According to various popular scientific websites, it is the solution for the world energy shortage: solar panels in space. What are the pros and cons of using satellites that collect solar energy in space? An analysis.
What will the solar power plants look like in practice?
A solar power plant floats above the earth to catch the sunlight in space. Because unfortunately no space elevator exists, the collected solar energy must be sent wirelessly to earth and converted there into electricity. In various plans, microwaves (known from the magnetron), a kind of radio waves, are proposed for this purpose.
In the proposed configuration, the solar panels will be placed in geostationary orbit (GEO) around the Earth. This altitude, at around 35 786 km above sea level, has the advantage that the satellite will always hover over the same spot. GEO is of course a popular place for communication satellites, for example; at the moment many satellites are already floating in GEO.
What are the advantages of a solar power plant in space?
- The satellite receives sunlight almost 24 hours a day, so that the solar plant can supply power almost continuously, even if solar panels on the earth's surface end up in the night zone. The satellite can maneuver in such a way that the solar panel is always perpendicular to the sun and thus achieves maximum efficiency. Because of this effect alone, a solar panel in space delivers more than twice as much power as a solar panel on the equator, the most favorable location, geographically.
- Atmospheric gases do not absorb solar radiation. It is estimated that this yields about 44% capital gains. This advantage is even greater compared to non-desert areas where it is often cloudy.
- In the absence of an atmosphere, there are no problems due to bad weather conditions.
- No land is needed to place the solar panels.
- The wireless transmission allows the solar plant to send energy to the points where there is a shortage of electricity, for example in parts of the world where it is evening or winter.
- Each country can place its own solar plant in orbit around the earth. As a result, the country is no longer dependent on other countries. This is a major advantage for Japan, for example.
.. and the cons?
- Space is an extremely grueling environment. Cosmic particles move through space at a percentage of the speed of light and leave little harm to solar panels. In practice, this halves their lifespan.
- Countless micrometeorites move through the universe at tens of kilometers per second. These also damage a solar panel.
- A heavy solar flare can roast insufficiently protected satellites.
- The necessary power (fifteen to fifty percent) is lost when the solar energy is sent to Earth in the form of microwaves.
- Launch costs are high. To escape the Earth's gravitational field, a minimum of 17.4 kWh of energy per kg mass is required. Added to this is the hefty price for the rocket and the fact that a rocket is far from efficient.
- Repairs require an expensive manned flight, although you could in principle solve this by deploying remote-controlled robots.
- A receiving station for the radiation must be set up. This must be set up sufficiently far from civilization and have an enormous diameter: around 10 km in diameter. In comparison, such an area, when covered with solar panels in the Sahara, is already large enough to provide one third of the Netherlands with energy. We also do not know whether this microwave radiation does not have harmful biological consequences. Experiments in Wageningen have shown that at least the high-frequency radiation from the WiFi router possible unpleasant consequences for plants has.
- If a concentrated bundle is chosen, for example on an area of several hectares, then safety risks arise. If a hacker decides to aim the bundle at Goldman Sachs headquarters for fun, or worse, elsewhere, the consequences are similar to being baked in a microwave oven.
The French aerospace company Astrium developed this concept.
To do or not to do?
In any case, the current proposed form is nonsensical. There will either have to be a safe, but enormously large construction for safe power transmission, or an unsafe, concentrated directional antenna. It is more sensible to install solar power stations floating on the sea or in the desert (plus on the roofs of houses and businesses). This is much cheaper.
If the transmission problem is solved with the advent of a space elevator, it will be interesting. Enormous amounts of solar panels could then be connected to the space elevator - carbon nanofibres conduct electricity reasonably well.
More sensible is the idea of extracting minerals from the moon or asteroids, powered by solar energy. The molten ores can be launched on a maglev rail towards Earth or, even smarter, used on the moon to fabricate spacecraft that can colonize the rest of the solar system. Very energy-consuming manufacturing processes - such as the manufacture of carbon nanofibers and artificial diamonds - can also be carried out in space, using solar energy.