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story:New science, new materials, new power

scene:New power

Electricity supply began in a small way, with generators housed in a shed or small brick building in any odd space or backyard. There might have been only a few dozen households connected and they would be using electricity solely for lighting. The supply was direct current (DC), which is a continuous flow of electric current. These generators were shut down overnight and the small amount of power required was provided from batteries charged up during the day.

The system only really worked when the demand was just for domestic lighting. As more users were connected more power was needed. Thomas Edison built the world's first generating stations for public supply in both London and New York during 1882. They supplied DC to areas of about one square mile. Soon there were many more such stations. Further demand came as households introduced electric heating and cooking. Factories started to use electric motors to drive machine tools and electric tramways were introduced.

Tesla's alternating current (AC) induction motor was simple in concept and could be made sufficiently small to power individual machines in factories. This demonstration model was made in 1888. picture zoom © Science & Society Picture Library

DC motors were simple to make and use. However, as the DC system expanded, with wires extending even further, the cost of lost electricity from the wires became a concern. Already some engineers were looking to a different type of electricity. Alternating current (AC) – current that surges rapidly back and forth in the circuit – was the rival. Nikola Tesla, a brilliant Serbian scientist who had emigrated to the United States, led the thinking. Ohm's Law states that for an electric wire carrying a given amount of power, the higher the voltage the lower the current and the lower the losses in the wire. A device known as a transformer was developed that could raise or lower the voltage of AC electricity economically and transmission losses compared to DC were significantly reduced.

Engineers such as George Westinghouse in the United States and Sebastian Z. de Ferranti in Britain argued strongly for an AC system that allowed for more efficient electricity transmission over longer distances. This brought into play the possibility of generation from more remote sources such as hydroelectric power and allowed generating stations to be built as large as possible where land was cheapest. Other engineers, such as Edison in the United States and Crompton in Britain, saw advantages in a decentralised network of small power stations using DC. This dispute, largely fought out in the technical papers, became known as the ‘battle of the systems'.

In the early twentieth century the advocates of high-voltage AC were the victors. Charles Parsons invented the steam turbine, ideally suited for powering high-speed alternators. In the years up to 1914 the great engineers Charles Merz and William McLellan established on Tyneside a network of large coal-burning steam-turbine power stations feeding into a high-voltage AC distribution system. Carville ‘A' power station near Newcastle upon Tyne, commissioned in 1904, set the pattern for power station layout and design for most of the twentieth century.

In just 25 years electricity generation went from small sheds in backyards to ‘cathedrals of power'.

Resource Descriptions

The earliest power stations were little more than sheds in backyards. This is Brighton Electric Light Station in 1887. Stationary steam engines drive tiny direct current (DC) generators by means of leather belts.
Tesla's alternating current (AC) induction motor was simple in concept and could be made sufficiently small to power individual machines in factories. This demonstration model was made in 1888.
Carville power station on Tyneside, 1904, designed by Charles Merz and William McLellan. High-speed Parsons steam turbines drive alternators.
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