Solar.
Talk of an impending crisis for humanity energy and mineral resources has long been commonplace. However, all estimates in this regard based on the projected slowing of world population growth, though some unknown reason (although a lot of different options for reducing the birth rate).
If extraordinary measures against the rapid multiplication of mankind will not be accepted, then, according to the United Nation to the top XXII century (after 2100) the Earth's population will reach 11 5 billion people (today - less than half)!
Assume that the consumption of the earth's resources at that time will be equal to the current American (apparently it's not so unbelievable after 100 years ') In this case, even the immediate future of our descendants emerges simply appalling' If the current rate of oil consumption in its known reserves, according to Scientists will last for 40 years, then the "American tempo after a century - only 7 years of coal. Believe that's enough for 220 years. And 100 years later it was sufficient for only 30 years' Copper have for 40 years. But after 100 years - 4 years' Zinc - instead of 20 years, called the year etc... Etc... Do not say anything about food and fresh water.
What to do? Only one way out - to look for new, high-energy sources not dependent on our planetary resources. Importantly, clean. You can certainly count on the fact that for 100 years people will learn something but seems now is not too early to think about it.
Nuclear and thermonuclear power engineering course would be very good if it were not for co-existence, such as Chernobyl , and if people learned to control the fusion reaction (which for many years did not get). It is hoped to help the cosmos.
This refers to the endless sea of solar energy is poured into cosmic-the space that could be in principle as a focus and send to Earth According to a preliminary drafts of this task could be carried out by satellites carry solar panels similar to those used today on Russia's space station world.
The idea of satellite with solar panels is not new it was made in 1968 and patented in 1973, however, elaboration of the project completed in the late 70's - early 80-ies have shown clear economic unreasonableness of its implementation but in subsequent years by increasing the efficiency of solar batteries and opportunity, relatively cheap to start with the idea of Russia's missiles gained economic sense
Of course the battery on the satellites must be gigantic proportions is now the largest construction in orbit - space station Mir She has a length of 24 meters and weight over 100 tons of Sputnik also able to concentrate on their batteries and send it to the ground is enough energy to heat 5 million of household electric ovens (a major nuclear power plant warms only 1 million stoves! must have a size of about 10 kilometers length C) and 3 km width This design even made of ultra light materials will weigh hundreds of tons of 'Run its course to orbit would be very difficult
The principle of operation of the satellite with solar panels is to ensure that sunlight falls on a flat surface of the battery composed of semiconductor elements and semiconductors, an electric current flowing from the illuminated side panels on the shading in the electrical current is converted from 5 to 10 percent of solar energy is of course little is encouraging new compound semiconductors of gallium arsenide, and that this increases the pro cents to 40.
Now both convey the electricity to Earth? It is proposed to use microwave radiation to all known from domestic microwave ovens microwaves - is electromagnetic radiation like visible light but with a much longer wavelength - from one millimeter to one meter Microwave radiation passes through Earth's atmosphere with minimal loss of energy - in good weather, lost only 2 per cent.
This radiation was first used in radar during World War II in the postwar decades, devices convert electric current into microwave radiation greatly improved experimental system today is already transforming the current in the microwaves that are received from the radiating antenna to the reception and it once again become an electric current is then stored 60 percent of energy.
The system of satellites with solar panels would have several hundred generators of microwave radiation "They will work on the orbiting antenna diameter of 1 kilometer from the radiation she would go to a ground antenna size is also considerable - 10 to 13 kilometers . There is a project to erect a structure on a floating basis in the ocean heat from it will heat the water and it will be possible to breed the fish under this structure, in quantities up to 5 percent of all fish consumed in the United States.
Microwave radiation from outer space orbit will be highly targeted so that it does not present a health hazard even if all the power of the United States is covered by satellites with solar panels microwave radiation does not go beyond the current allowable Such a system of specialists' calculations, you may be in space and approximately 2030.
In addition to the above may be added that the satellite with solar panels can be placed in geostationary orbit (so that it remains permanently on the same place on Earth) to an altitude of 36 kilometers This satellite will be solar energy is practically year-round and direct it on the same ground receiving antenna Hence the electric current is going to the consumers of such complexes "Space-Earth' can be any number.