Energy by Vaclav Smil

Author:Vaclav Smil [Smil, Vaclav]
Language: eng
Format: epub
Publisher: Oneworld Publications

Figure 19 James Watt’s steam engine (left) and detail of separate condenser (right)

The typical power of Watt’s engines was about twenty-five horsepower (about 20 kW); the largest engines, built in partner­ship with Matthew Boulton, were five times more powerful, matching the performance of the largest contemporary water­wheels. These more (up to five per cent) efficient engines were not only used in coal mines to pump water and operate winding and ventilating machinery, but were also gradually adopted by a growing number of industries whose locations were previously restricted by the availability of flowing water or steady winds. Iron making was a notable beneficiary, where steam engines were used to operate blast furnace bellows. In manufacturing, a single engine in a large workshop or a factory often powered a rotating axle from which a number of belts transmitted power to individual (weaving, grinding, boring, polishing, etc.) machines.

The inherently large size of steam engines was not a major consideration in stationary industrial applications, but this had to be reduced (that is, their operating pressure had to be increased) for mobile use. Because Watt refused to experiment with high-pressure engines, their development had to wait until after his renewed patent expired in 1800: the celebrated inventor thus delayed the machine’s progress. Soon after its expiration Richard Trevithick (1771–1833) in England (1804) and Oliver Evans (1755–1819) in the USA (1805) built high-pressure boilers that were first tested on steam boats. The concurrent development of steamships and steam-powered railways soon led to successful commercial uses and, a mere generation later, to an enormous extension of these modes of transport. By the 1830s, the proven paddle-wheel designs of river boats were replicated in larger ocean-crossing ships. The first reliable screw propeller was introduced in 1838, the same year as the first westernward crossing of the Atlantic under steam power.

Large steamships then rapidly replaced unreliable sailing ships, first on the North Atlantic route (where they eventually cut travel time from more than two weeks to less than six days) and then on other inter-continental runs. Larger engines and, after 1877, the use of steel in hull construction led to luxurious passen­ger liners. Steamships carried most of the fifty million emigrants who left Europe between 1850 and 1914, while steam-powered naval vessels provided new means for the projection of Europe’s colonial power. Steam engines transformed land transport in a similarly rapid and radical fashion. The first public railway (from Liverpool to Manchester) opened in 1830 but its first locomotive (George Stephenson’s (1781–1848) famous Rocket) soon appeared laughably slow. By 1850, the fastest locomotives travelled at over 100 km/h; the relentless extension of railways soon spanned Europe and North America (but the completion of the trans-Siberian railway had to wait until 1904). A profusion of new locomotive designs brought ever more efficient and faster machines. By the end of the nineteenth century, speeds over 100 km/h were common and locomotive engines had efficiencies of more than twelve per cent.

Besides providing coke, heat, and stationary and mobile power, coal also became a leading source of urban light, as its gasification produced low-energy coal, or town, gas.

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