UNEXPLODED ORDNANCE - Wind Energy Network

Sponsors of GEARBOX V DD
Wind
Turbines
Go Back to
Basics
Renewable energy generation
simplifies its technology, as wind
installations begin to reject gearboxes
in favour of the good-old direct drive
turbines, states a new report by
energy experts GlobalData.
Advantages and drawbacks
The new report discusses the advantages
and problems associated with advanced
technology in the wind power industry.
A gearbox allows the generator’s
internal shaft to spin 50–250 times for
each rotation of the turbine blades, and
provides advantages including low noise
levels and high efficiency. However,
drawbacks include a high level of
maintenance and low reliability.
Expectations
The global wind turbine gearbox market
is dominated by Winergy and China High
Speed Transmission Equipment, who
combined accounted for a 52% share of
global wind turbine gearbox production
in 2011. The total amount of gearbox
units installed in the global wind market
increased from 9,075 in 2006 to 21,192
in 2011 at a Compound Annual Growth
Rate (CAGR) of 19%, but an increase
in average turbine size and growing
prominence of direct drive systems is
expected to result in a decline in turbine
installations with gearboxes during the
forecast period, from present levels to
12,662 by 2020.
Direct drive technology
In contrast, direct drive technology
does not use a gearbox, offering slow
movement of all the parts of the wind
turbine systems and therefore reduced
wear and tear of the system and superior
reliability. Direct drive turbines have been
in the wind power market for a long time,
but have gained increasing popularity
in recent years due to the low reliability
and high refurbishment costs of gearbox
components.
Enercon GmbH of Germany and Xinjiang
GoldWind Science and Technology
Company Limited of China are major
companies manufacturing direct drive
turbines, and both are perfecting their
industry offerings. Enercon’s annular
multiple poles generator reduces the
number of moving components used,
while Xinjiang’s GoldWind uses permanent
magnet direct drive technology.
This increases reliability substantially, and
reduces maintenance costs and time,
increasing production time and therefore
providing improved returns. However, the
cost of permanent magnet generators
depends upon the cost of rare earth
materials such as Neodymium.
The share of global wind turbine
installations accounted for by direct drive
turbines has grown from around 18% in
2006 to 22% in 2011, and is expected
to increase to 29% by 2020, with wind
turbine manufacturers such as Siemens
and GE shifting from gearbox turbines to
permanent magnet direct drive turbines.
GlobalData
www.globaldata.com
46
www.windenergynetwork.co.uk