outside of our atmosphere to absorb the broader range of spectral wavelengths available. Additionally, such solar energy capture objects will not be hampered by clouding and nighttime and would be able to transmit substantially more energy than terrestrial solar panels.
The energy in the form of electromagnetic radiation can be beamed back to Earth in either laser or microwave form through antennas. An antenna on the ground could collect the waves or electromagnetic radiations from lasers and convert them back into electricity to be distributed. This would make it possible to directly transmit energy even to remote regions without extensive electrical infrastructure and overcome the drop in electricity generation from solar sources overnight.
The proposed devices for microwave transmission of solar power are huge – more than 3 km in diameter and weighing over 80,000 metric tons. Moreover, these devices need an extensive area of 3-10 kms on Earth for transmission catching. Hence laser-based transmission might be a better alternative with more compact instruments and smaller transmission areas. However, more satellites will be required to deliver the same amount of power as the microwave giants.
Secondly, such beaming devices will bypass the problem of energy storage. According to energy matching service Greenmatch, Space-based solar power (SBSP) could generate 40 times as much energy as Earth-based solar power.
There are some drawbacks to this alternative source of energy—the astronomical cost. The cost of production, launch, and assembly (which would most likely have to happen in space), currently make it commercially unviable. However, the technological advances made in recent years have brought down the costs, making SBSP a viable option. Currently, the key players in SBSP are China, the US and Japan. China is planning to send the first functioning prototype into space in 2022.
Researchers say that satellite and photovoltaic technologies have advanced sufficiently that the idea of solar energy satellites powering the Earth is now a real possibility.
Jeff Bezo’s Blue Origin and Elon Musk’s SpaceX have demonstrated the efficacy of putting out satellites in space. SpaceX’s Starlink broadband network plans to put out 30 tons of satellites a month. It is on course to potentially manufacture 40,000 satellites within five years, and launch all of them.
“The path to low-cost hardware has been shown,” said John Mankins, president of Artemis Innovation Management Solutions. “It’s modular and mass-produced. The hurdles of less-expensive launch and lowering hardware costs have been overcome.”
Photovoltaics were used for the first time on the Vanguard 1 mission in 1958.
