In what might seem to be an ironic footnote to the history of energy, mining engineer Karl Twitchell, in 1931, put up a 16-foot windmill in Jiddah to help pump water. It raised, Twitchell says in his book Saudi Arabia, "an average of 40 gallons a minute."
Today, however, Twitchell's windmill no longer seems even slightly odd, because the windmill, as a source of energy, is re-entering history.
Last autumn, for example, the government of Quebec announced it would build an experimental $17.5 -million, 327-foot-high windmill to generate electricity - a recognition of the continuing energy crisis. And Quebec's windmill is only one of many that governments, companies and individuals were constructing in late 1979.
In Yorkshire, England, Sir Henry Lawson - Tancred of Aldborough Manor has already built two experimental windmills and plans, eventually, to manufacture and sell them.
Standing on a rise amid the rolling farmland of Yorkshire, Sir Henry's windmill - or, more accurately, wind turbine—is distinctly different from the windmills of the past. Its blades - 56 feet in diameter - are bigger, its ball bearings are more efficient and its gearing and alternator systems are adjusted to permit unattended, wholly automatic operation.
The blades, moreover, unlike the windmills of Holland in other days, are exceptionally light; they are built of hollow fibreglass panels affixed to a steel frame. At speeds of about 30 miles per hour, they can generate an estimated 100 kilowatts - enough electricity for 25 average American homes.
Because the problems of storing power have yet to be solved, Sir Henry's wind turbines - called "Aldborough aerogenerators" - may have a limited market; batteries would cost nearly as much as the turbines. But in some areas of Britain, such as the Hebrides, Wales and the west coast of Scotland, the wind is so strong and constant that wind turbines could prove invaluable, says Rupert Nichols, an aide to Sir Henry. Because the turbine is almost wholly automatic - a satellite windmill on the top of the tower, for example, turns the main blades into the wind automatically - and because it can be shut down in high winds, the turbines could provide small communities and farms with electricity as efficiently as central urban generators do now.
Another, much bigger, experiment is underway in Boone, North Carolina, where the Department of Energy and NASA have built the world's largest wind turbine: a $21-million giant with blades 200 feet in diameter. This turbine, part of the U.S. government's experiments with wind power, can generate two megawatts of electricity - two million watts - from winds of 25 mph, enough to service 500 homes.
Despite the differences in size and output, however, the purpose of the windmills in Quebec, Yorkshire and Boone is the same: to produce power for the present with the technology of the past.
Until the energy crisis reminded the industrialized world that petroleum reserves were not inexhaustible, windmills, to most people, were quaint relics of the past-charming structures that were particularly popular in The Netherlands or associated with the story of the gallant Don Quixote - who mistook windmills for giants, charged one with his lance and was knocked from his horse by one of the sails. Yet windmills, when Cervantes wrote in the 16th century, were a common feature of Renaissance technology in Europe - a technology which would eventually culminate in the Industrial Revolution.
The Industrial Revolution, of course, had to await the invention of the steam engine. In the meantime man's sources of power were limited to his own muscles, draft animals, the watermill and - from the 12th century on - the windmill.
The most ancient of these sources was the watermill - it was known to the Romans. But the windmill did not appear in Europe until the beginning of the 12th century, when it was used for grinding wheat in Normandy. Thereafter windmills spread rapidly throughout Europe and in the early 15th century the Dutch began to use them to pump water out of the marshes and reclaim land from the sea.
Oddly, the windmill, like the tulip - both of which Holland made famous - came from the East: the tulip in the 16th century from Turkey (See Aramco World, May-June 1977), and the windmill via a longer and more circuitous route.
The first known reference to windmills is in a Hindu book written about 400 B.C., and Hero of Alexandria, a Greek inventor of the third century B.C., once described a small wind-driven "motor" which he had designed to provide air pressure for an organ. There are also references, in A.D. 400, to wind-driven prayer wheels in central Asia, where they are still used today. But Hero's "motor" was really just a toy and although the prayer wheels did embody the principle of the windmill, they never seem to have been developed beyond their initial function. Like other innovations in technology, the windmill was brought to the West by the Islamic world.
The first definite reference to the use of the windmill came early in the Islamic period. 'Umar, the second caliph, had heard that a Persian in his entourage had boasted of being able to construct a wind-driven mill. When challenged to do so, the Persian said, "I will build a mill of which the whole world will talk". Unfortunately, he never did, but the story shows that windmills were known in Persia in the early seventh century - a fact confirmed by Arab geographers writing somewhat later.
Al-Mas'udi, for example, writing in the 10th century notes that windmills were used in Sijistan to raise water for irrigation, as well as for grinding corn. Still visible today, these mills are scattered through the huge arid expanse between Mashhad and the eastern border of India where, probably, the windmill was invented.
In the 13th century, the Arab writer al-Dimashqi described a typical mill of Sijistan:
When building mills that rotateby thewind, they proceed as follows. They erect a high building, like a minaret, or they take the top of a high mountain or hill or a tower of a castle. They build one building on top of another. The upper structure contains the mill that turns and grinds, the lower one contains a wheel rotated by the enclosed wind. When the lower wheel turns, the mill stone above turns too. Whatever wind may blow, the mill works, though only one stone moves. After they have completed the two structures, as shown in the drawing, they make four slits or embrasures like those in walls, only they are reversed, for the wider part opens outward arid the narrow slit is inside, forming a channel for the air in such a way that the wind penetrates the interior with force, as in the case of the goldsmith's bellows. The wider end is at the entrance and the narrower end on the inside so that it is more suitable for the entry of the wind, which penetrates the mill house from whatever direction the wind may blow - hence the four openings in the structure. If the wind has entered this house through the entrance prepared for it, it finds in its way a reel like that on which weavers wind thread. This device has 12 ribs; these could be diminished to six. Fabric is nailed over them, like the covering of a lantern, only in this case the fabric is divided over the different ribs, so that each one is covered. The fabric has a hump which the airfills and by which the rib is pushed forward. Then the air fills the next one and pushes it on, then it fills the third. The reel then turns, and its rotation moves the mill stone and grinds the corn. Such mills are suitable on high castles and in regions which have no water, but have a lively movement of the air.
Obviously, from this description and the illustration accompanying it, these mills were very simple. A hopper filled with grain rested on a fixed stone which had a hole in the middle to allow the grain to sift onto the surface of the lower, moving, stone. That was in turn attached to a vertical axle to which sails - fabric-covered ribs - were affixed. But at some unknown date, this arrangement was reversed so that the sails were above, the hopper and the millstones were below, and the top millstone was the one that moved.
Windmills like this are still used in some parts of Iran and Afghanistan, and it has been estimated that they generate about 75 horsepower and can grind a ton of wheat every 24 hours.
During the Middle Ages improvements in gearing, and the development of watermills with a horizontal shaft and a vertical wheel, led to an increased power output. These improvements were applied to the windmills when they were introduced to the West and gave them their characteristic form. In the Middle East, windmills were used more extensively than watermills. Although tidal mills were used in Basra, at the head of the Arabian Gulf, there were few fast-running streams elsewhere that would make the construction of watermills practical. Windmills were used, for example, in today's Iraq, as part of the elaborate irrigation systems in that area, and in Egypt, for crushing sugar cane on a large scale. It was from Egypt, in fact, that the Spanish, in the early 16th century, recruited technicians to build windmills in the West Indies.
Today, windmills are not found in the Middle East, except in Iran and Afghanistan. The Mongol conquests of the 13th century destroyed the irrigation systems, and with the decline of the sugar industry in Egypt they fell out of use there as well. The availability of cheap fuels has done the rest, and even in Iran and Afghanistan, today the old windmills have for the most part fallen to ruins.
Fortunately, the principle of the windmill had been brought to Spain and Portugal by the Arabs before the Mongol invasions, and this principle, combined with the technical advances which had previously been made in watermill construction, gave Europe an inexpensive and efficient source of power. The windmills tilted at by Don Quixote, like so much in Spanish culture, had an Arab ancestry.
It is ironic, therefore, that when Karl Twitchell set up his windmill in Jiddah, in the western region of Saudi Arabia, in the 1937's, he was unwittingly bringing the windmill full circle.
