AN INTRODUCTION TO ELECTRICITY GENERATION:EVOLUTION OF ELECTRICITY-GENERATING TECHNOLOGIES

EVOLUTION OF ELECTRICITY-GENERATING TECHNOLOGIES

The development of the electric power industry can be dated from the develop- ment of the dynamo or alternator. This allowed rotating machinery to be used to generate electricity. There were two sorts of generator used in the industry initially: the dynamo, which produced direct current, and the alternator, which produced and alternating current (the word “generator” can be used for both but it has become associated with the latter). The first practical dynamo was devel- oped independently by Werner Siemens and Charles Wheatstone in 1867 and it was through the dynamo that the electric motor was discovered. However, the dynamo became displaced in most uses by the alternator, because alternating current distribution of power proved more efficient based on the technologies available at the time.

The first recorded power station appears to have been built in the Bavarian town of Ettal in 1878. This station used a steam engine to drive 24 dynamos, with the electricity used to provide lighting for a grotto in the gardens of the Linderhof Palace. Meanwhile, the first public power station was built in 1881 in Godalming in Surrey, United Kingdom. This station used two water- wheels to drive an alternator and provided power to two circuits—one at 250 V supplying power to 7 arc lights, and the second at 40 V providing power for 35 incandescent lamps.

As this brief historical snapshot demonstrates, both hydropower and steam power were already being used in the early days of the industry. Steam power was at this stage based on reciprocating steam engines, similar in concept to a piston engine. These engines were not ideal for the purpose because they could not easily develop the high rotational speeds needed to drive a generator effectively. This difficulty was eventually overcome with the invention of the steam turbine by Sir Charles Parsons in 1884. Fuel for these steam plants was usually coal, used to raise steam in a boiler.

Hydropower was an established source of mechanical power long before the steam engine was invented, so it was natural that it should provide one of the first engines used to drive dynamos and alternators. Water wheels were not the most efficient way of harnessing the power in flowing water but new turbine designs soon evolved. Much of the work on the main turbine types that are used today to capture power from flowing water—designs such as the Pelton and Francis turbines—was carried out in the second half of the 19th century.

By the beginning of the 20th century both the spark-ignition engine and the diesel engine had been developed. These too could be used to make electricity. Before World War II, work also began on the use of wind power as a way of generating power. Even so, steam turbine power stations burning coal, and sometimes oil or gas, together with hydropower stations provided the bulk of the global power generation capacity until the beginning of the 1960s.

In the 1950s the age of nuclear power was born. Once the principles were established, construction of nuclear power stations accelerated. Here, it was widely believed, was a modern source of energy for the modern age—it was cheap, clean, and technically exciting. Nuclear power continued to expand rap- idly in the United States up to the late 1970s. In other parts of the world, uptake was less rapid but in western Europe, Great Britain, France, and Germany invested heavily, and in Scandinavia, Sweden developed a significant fleet of plants. In the Far East, Japan, Taiwan, and South Korea worked more slowly. Russia developed its own plants, which were used widely in eastern Europe, and India and China each began a nuclear program.

From the end of the 1970s the once-lustrous nuclear industry began to tarnish. Since then its progress has slowed dramatically, particularly in the west.

In Asia, however, the dream remains alive, although Japan’s nuclear industry has been seriously damaged by the Fukushima disaster in 2011, the repercussions of which have reverberated around the world.

At the beginning of the same decade that saw nuclear fortunes turn, in 1973 to be precise, the Arab–Israeli war caused a major upheaval in world oil prices. These rose dramatically. By then oil had also become a major fuel for power stations. Countries that were burning it extensively began to seek new ways of generating electricity, and interest in renewable energy sources began to take off while the use of oil for power generation began to wane in all but the oil- producing countries of the Middle East.

The stimulus of rising oil prices led to the investigation of a wide variety of different alternative energy technologies, such as wave power, hot-rock geo- thermal power, and the use of ethanol derived from crops instead of petrol or oil. However, the main winners were solar power and wind power. Develop- ment took a long time, but by the end of the century solar and wind technologies had reached the stage where they were both technically and economically via- ble. By the end of the first decade of the 21st century both were growing strongly in overall installed capacity and, with prices coming down, this trend appears set to continue well into the century.

One further legacy of the early 1970s that began to be felt in the electricity industry during the 1980s was a widespread concern for the environment. This forced the industry to implement wide-ranging measures to reduce environmental emissions from fossil fuel–fired power plants. Other power generation technologies, such as hydropower, were affected too as their impact on local environments and people were reassessed.

The gas turbine began to make a major impact during the 1980s as an engine for power stations. The machine was perfected during and after World War II as an aviation power unit but soon transferred to the power industry for use in power plants supplying peak demand. During the 1980s the first large base-load power stations using both gas turbines and steam turbines in a configuration known as the combined cycle plant were built. This configuration has become the main source of new base-load capacity in many countries where natural gas is readily available.

The first years of the 21st century have seen increased emphasis on new and renewable sources of electricity. Fuel cells, a technically advanced but expensive source of electricity, are approaching commercial viability. There is renewed interest in deriving energy from ocean waves and currents, and from the heat in tropical seas. Offshore wind farms have started to multiply around the shores of Europe.

The story of power generation across the 21st century is likely to be the con- test between these new technologies and the old combustion technologies for dominance within the power generation industry. And while they battle for supremacy there remains one technology—nuclear fusion—that has yet to prove itself but just might sweep the board.

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