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Power Electronics

What Will This Millennium Bring?

Now that we're really at the beginning of the millennium in 2001, this millennium is certain to produce changes in the world of power electronics. A glimpse of some of the far out things projected for the future indicate what may occur. One of the more intriguing concepts for the future is "nanotechnology," the science of small things. Using nanotechnology, some companies are already working on single-electron transistors that can be created with current lithographic techniques. This technology might make it possible to develop new types of semiconductors by building them with individual atoms and molecules. This could result in devices that operate efficiently at very low voltages or at very high voltages and current.

Although some scientists claim nanotechnology isn't a sure thing, others suggest it will be inevitable in this millennium. According to the Web site, nanotechnology examines the world at a millionth of meter and manipulates our universe at a molecular or atomic perspective. Some scientists believe that the worlds of medicine, computers, biotechnologies and eventually all manufacturing will never be approached in the same way again.

There are two approaches: One is to learn how to manipulate material at the molecular and atomic level, which is considered by most researchers to be more probable. The second approach, considered the greater challenge, is to develop self-replicating nano machines to perform the work, but many will be needed.

Going from the nano to the giga world is the generation of power from space. Estimates indicate the world's electricity capacity will require about 10,000 gigawatts in the next century - which is about 10 times today's capacity. One approach to obtain that capacity is through solar energy from photovoltaic cells in space. Several different methods are possible, but the one that has involved the most effort so far is the use of microwaves to send the solar-generated power to Earth.

The space around Earth is filled with intense sunlight, undiffused by the atmosphere. It is an inexhaustible supply of energy that can be converted to electricity using semiconductors. In addition, it could do it without the need for any kind of fuel, and without producing any waste product. This approach needs sun collectors that are thousands of square kilometers.

In 1968, Peter Glaser described how the collected power of the sun could be used with photovoltaics in space and the resulting electricity could be transmitted to Earth as microwaves. The sun is intense, it shines 24 hours a day, and the power could be delivered anywhere - even under cloudy conditions. In the 1970s, the U.S. Department of Energy (DOE) studied this Solar Power Satellites (SPS) technique and designed a "Reference System" consisting of a 5210 km rectangular satellite using solar cells to generate dc and transmit it to Earth on 2.45 GHz microwave beams.

DOE concluded that SPS might be feasible, though on a scale a million times larger. However, they concluded it was much too expensive. Interest in the SPS is rekindled, now that there's need for large-scale, environmentally clean energy sources. The only question is who will cover its expense.

These ideas seem pretty far out, but time will tell.

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