Harvesting Solar Energy from Outer Space

“Any intelligent civilization on any planet will eventually have to use the energy of its parent star, exclusively.”

The quote above was made by Carl Sagan, one of the most prominent astronomers and science popularizer of the late 20th century. The statement brings a sense of wonder, as it seems to predict that we would eventually abandon all other initial or base sources of energy that we have on this planet.

But even if this vision might still seem very far for our own civilization for now, we do have been active in developing solar energy technology for the last couple of decades. Does this mean that we are on our way to its fulfillment? Not quite. You see, our method of harnessing solar energy today isn’t exactly what’s in the context of this statement. The message implies that solar energy must be harnessed from a point far from the grounded bounds of our planet; it tells us that we should someday be able to harvest solar energy directly from outer space.

Why Gather Sunlight from Space?

Telescopes on Earth not capable of taking images of space as clear as what space telescopes can, primarily because the atmosphere causes light from space to become distorted and bent. The same thing is also true for ground-based solar arrays. Aside from the default reduced extraction efficiency of silicon-based PV cells, the amount of sunlight that it receives is greatly reduced by the atmosphere that envelops the Earth. But, just like in space telescopes, we can circumvent this problem and improve sunlight concentration efficiency by simply placing the solar arrays outside our atmosphere, in space.

There are also other projected benefits of space based solar power, which are enumerated as follows:

• No energy collection disruption (no night or day). Space based solar panels can work 24/7 non-stop.
• No meteorological phenomenon to be concerned of (no storms, typhoons and hurricanes).
• Totally and perfectly non-disruptive to the environment (as they are well outside of it)
• On-demand instant power redirection (if the solar array uses wireless energy transfer technology).

How Do We Distribute the Energy?

The issue of proper power transmission is always one of the most asked problems whenever the topic of space based power generation is discussed. Theoretically, there are two possible methods that we could use to distribute the energy that space based solar panels collect, and these are:

• Via Space Tether/Elevator – The method is very straightforward, simply send a long and thick cable from space down to earth and connect it to the grid. Of course, the material used for the cable must be tough enough to be able to resist the extreme tensional forces that would be caused by the Earth’s rotation. It is still very impractical as of this moment, although there are already a couple of candidate materials that could be theoretically used to fabricate the needed space tether.
• Via Wireless Energy Transfer – Considered as the best candidate method for properly transferring power generated by a space based solar array. The energy collected by the solar array is transformed in a powerful concentrated microwave, directing it into a collecting dish that would then transform the energy again into electricity. (Note that this is very different from the short range magnetic induction principle used by wireless chargers)

Technology Limitations and Other Implementation Difficulties

Of course, if it were that easy to deploy space based solar arrays then we would have seen it implemented already. There are currently so many technical challenges, as well as the addition of the usual economic hurdles that slows down the development of this concept. The most notable of these limitations is the fact that carrying anything into outer space is still very expensive ($10,000 worth of fuel and hardware per pound of payload). Building the space based solar array would definitely cost a lot, lot more compared to the already expensive ground-based solar array.

In addition, though clearly proven to be possible wireless energy transfer technology using microwaves is still far from being perfect. The receiving dish usually needs to be at least 10 times larger in diameter than the transmitting antenna. Heavy atmospheric phenomenon, such as precipitation build up could also lessen the transmission efficiency.

Despite the extreme challenges however, the dream of directly harnessing the energy or our parent star still lives on, as researchers and scientists continue to find a way to be able to set up space based solar arrays strategically and economically.

Photo credit: Some rights reserved by NASA via Wikimedia Commons

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Christian Crisostomo (250 Posts)

Christian Crisostomo is just your average tech geek that loves to see man's newest and most recent technological exploits. He holds great interest in the potentials of green technology, and is enthusiastic about the continuous development of environment-friendly alternative energy.

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