"Who forgets his history is condemned to live it again".
It seems logical to develop an energetic mix that uses "alternative", renewable, and environmentally clean energy sources.There are many options: solar, windmills, biomass, etc. What are their chances? And what about their economic viability?
In my opinion the best option is solar.
Solar Energy
For sunny countries, like Brazil, it seems the best alternative. The solar energy hits a fotovoltaic cell that converts light into electricity (in direct current). The larger the number of cells the higher the power generated. The efficience of conversion of a fotovoltaic cell is around 20 up to 30% (a generator of hydropower has an 97% efficiency). However there are no moving parts in the cells, therefore their maintenance could be easier and cheaper. The cost of these cells are diminishing, and many communications stations (in faraway locations) use only solar energy.
But during some hours of the day there is no sunlight at all: is the time when we really need artificial light. In the northern hemisphere there is the cold winter too (and the need for warming). During cloudy days the output of fotovoltaic cells reduces dramatically...Many people say that this is the greatest problem of solar energy (or solar power).
The solar light is always (or almost always) present in space. A geosynchronous orbit satellite (36,000 km above the earth) is exposed to sunlight by 99% of the year. In 1964 Dr. Peter Glaser had the idea of the so-called "Solar Power Satellite-SPS": the satellite would be an immense set of fotovoltaics cells. The solar energy would be converted in electricity (in direct current), it would be sent to Earth by microwaves and converted again in power energy and delivered by the conventional power system. A satellite like that could generate almost 5,000 MW of power (like a big hydroeletric plant) without atmospheric pollution, without flooding forests or causing acid rain.During the 70's the United States government developed studies to produce the SPS, but the nuclear lobby (helped by the military) defeated the project. Today, Japan is trying to put in orbit a Solar Power Satellite in 2000.
For those who want to know more about the Solar Power Satellite there is a very interesting site about it:
SUNPOWER The Global Solution for the Coming Energy Crisis
It's a book written by Ralph Nansen. Mr Nansen participated in the Saturn/Appolo program, the Space Shuttle development, and led the Boeing team that developed the overall concept of solar power satellites under the auspices of the Department of Energy and NASA.