Wind Energy
Early Uses of Wind Energy
The earliest known designs of wind powered systems appeared in Persia around 500AD. A vertical axis windmill turning a vertical shaft giving direct drive onto a millstone used for grinding grain. The same technology was quickly adapted for pumping water to irrigate crops and provide for thirsty livestock.
Inefficiencies in Early Designs
This early design of windmill was widely adopted but suffers from a simple design flaw that dramatically reduces its efficiency. This design of vertical windmill is only driven by the wind that blows onto one half of the sails, the other half must be shielded from the wind otherwise there would be no rotation at all.
Horizontal Axis Windmills
By 1270AD the first windmills were appearing in Europe and favored a new horizontal axis design. It's the traditional design we all expect when we see a windmill and is illustrated in the photo above. Although much more efficient because the wind now drives all of the sails, the horizontal driven shaft now required a system of cogs and gears to convert the horizontal rotation into vertical rotation to drive grindstones and water pumps.
Perfecting Windmill Design
Over the next 500 years the design of windmills was slowly altered and perfected until the traditional windmill building employed all of the aerodynamic features that we see in modern wind turbine design.
Decline of Traditional Windmills
The use of large tower type windmill buildings declined during the 19th century as the world made way for the very latest technology... Steam Engines! Although certainly a technological miracle and the power house of the industrial revolution there's no doubt that the introduction of the steam engine, which derived energy from coal a non-renewable source of energy, took mankind on a path that has influenced and altered the environment in which we live in today.
Modern Wind Turbines and Windmills
Despite the decline of wind powered mills for grain processing the windmill has remained a permanent feature of landscapes all over the world. Compact, robust steel windmills are still in use today pumping water in remote areas to irrigate crops and provide for livestock.
The most noticeable modern use of wind energy is of course the wind turbine. At their very basic these are simply a windmill geared to turn a drive shaft that spins the input shaft of an electrical generator producing electricity from a wholly renewable source. They appear in various guises all over the world, huge wind turbines concentrated in wind energy farms for industrial level production down to small lightweight units designed to fit on marine craft and used for charging batteries and powering low power electrical devices.
Despite their excellent green credentials wind turbines are not without their problems and controversies. First of all, and most obviously, wind turbines only work in places that are windy!! Secondly the rotating blades, shafts and gears are far from silent and the low level noise and vibration is a source of discomfort to those living near large wind turbines.
Future of Wind Turbines
None the less, the use of wind energy is here to stay. It's hard to say just how great the spread of large wind turbine farms will be in the future, but one thing is certain small ones are cheap enough to buy and DIY wind turbines are easy enough to make such that it may become a common site in every windy back garden!
