UNEXPLODED ORDNANCE - Wind Energy Network

Sponsors of GEARBOX V DD
Gearbox v
direct drive
it is largely
about money
The choice between using gearboxes
or direct drive systems to convert
the blade rotation of wind turbines
into electricity comes down largely to
money.
Doesn’t it
always
The basics
Choose a gearbox and get proven
technology, that does the job – but suffer
issues of reliability, turbine downtime
and too many technician visits. Pick a
direct drive system and you’ve eliminated
the technically most complicated and
vulnerable part of the turbine - but paid the
penalty for higher capital cost in the drive
train, generator and nacelle.
Return on investment
Other than health and safety, it’s about how
much money the turbine generates over its
life, minus the installed capital cost and the
lifetime operations and maintenance – and
the stakes rise massively offshore. So what
horse do you back
Liquid friction reduction
At Lofrix they know they can improve the
gamble whatever the choice, and their ongoing
work with Huddersfield University
and some major wind turbine operators in
the UK supports that. Lofrix liquid friction
reduction products boast millions of hours
of commercial application and remarkable
results across a wide range of industrial
sectors.
Already in 10% of the UK’s large wind
turbines, Lofrix reduces turbine failures
by lowering friction on bearing and
gear interfaces. Dramatically reducing
component wear, hence lubricant
particulate contamination, it maintains
oil quality, and substantially lessens
unscheduled maintenance - positively
impacting on the life of gearboxes,
hydraulic systems, and bearings.
Jury’s out
The jury is out on the gearbox versus direct
drive case, but treating either system with
Lofrix will considerably lengthen operating
life and increase returns.
Lofrix
www.lofrix.com
Healthy friction
Direct Drive vs Gearbox wind turbines
The competition between direct
drive and gear box wind turbine
technology only seeks to strengthen
both technologies, ensuring improved
reliability, affordability, easier and less
frequent maintenance.
Recent comparisons
Gearbox wind turbines have gone through
a number of significant improvements in
recent years reducing the frequency of
the gearbox failures and adding to their
reputation of being reliable. However they
have come under strong competition
from newer direct drive machines that
are; simpler and more efficient but
questionably more expensive, heavier
and whose longevity is yet to be
proven.
This uses less moving parts, potentially
creating an even more reliable machine,
reducing operating and maintenance
costs over the long term and helping make
electricity from wind more competitive.
Many newer direct drive variants use
permanent magnets which are made
out of rare earth materials such as
Neodymium, whose future supply is
unknown and in recent years have seen
sharp increases in price.
History
Historically, most conventional wind
turbines have a gearbox located
centrally in the drive train, that takes
the low rotation speed shaft - coupled
to the wind driven rotor - and
increases the rotational speed through
the gearbox to a high speed shaft
sometimes as much as a hundred
times to reach the required grid
frequency, helping to reduce the size of
the generator needed in the process.
Industry response
As a response to growing concerns
over the operation and maintenance
costs of larger wind turbines, direct
drive wind turbines have been
developed where the gearbox has
been removed and the rotor shaft
is fed directly to a synchronous
generator.
Developments
The developments in direct drive
technology are forcing traditional gearbox
designs to become cheaper, lighter
and more efficient. This healthy friction
is set to ensure that both wind turbine
technologies help drive up efficiency and
reliability whilst driving down operating
costs within the industry.
ICE Renewables sells a range of tried
and tested medium scale gearbox wind
turbines and will shortly be introducing a
new 100kW direct drive machine to the
market.
Julian Martin
ICE Renewables
www.icerenewables.com
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www.windenergynetwork.co.uk