Harvesting energy from space might be a long way off, but there are many technologies that already exist to make this endeavor achievable. While we don't know the future of harvesting energy from space, it is stimulating to see such ideas.

Can We Harvest Energy from Space?

Len Calderone for | AltEnergyMag

There is abundant energy in space. Although most of deep space is cold and dark, space is flooded constantly by electromagnetic energy. All the stars in the universe produce energy and transmit that energy into space. Planets, asteroids and moons reflect that energy back. Because most of the objects in space are in motion, there is also kinetic energy in space.

Just to give you a perspective on the Sun’s energy—if you were to give each of the 7 billion people on earth a 60-watt light bulb, it would shine for that person’s entire lifetime. That’s like lighting 120 trillion 60-watt light bulbs and still having enough electricity in one hour of sunlight for all of those light bulbs to shine for 24 hours.

We largely depend on energy generated from fossil fuels. Fossil fuels come from living entities, which died, decomposed, and became assimilated into the earth’s geology. When fossil fuels are removed and combusted in the atmosphere, fossilized energy is released and put to work.

In addition to being inefficient, combusting fossil fuels for energy is also impractical, because burning them releases carbon into the atmosphere at a rate that disrupts ecological processes and damages the environment.

The world needs to find new sources of clean energy. Space is our new energy frontier.

Space-based solar power has had limitations in the past as it only works when the Sun is shining, but we will see this changing in the next few decades.

Even on cloudless days, the atmosphere itself absorbs some of the energy emitted by the Sun, cutting back the efficiency of solar energy. Even in the best of circumstances, Earth-bound solar panels are pointed away from the Sun during the night.

Scientists have come up with some plausible solution, including several proposals for making space-based solar panels a reality.

Most of these proposals call for a satillite equipped with an array of mirrors to reflect sunlight into a power-conversion device. The collected energy could then be released to Earth via a laser or microwave emitter.

This energy would not be restricted by clouds, the atmosphere, or the dark of night. Since the solar energy would be continuously absorbed, there would be no reason to store the energy.

One suggestion is to put self-replicating solar panels in space. These robots would build copies of themselves, autonomously, on the surface of the moon. Then, they would be placed into Earth's orbit, collect the sun's energy, and wirelessly beam it to the ground.

Sound crazy? The idea of space-based solar power actually goes back several decades during the 1970s oil crisis. Since then, the world has become anxious to solve climate change.  

It would be difficult to build the solar panels in earth orbit, but we could send self-replicating robots to the moon. There, the soft lunar regolith for aluminum, iron, and silicon can be turned into parts for the solar satellites.

Dr. David Criswell, of the University of Houston, while researching how best to utilize lunar materials, discovered that all the materials needed for manufacturing photovoltaic cells existed in lunar rocks and dust. This means that no bulk materials would need to be launched from Earth. Instead, we could send equipment to the moon to manufacture more equipment, such as excavator and ore processing robots and specific-task robots.

Building self-replicating robots won’t be easy. Design is the trick. First, the solar panels would need to be simplified as much as possible. Instead of having 1,000 different types of screws, just use say—five. Then, eliminate the different molds and use a 3D printer.

By using a limited number of robots, each one performing a simple task, such as producing screws or solar cells, it is possible to turn the moon into an autonomous solar cell factory. The problem is that self-replicating robots don’t yet exist.

Another advantage to space-based solar power is that the arrays could beam power down wherever receivers are located on Earth. This means that it would be possible to send electricity to remote villages in developing countries, or to disaster-stricken areas.

Receivers anchored on earth would be inexpensive and low tech. A community connecting to space power would place its receivers in a designated area, and the beam system would be issued programming to supply the new receiving zone with the energy for electricity.

The launch cost is one of the most daunting factors in the cost of space-based solar power. Unless the launch cost comes down, this technology will not compete with fossil fuels.

There are plans to use microwave transmitting satellites that will orbit Earth in a geostationary orbit (GEO), about 20,000 miles above Earth. These microwave-transmitting satellites will be massive, with solar reflectors spanning up to 2 miles. They will be capable of generating enough energy to power a major U.S. city.

The long wavelength of the microwave requires a long antenna, and allows power to be beamed through the Earth’s atmosphere in any weather at safe levels barely stronger than the sun at noon.

The downside is that such an array will cost many billions of dollars to launch, assemble and operate, as it will take dozens of launches to get everything into orbit. The receiving rectenna on earth would take up an area about 3 miles in diameter, which limits where the receivers can be positioned.

Another approach is the utilization of laser transmitting satellites. They will orbit in low Earth orbit (LEO) at about 250 miles above the Earth’s surface. At 22,000 pounds, this satellite will be much lighter than the microwave satellite and cheaper to launch, assemble and operate at about $500 million. This is due to the ability to launch the entire self-assembling satellite in a single rocket.

The laser transmitter will only be about 6 feet in diameter, instead of several miles. To make this possible, the satellite’s solar power beaming system employs a diode-pumped alkali laser. This laser is still under development, and will be about the size of a coffee table; yet be powerful enough to beam energy to Earth at an extremely high efficiency of over 50 percent.

There are still serious challenges, such as using high-powered lasers in space for the militarization of space. Since the satellite is smaller, there is a similarly lower capacity of about 1 to 10 megawatts of power per satellite. Therefore, this satellite would work better if it was part of a group of similar satellites, working together.

Harvesting energy from space might be a long way off, but there are many technologies that already exist to make this endeavor achievable. While we don't know the future of harvesting energy from space, it is stimulating to see such ideas.

 
 
The content & opinions in this article are the author’s and do not necessarily represent the views of AltEnergyMag
Len Calderone - Contributing Author

Len Calderone - Contributing Author

Len contributes to this publication on a regular basis. Past articles can be found with an Article Search and are listed below. He also writes short stories that always have a surprise ending. He has also written a book on wedding photography on a budget. These can be found at http://www.smashwords.com/profile/view/Megalen

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