Energy Technology – Wind Energy
Not every good idea is a new one, as witnessed in the case of renewable energy technologies. Sailboats and windmills have had a long tradition of utilizing wind power. But what happens when the wind stops blowing?
Currents in the gaseous layer surrounding our planet-that is, the air—are perceived as wind. As a fundamental principle, air moves from high-pressure zones to areas where the pressure is lower.
These pressure gradients, in turn, are caused by temperature differences—which result from variations from place to place in the amount of the sun’s radiation reaching the surface. In other words: wind energy is solar energy. It is one of the oldest forms of energy used by humans.
The propeller principle
What distinguishes a modern wind turbine from a traditional windmill? At a glance there are two obvious differences: a wind turbine is significantly taller, and it has only three blades or less. The height of modern wind power systems is easy to explain, since average wind strength steadily increases with altitude. The shape of the blades, meanwhile, can be explained through comparison with airplane propellers.
Since propellers are used to move the plane forward, they are constructed for the efficient conversion of power into movement. A wind turbine simply reverses this process: the wind pushes on the propeller, and-since it cannot fly away—it is set in motion. Using wind energy The wind’s strength can vary from place to place and time to
time.
Because of this, the successful use of wind power requires either the addition of backup energy sources—to make up for power shortfalls during periods of low wind—or effective power-storage technology. Storage options include large, nearly friction-free flywheels and pump-based storage systems. With the latter, for in- stance, part of the generated wind power is used to pump water up to a higher level, where it is stored in a tank or reservoir.
In times of insufficient wind, the water is re- leased to flow downhill, turning a turbine and generating electricity.
OFFSHORE WIND PARKS
During the past 15 years, some 18,000 wind turbines have been installed in Germany, most of them on the north German plains. Unfortunately, however, most of the country’s favorable inland locations have been utilized.
Further expansion potential is offered by offshore wind parks in the North and Baltic Seas. Because the wind is significantly stronger there and blows consistently almost all year, these off- shore locations promise a substantially more efficient “wind harvest.”
Although questions of conservation and impact on wildlife remain problematic, these must be weighed against the potential environmental damage caused by coal-fired or nuclear power plants with similar levels of energy output. Plans for further development in the US’ and Canada are already in the works.