Sea levels are rising, glaciers
are melting, and extreme weather is becoming the norm. The negative
effects of man-made climate change are here to stay — and they're
getting worse.
One of the major culprits is
atmospheric carbon dioxide from the burning of fossil fuels like oil and
coal. Luckily for the Earth, the world's supply of fossil fuels is
limited. And for the past several decades, researchers have been looking
for renewable energy resources to provide power to everyone without
poisoning the Earth.
Some scientists think humans
could be getting clean power collected from solar panels in space and
beamed back down to Earth in our lifetime, and some industry startups
like California-based Solaren are predicting it will be a reality by the
end of the decade. Not only would the energy source be continuous, but
it would also be clean and unlimited (that is, until the sun explodes).
This idea may sound like science
fiction, and at one time it was. The concept originated in a short
story by sci-fi author Isaac Asimov. Asimov's 1941 story envisions a
world where the Earth is powered by a beam of light that draws its
energy directly from the sun.
The beam is controlled by two
engineers in a space station. As the story opens, they are training a
robot to take over the operation. The human explains to the robot: "Our
beams feed these worlds energy drawn from one of those huge incandescent
globes that happens to be near us. We call that globe the Sun ... "
The thought of harnessing the power of the sun with giant solar
collectors in space was pure fiction 75 years ago. But now, the day of
space-based solar power may not be so far away.Terrestrial Solar Power Versus Space-Based Solar Power
We typically think of a solar panel on the roof of
someone's house converting sunlight into energy during the daytime.
Sounds great, but Earth-based solar panels have their drawbacks. They
don't work at night or if the sky is too cloudy. Plus, our atmosphere
shields the Earth's surface from much of the sun's energy — bouncing
some of the light back into space.
Now imagine if we could put a solar panel in Earth orbit — around 22,000 miles up.
"If you put the solar
panel in space, it's going to be illuminated 24 hours a day, seven days
a week, 99% of the year," Paul Jaffe, a spacecraft engineer at the U.S.
Naval Research Laboratory, told Business Insider. Because the Earth's
axis of rotation is tilted, Jaffe explains that "even on the night side
of the Earth [the satellite could] be in sunlight almost all the time."
Jaffe predicts that
individual space-based solar arrays would be able to produce from 250
megawatts to 5 gigawatts of energy. But since the sun is a continuous,
renewable resource the "total amount of power that could be produced is
effectively infinite," he says. Take New York City, for example, which
requires 20 gigawatts of power. By Jaffe's calculation, as few as four
arrays [see picture below] — if each provided 5 gigawatts — would be
able to power the entire city. The cost to build one space-based solar
array is somewhat of an unknown but would likely be hundreds of millions
of dollars. But once the first one is manufactured, there would
probably be certain economies of scale that could make production of
multiple arrays cheaper.
The energy crises of the 1970s propelled the government to
look into alternative energy sources as it started to become clear that
oil was a limited resource and that its supply cold be subject to the
whims of international politics. According to Jaffe, the conclusion at
the time by NASA and the Department of Energy regarding space-based
solar power technology was that it could be possible, but it would be
very, very expensive.
In the intervening years, many nations studied space-based
solar power, including Japan, China, and several European nations. "A
lot of people have looked at this, but there has been a lot less actual
development of hardware and the component technologies," said Jaffe.
In 2009, Secretary of the Navy Ray Mabus announced a
series of goals to reduce the Navy's dependence on foreign oil and to
increase its use of alternative energy. That same year, Jaffe received
funding from the U.S. Naval Research Laboratory to improve the
technology that would convert the solar energy collected in space into a
different form of energy that could be transferred to Earth.
How The Technology Works
While the technology needs some improvement, the basic idea is pretty
clear: The sun sends out photons, energetic packets of light, in every
direction. A regular solar panel converts those photons into electrons
of direct current electricity. Then, in order to power an electronic
device plugged into a wall outlet, the direct current is transformed
into an alternating current and sent through the power grid.In space, the big issue is how we would get that power to the grid.
With the solar farm in space, researchers needed to figure out the most efficient way to transfer the direct current from the solar reflectors to Earth. The answer: electromagnetic waves, like those used to transmit radio frequencies or heat up your food in the microwave.
"People might not associate radio waves with carrying energy because they think of them for communications, like radio, TV, or cellphones. They don't think about them as carrying usable amounts of power," Jaffe said in a statement. Though we do know that microwaves (another subset of electromagnetic waves) carry power — their energy heats up our food!
Jaffe calls the technology he is
working on the "sandwich" module. The image below shows mirror-like
solar reflectors concentrating the sun's photons onto the array of
sandwich modules. The top of the sandwich module array receives the
solar energy. Antennas on the bottom side beam the radio waves to Earth.
Business Insider/ Mike Nudelman
The image above isn't to scale. The sandwich modules would be about 10
feet long on a side and about 80,000 would be needed. The array of
sandwich modules would be about the length of nine football fields, or
more than 1/2 a mile long. This is about nine times bigger than the
International Space Station.
Dr. Paul Jaffe holds a module he designed for space solar power in front of the customized vacuum chamber used to test it.
Back on Earth, the
energy-containing radio frequencies from the space-based solar panels
would be received by a special antenna known as a "rectenna," which
could be as big as six miles in diameter.
"It would look like a field full
of wires sticking up. The rectenna elements receive incoming radio
waves and convert it back from that high frequency radio wave into
electricity," Jaffe said.
The power beam of radio waves
could be sent to a wide variety of locations on Earth, because the
direction of the beam can be changed by a method called "retrodirective
beam steering." According to Jaffe, "This works by sending up a small
'pilot signal' from the center of the ground receiving station. The
satellite sees this signal and adjusts its transmitter to send the radio
waves to the ground station." For example, the same beam would be able
to provide power to Seattle and redirected to provide power to Rio de
Janeiro in Brazil.
An advantage for the military,
as well as civilians, would be that they could build receivers at remote
operating bases and locations where it is logistically difficult and
incredible costly to deliver diesel fuel.
A Giant Beam Of Energy From Space
A giant beam of radio
waves coming down from space to Earth may sound a little scary and
dangerous to most people, like something an alien ship would use to
explode a city. But really, you wouldn't even be able to see the radio
beam with the naked eye — radio signals are flowing around us at all
times.
Though these radio signals contain more energy than an AM
or FM signal you'd pick up in your car radio, the power density of the
signal would still be quite low and wouldn't threaten people, airplanes,
or birds that would fly through it. Of course, the technology hasn't
actually been tested outside of the laboratory yet, so there's no
real-world proof the installation would be problem-free.
The biggest impediment so far to space-based solar power
isn't safety or regulation or design: It's cost. And this problem
affects all parties involved, whether government-, private-, or
commercial-funded research.
It's hard to say what exactly the full-scale
implementation of a space-based solar power system would cost, but it
would likely be hundreds of millions of dollars. There is a limit to how
big of an object can be launched into space, and strapping the
components to rockets doesn't come cheaply. For example, the
International Space Station had to be built in space part by part because there wasn't a rocket big enough or strong enough to launch the completed apparatus into space.
Jaffe's research was funded by the Office of Naval
Research, and he had funding to produce prototypes of one section: the
sandwich module, but not to see the project to completion. He also
tested the modules in space-like conditions to ensure they could
withstand (and continue to work in) the incredible heat of the sun in
space, which hadn't been done before. "The work that we did demonstrates
the state of the art and suggests the path forward," said Jaffe.
He is trying to find sponsors to secure funding for continuation of
his project. But he stressed that it is hard to sell long-term energy
projects, especially when he can't show people the technology in action,
aside from prototypes. He thinks the real motivator will be foreign
competition, like in the 1950s when the Russians developed Sputnik and
launched the U.S. into the space race. This time it's likely that the
Japanese government may launch the technology first.The Path Forward
But even without government funding, small startups like
California-based Solaren are looking to make space-based solar power a
reality in the next few years. Gary Spirnak, CEO of Solaren, had a long
career in space engineering for both the government and private
industry. He had watched for years as government funding for space-based
solar power waxed and waned and private industry seemed to take little
interest.
Spirnak told Business Insider
that he saw a "system problem" he thought he could engineer his way out
of by building lighter versions of the prototypes already being tested.
And, in 2009, he convinced Pacific Gas & Electric
that his design (which is different from Jaffe's explained above but
based on similar concepts) for space-based solar power was viable, and
they awarded him the "first power purchase agreement in the world for
space solar power," meaning that the electricity company would buy the
solar energy that he was collecting from space and deliver it to some of
their California customers.
The original terms of the
contract were to provide energy from space starting in 2016. The start
date has now been pushed back because of funding issues, but they are
just closing another round of $35 million to $50 million, and Spirnak
says he expects it to be functioning by the end of the decade.
