Role of Wind as a Renewable Energy - Wind Energy Systems for Electric Power Generation - page 7

there will be further increase of average rated power in the Megawatt class. At
present units of up to 5 MW are in operation as pilot systems.
1.2.2 Technical Standardization and Local issues
Rapid technical and economical progress has led to the present situation where wind
energy is used on industrial scale and is meanwhile in some countries contributing
a considerable share to national energy consumption. While the profusion of wind
parks has been supported by National legislature in several regions, wind energy is
expected to become competitive in the near future.
The state of the art is being laid down in technical standards. Internationally rele-
vant documents have been published by the International Electrotechnical Commis-
sion (IEC) [IEC61400]. These standards are developed by international groups of
experts and revised in appropriate intervals. They provide guidelines for the design,
establish safety regulations and address environmental issues such as noise emission
and power quality of wind energy systems.
Wind farm installation starts with the assessment of the annual wind regime in
the location selected for erection. Cost of technical equipment and maintenance are
figures in the consequent economic study, leading to a prospect of revenue within,
say, 20 years. The owners of wind parks reflect a wide variety of investor types,
comprising local groups of rural land owners, private companies of limited partner-
ship and institutional investors including the regional utilities themselves. It must be
noted that in some countries with already high degree of wind power utilization the
identification of locations for erecting wind farms and the process of obtaining per-
mission from regional and local bodies has become difficult and time-consuming.
It is almost generally accepted that the utilization of renewable energies is, be-
sides energy saving, the best means to reduce pollution and decelerate climate
change. Arguments denouncing wind system technology as inefficient and too costly
are heard less in recent years. On the other hand, issues of features detrimental to
environment in a broad sense are subjects of public discussion, eventually slowing
down the progress of wind utilization:
- Noise emission
Like any machine WES are sources of noise emission. Aerodynamic noise of the
blades prevails over other components. To minimize noise emission manufactur-
ers have made intensive efforts. To protect humans in the vicinity of WES, noise
limits have been established (see 7.7). Besides noise in the audible frequencies
so-called infra-noise has also been the subject of concern.
- Oscillating shadow
The oscillating shadow of a WES due to the rotating blades optical can also be
a source of optical disturbance for residents (“disco effect”). Depending on local
conditions, minimum distances are required, e.g. 6 times the overall height as
mandated by a court.