What Is Solar Power?
When it comes to solar energy, the working principles are pretty much straight forward. You install solar panels on your roof and then they convert the sunlight into electricity mostly during the daytime, although higher-performance systems can generate energy even during cloudy days or during the night.
You should keep in mind that although they will work under these more challenging conditions, the solar panels efficiency will drop, naturally. Furthermore, Earth’s atmosphere shields the planet from too much of the sun’s energy, some of the light being bounced back into space.
Now imagine we could put a solar panel into the Earth’s orbit at around 22,000 miles up. The concept of space-based solar power was theorised over 40 years ago by the renowned scientist doctor Peter Glaser.
After his discovery and in response to the periodical energy crises, the idea has been followed up once again by the U.S. Department of Energy, NASA, and also major aerospace companies and countries such as Japan and India. T
he research studies that followed have concluded there is no technological barrier to start implementing space-based solar power (SBSP). The major impediment has been identified as being economics, due to the fact that it would be a challenge to provide SBSP at a competitive price.
Solar power satellites would use a large amount of photovoltaic panels assembled in orbit, which use a low power radio waves transmitter to send solar energy to huge receiving antennas on Earth. The resulting sun power can both supplement or even substitute conventional electricity sources. Welcoming news have already started coming in from this industry with data revealing that several technologies required to build a working SBSP satellite already exist and undergo continuous development. Also, some of the component technology is put to good use in a variety of sectors.
Paul Jaffe, spacecraft engineer at the U.S. Naval Research Laboratory, declared that if there are solar panels in space, they are going to be illuminated 24 hours a day, seven days a week, 99% of the year. Due to the fact that Earth’s axis of rotation is tilted, the solar satellite could pick up sunlight almost all the time. Jaffe continues by explaining that individual space-based solar arrays would be able to produce 250 megawatts, and go up to 5 gigawatts of energy.
We must take into consideration that the sun is a continuously renewable resource which means that the total amount of power that could be produced is close to infinite. As an example, Jaffe has given New York City, which needs around 20 gigawatts of power. By his calculations, the system required would consist of four arrays, each providing 5 gigawatts, thus being able to power the entire city.
The only concern here would be the costs of building a space-based solar array, many estimating it in the region of hundreds of millions of dollars. The plus side here would be that once the system would be manufactured, economies of scale could help make production of multiple arrays much cheaper.
Another avid supporter of this technology is Ralph Nansen from the US-based advocacy group Solar High. He has stated that space-based solar power will become the ultimate energy source for the world and eventually it’s going to replace almost everything. In his opinion there aren’t any doubts that within the next 100 years, Earth will get most of its power from space. The only issue here is when this is going to happen.
Nansen suggested the US government to start investing in SBSP research and development rather soon. The USA should start building solar farms in the geostationary orbit 35,800km (22,000 miles) above Earth’s surface. At that altitude, the sunlight has an intensity of 1,347 watts per metre squared, which means 30% more intense than on the ground, thus translating into a greater electricity production. Nansen urges the US to act on this because he believes that whoever develops SBSP first, will have a monopoly position in the world economy, just like England did during the industrial revolution because of coal.
Possible SBSP Systems
As mentioned above, the solar energy that is available in space is far greater than what we use on Earth today. Given the sun’s lifetime of an estimated 4-5 billion years, makes space solar power a strong candidate for a long-term energy solution.
Because the Earth receives only one part of the 2.3 billion of the sun’s output, space-based solar power is by far the biggest potential energy resource available. Solar energy is constantly being used on nearly all spacecrafts nowadays, but using this technology on a larger scale, combined with proven wireless power transmission can supply nearly all the electrical needs of our planet.
Instead of hooking a very long cable 5 km upwards, most designs foresee wireless transfers of energy through a concentrated microwave or laser beam to a huge receiving antenna (rectenna) spread over several kilometres on Earth.
There are a lot of other technologies and infrastructures required to make space solar power feasible such as:
- Low-cost, environmentally-friendly launch vehicles - Current vehicles are very expensive and pose a real threat to the atmosphere. Less expensive and cleaner launch vehicles are needed.
- Power transmission - Certain effort is required to assess how to best transmit power from satellites to the Earth’s surface with minimum impact on the environment.
- Large scale in-orbit construction and operations - In order to gather as much energy as possible, solar power satellites must be large, larger even than the ones at the International Space Station (ISS). An advantage would be that these satellites will be simpler than the ISS due to the fact that they consist of many identical parts.
Although a great deal of work is required in order to bring these technologies to practical fruition, they are reasonably near-term and have numerous attractive approaches. Space-based solar power can solve our energy problems for a long time. The sooner we start, the sooner we will reach the “long term”.
That being said, given the cost of solar panels currently, this kind of project will be very expensive.
One last example where SBSP could prove influential is shifting away from fossil fuels when it comes to our transportation systems. Although electricity powers very few vehicles today, hybrids will start evolving into plug-in hybrids which can use electricity straight from the grid.
This can be possible because of the continuous development of batteries, supercapacitors, and fuel cells, the only condition is that we can generate tremendous amounts of electrical energy. Space solar power can provide the necessary clean power to switch to a complete electric transportation system.
Although there are other renewable energy sources that can produce decent amounts of energy, space solar power has a plethora advantages over them.