Large Scale Windmills
Wind turbines come in all sizes from small windmills designed to power fountains and garden lights to larger home wind turbines up to giant turbines whose blade area covers the space of 2 soccer fields. The largest turbines are usually grouped into wind farms and more and more often are used in offshore installations, especially in Europe where wind power generation is a larger part of total power generation than it is anywhere else in the world. Germany and Spain lead the world in percentage of wind power to conventional power but China, the US, Canada and France are experiencing very rapid growth which makes them major players in wind power also.The largest wind turbine in the world is currently the REPower 5M. According to RE Power’s web site at http://www.repower5m.com/index_flash_uk.htm the 5M has a rated output of 5 megawatts, a rotor diameter of 126 meters, and a hub height of around 90 meters at sea and 120 meters on land. This giant wind turbine is being used to power several wind farm projects including a demonstration project off the coast of Scotland.
To reduce weight, the three rotor blades are made from an innovative glass/carbon fiber hybrid fabric that is held together by synthetic resins. To further reduce weight, the 5M’s die cast rotor shaft is hollow.
Another innovation is a gearbox that may be repaired or removed without having to take apart the rotor. This could mean a significant saving in repair cost and downtime. To deal with one of the most persistent problems with any wind turbine system, wind turbulence, the nacelle, which also holds the inverter and transformer for the 5M, has 8 geared motors for tracking the wind. To keep the nacelle facing into the wind, the 5M is equipped with eight hydraulic brake calipers. As a backup, there are also electromagnetic disc brakes. This greatly minimizes problems with turbulence-related damage.
The 5M has many options: a helicopter platform for offshore sites and elevators to lift goods and workers to the top of the tower. The towers themselves may be made from tubular steel, concrete or a hybrid of both steel and concrete. Every tower is equipped with communication capacity and, of course, cables for energy transmission.
Safety is a priority with the 5M both for workers and the installation itself. Automatic high capacity fire extinguishers are programmed to operate when fire is detected and lightning protection - a must in the stormy offshore environment - is built in. All safety systems have backups built into the design. This means that the 5M has optimum power production with few offline instances.
No doubt, other giant wind turbines will come on line within the near future, especially since several companies, including Siemens and GE have announced wind power projects. At http://www.powergeneration.siemens.com/press/press-releases/search.htm Siemens has information about projects they’ve recently been awarded in Denmark and Spain.
As technology improves wind turbine design and technology, and more countries turn to wind to power their homes and factories, giant wind turbines will continue to play a big part in the wind power market. Siting them offshore ameliorates the problems of aesthetics, especially if they are out of sight of land.
Environmental concerns, while still a factor, are not as relevant. While the cables emit electromagnetic waves which are a problem for sharks and rays, technology has yielded designs that help to overcome this. The impact on the seabed is taken into consideration and every effort is made to make it as minimal as possible. Further innovations will emerge as designers find new ways to make the giant wind turbines as environmentally friendly as possible. When everything is taken into consideration, including how much pollution and environmental damage the wind farms prevent by replacing conventional power generating technologies such as coal and gas, it seems apparent that giant wind turbines are a reasonable alternative energy source.
