Japan’s ambitious plan to develop an orbital solar farm


Existing, land-based solar farms come with several complications. They are costly, take up large swaths of land that endangers local habitat, and they do not continuously harness the sun’s energy due to changing weather conditions. Yet, solar energy remains an essential technology for helping humanity rid its reliance on burning fossil fuels, which is wreaking havoc on the earth’s environment at record breaking speed.

Desperate times inspire daring innovation, and the Japan Aerospace Exploration Agency (JAXA) has embarked on a bold plan to play their part in solving the world’s energy needs. With serious plans and experimentation underway, JAXA is proposing to develop an orbital solar farm in space to be completed within the next 25 years. Not only will these space-based solar panels collect energy from the sun continuously, but also beam collected energy down to earth using microwave technology.

Illustration: John MacNeill

Illustration: John MacNeill

Japan’s geosynchronous orbital solar farm will be a “1-gigawatt commercial system—about the same output as a typical nuclear power plant.” It will also rely on wireless power transfer based on microwaves whose wavelengths will range between 5 and 10 centimeters, perfect for transmission that will not be hindered by weather or cause damage to people or animals.

Another innovative feature of JAXA’s SPS (solar power system) will be constant power generation: two, free-flying reflective mirrors will “direct light onto two photovoltaic panels 24 hours a day.” On the ground, beams directed from above will reach a receiving site where where an array of rectannas will “convert the microwave power to DC power with an efficiency greater than 80 percent.

Below is a brief summary describing the process of JAXA’s solar power system:

The Japan Aerospace Exploration Agency is working on several models for solar-collecting satellites, which would fly in geosynchronous orbit 36 000 kilometers above their receiving stations. With the basic model [top left-hand side], the photovoltaic-topped panel’s efficiency would decrease as the world turned away from the sun. The advanced model [top right-hand side]would feature two mirrors to reflect sunlight onto two photovoltaic panels. This model would be more difficult to build, but it could generate electricity continuously.

In either model, the photovoltaic panels would generate DC current, which would be converted to microwaves aboard the satellite. The satellite’s many microwave-transmitting antenna panels would receive a pilot signal from the ground, allowing each transmitting panel to separately aim its piece of the microwave beam at the receiving station far below.

Once the microwave beam hits the receiving station, rectifying antennas would change the microwaves back to DC current. An on-site converter would change that current to AC power, which could be fed into the grid.



About Author

Kristian strives to enlighten and entertain readers. In addition to his teaching and editorial responsibilities, he is working on a science-fiction novel that promises not to include exoskeleton suits and anemic aliens floating in mysterious vats of green-tinted goop.

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