Renewable Energy – Solutions for application in the communal energy infrastructure

WIND POWER |
19
1
2
3
4
10
5
6
7
8
floating foundations. The control technology for the
system is located at the bottom of the tower.
Wind turbines for off-grid applications are often not
only smaller but also technically simpler and more robust
than their larger relatives. They require minimum
maintenance. Many of the small installations do not
involve free-standing towers, but rather masts braced
with steel cables. In addition to the classic three-blade
models, there are also various models with a vertical
axis.
11
12
9
13
Construction of a wind turbine:
1) Rotor blade 2) Blade pitch
3) Blade hub 4) Generator brake
5) Gearbox 6) Measuring instruments
7) Nacelle 8) Generator
9) Transformer station 10) Ascent
11) Cable route 12) Tower
13) Foundation
Functional principle and design
Modern wind turbines typically have three rotor blades
made of lightweight and stable fibreglass. The rotor
hub connects the blades and transmits the movement
to the shaft, which leads to the inside of the nacelle situated
at the top of the tower. The nacelle can be rotated
and can, therefore, be aligned according to the wind’s
direction. The rotor blades can also be adjusted, in
order that different wind strengths can be utilised to an
optimum, while damage can be avoided during storms.
The gears translate the slow rotation of the rotor shaft
into the fast movement of the generator.
When planning a wind farm, the first priority is to select
the right location. Wind speed must be measured at
different heights, while the distance and capacity of the
nearest power line must be taken into consideration.
Negative effects on human health have not been proven
to date, but a certain distance from settlements and
houses contributes to their acceptance by the broader
population. In order to protect bird and bat species,
wind farms should also be built outside breeding areas,
bird resting places and nature reserves.
Involving people from the neighbourhood in the wind
farm and its profits – through the purchase of shares –
has also proven successful.
Wind turbines are generally designed to have a service
life of about twenty years. Depending on their condition,
a general overhaul is then due in order to ensure
further years of operation. Alternatively, the turbines
can be dismantled and replaced by a new, more efficient
turbine. This is known as “repowering”. In view
of the fact that the turbines are primarily made of concrete
and steel, the materials can be further recycled in
the usual processes. Recycling processes are currently
being developed for the rotor blades.
In contrast to a photovoltaic system, a wind turbine
supplies alternating current. The wind turbine tower
can be made of steel or concrete. Lattice towers made
of steel require less material than tubular steel towers.
This makes them lighter and cheaper, but also more
complex to assemble. A foundation of steel and concrete
ensures a solid anchoring. There are various special
construction forms for offshore foundations, ranging
from simple piers to gravity-based foundations and